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Sussex Building Control’s guide to extending or converting your home 1

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2 Sussex Building Control’s guide to extending or converting your home

ContentS


About this Guide 5About Sussex Building Control 7What our clients say about us 9Introduction 11How to find a designer or builder 13How to plan your project 15Making a Building Regulation Application 17Self Certification 19Building an Extension 21Loft Conversions 28Garage Conversions 33Cellar Conversions 38Radon 43

We gratefully acknowledge the support of the firms whose advertisements appear throughout this publication.As a reciprocal gesture we have pleasure in drawing the attention of our readers to their announcements.It is necessary however for it to be made clear that, whilst every care has been taken in compiling this publication and the statements it contains, neither the promoter involved nor the Publisher can accept responsibility for any inaccuracies, or for the products or services advertised.Designed and published by Ten Alps Publishing, Trelawney House, Chestergate, Macclesfield, Cheshire SK11 6DW. Tel: (01625) 613000. www.tenalpspublishing.com Ref: BWC 2019 © LABC Publishing. All rights reserved.

this publication is also available as an ebook: www.extendingyourhome.com/sussex

01798 815574www.padwickbuilders.co.uk

Dove House, The Sinnocks, West Chiltington, RH20 2JX

Planning to completion• New Build • Extensions • Refurbs

• Kitchens & Bathrooms • Drive & Landscaping • Trained & Qualifi ed Staff


ABoUt tHIS GUIDe

It contains information on:

• TheBuildingRegulationsandhowtheyapplytotypicalhomeimprovementprojects

• TherolethatBuildingControlplaysinprotectingpeopleandhelpingthemcreatesafe,comfortable and energy efficient homes

• Howtofindadesignerorbuilder

• Buildinganextension

• Loftconversions

• Garageconversions

• Cellarconversions

• Radon

Thisguideisnotasubstituteforprofessionaladviceandwerecommendthatyouspeakto an architect or designer before you start work. Our registered partners will be happy to help visit www.horsham.gov.uk/buildingcontrol/labc-partner-architects

ThisguidehasbeenproducedbyLABCpublishingonbehalfof Sussex Building Control to provide advice and guidance to homeowners who are thinking about extending or improving their homes.


To find out if your work is covered by the Building Regulations visit the homeowner section of the LABC website www.labc.co.uk email: [email protected] tel: 01403 215151.

Tel: 01293 851 852 • 07570 363 809

Some of the Services we provide...

3 Beale Close, Broadbridge Heath, Horsham, RH12 3GY.

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ABoUt SUSSex BUIlDInG Control

Sussex Building Control is the Local Authority Building Control (LABC) service forHorshamDistrictCounciland Crawley Borough Council. Our building controlsurveyors,basedattheCouncilOfficesinHorsham,lookafterprojectsincentral and north Horsham and throughout Crawley.Inaddition,wehaveanofficein Steyning which serves the south of the Horsham district.

TheadvantagesofworkingwithLocalAuthority Building Control:

• LABCsurveyorsareexperienced,qualified and professional

• Thesurveyorshaveindepthknowledgeof ground conditions and know what you are likely to find below ground

• Theirknowledgecanhelpyouavoidcostly mistakes

• LABCistheonlytrulyindependentandimpartial building control provider

• Theyworkwithallparties,owners,architects and builders to help create safe and energey efficient buildings

• Theyarepubliclyaccountable

• Theycheckyourplansandinspectthework on site to make sure the design meets building regulations standards and the work is being done correctly using the materials specified

• Theserviceisnon-profitmaking

• TheBuildingRegulationsstandardsareimplementedinawaythatispractical,fair and professional

• Theirtechnicalexpertiseisthebestinthe industry

For more information please visit: www.horsham.gov.uk/buildingcontrol; email: [email protected] or call 01403 215151

Sussex Building Control C/O Horsham District Council Parkside, Chart Way, Horsham West Sussex RH12 1RL

Our offices are open from 9am – 5pm Monday to Friday. To speak to a building control surveyor please call after 3.00pm. Site visits take place between 10.30am and 3.30pm (approximately).

To make a building regulations enquiry visit www.planningportal.co.uk

Further advice is

also available from the

Planning Portal www.planningportal.co.uk


Call for a Quote: 0845 600 [email protected]

Building IssuesLeasehold Specialities

Having Disputes?

Acorn - Chartered Surveyors, 2 Kings Court, 57 Harwood Road, Horsham, West Sussex, RH13 5UR.

If you are moving home, minimise the risk of costly problems by obtaining one of our surveys or valuations.

As experienced Chartered Surveyors, we can advise you what to do about these problems and how they may affect the price you have agreed. We can also help you

with issues relating to an existing property.

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THAT My BuiLDeR WAS uSing THe LATeST

MATeRiALS i FeLT ReASSuReD THAT My

BuiLDeR WAS DOing A gOOD jOB.”

“WHen i ReMOveD THe WALL BeTWeen My LOunge AnD

Dining ROOM, BuiLDing COnTROL CAMe TO inSPeCT THe

WORk. THey COnFiRMeD THAT THe BuiLDeR HAD CARRieD

OuT THe WORk CORReCTLy AnD nOW, WHen i’M SiTTing

in My LOunge, i knOW THAT THe HOuSe iS SAFe AnD THe

CeiLing WOn’T FALL in On Me. i See BuiLDing COnTROL AS

A TyPe OF inSuRAnCe POLiCy!”

“i WOuLD Like TO THAnk SuSSex BuiLDing COnTROL FOR ALL THeiR HeLP WiTH THe WORk On My PROPeRTy – THe

inFORMATiOn THey PROviDeD MADe THe jOB A LOT eASieR!”

“THe BuiLDing COnTROL SuRveyOR WAS veRy HeLPFuL AnD CLeAR ABOuT WHAT We

neeDeD TO DO TO MAke SuRe THe WORk WAS SAFe.”

“BuiLDing COnTROL PROviDeS An

eFFiCienT SeRviCe THAT DOeSn’T geT

in THe WAy OF THe BuiLD.”

“THe BuiLDing COnTROL TeAM PROviDeD ASSuRAnCe THAT My BuiLD WAS DOne

CORReCTLy.”

“THe BuiLDing COnTROL inSPeCTOR WAS ALWAyS APPROACHABLe AnD

HAPPy TO DiSCuSS queRieS.”

“i WORk WiTH LABC BeCAuSe THe SuRveyORS

knOW THe LOCAL gROunD COnDiTiOnS AnD

CAn ADviSe Me On WHAT’S BeLOW gROunD. THe

ADviCe THey give HeLPS Me PROviDe A BeTTeR

SeRviCe TO My CuSTOMeRS AnD POTenTiALLy

SAveS THeM MOney.”

usWhat our clients

say about

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Whether you are looking for a full re-roof or minor repairs and generalmaintenance we apply the samestandards to all of our work no matterhow big or small the job.

LJT Roofing & Sons believe thateveryone should receive a greatservice that will protect their propertyfor many years.

Our skilled team are on hand to helpwith any queries that you may have.We are happy to help and offer freeadvice, non-obligatory quotes andestimates.

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Your home is probably one of your most valuable assets and a long-term investment which is why you need to make sure that building work is done properly so that it improves the value of your property.

Sussex Building Control helps you do that by making sure that your work complies withBuildingRegulationsStandards.TheBuilding Regulations help protect you from poor workmanship and ensure that your project is carried out correctly.

TheBuildingRegulationsdonotcoverquality of workmanship beyond that requiredtoensurethebasic,safeconstruction of the building so it is possible that even though your work complies with the Building Regulations it may not meet the finishing standards that you require. You should be mindful of this when you are entering into contractual arrangements with your builder.

Within England and Wales most building work is covered by the Building Regulations.Theseareminimumtechnicalstandards which have been set by the Government to ensure building work is carriedoutcompetentlyandsafely.TheBuilding Regulations cover most aspects of the work to ensure that your finished project isstructurallysafe,comfortable,energyefficient and accessible.

TheBuildingRegulationsprovideyouwithreassurance that your work is being carried out to a standard that will ensure your home remainsstructurallysafe.Theregulationsalso cover ventilation and insulation which meansthat,providingtheworkmeetsthe

standards,itwillprovideasafeandhealthyenvironment for your family to live in. If you work with a designer or builder who isanLABCregisteredpartner,youcanbesure they are designing and building in accordance with the building regulations.

IntroDUCtIon

within england and wales most construction work is covered by the Building regulations. these are technical standards set by the government and all but the most , minor building work, must conform to these standards

“

“Sussex Building Control’s guide to extending or converting your home 11

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As a well-established local team (and part of your Local Council) Sussex Building Control know most of the architects and builders whoworkinHorshamandCrawley.Infact,we have worked with most of them for more than 20 years.

ThroughtheLABCPartnerAuthorityScheme,SussexBuildingControlis‘partnered’ with a number of local charteredarchitects,architecturaltechnologists,plandrawers,contractorsand builders.

Theseindividualsandcompanieshavechosen to partner with us because of the service we provide to them and their

clients. We take the time to listen to their needs and work with them to provide solutions. Our relationship with these companies means that we can provide a service which is tailored to their needs. It also means that we can be sure their work meets building regulation standards.

So,ifyouarelookingforacompetentdesigner or builder look for companies who are registered with the LABC Partner Authority Scheme. You can easily identify those companies as they display the LABC Partner logo on their website and company literature and some of them also advertise in this guide.

How to FInD A DeSIGner or BUIlDer


For details of some of our partners please visit https://www.horsham.gov.uk/buildingcontrol/labc-partner-architects

01293 532005 • 07818 445392GET IN TOUCH TODAY FOR A FREE ESTIMATE!

42 Cotton Walk, Crawley, West Sussex, RH11 9SX.

• Extensions

• Renovations

• Home Improvements

• Garage/Loft Conversions

• Kitchens & Bathrooms

• Patios

• Structural Works

• Plastering

• Painting & Decorating

• Decking

• Upvc Fascia’s & Guttering

Email: [email protected]

Local family run electricalcontractors, specialising in domesticelectrics and new builds. we focuson 100% customer satisfaction.

Call 07980 653550Email: [email protected]


How to PlAn yoUr ProjeCtHow to PlAn yoUr ProjeCt Beforeyoubegindoyourresearch!TakealookattheLABCvideosonYouTube,the LABC website (www.labc.co.uk) and the Home and Build website (www.homeandbuild.co.uk).

Seek professional adviceUnless you are experienced in construction you will need to get professional advicefromanarchitect,architecturaltechnologist,plandrawerorbuilder.

Working with a designer Anarchitect,architecturaltechnologist,plan drawer or building surveyor will prepare drawings (plans) and specifications for your proposal and obtain the necessary approvals.Theycanalsohelpyoufindabuilder and project manage your build.

Working with a design and build companyA design and build company can offer a one-stop shop for construction projects. Theirdesigndepartmentwillpreparethe drawings and obtain the necessary approvals and their construction department will carry out the build.

Working with a builderAlways make sure you work with an experienced builder and preferably one that works with LABC. Some experienced builders may be able to offer you a package similar to the design and build companies.

PlAnnInG PerMISSIonPlease check whether you need Planning Permission. If you live in Horsham please visit www.horsham.gov.uk/planning/Pre-Application-Planning-Advice

If you live in Crawley please visit www.crawley.gov.uk/pw/Planning_and_Development/Planning_Permission___Applications/Do_I_Need_Planning_Permission_/index.htm

otHer PerMISSIonS yoU MAy neeDListed Building Consent: if your property isalistedbuildingorinaconservationarea,you may require Listed Building Consent. Thisincludeschangestotheexteriorandinteriorofthebuilding,plusalterationsand extensions to outbuildings within the curtilagethatwereconstructedpriorto1stJuly1948.Unauthorisedalterationstolistedbuildings are a criminal offence under the Planning (Listed Buildings and Conservation Areas)Act1990sopleasecontacttheCouncil’s planning team at an early stage to ensure the necessary permissions are obtained.

Party Wall Act: if your proposed project affects a Party Wall or you need to excavate foundations close to your neighbour’s house you may need to give them notice underthePartyWallAct.ThisisaCivilActand Building Control does not have any enforcingpowerundertheAct.Formoreinformation please visit www.gov.uk/party-wall-etc-act-1996-guidance

Protected trees: It is a good idea to check whether any nearby trees are protected. ThiscouldincludetreesprotectedbyaTreePreservationOrder(TPO),orthosewithin a Conservation Area. If you damage a protected tree either by lopping off branches or digging trenches you could be fined. Contact the Council’s planning team to find out whether any trees in the vicinity are protected.


Green Manor BuildingExtensions | New Builds | Refurbishments

T: 01273 495090 / M: 07713 118898 • E: offi [email protected]


MAkInG A BUIlDInG reGUlAtIonS APPlICAtIon

the Building Control ProcessWhen you employ a Building Control provider you are paying to have your plans checked and your building work inspected. You are also paying for the advice and guidancewegiveyou,yourbuilderorarchitect. You start by completing an application form and at the end of the project you will receive a Completion Certificate.

Sussex Building Control accepts Building NoticeApplications(forminorworks)andFullPlansApplicationsforallotherwork. If you are extending or converting yourhome,youshouldmakeaFullPlansApplication. Visit www.labcportal.co.uk.

A Full Plans ApplicationThisisrecommendedformajorbuildingwork because the surveyor checks the plans before you start building.

You (or your agent) submit the application form,plans,specificationsandfeetothe Local Authority and they issue your Acknowledgement Letter and Building ControlReferenceNumber.Thesurveyorchecks the plans and consults with the designer and once they are satisfied that theworkcomplies,theyissueaBuildingRegulationsApprovaltotheagent.ThisisknownasyourDecisionNotice.

You can start work any time after you receive the Acknowledgement Letter and Building Control Reference number – but it iswisetowaituntilyoureceivetheDecision

Notice.Thistakesapproximately3weeks(providing your application contains all the information they need in a format they accept). If they have to wait for additional information your decision notice can take upto8weeks.

Once work starts on site our surveyors liaise with your builder and inspect the work as it progresses. When the project is satisfactorily completed a Building Regulations Completion Certificate will be issued confirming that the project has been independently inspected and complied with the Building Regulations.

A Building notice ApplicationThisrouteisbestsuitedtosmallprojectsthat are carried out by a competent builder. It is not recommended unless your builder and architect/designer have lots of experience of the type of work you are doing and are fully aware of the requirements of the current Building Regulations.


IfyousubmitaBuildingNotice,youragentdoesn’t provide any plans which means the surveyor can’t confirm that the design complies with building regulations. You will not receive a Building Regulations Approval and the work will have to be checked on site as it progresses. Only use this route if you are confident that your builder is experienced and competent.

SubmityourBuildingNoticeApplication with a site location plan and payment of the fee.Uponreceipt,SussexBuildingcontrolwill issue your Acknowledgement Letter and Building Control Reference number. Youcanstartwork48hoursafteryoureceivethis.Onceworkstarts,abuildingcontrol surveyor will meet with your builder on-sitetodiscussyourintentions,andagree: • howtheworkshouldbecarriedout• whentheworkwillneedtobe

inspected • whetheranyfurtherinformationwillbe

required e.g. structural calculations or drawings.

Often,withabuildingnotice,customersfind that the build cost increases because theyneedtoaddfiredoors,ventilationorinsulation which hasn’t been considered at the start of the job.

If you want to use a building notice try to thinkaboutwhatmaterialsyouwillneed,andthecostofthese,attheoutset.

When the project is satisfactorily completed a Building Regulations Completion Certificate will be issued showing that the project has been independently inspected and that it complied with the Building Regulations.

SIte InSPeCtIonSBeforeworkstarts,SussexBuildingControlwill send you a Site Inspection Plan telling which stages of the build they want to inspect.Thesiteinspectionplanwillbedesigned around your project. You must give this to your builder so they can contact Sussex Building Control and arrange site inspections.Thesurveyorwillinspecttheworkasitprogresses,askthebuildertoalter something (if necessary) and make sure the work complies with the Building Regulations.Ifyouhaveanyconcerns,want Sussex building control to inspect somethingspecific,orwouldliketomeet to discuss the work please email [email protected] orcall01403215151.

CoMPletIon CertIFICAteSWhen your project has been satisfactorily completed and inspected to confirm that it complies with the Building Regulations wewillissueaCompletionCertificate.Thisis a legal document which you will need to produceifyouarere-mortgaging,insuringor selling your property.

Please make sure that you contact Sussex Building Control to carry out their final inspection at the end of the work (once your builder has finished but preferably before they have left site) so that they can sign it off and issue your Completion Certificate.

My builder advised me to submit a Full Plans application because my property renovation was complex and tricky. we wanted to be sure that all aspects of the build had been thought through at design stage so there were no expensive surprises during the build

“

“18 Sussex Building Control’s guide to extending or converting your home

Some minor work can be self-certified by contractors who are members of a competent persons’ scheme. Registered contractors can issue certificates to show the work complies.

Theseinclude:

• FENSA–forreplacementwindows;

• CERTASS–forreplacementwindows;

• GASSAFE–forinstallationsandalterationstogas,hotwaterandheatingsystems so long as the contractor is a registered installer and not just a service engineer;

• OFTEC–forinstallationof,andalterationto,oilburningboilersandappliances;

• HETAS–forinstallationofandalterationto solid fuel burning boilers and appliances;

• PartP–ElectricalContractorsregisteredunder one of the Part P schemes can issue certificates for domestic electrical work.

tIPS For workInG wItH SelF CertIFIeD ContrACtorS• Alwaysensurethecontractoris

registered for the work they are undertaking,eg.Ifyouarehavinga new heating system installed ensure the contractor is a registered installer notaserviceengineer;

• Alwaysensurethatattheendofthejob the contractor issues you with a Certificate confirming that the work complies with the Building

Regulations because you will need this whenyousellyourproperty;

• Ifyouareinanydoubtaboutanythingcontact the relevant trade association or contact Sussex Building Control for advice.

ThisisseparatetotheBuilding Control Process.

SelF CertIFICAtIon


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Thischaptercoverssomeofthetechnicalaspects that affect the design and construction of an extension. It also provides information on how the Building Regulations apply to this work.

Can your home be extended?Todecideifyourhomecanbeextendedyou should think about:

• Howyouwillgetinandoutofyourextension?

• Whetheryouhavethespacetoextend

• Theeffectyourextensionwillhaveonthe way you move around your home

• Theeffectyourextensionwillhaveonyour existing house and garden

• Willtheextensionblockoutlightfromexisting rooms or make some rooms unusable?

• Willyoustillbeabletogetintoyourgarden?

• Whatyourexistinghouseisbuiltfrom.Is it an unusual construction such as prefabricatedpanels,concreteframeetc?

• Whateffecttheextensionwillhaveonnearbytrees,especiallyyourneighbour’s

• Whetheranyofthesetreesareprotected

• Whetheryourextensionwillreceiveenough daylight/sunlight if nearby trees overhang it

teCHnICAl GUIDAnCeFoundations: the foundations are one of the most important and generally the mostexpensivepartsofthebuild.Fordomestic extensions trenchfill foundations arecommonlyused.Theseshouldbetaken

A well designed and constructed extension will enhance your property and add value.

BUIlDInG An extenSIon

your home is probably one of your most valuable assets and a major long-term investment which is why you need to make sure that any building work is done properly so that it improves the value of your property.

“

“Sussex Building Control’s guide to extending or converting your home 21

down into firm natural ground and are generallyaminimumof1mdeep.

Inareaswithclaysubsoil,treesupto20m away can have a significant effect on foundations which usually means that they needtobedeeper,sometimesasdeepas2.5m.Ifyouareconcernedaboutanytreesplease get in touch with Sussex Building Control and they will give you advice regarding foundation depths. If a tree causes a problem or adds to the cost of your work because the foundations need to be deeper,don’tassumeitcanberemovedasit might be protected.

If you have to keep the trees that are close to the area you have chosen for your extension,complexfoundationssuchaspiling,padandbeamora‘Housedeck’systemmayberequired.Formoreinformation visit www.labc.co.uk and take a look at the LABC Registered Construction Details(foundationcategory).

ground Floor: the ground floor supports thefloorloading,keepsoutdampandprovides thermal insulation. If your property is within a Radon Protection Zone (or if you’re not sure what this means) please see thesectiononRadononpage47becauseyou may need to carry out additional work.

Walls: the walls of your extension must carry the loads from the floors and roof,keeptheweatheroutandprovideinsulation.Cavitywalls,madeupfrombricks and blocks which are subsequently filled with insulation are commonly used for domestic extensions.

When building walls you must ensure that you:

• haveadequatesupportatthecornersofyourextension;

• havelintelsoveralldoorsandwindows;

• usewalltiestojointheleavesofyourcavitywalltogether;

• includeasuitabledampproofcourse;

If you are building up against your neighbour’s house you must ensure that your wall provides adequate sound resistance. Visit www.labc.co.uk/our-services/consultancy-services/acoustics

First Floor: a two storey extension will haveanupstairs.Thefirstfloorisgenerallymade up from timber floor joists which span betweenloadbearingwalls.Theysupportfloor boarding above and plasterboard is then fixed to the underside of the joists to provide a ceiling finish and fire resistance. Thesizeofthefloorjoistswilldependonthespan.Thefloorwillalsoneedtoincludesoundinsulation-100mmofsounddeadening mineral wool placed between the joists is generally sufficient for domestic extensions.

The Roof: the roof of your extension will need to be designed to protect you from the elements and provide you with some storagespace.Therearetwotypesofroofwhich are generally used for domestic extensions:

Flat Roofs: this is the simplest type of roof structure and for single storey extensions a flat roof can provide a practical and economic solution. Critical things to consider with this type of roof are the sizeandsupportoftheroofjoistsandtheinsulation and ventilation (if necessary

Pitched Roofs: pitched roofs are used whenflatroofsaren’tsuitable.Thesearegenerally more substantial structures andfinishedwithrooftilesorslates.Thesupporting structure of the roof can be formed in two ways:

Trussed Rafter Roofs: these are quick toconstruct,measurementsaretakenfrom site and roof trusses are made up in a factory and delivered to site ready for installation. Each roof is individually designed by the roof truss manufacturer usingspecialistcomputersoftware.Thismethod minimises the carpenter’s time on-site.


Traditional Roofs: A carpenter cuts a traditionalroofon-site.Theroofstructurewill generally be designed by an architect or structural engineer and the timber is then delivered to site where the carpenter will set out the roof and cut each of the individualtimberstosizebeforeinstallingthem.Thistypeofroofoffersthegreatestflexibility in roof shape and is often the only way of roofing complicated extensions especially where the new roof must join onto an existing structure.

Thesizeofthetimbersandsupportingbeams will depend on the loadings andspansinvolvedineachcase,complex roofs will require a structural engineer’s design.

Once the support is in place the roof must be covered to provide weather protection,pitchedroofsaregenerallyfinished with tiles or slates with a layer of roofing membrane or felt under

them.Forextensions,itiscommontousetiles or slates that match the main house although this is not always possible if the extension roof has a very low pitch.

Stairs: if your extension has more than one storey and you need to install a newstaircase,itshouldbedesignedinaccordance with the following guidance.

DID yoU know?“the clear

headroom over the stair should be at

least 2m.”


Width: In the Building Regulations there is no minimum width for stairs but they are generally850–1000mmwidesothattheyare wide enough to use.

Headroom: the clear headroom over the stair should be at least 2m.

Handrails and Balustrades: the stair should have a handrail which is at least 900mmhighandanyexposededgesofstairs or landings should have balustrading whichisalsoatleast900mmhigh.Thebalustrades should be designed so that they can not be climbed and do not have gapsexceeding100mm.

Fire Precautions: House fires can kill so it is important to think about how your family would escape in the event of a fire. Themostdangerousfiresgenerallyoccurat night when everyone is asleep so you should consider installing early warning devicessuchassmokealarms.TheBuildingRegulations suggest that when your house isextended,youinstallmainsoperatedsmoke alarms on each floor.

Topreventyourfamilybeingtrappedbyafire,allfirstfloorrooms,androomsthatdonotopendirectlyontoahall,shouldhavea window or door (known as a secondary fire escape) that is large enough to escape through.

If you are using a window as your secondary fire escape it should have a clear opening ofatleast0.33m2andbeatleast450mmwidewithacillheightofbetween800and1100mmabovefloorlevel.

If your extension is designed and built in accordancewiththeBuildingRegulations,you will be protecting your family from the dangers of fire.

ventilation: to create a comfortable and healthy environment for your family to livein,youneedtomakesureyouhavearegularsupplyoffreshair.Tohelpyoudothis,theBuildingRegulationsstatethatyourextension should have adequate ventilation such as a window with a ‘trickle vent’ in the

framethatcanbeopened.Thetrickleventis a small slot type vent (usually in the top of the window frame) which can be left open toallowfreshairin.Thewindowshouldhave an openable area equivalent to at least1/20thofthefloorareaoftheroom.Ifyourextensionhasakitchen,utilityroomorbathroom you’ll need to install an extractor fan in these rooms.

Drainage: you can usually connect the new drainageintoyourexistingsystems.Thereare two types of drainage: foul water and rainwater and they should be kept separate.

Fouldrainageisusuallydischargedthrougha series of pipes and manholes to a public sewer although some properties have septic tanks or private sewage treatment plants. When planning your extension check where the manholes are located and find out where your drains are running so you can decide how any new drains will connect to them. It is important that all new underground drain pipes have a diameterofatleast100mmtoensure theydonotblockorfreeze.Theymust also be watertight and have manholes or access points so that any blockages can be cleared.


If you share a drain with your neighbour the WaterAuthority(ThamesorSouthern)maybe responsible for the maintenance of the pipes and this could have an impact on your plans so please check with them before proceeding.Wherepossible,rainwaterdrainage should not be discharged to foul sewers because it can cause flooding. Rainwater should be discharged to soakaways in your garden (make sure they areatleast5mfromanybuilding)ortostormwatersewersiftheyareavailable,

When designing the routing of new drainagesystems,(stormwaterandfoul)andthepositioningofsoakaways,particularattention should be paid to nearby trees. Excavations and trenching should ideally be sited well outside the root protection area of any retained tree – for advice on root protection areas please consult a suitable arboricultural consultant. Routing trenches and other excavations through the root systems of trees can be expensive and cause severe damage to the tree.

NB:ifyoudamageaneighbourstree whichisprotected(iehasaTPO)youcouldbe fined.

Heating: if you want to heat your extension please check with your heating engineer that your existing system has the capacity to heat your extended house. If your extension isgoingtocovertheboilerflueoutlet,youwill need to move the boiler. Any alterations to your heating system should be carried out by a suitably qualified plumber or heating engineer registered with Gas Safe forgasfiredboilersorOFTECforoil fired boilers.

If you are installing a new boiler it must be a highly efficient condensing boiler and all new radiators should be fitted with thermostatic radiator valves so you can ensure that they use heat efficiently.

Sound insulation: if there are any bedroomsinyourextension,youwillneedtoinsulatethewallsandfloortominimizesoundtransmission.Thisisgenerallyachievedbyplacing100mmofsound


deadening quilt in the floor void and in the partitions around the bedrooms.

electrical installations: for most new electrical installations you need to provide buildingcontrolwithBritishStandardTestCertificates. Please ensure your electrical contractor is registered to provide these. Iftheyarenotprovided,SussexBuildingControl can arrange for a test to be carried out. Please ask your Building Control Surveyor about the cost of this service.

glazing:glazinginandarounddoorsandallglazingwithin800mmoffloorlevelshould be either toughened or laminated glass.Thisistoprotectpeoplefrominjury.

Solar panels: if you are thinking of installing solar panels please check whether planning permission is required. Check that the roof structure is strong enough to support them. If you need to strengthen the roof please submit a Building Regulations

applicationtous.Thinkcarefullyaboutwhere the panels will be placed to ensure they receive enough sunlight to make them efficient.Ifthereareoverhangingtrees,the amount of sunlight they receive will be limited.

Thermal insulation: the government is committed to reducing the amount of CO2 emissions and one of the ways they are doing this is by making sure buildings are properly insulated. High levels of insulation minimise the amount of heat lost from your home.

Theroof,wallsandfloorsofyourextensionshouldallincludethermalinsulation;generally,wallshaveinsulationwithinthecavity,roofshaveinsulationintheloftareaand floors have sheets of insulation placed beneath the concrete on the ground floor.

Windows are a major source of heat loss so 24mmdoubleglazingunitsincorporating


Conclusion: A well designed and constructed extension will enhance your property and add value. A poorly thought-out extension can reduce the value of your property and in some cases compromise your safety and the structural integrity of your home.

So make sure you:

• seekadvicefromanLABCpartnerarchitect(seepage13)

• planyourextensioncarefully

• employandexperiencedcontractor

TheBuildingRegulationsaretheretoprotectyouandtoensurethatbuildingsareconstructed to a reasonable standard. Your Local Authority Building Control team provide advice and guidance to help you achieve this visit


low emissivity glass are generally required. ThewindowareaofyourextensionislimitedbytheBuildingRegulationsto25%of the floor area plus the area of any existing openings covered by the extension. If you have carried out energy improvements elsewhere in your home you may be able to have a larger window area.

High levels of insulation can cause problems with condensation so make sure the rooms and roof have adequate ventilation.

You must also install energy efficient services such as low energy light fittings andheatcondensingboilers.Newheatingsystems should have suitable thermostats and controls.


Most houses have a large unused loft space that could be converted into an additional room.Thischaptercoverssomeofthetechnical issues that affect the design and construction of a loft conversion and provides information about how the Building Regulations apply to this work. Loft conversions are complex and must be done properly to ensure your home is safe for your family to live in. Always seek advice from a professional architect - see page xx for details.

Can your loft be converted?Todecidewhetheryourloftcanbeconverted you should think about:

• Whetherthereisenoughheadroomforyou to stand comfortably once the new floor is put in. Your new floor is likely to be around 200mm higher than your existing ceiling joists.

• Whethertheloftspaceislargeenoughfor you to create a useable room

• Whetherthereanychimneysorservicespassing through the loft space that will need moving

• Whethertheroofisfullyweathertight.

teCHnICAl GUIDAnCeThe Roof Structure: roofs are designed to protect you from the elements and the loft is designed to accommodate some lightstorage.Ifyouconvertyourloft,yourroof will have to cope with significantly

different loadings (more weight) because youwillhavetoinstallanewfloorstructure,possibly alter the structural elements to install roof windows and open up the room so you can move around it. Roofs are generally divided into two types.

Trussed Rafter Roofs: these have been commonsincethe1970sandaredifficultto convert. Roof trusses are complex pieces of engineering and they should not be altered without the advice of a structural engineer. When converting this type of roof it is common for a series of beams to be installed to provide support to the new floorandtostrengthentherafters,sothebracing sections of the trusses can be cut out to create a clear floor area.

loFt ConverSIonS...Awellconvertedloftisadefiniteassettoyourhome,itcan provide extra space and add value to your property.


Traditional Roofs: these are generally made up from a series of rafters and purlins spanning between load bearing walls. Theseroofsarelesscomplicatedtoconvertthan trussed rafter roofs but beams are generally required to provide support to the new floor structure and the existing purlins. A structural engineer’s design will be required for all but the simplest conversions.

Whenconvertingyourloft,don’tbetempted to simply board over your existing ceilingjoistsandrafters.Thestructurewon’t be strong enough or safe to use. It may also adversely affect the value of your property.

Accessing your Loft Conversion: if you wanttousetheloftasaproperroom,youwill need to install a staircase. If there’s enough headroom it is best to continue the stair from the existing stairwell because this saves space and gives a feeling of continuity.Ifthisisn’tpossible,you’llneed to partition off part of a room to

accommodate the new staircase which should be designed in accordance with the following guidance.

Headroom: the clear headroom over the stairshouldbeatleast2m,butinsomeinstances the Building Regulations allow youtohaveareducedheadroomof1.9moverthecentreofthestairand1.8montheoutsideedge.Forloftconversionswherespace is very limited and only one room iscreated,aspecialistalternatingtread

...loft conversions are complex so unless you are experienced in construction please seek professional advice

“

“


staircasecanbeused.Thesearesteeperthan standard stairs but can provide the valuable space you need.


Fire Precautions: House fires can kill so it is important that you consider how your family would escape from your home in the eventofafire.Themostdangerousfiresgenerally occur at night when everyone is asleep so you should consider installing early warning devices such as smoke alarms to allow you to escape. When converting yourloft,theBuildingRegulationsstipulatethatyoumustinstallmainspowered,interlinked smoke detectors in the hall and landing areas on every floor of your house. Firecankillsocarefuldesignandplanningare essential to ensure that the risks are minimised.

Creating a Two Storey House: the Building Regulations assume that if a fire occurred in a two storey house (and you were unable to escape down the stairs) youwouldjumporberescuedfrom,afirstfloor window. If you are converting the loft of a bungalow you must ensure that you have mains powered interlinked smoke detection on the ground and first floor and

A poorly converted loft can reduce the value of your property and compromise the safety of your home so make sure you build to building regulations standards.

“

“30 Sussex Building Control’s guide to extending or converting your home

all habitable rooms on the first floor have an ‘escape window’.

escape Windows: these are windows that are large enough for you to escape or be rescuedfrom.Theyneedtohaveaclearopeningareaofatleast0.33m2andaclearwidthofatleast450mm.Thebottomofthe opening light should be no more than 1100mmabovefloorlevelandtheyshouldallow you to escape to a place free from danger. Escape windows need to be fitted with escape hinges so that the window can be fully opened. Some of the standard hinges fitted to Upvc windows prevent the windows from fully opening so check with yourglazingsupplierwhenorderingthem.

Creating a Three Storey House: when you convert the loft of a house and create a third floor,theBuildingRegulationsrequireyouto consider the fire precautions a lot more seriously. Mains operated smoke detection needs to be fitted to provide early warning of a fire so your family can escape. As you will be unable to escape through the third floor window the only safe way out of the house will be down the stairs so it is vital that they are protected from fire. Which means all doors that open onto the stairs need to be half hour fire doors and the staircase should finish in the entrance hallwithadoortotheoutside.Generally,unless a sprinkler system or alternative fire escapeisprovided,stairsinthreestoreyproperties cannot finish in other rooms.

Four Storey Houses: if your house alreadyhasthreestoreys,loftconversionsbecome even more complicated as the means of escape in the event of a fire is more problematic. You may need to install a sprinkler system or a second escape stair which will need specialist design. Please email [email protected] and they will be happy to provide advice

Bathrooms: if you want to include a bath orshowerroominyourloftconversion,itisbest to put it above your existing bathroom so that you can connect pipes into the existing drainage and water supplies. Bath and/or shower rooms will also need

to be fitted with an extract fan to improve ventilation. It is a good idea to decide on the location of bathrooms at an early stage of the design.

Thermal insulation: the government is committed to reducing the amount of CO2 emissions and one of the ways they are doing this is by making sure buildings are properly insulated. High levels of insulation minimise the amount of heat lost from your home.Themostcommonwaytoprovideahigh level of insulation in a loft conversion is to install a high performance insulation board in between and below the rafters. If your roof doesn’t have a breathable felt you will need to leave a void above the insulation and ensure that you have effective roof ventilation to prevent the build up of condensation.

Heating: the most effective way of heating your loft conversion is to extend the existing central heating system. Check with your plumber or heating engineer that your boiler has sufficient capacity to serve the additional radiators. Any new radiators should be fitted with thermostatic valves to control the room temperature. If it is not possibletoextendtheexistingsystem,orifyoupreferanalternativemethodofheating,


e.g.electricpanelheaters,considerhowthese can be switched and controlled to ensure that they function efficiently.

Sound insulation: to reduce sound transmission the bedroom walls and floors willneedtobeinsulated.Thisisgenerallyachievedbyplacing100mmofsounddeadening quilt in the floor void and in the partitions around the bedrooms. If you are converting the loft of a semi-detached or terraced property you will need to ensure that the sound resistance of the Party Wall is also upgraded so that sound transmission to your neighbour’s is minimised.

electrical installations: for most new electrical installations you will need to provide building control with British StandardTestCertificates.Pleaseensureyour electrical contractor is registered to provideyouwiththese.IfTestCertificatesarenotprovided,SussexBuildingControlcan arrange for a test to be carried out on the installation (there is a charge for this service.) Please talk to your Building Control Surveyor for details.

Windows and ventilation: all new habitable rooms need to be ventilated. Generally this is achieved by providing an opening window or roof light (which has a trickle vent at high level) which is equivalent to1/20thofthefloorareaoftheroom. All new windows must be fitted with highly efficientdoubleglazedunits.Anextract

fan should be fitted in all bath and shower rooms.Inroomswithoutopeningwindows,extract fans that are triggered by the light switch with overrun timers that allow the fan to remain on after the light is turned off should be fitted.

Dormer Windows:Dormerwindowscan increase the amount of useable floor space in your loft conversion but they can have implications on the design of the conversion. Some dormers need planning permission–dependingonsizeandlocation. If the side of the dormer is less than1metrefromyourboundary,itwillneedtoachieve30minutesfireresistancefrombothsides.Thismeansyouwillneed to include special boards within the construction and this may restrict the use of somematerials,suchastimberboarding,on the outside.

Down Lighters:Flushfittingdownlightersareverypopularbut,ifyoufittheseitcouldmean that your conversion doesn’t comply with the requirements of the Building Regulations.Theyrequireyoutohaveacontinuous insulation layer and this can be difficult to achieve if you have limited construction space (particularly in a flat roof).Downlightersneedspacearoundthem to dissipate the heat which means that gaps have to be created in the insulation – and this does not comply with building regulations.

Conclusion: A well designed and constructed loft conversion will provide extra space and add value to your property. A poorly thought-out loft conversion can reduce the value of your property and in some cases compromise your safety and the structural integrity of your home.

So make sure you:







Can your garage be converted?If you have a brick or block garage which is attached to your house you can probably convertit.Todecidewhetheritissuitable,ask yourself the following questions:

• Doesyourgaragehaveanyknownproblemssuchascracks,damporaleaking roof?

• Hasthefloorbeencontaminatedwithfuel or oil?

• Isthereadoorfromthehousetothegarage or can one be put in easily?

• Willyouhaveenough/alternativeparking and storage space?

• Isthereenoughroominyourgaragetoprovide the accommodation you need or would it be better to extend your property?

GArAGe ConverSIonS

Certain ground conditions will effect the ground floor detail

If you need more space but don’t want to move you could considerconvertingyourgarage.Thischaptercoverssome technical aspects that affect garage conversions and provides useful information about how the Building Regulations apply to this work.


• Isyourexistinggaragebuiltfroman unusual construction such as prefabricatedpanels,concreteframeetc.?

• Isyourexistinggarageaffectedbytreesthat would impact upon the conversion?

Thenseektheadviceofaprofessionaldesigner–seepage13.

teCHnICAl GUIDAnCeinfilling the garage Door Opening: this is the most visible part of your conversion from the outside so think carefully before you deciding how to fill it in. You can fill it in withawall,windowordoor.Theinfillwillneed to be supported with a foundation. Some garages already have a foundation that runs across the garage opening which canbeused,butyouwillneedtodigaholeto check. If your garage doesn’t have a foundationunderthedoor,youhavetwooptions:

Option 1.Digafoundation1mdeeporto the same depth as the foundations of theexistinggarage,callSussexBuilding

Control to inspect it and then fill it with concrete.

Option 2.Installtwo150mmdeepconcrete lintels across the opening supported by the existing foundations but only if the opening is the width of a single garage door.

Oncethefoundationsareinplace,theopening can be filled in using either of the following options.

Option 1. Create a brick wall that matches the house and install a new window. You should insert a window that is narrower than the garage door opening as a full width window can appear out of proportion (please see the photo on page xx). It is best to use a cavity wall and install a new double-glazedwindowtokeepthedampoutandprovide insulation.

Option 2. Installalightweight,timberframed panel with a weatherproof external surfaceandinsulation.Thiscanbequickerandcheaperthanoption1andcaneasilyberemovedifyou,oranyfutureownersofthehouse,wanttoreinstatethegarage.


Whichever option you choose it is important that the infill provides adequate weather resistance and insulation and that all of the new work is tied into the existing construction.

Raising the Floor Level: garage floors are usually lower than the floor of the main house and slope towards the garage door so it is normal to raise them during theconversion.Thereareseveralwaysto do this but whichever you choose it is important to consider insulation and damp proofing.

Lining the external Walls: garages aren’t built to be lived in and their walls are often formed from a single thickness of brickwork or built from cavity masonry that isuninsulated.So,whenyouconvertyourgarage you will need to upgrade the walls.

When upgrading garage walls there are three key areas to consider:

• weatheranddampresistance;

• insulation;

• soundresistance.

Theupgradingschemewillbeinfluencedby the original construction of your garage walls and these can be broadly divided into two categories.

Cavity Walls: if your garage is built fromcavitywalling,weatherresistanceand damp proofing are unlikely to be aproblem.Thesewallsgenerallyhavedamp proof courses so if your wall is in good condition and is not showing signs ofwateringressorrisingdamp,itwillsimply require insulating and plastering ready for decoration.

Therearetwooptionsforinsulatingthewall: either the cavity can be injected with cavity wall insulation or an insulated lining board can be fixed to the inner face of the wall prior to plaster boarding or plastering. Various boards are available and your Building Control Surveyor will be happy to provide advice about ones that are suitable for your project.

Solid Brick Walls: these are generally only asinglebrickapproximately100mmthickwith intermediate piers that buttress the walls to give them additional strength. A single brick wall will not provide adequate weather resistance to a habitable room so a supplementary wall will be needed behindtheoriginalwall.Thiscanbedoneby building an additional skin of masonry to formacavitywall,whichcanbeinsulatedasthewallisbuilt,thendrylinedorplastered.Alternatively,anindependenttimberframed wall can be constructed with a cavity between the new framing and the existing wall.Theframeshouldbeconstructedfromtreated timber and insulation should be placed between the timber studs. Once the frameisinplace,aninsulatedplasterboardfinish can be applied ready for decoration.

Ifyourgaragewasbuiltwith225mmthick solid brick walls that are still in good conditionandhaveadampproofcourse,this should provide adequate weather resistance.Ifthisisthecase,youwilljustneed to line the walls with an insulating board to improve the insulation.

Party Walls: if any of the garage walls are shared with a neighbour they are consideredtobePartyWalls.Thesewalls


need to be upgraded to reduce sound transfer between your new room and your neighbour’s property.

The Ceiling: unless your garage already has an adequate ceiling you will need to provide one as part of the conversion. Plasterboard is the most common material used for ceilings as it has good fire resistance and flame spread properties. Other materials can be used but they usually need to be treated to improve their fire performance. If the garage is open to a roof you will need to provide insulation above the ceiling. Theroofvoidwillneedtobeventilatedabove the insulation to reduce the risk of problems with condensation. Inapitchedroof,fiberglassinsulationwill normally suffice but with flat roofs,wherespaceisconfined,highperformance insulation boards are often required.

Heating: if you want to heat your new room please check with your heating engineer that your existing system has the capacity to heat your extended house. Any alterations to your heating system should be carried out by a suitably qualified plumber or heating engineer registered with Gas Safe forgasfiredboilersorOFTECforoilfiredboilers. If you are installing a new boiler it must be a highly efficient condensing boiler and all new radiators should be fitted with thermostatic radiator valves so you can ensure that they use heat efficiently.

Drainage:ifyouwanttoincludeasink,bathroom,showerroomorcloakroomthinkabout your drainage at an early stage. Any new appliances will have to connect to your existing foul drainage system because they cannot be connected into rainwater drains. When planning your layouts make sure there are suitable routes for pipes to run to a point where they can be connected toexistingdrains.Wherepossible,avoidroutes through the root protection areas of trees.

Windows and ventilation: any new habitable rooms need to be ventilated. Generally this is achieved by providing anopeningwindowequivalentto1/20thof the floor area of the room with a trickle vent at high level. All new windows must be fitted with highly efficient double glazedunits.Theyshouldhaveanopenerwithaclearareaofatleast0.33m2and450mmwideandbigenoughforyoutoescapethroughiftherewasaoffire.Thisisessential if the door from your garage opens into another room rather than the entrance hall. Special fire escape hinges should be fitted to this window to ensure that it can be fully opened. In bath and/or shower rooms an extract fan should be fitted and in rooms without opening windows these should be triggered by the light switch and have overrun timers that allow the fan to remain on after the light is turned out.

Fire Precautions: home improvement work provides you with the ideal opportunity to check that you have adequate fire precautions in your existing house. Mains operated smoke alarms significantly improve your chances of escaping from a


housefire.TheBuildingRegulationsrequirethese to be installed when garages are converted to habitable rooms.

electrical installations: for most new electrical installations you need to provide buildingcontrolwithBritishStandardTest

Certificates. Please ensure your electrical contractor is registered to provide these. Iftheyarenotprovided,SussexBuildingControl can arrange for a test to be carried out. Please ask your Building Control Surveyor about the cost of this service.XET)

Conclusion: A well designed and constructed garage conversion will provide extra space and add value to your property. A poorly thought-out conversion can reduce the value of your property and in some cases compromise your safety and the structural integrity of your home.

So make sure you:







Can your cellar be converted?Todecideifyourcellarcanbeconvertedask yourself the following questions:

• Willtherebesufficientheadroominthecellar once the new ceiling and the floor treatments have been installed?

• Doesthecellareverflood?

• Canyouuseanexistingstaircasetoaccess the basement or will you have to install a new one?

• Willyouhaveenoughstoragespaceifyou convert your cellar?

• Isthereenoughroominyourcellartoprovide the accommodation that you need?

• Isthereventilationinyourcellarorcould any be provided?

Cellar conversions can be complex so,unlessyouareexperiencedinconstruction,youwillneedtogetsomeprofessional advice. Please see page xx.

teCHnICAl GUIDAnCeLowering the Cellar Floor: if there isn’t sufficient headroom in your cellar it is sometimes possible to lower the cellar floor.Thisisnotasimplejobanditmayundermine the foundations of yours or

yourneighbour’shouse.Thefloormayalso end up below the water table which will make the property more vulnerable to flooding. Seek advice from a specialist structural engineer if you are considering lowering the cellar floor.

Access: some cellars already have stairs but they may not provide suitable access to a habitable room. Your Building Control Surveyor will be happy to discuss this with you.Iftherearenosteps,oriftheexistingonesareinadequate,youwillneedtoinstalla new staircase. When considering where

CellAr ConverSIonSIf you have a cellar beneath your house you may be able toconvertit.Thischaptercoverssomeofthetechnicalissues that affect cellar conversions and provides information about how the Building Regulations apply to them.

DID yoU know?“the maximum pitch

for the stair should not exceed 42 degrees.”


to put the staircase think about the layout of theexistinghouseandcellar,theheadroomavailable and whether a secondary means of escape can be provided from the cellar. Thestairshouldbedesignedinaccordancewith the following guidance.

Width: In the Building Regulations there is no minimum width for stairs but they are generally850–1000mmwidesothattheyare wide enough to use.

Headroom: the clear headroom over the stair should be at least 2m.


waterproofing: as most cellars are underground they tend to suffer from damp

so it is vital that you damp proof your cellar. A number of systems are available and most use a proprietary waterproof system known as tanking which forms a continuous damp proof layer across the floor and up thewalls.Thesearenormallyinstalledbyspecialist companies who offer an insurance backed guarantee but your Building Control Surveyor will need to approve the installer and the details of the system before it is installed.

Fire Precautions: House fires can kill so you must consider how you are going to provide suitable escape routes from your cellar. If your cellar has a light well you mightbeabletoupgradeitsothat,aswellasprovidingventilation,itwillprovideasecondary fire escape.

Tobeconsideredasasecondaryfireescapeit would need to be fitted with a door or windowwithaclearareaofatleast0.33m2and450mmwide.Specialfireescapehinges should be fitted to this window to


ensure that it can be fully opened in the case of an emergency and you should be able to climb from the light well up to ground level easily. If you cannot provide asecondaryfireescape,thestaircasewillneed to finish in a fire protected entrance hall which has a door direct to the outside.

When you are improving your home it is a good opportunity to check that you have adequate fire precautions in your existing house. Mains operated smoke alarms significantly improve your chances of escaping from a house fire which is why the Building Regulations require them to be installed when cellars are converted to habitable rooms.

Drainage:ifyouwanttoincludeasink,bath/shower room or washing machine in your cellar it is important that you think about the drainage at an early stage. Any new appliances will need to connect to your existing foul drainage system which is probably above the level of the appliances that you wish to install. You will probably need to install a pumped drainage system and there are various package systems available that macerate the drainage and pump it via a small diameter pipe to the existing drainage system. When planning your layouts make sure that there are suitable routes for pipes to run to a point where they can connect to existing drains and avoid root protection areas of trees wherever possible.

The Ceiling: unless your existing cellar has an adequate ceiling you will need to provide one. Plasterboard is the most common material used for ceilings as it offers good fire resistance and flame spread properties. Other materials can be used but they will generally need to be treated to improve their fire performance. If the cellar,ortheroomabove,istobeusedasabedroomyouwillneedtoinstall100mmofacoustic quilt within the floor void between the rooms.

Heating: if you want to heat your new room please check with your heating engineer that your existing system has the capacity to heat your extended house. Any alterations to your heating system should be carried out by a suitably qualified plumber or heating engineer registered with Gas Safe forgasfiredboilersorOFTECforoilfiredboilers.

If you are installing a new boiler it must be a highly efficient condensing boiler and all new radiators should be fitted with thermostatic radiator valves so you can ensure that they use heat efficiently.

ventilation: all new habitable rooms need to be ventilated which can be problematic in cellar conversions. If there is a light well it might be able to be adapted to include anopeningwindowequivalentto1/20thof the floor area of the room (with a trickle vent at high level). If the cellar includes a bath/shower room an extract fan should be fitted. If there are any rooms without opening windows extract fans should be fitted that are triggered by the light switch with overrun timers that allow the fan to remain on after the light is turned off. If it isnotpossibletogetnaturalventilation,a mechanical ventilation system will need to be installed and various package systems are available. Ventilation should be considered early in the design stage because,ifmechanicalventilationis

DID yoU know?“all new habitable rooms need to be

ventilated”


required,theductworkwillneedtobedesigned.

Thermal insulation: CO2 emissions are a major environmental problem so you need to provide a high level of insulation within your conversion. Your cellar should have an insulated envelope to minimise theamountofheatloss.Thewallsandfloorshould be lined with insulating boards and the windows (if installed) should include 24mmdoubleglazingunitsincorporatinglow emissivity glass. You will also need to consider the efficiency of any services you install and low energy light fittings should

beusedwherepossible.Newheatingsystems should work to high levels of efficiency and have suitable thermostats and controls.

electrical installations: for most new electrical installations you need to provide buildingcontrolwithBritishStandardTestCertificates. Please ensure your electrical contractor is registered to provide these. Iftheyarenotprovided,SussexBuildingControl can arrange for a test to be carried out. Please ask your Building Control Surveyor about the cost of this service.

Conclusion: A well designed and constructed cellar conversion will enhance your property and add value. A poorly thought-out conversion can reduce the value of your property and in some cases compromise your safety and the structural integrity of your home.

So make sure you:







why is it a risk to our health?Radioactive elements decay and emit radiation. Any exposure to radiation is thought to be a risk to health - radiation is a form of energy and can cause damage in living tissues increasing the risk of cancer.

where is radon found?Radoniseverywhere;formedfromtheuranium in all rocks and soils. Outdoors everywhere and indoors in many areas the radon levels are low and the risk to health is small. Public Health England has

rADonRadonisacolourless,odourlessradioactivegas.Itisformedby the radioactive decay of the small amounts of uranium that occur naturally in all rocks and soils.

Figure 1 Routes by which radon enters a dwelling

Key to ingress routes

1 Through cracks in solid floors

2 Through construction joints

3 Through cracks in walls below ground level

4 Through gaps in suspended floors

5 Through cracks in walls

6 Through gaps around service pipes

7 Through cavities in walls


prepared maps indicating the chance of a buildinghavingahighradonlevel.ThesemapscoverEngland,Wales,ScotlandandNorthernIreland.Butevenintheareaswiththe highest chance of a building having a high radon level not all buildings will have highlevels.Themapscanbeviewedatwww.UKradon.org.

what is a low level?Theamountofradonismeasuredinbecquerelspercubicmetreofair(Bqm-3).TheaveragelevelinUKhomesis20Bqm-3.Forlevelsbelow100Bqm-3,yourindividual risk remains relatively low and notacauseforconcern,however,theriskincreases as the radon level increases.

How does radon enter a building?Thefloorsandwallsofdwellingscontainmany small cracks and gaps formed during and after construction. Radon from the ground is drawn into the building through these cracks and gaps because the atmospheric pressure inside the building is usually slightly lower than the pressure intheunderlyingsoil.Thissmallpressuredifference is caused by the stack (or chimney) effect of heat in the building and by the effects of wind.

radon protective measuresThesecanbeincludedrelativelyeasilyandcost-effectively during the building of your extension.

All extensions which fall within a full or basic radon protection area will be required to incorporate an appropriate level of radon protection if a new ground floor is provided.

Fullradonprotection:inthissituation,thedampproofmembrane(minimum1200g)acts as the radon barrier so it is important that the membrane extends through the cavity and is linked with a cavity tray. In addition,asubfloorsumpisalsorequiredandiftheexistinghousehasasolidfloor,this can be used to reduce the level of radon in both the extension and the existing building.

Basic radon protection: Only the continuous dampproofmembraneisrequired.Thedetailing in both cases will depend on the type of construction used and the positioningofthedampproofmembrane,your Building Control Surveyor will be able to give you further guidance.

Wherever possible the construction joint between the new floor and the existing house should be sealed. Where radon barriers have been incorporated in both thenewfloorandtheexistingfloor,theaimshould be to joint the two barriers where theymeetwithinthewallofthehouse.Thisis difficult to achieve in practice without damaging the existing barrier and a simpler alternative is to cut a chase in the wall slightly above or below the existing one to tuck the new barrier in to.

If the existing house has a beam and block orsuspendedtimberfloor,careshouldbe taken to ensure that the provision of subfloor ventilation is maintained.

It is recommended that you have your house measured for radon before plans are prepared. Ideally measurement should beoveratleast3months;PublicHealthEngland can provide detectors for this purpose. If radon levels at your property exceed the current recommended action level,youcanincorporateappropriateprotection measures into your building project.

uSeFuL COnTACTS

CentreforRadiation,ChemicalandEnvironmentalHazards

Chilton,Didcot,Oxon.OX110RQ Telephone+44(0)1235822622 Fax+44(0)1235833891 www.ukradon.org

British Geological Survey

Keyworth,NottinghamNG125GG E-mail: [email protected] Telephone:01159363143 Fax:01159363276 www.bgs.ac.uk/radon


DISCLAIMER

The information about the Building Regulations is accurate at the time of printing June 2019 but Building Regulations are updated and amended on a regular basis so for the most up to date information please visit: www.labc.co.uk

CONTACTS

Sussex Building control, C/O Horsham District Council, Parkside, Chart Way, Horsham, West Sussex RH12 1RL

T: 01403 215151

Email: [email protected]

Web: www.horsham.gov.uk/buildingcontrol

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LABC

Third Floor, 66 South Lambeth Road, London. SW8 1RL

T: 020 7091 6860

www.labc.co.uk

Useful websites

www.horsham.gov.uk/buildingcontrol

www.crawley.gov.uk

www.westsussex.gov.uk

www.labc.co.uk


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