Learning Package 3: Building Adaptation: Technology and

Document technical information

Format docx
Size 1.9 MB
First found May 22, 2018

Document content analysis

Category Also themed
Language
English
Type
not defined
Concepts
no text concepts found

Persons

Organizations

Places

Transcript

Building Adaptation and
Conservation
By Tony Burke – licensed under the Creative Commons Attribution –
Non-Commercial – Share Alike License
http://creativecommons.org/licenses/by-nc-sa/2.5/
OPEN RESOURCES FOR
BUILT ENVIRONMENT EDUCATION
(ORBEE)
Module Title:
BUILDING ADAPTATION AND CONSERVATION
Author:
TONY BURKE, University of Westminster
Title of this learning package:
Learning Package 3: Building Adaptation: Technology and Practice
Titles of associated learning packages (not included here):
Learning Package 1: Principles of Building Adaptation and Conservation
Learning Package 2: Building Conservation Practice
Module: BUILDING ADAPTATION AND CONSERVATION
LEARNING PACKAGE 3: Building Adaptation: Technology and Practice
Section 1
Introduction to the learning package (allow up to 2 hours)
Learning Outcomes
On completion of all work associated with this learning package you should be able to:
 Recognise the technical challenges associated with adapting and upgrading historic buildings, and apply
the principles of conservation to the problems associated with structure and materials.
 Assess the challenges associated with upgrading the thermal comfort and energy efficiency of historic
buildings.
 Explain the difficulties of accommodating modern mechanical and electrical services and fire protection
measures in historic buildings, and identify techniques associated with such work.
 Propose measures which satisfy the needs of disabled people gaining access to historic buildings whilst
ensuring that the character of buildings is not adversely affected.
 Discuss the factors which need to be considered in the management of projects involving works to historic
buildings.
Introduction to this learning package
Whenever adaptation works are carried out to existing buildings many of the challenges faced are very similar
to those involved in the construction of new buildings. The proposals have to be appropriately designed to
take into account the requirements of the new use of the building, materials have to be selected, and the
works have to be managed. However, it is important to recognise that works to existing buildings are
constrained by the fact that we are always operating within parameters imposed by the presence of an
existing structure. When the building is a historic building then further constraints are imposed by the need to
comply with the conservation principles.
This package is broken down into the following sections:
Section 1: Introduction to the learning package
Section 2: Materials and structural aspects
Section 3: Thermal comfort
Section 4: Mechanical & electrical services and fire protection
Section 5: Disabled access to historic buildings
Section 6: Project management issues
Section 6: Case Study
Before commencing Section 2, view this introductory presentation.
Introductory presentation (screencast)
Familiarise yourself with the overall content of the package and make sure you understand the learning
outcomes. Browse through all sections of the package to get an overview of the structure.
Section 2
Materials and structural aspects (allow up to 9 hours)
INTRODUCTION
This section provides an overview of some of the factors to be considered in works to existing buildings with
regard to:
o The structure of the building
o The selection and use of building materials
STRUCTURAL ASPECTS OF OLDER BUILDINGS
There is a fundamental difference between many historic buildings and their modern counterparts which
relates to the design of building structures. Modern structures tend to be designed in order to achieve the
maximum structural capability from the minimum amount of material, and a vast number of structural
calculations are used in the design process. In many older buildings structural calculations were never even
considered in the design. Often, in the construction of old buildings, the builders erred on the safe side in the
use of materials and if it was insufficient then the building might collapse and more material would be used
next time. This is sometimes referred to as the “PPI Rule” i.e.“put plenty in”. In other words, it was often a
process of trial and error. Over time, builders gained an instinctive knowledge about the amount of materials
required for given structural conditions.
CIRIA Report 111 (1994) refers to another important difference: the absence of a discrete structure in many
old buildings. The elements of the building combine to prevent collapse, even though it is not always clear
where the load paths in the building actually are. It is important to be aware of the potential weaknesses of
historic buildings as compared to modern ones. Older buildings may be just as strong, or even stronger than
modern buildings but their stability can be made marginal by such things as inadequate foundations or poorly
constructed walls. Many old buildings appear to defy modern structural calculations yet their continued
existence is evidence of their integrity. Distortion of the structure may have occurred, often with aesthetically
pleasing results, but there may be no serious structural problems visible. Often the building may simply have
reached a state of structural equilibrium. The critical point to realise is that even a relatively minor alteration
to the structure can upset this equilibrium, leading to potentially catastrophic consequences.
Constraints imposed by the need to comply with conservation principles
Work to historic buildings is generally required to comply with the principle of ‘minimum intervention’. In
other words, the works should not extend beyond that which is required to prolong the life of the building. The
degree to which the principle of minimum intervention has to be complied with will often depend on the
importance of the building, its current condition, and the attitudes adopted by the planning authority and
conservation professionals. Nevertheless, with any building which is afforded some statutory protection, there
is likely to be significant constraints on the extent to which the original structure and fabric of the building can
be altered. Specific examples of the type of constraints include:




The need to maintain the integrity of the building by retaining as much of the original fabric as possible.
The need to match existing materials and methods of construction, thus helping to preserve the
appearance of the building and its integrity. Modern substitute materials should only be used when their
use will permit the retention of more of the existing fabric or when there is an inherent problem with the
original material.
The need to ensure that any new materials used are compatible with the original and will not result in
adverse effects.
The need to avoid falsification by ensuring that replacement parts blend harmoniously with the original
parts, but at the same time are distinguishable from the original.
The general rule in carrying out works to historic buildings is that low-key repairs and reinstatements are
preferable to wholesale reconstruction. Clearly this approach results in significant conflicts, especially when
the expectations of the end-user of the building may be based on standards which would normally apply to
new buildings.
The need for assessment of existing building
Regardless of the nature of the existing building or the extent of the required works it is imperative that a
thorough assessment of the existing building is carried out prior to any works taking place.
If the building has some historic value then it will be necessary to undertake detailed recording of the building,
including documentary research, photographic survey and measured survey. This should provide a clear
understanding of the historical and architectural significance of the building. (See Learning Package 2)
In addition, for the design of the works to the existing building, it will be necessary to carry out the following
procedures:
 A survey of the structure of the building – involving a detailed appraisal of the loadbearing elements of the
building.
 An assessment of the condition of the existing building to identify specific defects or problems which need
to be rectified.
 An assessment of the implications of the proposed works for the existing structure, to identify how any
alterations will affect the structure.
Sources of problems
The structural and materials problems which need to be addressed in carrying out adaptation works to existing
buildings may be derived from various sources. The following list identifies some of the main potential sources,
but they are not mutually exclusive, i.e. there may be overlap between the sources.





Inherent defects: Some existing buildings were poorly designed or constructed, and therefore incorporate
inherent defects which may need to be addressed in carrying out works to the building. Examples include:
o Georgian terraced buildings where the party walls of the properties are not properly bonded to the
external walls, resulting in a lack of lateral restraint.
o Poorly designed weathering details resulting in inadequate shedding of water and possible moisture
penetration.
Failure of building elements: The building may have actually failed as a result of some external factor
acting on the building. For example:
o Soil movement resulting in subsidence and structural cracking.
o Thermal movement, leading to cracking of the structure or fabric.
Neglect or lack of maintenance: Failure to carry out day-to-day repairs and cyclical maintenance inevitably
leads to more significant problems. For example:
o Failure to clear gutters may result in water build up and eventual penetration
o Failure to repoint masonry may lead to moisture penetration and/or decay of walls
o Lack of decoration may lead to decay of external timber components
Earlier repairs and alterations to the building: these may have had significant implications for the structure
and fabric which were not necessarily recognised at the time. For example:
o New openings may have been formed which affected load distributions in the building
o Repointing may have been carried out using inappropriate mortar.
o Replacement of roof coverings may have resulted in changes in loadings
Problems likely to arise from the adaptation of the building: Many of the problems which have to be
addressed will not be pre-existing problems but will be derived from the alteration works which are to be
carried out to the building, or the new use to which the building will be put. For example:
o Removal of walls to create larger spaces
o Increased floor loadings as a result of new uses.
SPECIFIC PROBLEMS
There now follows a review of some of the typical problems encountered when carrying out adaptation works
to existing buildings. It is important to stress that this is by no means an exhaustive list. It tends to concentrate
on some of the more common problems found with traditional buildings. Clearly there are countless other
potential problems when dealing with unusual buildings or particular types of adaptations.
For each of the problems covered there will be a brief overview of the nature of the problem. Common
solutions to the problems are then identified.
Dampness and rot
Nature of the problem
One of the most common problems encountered in older buildings is dampness and the resultant damage that
can arise. Dampness can arise in several different ways. For example:
o Absence, failure or bridging of damp proof courses and membranes
o Water penetration due to lack of maintenance or poor detailing
o Condensation due to lack of ventilation
o Plumbing leaks
Once dampness is present it can give rise to specific problems, the most notable of which is timber decay as a
result of rot. The term ‘rot’ is generally used to refer to fungal decay, i.e. the decay of timber as a result of the
action of fungi. A fungus can develop on timber when microscopic airborne spores come into contact with
timber that is damp.
Fungal decay is normally classed as either wet rot or dry rot. Wet rot tends to occur in timber with high levels
of dampness. Typically it is found in external timber such as window and door frames where poor maintenance
has resulted in inadequate protection to the timber.
Much more serious problems are associated with dry rot, which typically
occurs in timber with a moisture content of 20% or above. The
microscopic spores from which the fungus is derived are airborne and in
most environments are omnipresent. When the spores come into contact
with timber and the environmental conditions are appropriate, they will
germinate. The conditions required are related to the moisture content
of the timber, the ambient air temperature, and the level of ventilation.
Typically such conditions exist within voids in buildings, such as roof
spaces, floor voids, and behind panelling. Once the spores germinate,
very thin strands known as hyphae are formed, which in turn combine to
form thread-like mycelia. These feed on the timber by breaking down the
cellulose in it and leaving fragile shell which is incapable of bearing any
significant load. As the fungus grows a ‘fruiting body’ may develop (e.g.
like a mushroom) and this in turn produces further spores into the air
and so the cycle continues.
Dry rot can have catastrophic consequences for buildings if left
unchecked. If significant decay occurs in structural timber (e.g. roof or
floor timbers) then failure of the building can result. Even in nonstructural timber the implications for historic buildings can be disastrous,
particularly if important features such as panelling become affected.
Dry Rot 6 : taken from http://www.flickr.com/photos/lesdray/5137732876/
Author: leslie.dray
http://creativecommons.org/licenses/bync/2.0/deed.en
Treatment
The priority in tackling timber decay is to remove the source of the dampness which is giving rise to the
problem in the first place. This may mean dealing with a faulty damp proof course or correcting a fault which is
causing moisture penetration. The affected timber must then be allowed to dry out completely.
Once the conditions giving rise to the decay have been tackled it will be necessary to deal with the resultant
damage. This generally means cutting out all affected timber and replacing with new timber. Often, the advice
provided is to cut out significant areas of timber beyond the zone immediately affected by the rot. In addition,
it is usually recommended that a fungicidal spray is applied to affected areas, including the adjoining walls and
plaster.
Note: Typically when a building is affected by dampness and dry rot the advice of specialist companies is
sought. It is important that such advice is treated with caution. Often the specialist will advise that extensive
stripping out of affected areas is required. This can involve the removal of large amounts of timber and plaster,
and consequently a good deal of historic fabric will be lost. In many cases it will only be necessary to remove
the source of the dampness and cut out only those sections of the fabric which have been affected. In historic
buildings any unnecessary loss of fabric must be avoided.
Insect infestation
The nature of the problem
Wood-boring insects such as beetles may lay eggs on the
surface of timber, usually in splits or knots. Timber already
softened by decay or dampness may be more attractive to
some insects, and low levels of ventilation can also help. The
eggs hatch and the larvae bore their way into the wood
creating a network of tunnels within the body of the wood
(hence the expression ‘woodworm’). After several years the
larvae pupate and emerge from the wood via flight holes as
adult insects. The network of tunnels can reduce the cross
sectional area of the timber and thereby weaken it.
Woodworm : taken from http://www.flickr.com/photos/lwr/2180527888/
Author: Leo Reynolds
http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en
Treatment
If there are underlying problems relating to dampness or lack of ventilation, then obviously these must be
addressed. The extent of the damage caused to the timber needs to be carefully assessed. If the infestation
has been going on unchecked for several years then the damage may be extensive. It may be necessary to cut
out affected timber and replace with new timber. If the outbreak is fairly fresh it may be sufficient to treat
affected timber by spraying with insecticide. The difficulty with this technique it is that it can be difficult to
determine how effective the treatment is, so ongoing monitoring will be necessary.
Slenderness of solid walls and inadequate lateral restraint.
Nature of the problem
Traditional buildings are typically constructed with loadbearing walls, usually of brickwork and/or stone. Many
loadbearing walled buildings dating from the Georgian and Victorian periods (particularly in the London area)
were constructed in accordance with established rules as to the thickness and consequent slenderness such as
those derived from the London Building Acts of 1884.
Obviously if walls were built in accordance with established rules, and loadings were within reasonable limits,
then there is unlikely to be a major problem with slenderness. However, various situations can give rise to
problems:
 Walls which do not have floors bearing on to them may not have adequate lateral restraint. For example,
if floor joists span in the direction front to rear, then the flank walls will not have any joists bearing on to
them and will not therefore receive any significant lateral restraint.
 Partition walls may not be bonded to external walls, so no lateral restraint will be provided by the
partition walls.
 The feet of the rafters at roof level may be spreading under roof loads, thereby pushing out the walls at
the top.
Problems may manifest themselves in various ways:
 Bulging walls
 Walls out of plumb
 Walls inclining outwards at the top
Possible solutions
The traditional method of dealing with a lack of lateral restraint to walls was to provide through ties. An iron
bar was typically threaded through the floor void and terminated externally with a pattress plate. This
provided a means of literally pulling the walls inwards to counteract the
outward movement. Other techniques involve the use of lateral restrain
straps fixed to floor joists and to the external walls, or reinforced concrete
elbow ties built into the walls at corners. In addition there are various
modern techniques such as the Helifix Bow Tie. For further information see
http://www.helifix.co.uk/products/remedial_products/bt.aspx
Formation of new openings in walls
The nature of the problem
It is often deemed necessary in the adaptation of existing buildings to form
Window with Pattress Plates : taken from new openings in existing walls. This can be required in order to create new
http://www.flickr.com/photos/el_ramon/4
167999192/
door openings, or simply to create larger internal spaces by the removal of
Author: Timoty Valentine
dividing walls. If the wall in question is providing structural support to floors
http://creativecommons.org/licenses/bync-sa/2.0/deed.en
or roof structures then clearly any significant removal of loadbearing
masonry could have major implications for the structural integrity of the building. At the very least, the loads
from floor and roof structures may become concentrated along new lines in the building which may not have
been designed to carry such loads. At worst, the entire support for the floor or roof structure could be lost,
resulting in structural collapse.
Suggested approach
A detailed assessment of the nature of the loads and the load paths involved must be undertaken.
Comprehensive temporary support must be provided to the loads which the wall supports. Once the
temporary support is in place the required new opening can be carefully formed. A replacement permanent
support such as a new beam must then be inserted, ensuring that the beam has adequate bearings such as
padstones or piers. Once the new beam is capable of sustaining loads the temporary support can be removed
and the new opening made good as required.
Decay at ends of timber beams or joists
The nature of the problem
As described above, decay in timber can result from fungi and from insect infestation. In traditional buildings it
is common for beams, joists and trusses to be built directly into the walls which support them. Typically these
walls would be solid external walls. Consequently, any dampness present in the wall may spread to the timber
and create the conditions necessary for decay mechanisms.
If decay occurs in timber at the point at which it bears on to its supporting structure, then clearly the potential
consequences are very serious.
An early warning sign that decay is occurring at the ends of floor joists is a ‘spongy’ feel to the floor structure.
Possible solutions
Various traditional solutions are available, and in addition some modern techniques have been effectively
used.
Examples of solutions include:
 Cutting out decayed sections of timber and replacing with joist hangers.
 Cutting out decayed sections of timber and fixing steel sections in replacement.
 Cutting out decayed sections of timber and splicing in new sections of timber or fixing additional sections
of timber.
 Resin based repairs – specialist techniques involving the use of epoxy resin usually in conjunction with
reinforcing bars.
Excessive notching of joists and beams
Nature of the problem
It is common for older buildings to have had services installed in the floor voids retrospectively, including
heating pipework, electrical cables and telecommunications. Invariably, floor joists and beams will have been
notched to accommodate the services. If the notches are excessive, or if little thought has been given to their
location, then there is a risk of deflection in the joists or beams.
Solution
Hardwood wedges can be used to fill the notches. This does not cure deflection which has already taken place,
but should reduce the risk of further deflection.
Splits
Nature of the problem
Splits and shakes are common in old timber. Often they have no real structural significance. However, where
they occur close to supports there is a danger of shear failure .
Solution
One way of dealing with the problem is to drill and install bolts through the timber section. An alternative
might be to install straps around the entire timber section.
Strengthening timber floors
Nature of the problem
Many adaptation schemes will result in higher loads being imposed on floors. It may be considered necessary
to strengthen the existing floor structure to improve its loadbearing capacity.
Solutions
Various techniques are available, including:
o Increasing the depth of the timber by adding timber laminations with epoxy adhesive.
o Increasing the depth of the timber by adding a single section of timber bonded to the existing with
dowels and epoxy resin.
o Flitching a beam – cutting a slot and inserting a steel plate which is then bolted through.
o Cutting a slot, inserting steel reinforcing bars, and pouring epoxy resin to bond.
Repair of roof truss ends
Nature of the problem
The ends of roof trusses are particularly vulnerable to decay because there is a high risk of rainwater
penetration in the vicinity. This can be due to problems with the roof covering or the guttering. As with floor
joists and beams, this could ultimately result in structural collapse.
Solutions
Techniques are similar to those for floor joists and beams and include:
 Splicing on new timber sections
 Fixing gusset plates
 Resin based repairs
OTHER CONSIDERATIONS
In addition to the various possible problems outlined above there are many other considerations which need
to be taken into account. For example:
Foundations
Are existing foundations adequate? Will the adaptations result in significantly increased loads on foundations?
Will existing foundations require underpinning or some other form of strengthening or upgrading, such as
mini-piles?
External joinery
What is the condition of existing windows, doors, fascias, soffits and other joinery? To what extent does the
existing joinery contribute to the character of the building? Will it be possible to refurbish existing joinery or
will some replacement be necessary? If it is necessary to replace joinery, will it be necessary to provide exact
matches to originals?
External surfaces
What is the condition of external wall surfaces? Will masonry cleaning be necessary, and if so what techniques
are appropriate? Some techniques may result in potential damage to the masonry, so very careful selection of
a suitable technique is required.
Ironwork
What is the condition of existing ironwork such as balconies, railings, hoppers, guttering and downpipes?
Corrosion is often a problem if the ironwork has not been adequately maintained. Replacement may be
necessary in some situations, but materials should be matched to the original wherever possible. Plastic
replacements should be avoided.
Partial demolition and façade retention
The partial demolition of an existing historic building behind a retained façade is a contentious issue in
conservation terms. It is often seen as a compromise - retaining a streetscape whilst allowing the development
of a new building behind the façade.
In strict conservation terms facadism as it is known is frowned upon, because the integrity of a historic building
is derived from its entirety. Facadism is said to reduce a building to stage scenery.
Internal alterations
Internal alterations proposed as part of an adaptation scheme require very careful consideration. Typical
alterations might include:
 Removal of chimney breasts
 Insertion of new partitions to divide up space
 Insertion of new stairwells
All these alterations may have significant impact both in structural terms and in terms of the character of the
building.
ECONOMIC CONSIDERATIONS
Whenever choices have to be made about alternative repair techniques or materials cost will always be a
factor to consider. The relative cost of different materials must be balanced against the anticipated
performance in use of those materials. The same principle will apply to some extent in conservation work but
the economic argument does not carry as much weight as it might in general building work. The simple fact is
that the conservation of historic buildings may demand more expensive materials and techniques, but the
additional costs must be met if the country’s built heritage is to be maintained for future generations.
Activity
Try to answer the following questions without looking back at the notes above:
1.
What do you understand by the term “structural equilibrium”? What might the significance of this
term be in respect of a building such as this:
2.
Give some examples of how neglect or lack of day-to-day maintenance can lead to much more
significant problems.
3.
Assume you are involved in a project involving a listed building. Dry rot has been identified in the
building and a specialist has been consulted. The specialist has recommended that that sections of
timber should be cut out at least a metre beyond the affected area and that all plaster to the affected
room should be removed. Why should you treat this advice with some caution?
4.
You are carrying out a survey of an old building and you lift the floorboards at first floor level. The
floor joists have numerous notches cut in the upper and lower sections, and there are countless holes
drilled through the joists at various points along their length. What would you suggest is the reason
for these holes and notches, what potential problems can they cause, and what remedial measures
would you recommend?
5.
What do you undertand by the term ‘flitch beam’ and when would you consider using one in the
adaptation of an existing building?
Check your answers by viewing this short presentation (screencast)
Section 3
Thermal comfort
(allow up to 6 hours)
INTRODUCTION
The previous section dealt with the technical challenges associated with the structure and materials of historic
buildings. Clearly those challenges are a priority in order to preserve the fabric of a historic building. However,
if old buildings are to be successfully adapted for modern use there will naturally be an expectation that the
environment created in the new building is thermally comfortable and capable of supporting modern living.
This section provides an overview of the issues associated with the thermal upgrading of a historic building.
ENERGY EFFICIENCY
Building Regulations
Under normal circumstances when building works are carried out to existing buildings the Building Regulations
will require that Part L (Conservation of fuel and power) is complied with. However, the Building Regulations
make specific provision for historic buildings. Regulation 9 of the Building Regulations provides for exempt
buildings and work and effectively states that the energy efficiency requirements do not apply to listed
buildings or buildings in conservation areas if compliance would unacceptably alter their character or
appearance.
Further guidance is given in Approved Documents L1B and L2B, which recommend that “the aim should be to
improve energy efficiency where and to the extent that it is practically possible”. The guidance indicates that
works should not “prejudice the character of the host building or increase the risk of long term deterioration
to the building fabric or fittings”.
Further specific guidance is available from English Heritage:
English Heritage (2010) Energy Efficiency and Historic Buildings
http://www.english-heritage.org.uk/publications/energy-efficiency-historic-buildings-partl/
English Heritage (2004) Building Regulations and Historic Buildings
http://www.english-heritage.org.uk/publications/building-regulations-and-historic-buildings-balancing-theneeds/
The subsequent notes in this paper will be based on the English Heritage guidance.
General approach
The English Heritage guidance suggests that, when seeking to improve the energy efficiency of a historic
building, the following broad principles should be observed:
 Do not undertake unnecessary changes
 Do not cause the physical or visual loss of important features
 Avoid changes which increase the risk of damage elsewhere in the structure.
Fundamental risks
Works to improve the energy efficiency of existing buildings typically involve the upgrading the insulation and
making changes to the fabric to reduce heat loss. However, with historic buildings it is essential that
consideration is given to the risks associated with such works:
 Thermal bridging can result if insulation is not upgraded uniformly. This can be a particular problem at
junctions between different elements of construction.
 Condensation risks can increase if air circulation is significantly reduced, particularly within voids in a
structure.
 The ‘breathability’ of the structure may be adversely affected by the desire to seal air gaps with the
intention of reducing heat loss.
Windows
When upgrading an existing building one of the most common ways of improving its energy efficiency is to
replace the old windows with modern, double-glazed, thermally efficient windows. However, with historic
buildings the fenestration is often a key feature in the character and appearance of the building. The English
Heritage guidance indicates that over 90% of appeals against the refusal of listed building consent for replacing
traditional single glazed sash windows with double glazed PVCu windows have been dismissed. The
replacement of original windows is generally unacceptable for one of the following reasons:
 The window frames form an important part of the appearance of the building, in terms of the materials
used, the style of the frames, the dimensions of the glazing bars, and the relationship between the
proportions of the windows and those of the elevation as a whole.
 The position of the window frames within the depth of the wall contribute to the appearance and
character. If recesses are altered the character can be adversely affected.
 Replacement windows invariably have frame styles and dimensions which differ to the original, and
provide a poor imitation.
 If original glass survives this will often have much greater character than modern replacements, due to the
historic production processes.
For the above reasons English Heritage will encourage the retention of original windows wherever possible
and will suggest that the efficiency of windows be upgraded in other ways:
 Draughtproofing, e.g. by fitting tubes, fins or brushes to the existing frames.
 Secondary glazing – by installing independent glazed panels internally within the thickness of the wall.
 Repairing internal or external shutters, and draughtproofing them.
 Using insulated curtains or blinds.
Having said that, some manufacturers do claim to be able to produce replacement double glazed windows in
PVCu which are indistinguishable from the original. For example: Masterframe www.masterframe.co.uk
Doors
As with windows, the external doors on a historic building make an important contribution to its overall
character. There will normally be an expectation that doors will be retained, and thermal efficiency can be
upgraded by draughtproofing. One further possibility, if space permits, is the installation of an internal draught
lobby.
Walls
Historic buildings have walls of many different types, but most have one thing in common – they are porous,
and therefore allow moisture to pass through them. This is quite different to modern buildings which, by and
large are designed to protect the interior of the building from moisture. Works are often carried out to walls of
existing buildings with the objective of preventing moisture ingress, or sealing the walls to prevent
unnecessary heat loss. Typical works include:
 Repointing in hard cement mortar.
 Applying an external render coat.
 Applying impervious coatings to wall surfaces.
All these can impede the ability of a wall to transpire moisture and vapour, and thereby can have potentially
disastrous long term implications for the wall.
It can be very difficult to upgrade thermal insulation levels to the external walls of a historic building. The
normal approach would be to introduce additional layers of thermal insulation. On many housing
rehabilitation schemes this has been achieved through the application of a layer of insulating material to the
outer face of the wall, and then to render over the insulation. Clearly, this completely changes the appearance
of the building and will be unacceptable on most historic buildings. The exception to this might be where the
external finish to the building comprises some form of cladding (such as tile hanging or weatherboarding) and
it is necessary to re-clad the building because of defects in the cladding itself or in the supporting structure. In
such circumstances it may be possible to introduce some new insulation beneath the cladding.
Another common method of improving the insulation values of walls is to introduce new thermal insulation
internally, usually by some form of dry-lining. Whilst this may be an option in some cases, it is likely that one or
more of the following factors will make it unsuitable in a historic building:
 Internal finishes such as panelling or decorative plasterwork may have to be retained.


The impact on joinery such as skirting boards, dado rails, architraves, door linings, and picture rails may be
unacceptable.
Dimensional changes may be unacceptable at window and door openings.
Floors
The possibility of introducing thermal insulation to the ground floor depends heavily on the type of floor
involved.
Generally speaking, with solid floors, the opportunity for adding insulation is severely restricted:
 Invariably it will require the breaking up of the existing floor, which will certainly involve the loss of
historic fabric.
 With some important floor finishes such as tiles, stone, brick, etc. the potential loss caused by lifting an
existing floor would be unacceptable.
 Increases in floor levels have implications at door thresholds and at the base of stairs.
With suspended timber floors it is generally easier to introduce insulation by lifting floorboards and fixing
insulation panels between joists. However, great care is necessary to avoid damage to the floorboards being
lifted, and indeed to the joists.
Roofs
In many traditional buildings the pitched roof provides perhaps the best opportunity of improving energy
efficiency. Insulating material can be laid in the roofspace between joists in the usual manner. Care must be
taken to ensure that airflow through the roofspace is not restricted, thereby increasing the risk of
condensation.
Activity
Imagine a Victorian House located in a suburb of London. The property comprises a basement level and three
storeys. The house is constructed of solid brick walls which are rendered externally. The floors are of timber
construction and the roof has a timber structure with a slate covering. All windows are single glazed sliding
sash windows.
The property is owned by the local authority and a decision has been taken to refurbish it with a view to
reducing its carbon emissions by at least 80%.
The property is located in a conservation area and the conservation officer has indicated that any alterations to
the property must not adversely affect the external character and appearance of the building.
Refer to the text in this section and think about the challenges of this project. In particular, you should focus on
the problems of upgrading the thermal insulation and energy efficiency of the property without impacting on
the external appearance of the building.
Make some notes on what you consider the key issues to be.
When you have completed this exercise, watch this short (6 minute) video which describes a project undertaken
in Camden, London.
http://www.youtube.com/watch?v=Yv4NiNoBikE&feature=player_embedded#at=239
Further information on this project can be found at the project website:
Low Energy Victorian House http://www.levh.org.uk/ This is a really interesting website providing extensive
information on the experience of upgrading the energy efficiency of the property. The site has useful
information and data, and includes a series of videos covering various aspects of the project.
Section 4
Mechanical & electrical services and fire protection
(allow up to 7 hours)
INTRODUCTION
When historic buildings are occupied for modern uses there is inevitably an expectation that the occupants will
require modern standards of comfort and convenience. This causes particular problems for historic buildings
which will not have been designed to incorporate such facilities. Inevitably therefore, the mechanical and
electrical services which provide the required levels of comfort and convenience, and the fire protection
measures, will have to be installed in the building retrospectively. This can impact on a historic building in a
number of different ways:
o The appearance and character of the building can be adversely affected both by the services and by
associated pipes, cables, ducts and so on which are visible.
o The structure and fabric of the building can be affected by the need to provide routes for the services to
pass through.
o The environmental balance of the building can be upset by the incorporation of new services.
MECHANICAL AND ELECTRICAL SERVICES
Existing services
In some cases the existing services in a building may have some intrinsic historic value, in which case careful
consideration is necessary to determine whether or not they can be re-used. This may apply to radiators, light
fittings and switches. It may be possible to renew the supply and even the ‘inner workings’ of some
components whilst retaining the essential character.
Impact of installation
Regardless of the type of services we may be dealing with there is considerable potential for damage to the
structure and fabric of the building. When pipes or cables have to be installed they will inevitably have to pass
through walls and across joists and beams. Generally, holes drilled through walls will have minimal impact on
the structure, but care needs to be taken if the services have to pass through, for example, a pier which is
carrying substantial loads. Cutting chases in walls will obviously result in the loss of plaster and underlying wall
fabric. Drilling will always be preferable to breaking out holes with cold chisels or pneumatic tools, since
invariably such techniques lead to the creation of holes which are far bigger than necessary and thus result in
the loss of historic fabric.
Potentially, a more serious problem is notches being cut and holes being drilled in joists and beams. These will
be required for pipes or cables to pass through floor voids. If notches are cut at or close to the mid-span of a
joist, the increase in stress which results can be significant, and may lead to major deflection. Notches should
only be cut within zones where the impact on the joist is at a minimum as illustrated on the following page:
Precautions should also be taken to minimise the impact of notches by, for example, fixing wedges at the top
of the notch after pipes or cables are in place.
In the case of cables, it is preferable for them to pass through holes, which should be drilled in the centre of
the depth of the joist or beam.
In locations where visual impact is minimal such as cellars or roofspaces, it may be preferable for cables and
pipes to be run around joists or beams rather than through them.
Heating and hot water systems
The installation of a new heating and hot water system can result in dramatic improvements in the energy
efficiency of the building, particularly if careful thought is given to the selection of an appropriate boiler.
The selection of the system will depend on the particular circumstances of the building, but consideration will
need to be given to:








The fuel supply, e.g. gas, electricity, oil, renewable sources. The choice may depend on local availability,
but often there are many options. Will new infrastructure have to be provided? Could renewable sources
such as ground source heat pumps be considered?
Heat generation e.g. a boiler. Where will the boiler be located? What visual impact will it have?
Disposal of the products of combustion e.g. flues. Can existing flues be utilised? Will new flues be
necessary, and if necessary where will they be located?
The type of heating system, e.g. a wet system, warm air, underfloor heating. Most buildings have wet
systems, but if fitting retrospectively there will be a need for pipework. Warm air systems will require
ducts, but may obviate the need for radiators. Underfloor heating only possible if the floor is to be relaid,
but can minimise visual impact.
Distribution of heat e.g. pipework. As far as possible, use must be made of voids in the building for the
distribution pipework. This will include floor voids and voids behind panelling. There is considerable
potential for damage to the structure and fabric – see above. Micro bore systems allow for much more
flexible distribution, using only 8-10mm pipework.
Means of heat emission, e.g. radiators. A major consideration. If radiators already exist in the building can
they be re-used? If new radiators are to be installed – careful thought needs to be given to the style. Flat
panel radiators may reduce visual impact.
Hot water storage. Is there a requirement for a hot water cylinder? Where will this be located?
Controls, e.g. thermostats. How will heating and hot water be controlled and what will the impact be of
those controls?
Electrical, data and telecoms installations
It is highly unlikely that the electrical installation in a historic building (if there is one) will meet current
standards, and it is therefore highly likely that a new installation will be required. There is also a strong
likelihood that sophisticated data and telecoms installations may be required, particularly in non-residential
buildings.
If the installation requires simple cabling, then it may be fairly straightforward to accommodate this within
voids in the building, drilling holes and cutting chases as required, subject to the same constraints as described
for pipework above. However, more complex installations typically involve separate power, data and telecoms
cables being distributed around the building using cable trays and / or trunking. Clearly such an installation will
require much more careful design if it is not going to impact on the character of the building.
In many buildings it will be difficult to accommodate such an installation within floor voids. If suspended
ceilings can be installed, the void created may provide a route for the trunking, but in many cases it will not be
acceptable to put suspended ceilings in, particularly if there are decorative features such as plasterwork or
cornices. Raised floors provide another alternative, but this can cause problems at door thresholds and the
bottom of stairs. Skirting trunking and dado trunking might be considered, but these can have quite significant
impact on the character of the interior.
Another factor to consider is the location of socket outlets. If dado or skirting trunking is used then these
incorporate socket outlets, but if cabling is run separately then the location of outlets needs to be carefully
considered. It is difficult to balance the needs of the building user and the potential impact on the character of
the building. In commercial uses such as offices, floor outlets can minimise the impact whilst ensuring that
occupants have convenient access to electrical, data and telecoms services.
The style of sockets and switches should also be considered with regard to the character of the building. This
does not necessarily mean choosing ‘period’ style switches and fittings for any historic buildings. Clearly, the
age of some buildings is such that no previous style of electrical fittings is contemporary with the building
itself, so it may be better to simply use modern fittings.
Plumbing and sanitation
Many historic buildings were designed to incorporate basic water supply and sanitary facilities, so it may well
be possible to utilise existing pipes or at least to replace pipes using the existing routes. If soil stacks are
present on the exterior of the property these will often form part of the accepted appearance of the property.
Where new sanitary facilities are to be provided it may not be necessary to install new drainage pipework
which is visible externally. Often, the provision of new pipework externally can have a detrimental impact on
the appearance of the building. Wherever possible, such pipework should be run in vertical ducts inside the
building. Sound insulation of the ducts will probably be necessary. Careful planning of the siting of sanitary
facilities will be necessary to ensure that excessive pipework is not necessary.
Lighting
The design of a new lighting installation for a historic building can have a major influence on the way in which
the building is perceived. Lighting can create mood or atmosphere, so an inappropriate design can seriously
undermine the character of an important building.
If the building originally had some form of lighting, or indeed if lighting has been installed at some point in its
history, then this may provide the starting point for the design of the new installation. Can existing light fittings
or chandeliers be re-used, or provide the basis for the design of new fittings? It can be tempting to replicate
fittings which were originally designed for candles, but fit electric bulbs, though such an approach would be
seen by many as somewhat dishonest.
Consideration needs to be given to the purpose of the lighting. For some building uses it may be appropriate to
have relatively low levels of background lighting, combined with task lighting. In such circumstances it may be
acceptable to have free standing uplighters providing the background lighting, together with, for example,
desk lamps. Such an approach would have minimal impact on the original fabric.
Where new lighting is required this can cause difficulties in some situations, particularly if the existing ceiling
has decorative features such as plasterwork or covings which are historically important. New suspended
ceilings would generally obscure such features completely, and therefore may not be acceptable. A possible
compromise is to form a drop panel in the centre of the room which can accommodate some new lighting
whilst leaving the original ceiling perimeter and covings still visible.
The energy efficiency of lighting installations also needs to be considered. In some cases the aesthetics of
tungsten lighting may be appropriate to the age and character of the building. However, where possible,
consideration ought to be given to the use of more energy-efficient, long life modern alternatives.
FIRE PROTECTION
Fire protection strategy
In broad terms, fire protection strategies for historic buildings must be based around the same priorities as any
other building, namely the protection of life, the protection of the property and its contents, and containment,
i.e. preventing the fire from spreading to neighbouring buildings. The protection of life will invariably be the
main priority, but when dealing with historic buildings it is often the case that protection of the property takes
on a far greater significance than would normally the case with other buildings.
As with any building, careful attention must be paid to the provision of adequate means of escape in the event
of a fire, provision of adequate access for the fire service, and provision of firefighting equipment such as
extinguishers within the building. However, in terms of the design of the building itself the fire protection
measures can be divided into two categories:
 Active measures:
o Automatic fire detection and alarm systems
o Systems to suppress the fire and control the movement of fire and smoke

Passive measures:
o Compartmentation – the use of fire rated partitions and doors to prevent the fire and smoke
from moving from one compartment to another.
o Measures which improve the ability of the building structure to resist the effects of fire.
o Measures which are aimed at limiting the rate of growth of a fire.
Active fire protection measures in historic buildings
The main considerations which apply to the selection and installation of fire detection and alarm systems in
historic buildings are similar to those which apply to electrical installation systems in general. The visual
intrusiveness of cables, detectors, call points and alarms can often have an adverse affect on the character of a
building. Cables should be concealed wherever possible, and the selection of detectors and other items should
seek to minimise visual impact.
More recent technological developments have led to the development of aspirating or air sampling systems.
These consist of small diameter pipes with holes along their length. These can be concealed behind the ceiling
and very small penetrations made in the ceiling fabric. A sampling unit, which can be located some distance
away, draws air from the room, through the pipes and into a chamber. If smoke particles are detected, the
alarm is triggered.
In ordinary buildings the most common form of fire suppression system is a sprinkler system. Sprinkler systems
consist of a permanent water supply distributed via pipework to a series of sprinkler heads typically located at
ceiling level at appropriate points in the building. The sprinkler head usually incorporates a glass bulb
containing alcohol fluid. If the fluid is subjected to high temperatures it expands and the bulb breaks, allowing
water to be discharged from the head.
The use of sprinkler systems in historic buildings is highly contentious. This is mainly due to the fact that once a
sprinkler system is triggered it releases potentially large volumes of water. The water can cause a great deal of
damage to historic fabric and to the artefacts contained within a building. The distribution pipework also
causes similar problems to those described for heating systems above, and the sprinkler heads can also be
visually intrusive. Nevertheless, appropriately designed sprinkler systems should limit their water discharge to
the area affected by the far, and they do have a role to play in the protection of some historic buildings.
Another alternative is a water mist system. These systems are a relatively recent development. The concept is
similar to sprinkler systems in that there is a requirement for a water supply, some means of detection, and a
discharge triggered by the detection. However, rather than water, a mist is discharged which is intended to
remove heat and displace oxygen, thus suppressing the fire. Whilst such systems can cause less damage than
sprinkler systems there is a risk that they will not work effectively if, fore example, a window is open.
Furthermore, mist systems may just dampen down the fire rather than extinguish it completely, and there is a
risk that the fire could rekindle.
Passive fire protection measures in historic buildings
Compartmentation is one of the most effective ways of limiting damage due to fire. This involves dividing the
building into separate ‘compartments’ such that if a fire occurs within any compartment it is effectively
prevented from spreading to another compartment. Such an approach also facilitates the safe evacuation of
the building, since the corridors and stairwells leading to the final exit from the building will be made up of a
series of enclosed compartments.
It will be apparent that the elements which make up the enclosure to any compartment are the critical
elements in resisting fire. Thus the walls surrounding a compartment (together with doors set into those walls)
plus the floor structures and associated ceilings, must have adequate standards of fire resistance. Typically
these are expressed by reference to a time period, e.g. thirty minutes’ fire resistance.
In many historic buildings, if the walls are of masonry construction, there will be inherent fire resistance.
Attention will however have to be paid to locations where the wall has been breached, perhaps by a crack or
by a pipe run. Provision for sealing will have to be made at these points.
The weak spots in walls are the door openings and the doors themselves, and it is often necessary to upgrade
the doors and the door frames and linings. Various techniques are available to achieve this.
For the door / frame perimeter, intumescent seals can be fitted to the frame or the door edge. In the event of
a fire these swell and seal the door opening and prevent the passage of fire and smoke.
If doors are solid and are at least 44mm thick, they are generally considered to have 30 minutes fire resistance.
For thinner doors, fire resistant calcium silicate boards such as Supalux can be applied over the face of the
existing door. This can also be done to panelled doors, though normally this would not be acceptable because
of the loss of the panelled effect. In such circumstances there are other techniques, including the splitting of
panels and the insertion of a fire resistant board. However, such techniques are very labour intensive and time
consuming.
Other points to consider with doors are the provision of door closers and increasing the depth of door stops.
Floors can also present major problems unless the existing construction is naturally fire resistant, such as
concrete floors. Fire resistant boards can be applied to the ceiling beneath, but this may not be possible if
there are important decorative features on the ceiling. In the case of suspended timber floors it may be
necessary to lift the boards and incorporate some means of fire resistance within the floor void. This could
involve the installation of mineral wool slabs into the void. Clearly, such a technique presents further problems
if the void is being used for the distribution of services.
Another aspect of passive fire protection is the prevention of internal fire spread across the linings a room.
This can present problems in historic buildings where, for example, you might have fine timber panelling. One
way of addressing this is to apply intumescent coatings such as those produced by Nullifire
(www.nullifire.com). These are available in a clear finish, which allows the natural appearance of the wood to
be retained. At ambient temperatures the coating remains stable, but in a fire the coating will soften and
expand.
Activity
Section 5
Disabled access to historic buildings
(allow up to 6 hours)
STATUTORY REQUIREMENTS
The key piece of legislation is the Equality Act 2010, which came into effect on 1 st October 2010 and effectively
replaced the Disability Discrimination Act 1995. In relation to buildings, the law imposes a duty to make
‘reasonable adjustments’ in order to ensure that disabled people are not disadvantaged or do not experience
unreasonable difficulties in using the services offered by a building.
The definition of a disabled person is “someone who has a mental or physical impairment that has a
substantial and long-term adverse effect on the person’s ability to carry out normal day-to-day activities”.
The other main statutory requirement which needs to be considered is Part M of the Building Regulations
2010. Part M applies to non-domestic buildings which are extended or materially altered, or subject to a
change of use. Reasonable provision must be made to ensure that buildings are accessible to and usable by all
those who could be expected to use them.
GUIDANCE
There are various sources of guidance and good practice when a designer wishes to make provisions for
disabled access:
 Approved Document M – Access to and use of buildings
 BS 8300: 2009 - Design of Buildings and their approaches to meet the needs of disabled people (Note:
Approved Document M is largely based on BS 8300).
 Extensive guidance is available from the Centre for Accessible Environments www.cae.org.uk
For guidance specifically related to historic buildings the English Heritage publication entitled “Easy Access to
Historic Buildings” is one of the best sources.
www.english-heritage.org.uk/publications/easy-access-to-historic-buildings/
The fundamental challenge
It is a generally accepted principle that disabled people should have dignified access to and within historic
buildings. However, insensitive adjustments to historic buildings can damage historic fabric and adversely
affect the character of a building. It is therefore important that careful attention is paid to the design of works
carried out to meet the needs of disabled people.
Important note: The Equality Act does not override the provisions of the Planning (Listed Buildings and
Conservation Areas) Act 1990. Listed building consent will still be required for access works to historic
buildings.
General points
It is important to recognise that sometimes it may not be necessary to make substantial changes to the
building in order to comply with the DDA. It may be possible to implement changes to the way in which a
service is provided or to the way in which an organisation works without having any impact on the building
itself. This might involve something as simple as changing the location of a service within a building rather than
having to make substantial access provisions.
A second general point to recognise is that, by and large, the adjustments made to a building for disabled
people will generally make the building more easily accessible for able-bodied people and for the temporarily
disabled. For example, adjustments to accommodate wheelchair users will make the building more suitable for
parents with pushchairs.
Access into the building
One of the aspects of disabled access which can potentially have a significant visual impact on a historic
building is the need to provide a suitable means of access to the building. Typically this will involve the
provision of a ramped access to allow ease of access for wheelchair users. It will not generally be acceptable to
direct wheelchair users to an alternative access located a considerable distance away from the main entrance,
since this is harmful to their dignity.
Ramps require very careful design. The symmetry of the elevation must be respected if possible. Curved ramps
are often less obtrusive than rectilinear ones, particularly if they utilise existing slopes to help them blend in.
The materials used should harmonise with the materials of the building. Portable ramps are unlikely to provide
an adequate permanent solution, but may be used as a temporary measure.
In some cases it may not be possible to accommodate a ramp. A platform lift might offer an alternative
solution, but only if there is space to accommodate the lift, e.g, a basement area adjacent to the main
entrance.
For ambulant disabled people ramps do not offer the best solution, so suitably designed steps will be
necessary as well.
Once the access has been achieved to the main entrance, the next issue is the entrance door. The main
entrance door is often a key feature of the front elevation so it is unlikely that any significant changes to it will
be acceptable. For wheelchair users a door opening width of 800mm is generally considered to be the
minimum. However, in historic buildings a compromise of 750mm may be possible. What is equally important
for wheelchair users is manoeuvring space. It may be necessary to provide electromagnetic hold-open devices.
Door thresholds also need to be considered. If thresholds are too deep, then bevelled edges or short ramps
may have to be installed.
Circulation within the building
For wheelchair users the main issues are likely to be corridor widths and changes in level. The minimum
corridor width recommended is 1200mm, though for places of public assembly this increases to 1800mm.
Historic buildings, particularly those which have evolved over time, often have many changes in level within
the building. This can cause considerable difficulties for wheelchair users. As with external access, a ramp is
generally considered to be the favoured solution, though the space needed for a ramp may not always be
available. Platform lifts can also provide an alternative.
On existing and new stairs and on ramps, it will be necessary to provide handrails. If handrails are designed to
replicate existing styles they may not comply with current guidance, but this may have to be accepted as a
compromise.
Standard guidance recommends the use of tactile surfaces at the top of stairs, but this may not be acceptable
in historic buildings.
Lifts
To enable wheelchair users to gain access to the upper floors of an existing building it may be necessary to
install a lift. As a general rule lifts should not be installed in locations where they will have an adverse impact
on an important feature of the building. Ideally then, they should be installed in less sensitive parts of the
building. It may be possible to install lifts within existing stairwells or lightwells, or in sensitive additions to the
rear of a building.
Evacuation lifts, such as those retrospectively installed to existing staircases, can be very visually intrusive.
Lighting
Appropriate lighting is essential to enable partially sighted people to move around a building safely. Good
levels of lighting are essential where there are obstacles and changes in level. The lighting scheme should seek
to avoid glare, areas of bright light and areas of deep shadow. In addition, sudden changes in light levels
should be avoided, ideally by the use of areas of transition.
Signage
Where the main entrance to the building is not the accessible entrance, there should be clear signage to
indicate the location of the accessible entrance. Signs should also be used to indicate the presence of features
within a building designed to assist disabled people.
The design of signage should be sensitive, and care needs to be taken to avoid damage to the fabric in the
fixing of signs. Free standing signs may offer the best solution in some cases.
Toilets
Disabled toilets should be located in close proximity to standard toilets so as not to marginalise disabled
people. Toilets should be unisex so that carers of the opposite sex can accompany disabled users.
Activity
Section 6
Project management issues
(allow up to 8 hours)
Introduction
This section covers various project management issues associated with work to existing buildings, including the
following:
 Procurement issues, including project documentation, forms of contract and tendering
 Management of the works, including health & safety issues
 Management of costs
In many respects, the management of works to existing buildings is no different to the management of newbuild schemes. Both types of project have in common:
 A client requiring works to be carried out to produce a building which meets their expectations
 An individual or a team of people responsible for designing and specifying the works to be done to the
building, supervising the works on site and administering the terms of the contract.
 A contractor and subcontractors physically carrying out the works and managing the process.
However, it is important to recognise that works to existing buildings, particularly conservation works, have
particular constraints which make them quite distinct from a management perspective. As Sharpe (1999)
points out, projects involving conservation works are generally “single-purpose schemes operated to a
particular specification and to individually stated requirements”. Contrast this with new-build schemes which
often make extensive use of mass production and/or standardisation.
Of course, one could argue that virtually every building project is unique, even if it is new-build, and therefore
the management of works to existing buildings should not be significantly different. Nevertheless, it is
generally accepted that projects involving existing buildings involve a considerable element of ‘the unknown’
and this somehow has to be managed throughout the entire process from inception through to completion of
the scheme. The purpose of this paper is therefore to highlight some of the key issues which have to be
considered.
Procurement
For any project, whether or not it involves an existing building, procurement decisions are normally made
against the three central criteria of time, cost and quality:
In very broad terms the main procurement options for building projects are:
 Traditional systems: Perform well in terms of quality and cost certainty, but less well in terms of time.
 Design & build systems: Perform well in terms of time and cost certainty, but have been criticised in terms
of design quality.
 Management systems: Perform well in terms of time and quality, but less well in terms of cost.
For projects involving existing buildings, the basic criteria are the same, but they cannot necessarily be applied
in the same way as for new-build projects. As Riley & Cotgrave (2004) point out, we must also consider
secondary factors such as health and safety, environmental issues and disruption factors. These may be much
more difficult to control on adaptation projects than on new-build projects. In addition, CIRIA (1994) advise
that the contract strategy must take account of the inherent uncertainty associated with such projects,
possible continued occupancy of the building during the works, and the technical problems associated
renewing existing assets.
A comprehensive article in Building magazine (Davis Langdon & Everest and Mott Green Wall, 2004) indicated
that lump sum procurement, based on sequential design and construction delivers the best results for
refurbishment projects. Indeed, the majority of projects involving existing buildings are procured using a
traditional approach, where there is a designer/contract administrator (such as an architect or surveyor) who
prepares project documentation then invites competitive tenders from contractors. The contract will be
awarded following a conventional tendering process and works will be supervised by the contract
administrator.
Many people involved in building conservation will argue that that design and build methods of procurement
are entirely inappropriate for historic buildings. They will say that it is imperative to have close control over the
design and specification of the works and this can only be achieved with an independent professional architect
or surveyor specifying the works in full before the project commences on site, and continuing to keep close
control of the works throughout the duration of the project.
Management methods of procurement (such as construction management or management contracting) are
rarely used in projects involving existing buildings. Generally, such methods tend to be used for very large scale
projects where early occupation of the completed building is paramount and speed of construction is
therefore a priority.
On some building adaptation projects it is virtually impossible to determine the extent of the works required
prior to starting on site. This is particularly the case where the existing construction has not been uncovered at
design stage so the degree of repair or reinstatement cannot be accurately assessed. In such cases it may be
appropriate to appoint a contractor on a ‘cost reimbursement and fee’ basis. Under this arrangement the
contractor is paid the actual cost of carrying out the works, plus a fee which is usually a percentage of the cost.
This approach has the advantage of allowing the earliest possible start on site, because it is not necessary to
produce a detailed specification. However, from a client’s perspective this approach is rather risky in financial
terms, because the contractor has no incentive to work in a cost effective way, so the financial commitment is
open-ended.
Project Documentation
Unlike new-build projects, it will not be usual to have a bill of quantities for projects involving works to existing
buildings. It is very difficult to assess quantities for adaptation works accurately, so such works do not lend
themselves well to quantification in accordance with the very rigid rules of the Standard Method of
Measurement. It is far more likely that the project documentation will comprise drawings and a detailed
technical specification. The drawings should accurately detail the nature and extent of the works involved. The
format of the specification may differ depending on the type of works involved. In some cases it may be
possible to provide very detailed, prescriptive specification clauses which virtually describe the works required,
item by item. In other cases, where perhaps the work is more repetitive, schedules might be used. For small
projects it may be adequate to put all the specification notes on the drawings. Standard libraries of
specification clauses (such as NBS – the National Building Specification) can be used for works to existing
buildings, but many architects and surveyors believe that they are less suited to such projects because of the
‘unique’ nature of the works involved. Hughes (2005) suggests that “the use of standardised, word-processor
generated documents must be treated with suspicion”.
It should be noted that the use of drawings and specification has a number of potential disadvantages when
compared to the use of Bills of Quantities. Firstly, at tender stage, there is a danger that the contractors
tendering for the project may each interpret the requirements slightly differently. The tenders may therefore
not all be submitted on the same basis. Secondly, the use of drawings and specification imposes a significant
risk on the contractor. If the successful contractor has misinterpreted the requirements (which may be a result
of an ambiguous or poorly drafted specification) they may not be paid enough money to cover the costs of
carrying out the works in strict accordance with the specification. Invariably a contractor in such a situation will
look for other ways of reducing costs or increasing income, and this can result either in corners being cut, or in
disputes arising.
Form of Contract
As with new-build projects, the most commonly used forms of contract for projects involving existing buildings
are those produced by the Joint Contracts Tribunal (JCT). Of these, the Standard Form is likely to be used for
large projects, the Intermediate Form for straightforward, medium sized projects, and the Agreement for
Minor Works is used for very small projects. JCT produce a wide range of forms to cover all methods of
procurement and also produce variations to the standard forms to allow for quantities and for contractor’s
design. A form is also available for cost reimbursement contracts.
Tendering
The choice of tendering methods is essentially the same as for new-build projects, namely competitive
tendering, two stage tendering and negotiation. With competitive tendering the design needs to be
substantially completed before the tendering process is undertaken. The objective of competitive tendering is
to achieve the best price and to give cost certainty before works begin. However, works to existing buildings
involve so many unknowns that the final value of the contract often exceeds the tender sum substantially.
Two stage tendering requires contractors to tender competitively at an early stage on the basis of fairly limited
information. The contractor selected can then become involved in the planning of the project at an early stage
and negotiations will seek to arrive at an acceptable price for the fully designed scheme. This approach is
commonly used on projects involving existing buildings because it promotes a better working relationship
between the contractor and the design team.
Negotiation refers to the process whereby a client wishes to appoint a particular contractor for all or part of a
project and therefore simply negotiates directly with that contractor to agree an acceptable price for the
works. It may be used where the client has previous experience of using a particular contractor and wishes to
continue the relationship. The contractor may have performed well on earlier projects for the client, or may
have particular specialist expertise which the client wishes to take advantage of. Negotiation is commonly used
on phased projects, where a contractor who performs well on one phase is selected to continue on
subsequent phases.
Regardless of which method of tendering is used, there is one overriding priority: the contractor selected must
have the necessary experience and skills to be able to carry out the works required. Whilst this can be said of
any tendering process, it takes on much greater importance with works to existing buildings, particularly if
historic buildings are involved. This work is highly specialised and requires a very sensitive approach on the
part of the contractor. The appointment of inappropriate contractors can lead to irreparable damage being
caused to historic buildings. It is therefore essential that prospective tenderers are thoroughly vetted to
ensure that they have the expertise to carry out the required works. As Hughes (2005) indicates, this may
require visits to previous projects undertaken by the contractor, discussions with project teams from earlier
projects, and various other investigations into the suitability of the firm. In this regard, personal
recommendations from team members or the client can be invaluable.
Management of the works
It is generally recognised that works to existing buildings can be difficult to manage effectively. Invariably,
programmes are delayed and budgets are exceeded because of unforeseen works. Douglas (2002) highlights
the fact that such projects often involve a great deal of cutting out or opening up, and this exposes hidden
defects which have to be dealt with. Examples might include dampness, fungal decay, insect attack, the
presence of asbestos, structural problems and so on. These defects will inevitably result in increased costs and
may cause substantial delays in progress. The only way of reducing the risk of unforeseen works is to ensure
that a thorough analysis of the building is undertaken prior to the works. In many cases this may not be
possible due to time constraints, and as indicated by CIRIA (1994), even when detailed surveys are carried out
in advance, it is “unlikely that there will be no further surprises, and consequent expenditure, during the actual
execution of the work”.
Egbu (1996) identifies a wide range of difficulties associated with refurbishment projects. Several of these are
related to the fact that works to existing buildings often take place whilst the buildings remain occupied.
Consequently, there are particular difficulties in dealing with the following issues:




Dust control: demolition, breaking out, cutting out and opening up will invariably create high levels of
dust. There will be an expectation that measures are taken to prevent the dust from affecting activities in
the building and neighbouring buildings.
Noise control: In a similar way to the previous point, measures must be taken to reduce the impact of
noise on occupants, neighbours and the general public.
Site security: If the building remains occupied whilst the works take place, it can be difficult to effectively
control access to the works by persons other than those involved in the project. On some projects it may
also be necessary to control access by site personnel to sensitive areas of an existing building.
Site access: Many existing buildings occupy very tight city-centre sites. Access for materials and plant
deliveries can therefore be very difficult.
Riley and Cotgrave (2004) highlight the fact that programming of refurbishment works is generally more
complex than that for new-build. This is because of the fragmented nature of the work, such that lots of small
jobs may have to be done in order for a major process to be undertaken. The example they cite is the provision
of a new steel column for additional structural support. Clearly this is a significant item of work in its own right,
but when working in an existing building the installation of the column will require the excavation of a pit for
the foundation, fixing the holding down bolts, concreting the base plate, possibly forming openings through
floors, and of course, fixing the column. On a new-build project the installation of the column would generally
be treated as a single operation, but when the column is required in an existing building it will have to be dealt
with as a series of small activities, thus the programming is inevitably very complicated.
Another difficulty that Riley and Cotgrave (Ibid) identify is that of the interface between trades on a
refurbishment project. On new-build projects the interface is usually fairly clear cut, so that, for example, a
bricklayer builds a partition wall and plasterer provides the plaster finish. On a refurbishment project there
might be an existing partition wall which has a door opening to be blocked up. The existing door and frame has
to be removed, the opening has to be prepared, the blockwork infill has to be provided, loose plaster around
the opening has to be removed, and new plaster has to be applied to match in with the existing. The
responsibility for each of these separate operations is not always clear, so the interface management requires
close attention.
All of the challenges identified above need to be addressed by having a suitably qualified management team in
charge of the project. The people involved should be experienced in dealing with this type of work. It is
suggested by CIRIA (1994) that management control of refurbishment projects needs to be more extensive
than for new-build, because there are likely to be more unforeseen problems to overcome. Decision-making
procedures therefore need to be quicker and more effective. Close supervision of the works in progress will be
essential, and this calls for someone who has a good understanding of the construction techniques involved.
On works to historic buildings, this will usually have to be someone who has detailed knowledge of traditional
construction techniques and materials. The success of the project will depend heavily on effective
communication between all parties involved, and positive leadership.
Health and safety issues
The Health and Safety Executive claimed in September 2007 that one in three refurbishment sites seriously
endangers workers’ lives (Building, 2007). Obviously, many refurbishment projects are relatively small schemes
undertaken by contractors who may have neither an appreciation of the risks involved, nor the resources to
deal with them. Nevertheless, it must be appreciated that works to existing buildings involve particular risks.
The Construction Health & Safety Manual (CIP, 2007) contains a section which deals specifically with
refurbishment. The manual points out that many buildings which are the subject of refurbishment schemes
may have been constructed using methods vastly different from accepted good practice today. Timber may
have been widely used for structural purposes, but may have been subject to decay. Brickwork may be poorly
bonded, and foundations may be inadequate by modern standards. Unless the construction team is aware of
such risks then the works to the existing building could have catastrophic implications. For example, cutting
into the structure without assessing how loads will be redistributed could lead to a major collapse. In addition,
working within an existing building can impose severe constraints on construction processes, so very careful
planning is required.
The manual (op.cit.) identifies the following potential health and safety hazards:
 Temporary works: Invariably there will be a need for temporary works to provide support to the existing
structure. Great care needs to be taken in the installation of these temporary works and, perhaps even
more importantly, in their subsequent removal or adjustment.
 Scaffolding risks: If the scaffold is to be tied into the existing structure then a thorough appraisal of the
structure is necessary to ensure that the structure is adequate.
 Storage: Storage facilities are often very restricted. Care is necessary in providing storage for flammable or
toxic materials.
 Old services: Existing electrical and gas supplies must be identified and made safe.
 Disposal of materials. Where partial demolition is taking place, new openings are being formed, or
extensive stripping out is being undertaken there will obviously be large amounts of waste material to be
disposed of. How is the material to be moved from all parts of the building? Attention needs to be given to
the safe removal of the material. Chutes provide one possible safe option, but they need to be carefully
installed and managed.
 Openings: Works to existing buildings often involve the formation of new openings in walls and floors, the
lifting of floorboards, or the opening up of the structure to install new items. Such openings represent
particular hazards whilst work is in progress and must be managed accordingly.
 Dust: Dust is likely to be a major problem when working on existing buildings. Suitable protective
equipment must be provided, and steps taken to keep dust levels down.
 Asbestos: There is a significant risk in many buildings that asbestos will be uncovered during the course of
the works, whether in the form of insulation to old heating pipework, in ceiling tiles, insulated panels or in
coatings. Its removal must comply with the “Control of Asbestos Regulations 2006”
 Lead: Old decorative coatings may contain lead, so special precautions may be necessary in their removal,
whether by rubbing down or burning off. The “Control of Lead at Work Regulations 2002” will apply.
Of course, there are many other potential risks, many of which will be common to both new-build projects and
projects involving existing buildings. In all cases, the CDM Regulations 2007 will apply, and it will be necessary
to carry out a detailed appraisal of risks for the pre-construction information. The contractor will also have to
prepare, develop and implement a written plan to manage the risks which have been identified.
Management of costs
Cost control can be a significant problem throughout the entire life of a project involving an existing building,
from inception right through to completion.
At the very early stages of a project it can be extremely difficult to estimate the likely costs of a scheme
because the full extent of the works required will often be almost impossible to assess until a detailed analysis
of the existing building has been undertaken. It may therefore be very difficult to establish a budget for the
required works. Even when the existing building has been the subject of a thorough appraisal it is likely that a
significant contingency sum will have to be allowed in the budget for unforeseen works.
When the tendering process is undertaken, contractors will invariably be unclear as to the full extent of the
works required. There may be a wide variation in the tender sums submitted if contractors have interpreted
the requirements differently. Some contractors may recognise the potential for problems and build in
provision for this in their pricing, whilst others may price solely on the basis of the works described and expect
to recoup additional costs through claims as the work proceeds. Consequently the evaluation of tenders can
be troublesome, and it may be difficult to identify the tender which represents the best value.
Undoubtedly projects involving existing buildings have a greater potential for variations during the course of
the works. As Egbu (1996) indicates, variations could include anything from the realignment of floors to
accommodate services, to the strengthening of existing foundations which are inadequate. Existing finishes
such as plasterwork which were previously thought to be sound may, in fact, be found to be completely
detached from the sub-base, resulting in a need for large additional areas of replastering. All such unforeseen
works will result in additional costs.
Those responsible for the management of projects must have systems in place to ensure that the costs of
additional works do not spiral out of control. It is not acceptable to simply instruct the contractor to proceed
with additional works without an agreed price for the variation. Unless close control of costs is exercised from
the start of the project, the client’s budget may be exceeded before the works are complete.
When projects involve historic buildings, it has to be recognised that conservation works involving specialist
techniques and historic materials are invariably more expensive than modern equivalents. Compliance with
the principles of conservation is therefore likely to result in higher costs. Clients, developers and owners of
such buildings need to be advised of this at the earliest possible stage in a project.
Conclusion
Regardless of whether a building project involves new-build or works to existing buildings, effective project
management is essential to achieve success in terms of time, cost and quality. Clearly, there are some
fundamental requirements in project management which will apply whichever type of work is involved.
However, it will be apparent from this paper that for projects involving works to existing buildings attention
must be paid to certain issues to a far greater extent than would be the case with new-build projects. Three
aspects which may require particular attention are:
 The uncertainty associated with works to existing buildings. This can give rise to unforeseen problems
which have to be managed during the project.
 The difficulties of dealing with buildings which may remain partially occupied whilst works are in progress.
 The additional constraints imposed by the requirement to comply with the principles of conservation
where the buildings concerned are historic buildings and are statutorily protected.
Activity
Section 7:
Case Study (allow up to 12 hours)
References and suggested further reading
Books, articles and reports
 Ashurst, John & Nicola (1988) Practical Building Conservation Volumes 1 – 5 Gower Technical Press
 Building (2007) [News Item] “One-third of refurbishment sites endanger lives of workers” in Building 14th
September 2007
 Brereton, Christopher (1995) The Repair of Historic Buildings: advice on Principles and Methods – English
Heritage
 BSI (1998) BS7913: 1998 The principles of the conservation of historic buildings BSI
 CIBSE Guide to Building Services for Historic Buildings Chartered Institution of Building Services Engineers
 CIP (2007) Construction Health & Safety Manual Section 27: Refurbishment Construction Industry
Publications
 CIRIA (1986) CIRIA Report R111 - Structural renovation of traditional buildings Construction Industry
Research and Information Association
 CIRIA (1994) CIRIA Report 133: A Guide to the Management of Building Refurbishment Construction
Industry Research and Information Association
 Davis Langdon & Everest and Mott Green Wall; (2004) “Datafile - Cost Model: Office Refurbishment” in
Building 16th April 2004
 Douglas, James; (2002) Building Adaptation Butterworth Heinemann
 Earl, John (2003)Building Conservation Philosophy Donhead
 Egbu, Charles D; (1996) CIOB Construction Papers No. 66: Characteristics and Difficulties Associated with
Refurbishment Chartered Institute of Building
 Feilden, B (2003)Conservation of Historic Buildings Butterworth Heinemann
 Highfield, D & Gorse, C. (2009) Refurbishment and Upgrading of Buildings Taylor & Francis
 Pickard, R.D. (1996) Conservation and the Built Environment Longman
 Powys, A R (1929 – reprinted 1985) Repair of Ancient Buildings SPAB
 Riley, M & Cotgrave, A Construction Technology 3: The Technology of Refurbishment and Maintenance
Palgrave Macmillan
 Sharpe, GR (1999) Works to Historic Buildings Longman
WWW References
 The Building Conservation Directory http://www.buildingconservation.com/
Numerous articles relating to conservation materials and techniques, plus fire protection and building
services
 English Heritage London terrace houses 1660-1860: A guide to alterations and extensions Available via
the English Heritage website in two parts:
http://www.english-heritage.org.uk/publications/london-terrace-houses-1660-1860/
 Hughes, Nigel; (2005) Tenders for Conservation Work {Internet} Available online at
www.buildingconservation.com (Accessed 29th November 2010)
×

Report this document