A Guide for Designing House Alterations and Extensions

A Guide for Designing HouseAlterations and Extensions

S u p p l e m e nt a r y P l a n n i n g D o c u m e nt N u m b e r 2

October 2005

Supplementary Planning Document Number 2

If you would like this information in a different format, for example Braille, audiotape, large print or computer disc, or community languages, please contact theStrategic and Citywide Policy Team on: 0117 903 6724

CONTENTS

i

page no.

1.0 INTRODUCTION 1

2.0 RESIDENTIAL CONTEXT 2

3.0 LISTED BUILDINGS AND CONSERVATION AREAS 3

4.0 HOUSEHOLDER PLANNING APPLICATIONS 44.1 Do You Need Planning Permission? 44.2 Information with your Planning Application 44.3 Public Consultation 4

5.0 DESIGN GUIDELINES 55.1 General Points 55.2 Inclusive Home Design 65.3 Sustainable Design and Construction 65.4 Alterations 75.5 Extensions 85.6 Alteration to Roofs 155.7 Balconies and Terraces 175.8 Garages and Parking 18

6.0 ADVICE AND FURTHER INFORMATION 20

7.0 BIBLIOGRAPHY 20

8.0 GLOSSARY 21

APPENDIX 1: SUSTAINABILITY APPRAISAL

APPENDIX 2: SCHEDULE OF PUBLIC COMMENTS RESPONSES AND ACTIONS

Appendix 1 & 2 are available separately and can be viewed at:

www.bristol-city.gov.uk/planningpolicy

Any copying or reproduction of parts of this document must contain anacknowledgment of its source and title.

SUMMARY OF POINTS

Before you start work:

Find out whether a planning application isrequired. Contact Customer Services for aHouseholders Guide’ and a ‘permitteddevelopment’ enquiry form. Note that a BuildingRegulations application will be required formost types of house extensions.

Get advice if you need it:

If necessary, get skilled technical advice from anexperienced architect or surveyor to design,prepare drawings and make an application onyour behalf.

Follow the design guidance:

These notes will help towards a successfulplanning application and good design solution.Following the advice may also lead to an earlyapproval of your planning application.

Look at your surroundings:

Ensure your proposal respects the context ofyour neighbourhood.

Detailing and use of materials:

Ensure that your proposal fits in with thedetailed design and materials of your existinghouse.

Be a good neighbour:

Consult your neighbour if your proposal mayaffect their home or privacy, or if you will needto gain access for building work or maintenance.

Submit full information:

Support your application with clear, accuratedrawings showing the existing buildings andwhat is proposed, any adjoining or neighbouringbuildings, and notes to show existing andproposed materials. Photographs are alsorecommended.


ii


1

1.0 INTRODUCTION

This Supplementary Planning Document(SPD) sets out design guidance forhomeowners and building designers onthe design of house extensions and/oralterations. It is one of a series ofdocuments produced by the City Councilencouraging high standards ofdevelopment and environmental quality inBristol.

The design guide has been produced inrecognition of the visual and amenityimpact that extensions can have on thequality of individual houses and the streetscene in general. The document providesguidance to assist in the understandingand implementation of Policy B9 of theBristol Local Plan 1997, and the generalurban design policies B1-B7.

Bristol Local Plan Policy:

B9 House extensions and alterations will be permitted provided they:

• respect the form, siting, materials, details and character of the original property andits curtilage;

• respect the characteristics of the wider area,particularly where the property forms partof a semi-detached pair, a terrace, or aformal street pattern;

• would not cause unacceptable harm to theamenities of neighbouring occupiers;

• retain adequate car parking within the site.

The purpose of the design guide is to set out theCouncil's design expectations. It is not intendedto impose rigid controls over detailed designmatters or stifle originality or innovation. Thefocus is on encouraging good design, byconcentrating on the broad issues of scale, height,massing, layout, landscape and parking. Theguidance identifies the main design principlesand illustrates with examples the issues thatshould be considered. Bristol City Council iscommitted to promoting good design and willtake a positive view of development proposalsthat follow the advice set out below.

Status of SPD 2 and its use in the decision makingprocess

Design proposals for house alterations andextensions should be made in accordance withthe relevant policies of the adopted Bristol LocalPlan and SPD 2, an important materialconsideration with significant weight in thedecision making process.SPD 2 has been prepared as a SupplementaryPlanning Document (SPD) in accordance withPlanning Policy Statement 12 – LocalDevelopment Frameworks (2004) and theassociated Town and Country Planning (LocalDevelopment) (England) Regulations 2004. BristolCity Council is currently preparing its LocalDevelopment Framework and consequently, theadopted Bristol Local Plan (1997) and its policieswill be ‘saved’ until replaced by LocalDevelopment Documents. It is intended toinclude a policy to guide house and alterationsextensions as existing Policy B9.


2

2.0 RESIDENTIAL CONTEXT

Throughout Bristol there is great variety in thetype, style, age and quality of housing. Manyhousing areas have a distinct character whichwith the quality of the buildings, their layoutand landscaping have become much cherished.As every house contributes to the generalcharacter of its street, the street scene andneighbourhood, it is important that, whereexternal alterations or extensions are proposed,the changes are in keeping with both theoriginal house and the context of the local area.

Poor house extensions and alterations can havea detrimental effect on an area, the residentialamenity of neighbours and may reduce thevalue of a particular property. Extending oraltering the property to a high standard and in-keeping with the original design may, however,add value and enhance the character of the localarea.

T h e re i s w i d e va r i e t y i n t h e co nt ex t a n d c h a ra c t e ro f B r i s t o l ’s t o w n s c a p e a n d a rc h i t e c t u re

S o m e h o u s e s fo r m p a r t o f a fo r m a l l ayo u t s u c h a st h e a b ove ‘g a rd e n c i t y s u b u r b ’ at S e a m i l l s


3

3.0 LISTED BUILDINGS, CONSERVATION AREAS AND ARCHAEOLOGY

Some of Bristol’s older houses have statutoryprotection as ‘listed buildings’, and appear onthe Department of Culture, Media and Sport’s‘List of Buildings of Special Architectural orHistoric Interest’. A number of local areas havebeen designated as Conservation Areas becauseof their special character or appearance. Tighterplanning controls apply to both listed buildingsfor internal and external works, and inConservation Areas for demolition and/ordevelopment.

Furthermore, alterations or extensions tohistoric buildings (whether ‘listed’ or not) incertain parts of the city may have archaeologicalimplications. In Sea Mills, for example, there areextensive Roman remains which could well beaffected by even minor works. You should checkwith the Customer Services Team to find outwhether you are affected.

(Further guidance on archaeological issues canbe found in the City Council’s Policy Advice NoteNo.4 ‘Archaeology and Development’).

Rive

rSe

vern

North Somerset

South Gloucestershire

0 1 2Km

N

22

1

21

23

20

2

5

313

24

283033

32

12

26 17

29

1518

7

4

68

16

19

25

13

11

1014 9 27

Co n s e r vat i o n A re a d e s i g n at i o n s i n B r i s t o l

A s u c c e s s f u l ex t e n s i o n t o a n h i s t o r i c p ro p e r t y

Conservation Areas

1 Henbury

2 Westbury-on-Trym

3 Stapleton and Frome Valley

4 City and Queen Square

5 Clifton

6 Kingsdown

7 Shirehampton

8 Portland Square

9 St Michael’s Hill and

Christmas Steps

10 Park Street and

Brandon Hill

11 College Green

12 Whiteladies Road

13 Redcliffe

14 Tyndall’s Park

15 Montpelier

16 Old Market

17 City Docks

18 Cotham, Redland and

Gloucester Road

19 Stokes Croft

20 The Downs

21 Sea Mills22 Kingsweston and

Trym Valley

23 Sneyd Park

24 Avon Valley

25 Bedminster

26 Bower Ashton

27 St James Parade

28 Brislington

29 Brentry

30 Arnos Vale

31 Ashley Down32 Bishopsworth and

Malago

33 Bedminster West


4

4.0 HOUSEHOLDER PLANNINGAPPLICATIONS

4.1 Do you need Planning Permission?

If you live in a house, you can make certain typesof minor changes to your home without needingto apply for planning permission. These rightsare called 'permitted development'. In someareas tighter planning controls may exist andpermitted development rights may have beenremoved under an Article 4 direction. Otherlegal restrictions, such as covenants or planningconditions, may also restrict certain types ofwork or alteration.

If you are in any doubt as to whether you requireplanning permission you should obtain a'permitted development' enquiry form from ourCustomer Services Team. Alternatively, write toour Department enclosing drawings of yourproposals and photographs to show the areasthat are to be altered or extended. The Councilcan then clarify whether Planning Permission isrequired. It is advisable to discuss any proposalswith the City Council well before starting workor submitting a formal planning application.

You should write to:

Planning Services Planning, Transport & Sustainable DevelopmentBristol City CouncilBrunel HouseSt. Georges RoadBristol BS1 5UY

More information about the planning system isavailable in the ODPM publication, 'Planning - A Householder's Guide, What You Need to knowAbout the Planning System'. This explains whenplanning permission is required, and how toapply for Planning Permission. Copies areavailable free from the Customer Services Team.

The information can also be obtained on-line atwww.odpm.gov.uk along with PlanningFactsheet 1: Privacy and Overlooking; and,Planning Factsheet 3: Overshadowing.

Furthermore, the Planning Portal -www.planningportal.gov.uk provides usefuladvice on planning topics.

4.2 Information to submit with yourPlanning Application

When submitting an application it must besupported with clear, accurate drawingsshowing to scale your existing house, theproposed changes, with notes to indicaterelevant construction details and externalmaterials. These drawings should also show therelationship of your house with neighbouringproperties, i.e. the context. It is also helpful ifphotographs are included with your applicationshowing where changes are to take place.

It is recommended that a suitably qualifiedarchitect or building surveyor is employed to actas your agent. Usually they will be able toprovide design drawings and other informationappropriate to your application.

4.3 Public Consultation

Should you submit a planning application,Planning Officers will process your applicationand consult your immediate neighbours andanyone who may be affected by your proposal.Following public consultation, a formal decisionnotice will usually be issued within 8 weeksunder 'delegated powers'. In a small number ofcases it may be that Officers submit a reportwith a recommendation to one of the council'sDevelopment Control Committees. TheCommittee will make the decision on theapplication.


5

5.0 DESIGN GUIDELINES

5.1 General Points

A house is most people’s biggest investment.Building an extension, however, can beexpensive and may not increase the value ofyour home. Financially it might be more sensibleto move to a larger house.

Also, poorly designed extension can reduce thevalue of a house if it spoils its character or takesup too much of the existing garden.

As a starting point for any alterations orextension the original appearance of theproperty should be considered and any changesdesigned to reflect the character and style of theoriginal house and that of the local area.

Most houses however were not designed toincorporate extensions at a later date so carefulthought is needed if the most appropriatedesign solution is to be achieved. Wherepossible, alterations or extensions should beconfined to the rear or less prominentelevations.

Take a Look at Your Surroundings

Bristol is made up of a number ofneighbourhoods, many with a distinct characterand identity. This is often reflected in the shape,

layout and architectural style of the buildings,the materials they are made of and thelandscape in which they sit.

Any alterations or extension should generallyrespect but not necessarily mimic the style andappearance of the house, and the character ofthe locality, particularly in relation to:

• built form, scale and proportions;

• roof form and pitch;

• window and door shape, style and details;

• external materials;

• gardens and landscaping;

• boundary wall, gates and piers.

A l t e rat i o n s o r ex t e n s i o n s s h o u l d b e d e s i g n e d t o b ei n - ke e p i n g w i t h t h e o r i g i n a l d e s i g n o f t h e h o u s e

T h e d e t a i l s a n d m at e r i a l s o f a p a r t i c u l a r b u i l d i n g a d d t o a i t ’s c h a ra c t e r a n d v i s u a l i nt e re s t

5.2 Inclusive Home Design

The potential for improving the accessibilityof a property should be considered wherealterations or an extension are proposed.Creating level access and providing abathroom on the ground floor will, forexample, help visitors such as the elderly,those with a disability and/or in awheelchair. Also, recognising that needsmay change in the future, considerationshould also be given to designing flexiblyso that with the minimum of adaptationsuch access and use can be incorporated.

The Building Regulations provides guidanceon accessibility issues in Approved DocumentPart M - Access to and use of buildings.This is available at www.odpm.gov.uk.Further information and guidance can also befound in ‘Designing Lifetime Homes’,Joseph Rowntree Foundation (1997)(www.lifetimehomes.org.uk) and the guidancein ‘Design Manual’, Habinteg HousingAssociation (1992).

5.3 Sustainable Design and Construction

The City Council is committed to promotingsustainable development, minimising theadverse environmental impact of developmentand ensuring the prudent use of naturalresources.

There are many things that can be done whilstplanning to build an extension or carry outalterations to your home that will contribute toprotecting the environment and lesseningglobal warming, as well as improve energyefficiency.

The following sets out key elements to consider:

• Draught proofing of windows and doors;

• Double/triple glazed windows, with low ‘E’(emissivity) glass, argon filled betweenpanes;

• Highly efficient heating and lightingsystems;

• The orientation of an extension and itspotential for ‘solar gain’;

• High levels of thermal insulation in floors,walls and roofs;

• Renewable energy sources ofenvironmentally friendly, abundant,building materials;

• Recycled materials;

• Permeable paving and use of soakaways;

• Rainwater collection, use of grey waterrecycling systems and/or water butts.

In addition to the above soft landscaping is alsoimportant. Trees and soft landscape such asshrubs and grass may be used to not only softenthe visual impact of alterations and extensions,but also can help to improve air quality andreduce pollution.

It is also important to consider appropriatestorage of the household wheelie bin andrecycling box. These should ideally be screenedfrom public view, behind a front boundary wallor landscaping, or within a rear garden etc.

CREATE - Bristol's Unique Environment Centrehas, as a showcase project, built The Ecohome.This unique, purpose built dwelling has beenconstructed to demonstrate sustainable buildingdesign and lifestyles, and is full of ideas andinformation on eco-friendly construction andliving.


6

W h e e l i e b i n s a n d re c y c l i n g b oxe s s h o u l d o n l y b e p u to u t o nt o t h e s t re e to n t h e d ay o f co l l e c t i o n . W h e n b e i n g s t o re d t h e y s h o u l d b e s c re e n e d f ro m p u b l i c v i e w.


7

The property is managed by Bristol City Council'sCREATE Team and is open to the public daily:

Monday - Friday 12.00 noon - 3.00pm.To visit please contact the CREATE Centre,Smeaton Road, Bristol BS1 6XN

Tel: 0117 925 0505 or email: [email protected]

5.4 Alterations

Even where planning consent is not required,alterations to your property should be incharacter with the style of your house and theneighbourhood in general. For example, whenreplacing windows you should consider the style,proportions and materials suitable for yourhouse. Likewise, when repainting, re-renderingor re-pointing the exterior, you should respectthe original appearance of the property and itsrelationship to neighbouring buildings.

In older properties where timber sash orcasement windows are to be replaced, moderntimber versions will usually be preferred to anyother material for visual and sustainabilityreasons. It is rarely possible to achieve a goodreplica of older windows using uPVC. Not onlycan uPVC have an inferior appearance it isdifficult to repair and can releases harmfultoxins into the air when manufactured anddisposed of.

Changes to the external facing of a property,such as adding stone cladding or renderingbrickwork, needs careful consideration as it candetrimentally effect the appearance of theproperty. It is generally not recommended.

Bristol has a hilly landscape making manyproperties, and especially their roofs, particularlyvisible. As the shape, pitch and materials of aroof are an important feature of many homes,alterations affecting them should ensure theircharacter is retained. Pitched roofs areacceptable for most alterations, but they shouldbe set lower than the top of the main roof tomaintain its original character. Flat roofs may incertain circumstances be more appropriate andprovide the opportunity for a ‘living green roof’.

Elements such as chimneys stacks provide afunctional and attractive feature to many housesand so should not be removed.A l t e rat i o n s t o p ro m i n e nt ro o fs n e e d s c a re f u l

co n s i d e rat i o n

I n a p p ro p r i at e a l t e rat i o n s m ay e ro d e t h e c h a ra c t e ro f a p a r t i c u l a r p ro p e r t y a n d d e t ra c t f ro m t h ea p p e a ra n c e o f t h e s t re e t s c e n e . Re t a i n o r i g i n a lfe at u re s

Ta k i n g a d va nt a g e o f s o l a rg a i n i s a n i m p o r t a nt d e s i g n co n s i d e rat i o n


8

Many of Bristol’s houses are of a simple, well-proportioned design but often contain originalfeatures unique to a particular street. Whateverthe design or style of a property, where it formspart of a wider coherent street design it isimportant to ensure the original appearance ismaintained.

5.5 Extensions

Successful extensions usually appearsubservient to the original house. Over-largeextensions can affect the visual quality of anarea and the street scene, as well as unbalancethe appearance of the existing building. Tominimise the visual impact on the street,extensions should be located on the leastprominent elevations and, ideally at the rear.

To retain the existing character and appearanceof the property, the style, roof pitch, windowsand building materials used on any extensionshould generally match or respect those of theexisting building. High quality design alternativesmay also be acceptable.

Be a good neighbour

Care should be taken to ensure that yourproposals do not result in a significant loss ofsunlight, daylight or result in overshadowing ofyour neighbour’s property. Furthermore,extensions should not be overbearing, or resultin unacceptable overlooking or loss of privacy.

It is advisable to discuss your proposals withyour neighbours who may be affected so thatyou can address any concerns they may havebefore submitting a planning application. Thecouncil takes into account relevant planningobjections from neighbours when assessing aplanning application.

You will also need your neighbour’s permission ifyou intend altering a party wall, if any buildingworks encroaches or overhangs onto theirproperty, or if access is required for construction,or future repair or maintenance.

Extensions should not result in any significantloss of privacy to neighbouring houses andgardens. The best way of ensuring privacybetween houses is to avoid windows tohabitable rooms directly facing one another.Where this cannot be achieved and habitablerooms face each other, as a ’rule of thumb’, a gapof 21 metres should generally be provided. Inmore densely developed, inner urban locationsthis distance may be less. In exceptional cases,obscured glazing may be needed wherepotential overlooking problems cannot beovercome, or the window(s) set at an angle toavoid direct overlooking. Where windows tohabitable rooms face the end wall of a house thedistance should be not less than 12 metres.

The relative impact of an extension on theamenity of neighbours’ property may beincreased should there be a significant change inlevel between properties. In such situations itmay not be possible to design an extension thatwould be acceptable.

Loss of Daylight or Sunlight

Extensions should not cause any unreasonableloss of light or overshadowing to any existinghabitable rooms of neighbouring properties, orto gardens, in particular, to the area immediatelyto the rear of the house.

Where extensions are proposed the City Councilwill seek to prevent excessive daylight loss fromhabitable rooms of neighbouring properties. Inassessing proposals the City Council uses the

A n ex t e n s i o n s h o u l d b e d e s i g n e d t o m i n i m i s e t h ee ffe c t o n yo u r n e i g h b o u r ’s a m e n i t y


9

Building Research Establishments principlescontained in Site Planning for Daylight andSunlight: A Guide to Good Practice.

The likely impact of proposed extensions willnormally be assessed by a planning officer onsite, taking into account all relevant planningissues, including the sites general orientationand proximity of neighbouring properties.

Whilst not a planning issue, a property effectedby an extension may have ‘A right to light’ if ithas been enjoyed uninterrupted for 20 years ormore, granted by deed or registered under theRights of the Light Act, 1959. Planningpermission does not override a legal right tolight.

Loss of amenity space

When an extension to a property is proposed,the City Council will take into account thepotential loss of garden or private amenityspace. Extensions should maintain a usablegarden area to allow practical use and reflect theestablished character of the area and size ofhouse. The loss of such space should beminimised, particularly as extensions frequentlyallow for an increase in the number of residentsliving at a property.

Many houses have a direct access from the frontor side of the property to the rear other than bypassing through a habitable room. Wherealterations or an extension are proposed, anyexisting access should ideally be maintained.

Front Extensions and Porches

The front elevations of houses are the mostdifficult to alter or extend satisfactorily.Extensions that project forward of the buildingline will be required to make a positivecontribution to improving the character and theappearance of the area.

Small additions such as porches may bepermissible, but should generally echo the styleof the house and neighbouring properties,respect the existing roof pitch, windows, doorsand building materials.

8A n ex t e n s i o n t o o c l o s e t o a n e i g h b o u r ’s p ro p e r t ys h o u l d n o t c a u s e a d e t r i m e nt a l l o s s o f d ay l i g ht o rs u n l i g ht

84E S TA B L I S H E D B U I L D I N G L I N E

L a rg e ex t e n s i o n s o n t h e f ro nt o f p ro p e r t i e s a re g e n e ra l l y n o t a c c e p t a b l e


10

Side Extensions

The success of a side extension will generally bedetermined by its relationship to the style,character and appearance of the existingproperty.

i. Semi-Detached Houses

Side extensions to semi-detached houses shouldbe subservient to the existing house to maintainthe properties’ architectural integrity, thebalance of the pair and character of the street.

This can be achieved by setting back theextension from the front wall of the house, andstepping down the roof ridge height. As a guide,a minimum set back of 1 metre should beprovided.

An unsympatheticextension that has apoor relationshipwith the originalhouse end whichmay lead to a‘terracing effect’along a street. This is notacceptable.

A conventionaldesign solutionwhich is subservientto the originalhouse. Theextension is set backfrom the frontbuilding line of theoriginal house. Theroof ridge height isalso lower.

This solutionillustrates a firstfloor extension overa pre-existinggarage. In this casethe new upper flooris designed to followthe ‘subservient’principles.

An alternative to theabove is the ‘cat-slide’ solution withits large sloppingroof and dormerwindow. Thisperhaps has thestrongest characteralthough wouldprovide lessaccommodation.

8

4 4

4

Exa m p l e s o f go o d a n d b a d s i d e ex t e n s i o n s

4

44

4

Exa m p l e s o f s u c c e s s f u l s i d e ex t e n s i o n s


11

ii. Detached Houses

For detached dwellings there is greater flexibilityto extend the property and in many cases, it isless important for an extension to besubservient to the main house. However, this isdependent on the particular property and thecharacter of the area.

iii. End of Terraces

On end of terrace houses it is often moresuitable to continue the terrace building line androof ridge height so that the extension becomespart of the terrace.

iv. Gaps between Buildings

The gaps between detached or semi-detachedhouses are an important characteristic and theirin filling with side extensions can detract fromthe appearance of the neighbourhood. As acramped, ‘terracing effect’ can result, for thisreason, a side extension should ideally, wherespace is available, leave at least 1 metrebetween it and the adjoining boundary. Thisshould be larger if the existing properties havewider spaces between them.

8

4

4

4

A n ex t e n d e d d e t a c h e d h o u s e re f l e c t i n g t h e s c a l ea n d c h a ra c t e r o f t h e o r i g i n a l

A n ex t e n d e d t e r ra c e h o u s e

S i d e ex t e n s i o n s s h o u l d avo i d c re at i n g t e r ra c i n ge ffe c t


12

v. Extensions at Corners

Particular attention needs to be paid to thedesign of both single and two storey extensionson corner plots. This is because they canencroach over the building line on eitherhighway frontage, and therefore be particularlyprominent in the street scene. Over-dominantsolutions can sometimes create undesirablepinch points or enclosure at the entrance to aside road.

In the first instance, established buildings linesshould be respected. Developments includingside extensions on corner properties, whichbreak such lines, will not normally be permittedwhere the proposal harms the appearance ofthe street scene or open nature of the area.

Sufficient space should also be retained at theside of the site to ensure that the open aspect ofthe corner is retained.

The following general guidelines apply:

• Established building lines on both thestreet frontage and side should berespected. The presence of existingsubstantial hedging or fencing, orsubstantial highway verges would be takeninto account in assessing whether arelaxation to the above guidelines can bemade. This is particularly relevant for singlestorey extensions.

• The extension should not interfere with theforward visibility of drivers at junctions.

Before After

A cramped and enclosed feel can result if corner extensions occupy the entire space at the side of a property

8

BU I LDI NG LI N E

BUILDINGLINE

4

S i d e ex t e n s i o n s at co r n e r l o c at i o n s s h o u l d re s p e c t t h e e s t a b l i s h e d b u i l d i n g l i n e s a n d n o t e n c ro a c h b e yo n d t h e m

4


13

Rear Extensions

Extensions are usually most successful at therear of a property where they have the leastvisual impact on the neighbourhood and thecharacter of the street. However, they still needto be carefully designed to avoid a loss ofsunlight or daylight, and/or creating adetrimental sense of enclosure oroppressiveness to neighbouring properties.

You should consider the appearance and impactof your proposals from your neighbour’sproperty, particularly where there are significantdifferences in ground level or in the orientationbetween properties. A large rear extension mayalso have an adverse effect on your ownproperty by cutting off sunlight and/or daylightto existing rooms.

Rear Extensions

In assessing proposals for rear extensions theCity Council will use as a rule of thumb the ‘45°rule’. Extensions should be designed so as not tocross a 45° line (on plan and elevation) projectedfrom an adjoining neighbours’ nearest groundfloor habitable room window which isperpendicular to the proposed extension.

The reference point is the centre of theneighbours’ window to the extension. If theextension has a pitched roof then the top of theextension can be taken as the height of its roofhalfway along the slope.

The 45° rules of thumb seek to:

1. Maintain a reasonable relationshipbetween existing buildings and extensions;

2. Avoid an overbearing visual impact interms of bulk and proximity to boundariesboth from inside and adjacent propertiesand from neighbouring gardens; and,

3. Prevent excessive daylight loss orovershadowing to habitable rooms ofneighbouring properties.

Experience has shown that single-storey rearextensions should be designed to a maximumdepth of 3.5 metres but may need to besignificantly less in the case of terraced houses.

Permanent structures between properties suchas boundary walls, fences and hedges that affectthe application of the approach may justifyrelaxation of the tests.

450

3.5 metresmaximum

4

A s i g n i f i c a nt a m o u nt o f l i g ht i s l i ke l y t o b e b l o c ke di f t h e c e nt re o f t h e w i n d o w o n t h e ex i s t i n g b u i l d i n gl i e s w i t h i n t h e 4 5 ° l i n e , o r i f t h e ex t e n s i o n exc e e d s3 . 5 m e t re s i n d e p t h

R EA R E L EVATI O N

PA RT G RO U N D F LO O R P L A N

450

Two storey extensions can be problematic, andin any event are unlikely to be acceptablebeyond 2.75 metres.

On narrow width terraced properties, two storeyrear extensions are often not possible as theycan result in unreasonable loss of daylight oroutlook from adjoining houses, and/or adetrimental sense of enclosure oroppressiveness. Where such extensions areproposed the City Council will consider theabove rule of thumb and the context of the area.

The City Council will generally accept extensionsthat meet the above criteria although may relaxthese standards in consideration of the type orsize of property, its location within the city andthe historic context.


14

450 2.75 metres

maximum

A n a c c e p t a b l e f i r s t f l o o r re a r ex t e n s i o n

450

R EA R E L EVATI O N

PA RT G RO U N D F LO O R P L A N

1st floorextension

4


15

5.6 Alterations to Roofs

Loft Conversions

With loft conversions, the accommodationshould be lit by dormer windows or roof lightsset within the slope of the roof. Some roofs maynot be suitable for conversion as their pitch istoo shallow. In such situations, getting enoughheadroom may result in an overly large additionto the roof, which may have a detrimental effecton the character and appearance of theproperty. These will not normally be acceptableto the City Council. Some types of roofconstruction are also difficult to alter. They mayrequire substantial and costly building worksbefore an acceptable solution can be achieved.

Dormer Windows

There are many examples of inappropriatedormer window extensions that due to beingtoo large in relation to the roof-slope have a orpoor relationship to the original roof form. Toomany dormer windows in a roof slope may alsobe harmful. Large, box-like dormers areinappropriate for the majority of domesticproperties. To achieve a good design it isnecessary to pay particular attention to the sizeand form of the roof, and the arrangement andproportion of existing windows.

Traditional dormer windows obey recogniseddesign rules of scale, proportions and windowhierarchy. They are also subservient to the mainroof by being set comfortably within the slopeof the roof. In some cases however it may beappropriate to extend directly up from theexterior walls of the property.

8L a rg e b ox- l i ke ro o f a d d i t i o n s c a n u n b a l a n c e t h e a p p e a ra n c e o f t h e p ro p e r t y

Exa m p l e s o f go o d d o r m e r w i n d o w d e s i g n

Ty p i c a l d o r m e r w i n d o w d e s i g n s


16

The following are considered essential designcharacteristics of acceptable dormer windowsand are illustrated above:

• They are located only on the side or rearroof pitches;

• They sit comfortably within the plane of thehost building’s roof;

• They appear subservient in form to the roofof the host building;

• The front elevation of dormers arerestricted to the glazed area and necessaryconstruction width for dormer cheeks;

• The siting, scale and proportions of windowdetailing reflects that of the host building;

• Materials generally reflect that of the hostbuilding.

A n exa m p l e o f s u b s e r v i e nt d o r m e r w i n d o ws i n a s e m i - d e t a c h e d h o u s e

4

4

Exa m p l e s o f s u b s e r v i e nt d o r m e r w i n d o ws i n ad e t a c h e d h o u s e

F RO N T S I D E R EA R


17

Rooflights

Rooflights are anacceptable way ofallowing light into a loftspace as they maintainthe roof plane and haveless than dormerwindows visual impact.

Rooflights should not be of a size or numberthat will dominate the appearance of the roofslope. As such they should ideally be located onthe side or rear of a property. ‘Low profile’rooflights, which reduce projections above theroof finish are preferred as they have a reducedvisual impact. Light pollution from rooflightsshould also be considered and where possibleminimised.

Chimneys

As well as their purpose as a vent for fireplacesor modern gas fires, chimney stacks and theirpots can add character to a property and visualinterest to the roofscape. Where they exist theyshould be retained when alterations areproposed and in some cases, where extensionsare proposed, new ones included.

5.7 Balconies and Terraces

The addition of a balcony or terrace to aproperty above ground floor level can beparticularly problematic and in mostcircumstances would not be acceptable. Notonly may they allow direct overlooking intoneighbouring properties or private gardens, theycan also increase the general level of noise anddisturbance. The impact may effect both thoseat the sides and opposite the balcony/terrace inquestion.

A privacy screen can sometimes be used tomitigate against any overlooking ofneighbouring properties although this may notnecessarily overcome the level of noise anddisturbance. The impact of the screen in termsof its appearance or the sense of enclosure itmay have also needs careful thought.A ‘privacy’screen can sometimes be used to mitigateagainst any overlooking of neighbouringproperties. The impact of the screen in terms ofits appearance or the sense of enclosure it mayhave also needs careful thought.

Te r ra c e s a d d e d t o t wo h i s t o r i c p ro p e r t i e s w i t h ap r i va c y s c re e n e re c t e d o n t h e b o u n d a r y wa l l

A c c e p t a b l e exa m p l e s o f re a r t e r ra c e s

4


18

5.8 Garages and Parking

As with extensions, the design of garages andgarden buildings should generally respect thescale, character and materials of your property.

Ideally, garages at the side of a house should beset back from the main building line and a carspace provided in front of the garage. Where agarage directly fronts a pavement or highway,the garage doors should open in a way that willnot cause an obstruction to pedestrians orvehicles.

Parking

4

8

44

C u r t i l a g e p a r k i n g s c re e n e d b e h i n d b o u n d a r y wa l l s a n d e nt ra n c e g at e s

A n i nt e g ra l d e s i g n s o l u t i o n fo r a p o rc h a n d g a ra g e

G a ra g e s s h o u l d b e d e s i g n e d t o re s p e c t t h e c h a ra c t e r o f t h e h o u s e


19

Where a hardstanding for car parking andassociated pavement crossover are proposed,careful consideration should be given to theirposition as there may be a safety hazard withvehicles manoeuvring in and out and passingpedestrians and/or vehicles.

Where new entrances are proposed along aboundary these should retain as much originalwalling, fencing or railings as practical to ensurethe appearance of enclosure is preserved. Theconstruction of large open hard surfaced areascan have a significant and often detrimentalvisual impact on the setting to a house.

Where a hardstanding for car parking isproposed sufficient space for soft landscapingshould be incorporated to screen cars andminimise the visual impact of the hard surfacedarea. Planting can enhance residential areas andcan have excellent screening value. Its loss maycause privacy problems as well as reduce theattractiveness of an area. Space for the storageof a wheelie bin should also be considered.

The material used for the hardstanding shouldallow the permeability of rainwater through tothe subsoil rather than directly into stormdrains. This is a more sustainable means ofdealing with urban drainage.

For properties located within conservation areas,the City Council has further adopted designguidance with regard to how and when off-street parking may be achieved in the curtilageof residential dwellings. Further information canbe found in PAN 6, ‘Off-street Residential Parkingin Conservation Areas’.


20

6.0 ADVICE AND FURTHERINFORMATION

It is advisable to use a suitably qualifiedarchitect, or surveyor who is competent inproducing drawings, good design and othersupporting information should you wish tosubmit a planning application.

For copies of any of the guidance referred to inthis document, please contact the CustomerServices Team.

If you have a query of a general or factual nature(e.g. is planning permission required for aparticular proposal?), you are welcome to visitthe Planning Reception or telephone. If yourenquiry requires an opinion to be expressed, e.g.the likelihood of permission being obtained, andparticularly if you are a professional personacting on behalf of a client, please contact theCity Council in writing enclosing information toillustrate the proposals. The contact details are:

Planning Services

Planning, Transport & Sustainable Development

Bristol City Council

Brunel House

St. Georges Road

Bristol BS1 5UY

Customer Services

Reception/General Enquiries: Tel: (0117) 922 3097

Minicom: (0117) 922 3854

Email: [email protected]

Opening hours:

Mon, Wed & Thurs: 8.30am-5.00pm

Tue: 9.30am-5.00pm

Fri: 8.30am-4.30pm

7.0 BIBLIOGRAPHY

Bristol City Council, 1993Conservation Area Enhancement Statements

Bristol City Council, 1997Bristol Local Plan

Bristol City Council, 2003Proposed Alterations to the Bristol Local Plan

Bristol City Council, 2002Bristol Sustainable Development Guide forConstruction

Bristol City Council, 1994Policy Advice Note No. 4 Archaeology and Development

Bristol City Council, 1995Policy Advice Note No. 6Off-street Residential Parking in ConservationAreas

Joseph Rowntree Foundation (1997)Designing Lifetime Homes

Habinteg Housing Association (1992)Design Manual

Office of the Deputy Prime Minister, 2003Planning – A Guide for Householders’, What YouNeed to Know About the Planning System

Office of the Deputy Prime Minister, 2003Planning Policy Statement 12: Local DevelopmentFrameworks

P. J. Littlefair, Building Research EstablishmentReport, BR209, Garston, 1991Site Planning for daylight and sunlight: a guide togood practice


21

8.0 GLOSSARY

Amenity

The pleasant or normally satisfactory aspects ofa location which contributes to its overallcharacter and the enjoyment of residents orvisitors. (definition from the Planning Portalglossary of planning terms).

Building Line

A principal or flanking elevation of abuilding/group of buildings fronting a street.

Catslide Roof

A wedge shaped dormer or outshoot roof whichslopes in the same plane as the main roof.

Curtilage

The land around a property, forming acontiguous unit with it (e.g. the garden around ahouse).

Character

The combination of features of a building or anarea, such as their spatial relationship,landscape and building uses etc, that give itsdistinctive identity.

Conservation Areas

Conservation Areas are "areas of specialarchitectural or historic interest." Bristol hasdesignated 33 Conservation Areas with the aimof preserving or enhancing their character orappearance. Descriptions and policies for thefirst 29 Conservation Areas are available in theConservation Area Enhancement Statementsdocuments published in 1993.

Context

The setting of a site or area, including factorssuch as traffic, activities and land uses as well aslandscape spaces and built form.

Defensible Space

An area of semi-private space that is privatelyowned, surveyed, demarcated or maintained bysomebody.

Development Plan

A document (a Structure or Local plan) that setsout in writing and/or in maps and diagrams alocal planning authority’s policies and proposalsfor the development and use of land andbuildings in the authority’s area (definition fromthe Planning Portal glossary of planning terms).

Enclosure

Physical or sense of definition of space or area.

Fenestration

The arrangement, size and proportion ofwindows in a building.

Habitable rooms

These are considered to be the main roomswithin a house and include the living room,dining room, kitchen and bedrooms. Hallways,bathrooms, circulation areas or landings are nothowever considered to be ‘habitable’ rooms.

Listed Buildings

A building or structure identified by theSecretary of State for Culture, Media & Sport asbeing of special architectural or historic interest.There are three categories of listing: Grade I (thehighest quality), Grade II* and Grade II.

Local Distinctiveness

The essential character of a locality.

Local Plan

Statutory development plan prepared by a localplanning authority setting out detailed policiesfor environmental protection and development(definition from the Planning Portal glossary ofplanning terms).


22

Planning Policy Guidance Notes (PPGs)

A series of documents setting out governmentpolicy and advice on planning issues such ashousing and transport.

Policy Advice Note (PAN)

The City Council has produced a series of PolicyAdvice Notes which aim to encourage highstandards of development and environmentalquality in Bristol and raise awareness aboutsome of the design issues which the City Councilconsider priorities in development control. Thesenotes provide supplementary planning guidanceto in support of Local Plan policies.

Public Realm

The parts of a town or city open and accessiblefor general public use including streets, squaresand parks.

Ridgeline

The apex of the roof continued along the lengthof the roof span.

Roofscape

View resulting from a blend of roof pitches, sizesand heights within the built environment.

Roof pitch

Angle at which rafters form an apex from thesupporting walls.

Streetscape

The overall effect of street facades and linkedspaces.

Street Scene

That which is visible from the public domain.The street scene is considered to constitute anarea particularly sensitive to developmentproposals, requiring a high standard of design.

Supplementary Planning Document (SPD)

Additional advice or guidance issued by a localplanning authority, expanding on its statutorypolicies.

Sustainability

The principle that the environment should beprotected in such a condition and to such a degreethat ensures new development meets the needs ofthe present without compromising the ability offuture generations to meet their own needs

Townscape

The physical form and character of part of a built-up area.

Visual Amenity

The value of a particular area or view in terms ofwhat is seen.

Produced by Urban Design

Designed by Visual Technology, Bristol City Council

Job no. 0905-301BR