GUIDE TO EXTENDING HOME OR CONVERTING YOUR · 2016-12-05 · Thermo Graphic Survey PAT Tes ng...

HOMEGUIDE TO EXTENDING

OR CONVERTING YOUR

LOFT CONVERSIONS • GARAGE CONVERSIONS • CELLAR CONVERSIONS • DOMESTIC EXTENSIONS

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Peterborough City Council guide to extending or converting your home 1

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We specialise in a variety of electrical andmechanical services in the commercial, industrialand domestic sectors.Services we offer:• Electrical test• Electrical installation• Portable appliance testing• Heating installation and servicing• Plumbing• Gas servicing and installation• Gas appliance comissioning• Gas testing and purging• Fault finding and repair• Bespoke control panel design and manufacture• Intruder and fire alarms• It solutions• Air conditioning• On site maintenance

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The complete Architectural design service i-Lid Design Ltd is an architectural design company based in Peterborough who have a vast experience in both home

extensions, home remodeling and new build dwellings.What we offer:• Scheme design• Preparation of drawing packages for obtaining planning

and building regulations including Listed Buildings• Detailed drawing packages suitable for contractor pricing• Co-ordination with structural engineers and energy

assessment consultants• Interior design services • Personalised staged project fee packages • Initial site visit and consultation at no chargeWhy not email us with your specific project details. We canthen book in a free appointment to visit you and discussyour requirements prior to preparing your tailored feeproposal.

Norman's Roofing Service is the professional and reliable roofing service based in Peterborough andsurrounding areas.

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2 Peterborough City Council guide to extending or converting your home

Contents


About this Guide 5About Peterborough Building Control 7Introduction 9How to find a designer or builder 11How to plan your project 13Making a Building Regulation Application 15Self Certification 17Building an Extension 19Loft Conversions 27Garage Conversions 32Cellar Conversions 37Radon 41

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 LABC Publishing (part of zinc media), Kings House, Royal Court, Brook Street, Macclesfield, Cheshire SK11 7AE. Tel: (01625) 613000. www.zincmedia.com Ref: PQX 2016 © LABC Publishing. All rights reserved.

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

QUALITY BUILDERRELIABLE SERVICE

All Types of Building Workincluding:

� Alterations� Renovations� Wet Rooms

� Disability Alterations and New Work� All Types of Flooring

GREAVESBUILDERS

Tel: 01733 321 037Mobile: 0797 0396598

Peterborough

� Project Management

� Party Wall Surveyors

� Principal Designer

� Health and Safety ManagementAssistance in carrying Principal

Designer Duties

Direct Power

M: 07889667120E: [email protected]

Part P registered with ELECSA

� domestic and commercialelectrical installations

� electrical certification andcondition reports

� data cabling

� pat testing

AdvERt


ABoUt tHIs GUIDe

It contains information on:

• TheBuildingRegulationsandhowtheyapplytotypicalhomeimprovementprojects

• TherolethatBuildingControlplaysinprotectingpeopleandhelpingthemcreatesafe,comfortable and energy efficient homes

• Howtofindadesignerorbuilder

• Buildinganextension

• Loftconversions

• Garageconversions

• Cellarconversions

• Radon

this guide is not a substitute for professional advice and we recommend that you speak to an architect or designer before you start work. Our registered partners will be happy to help.

this guide has been produced by LABC publishing on behalf of Peterborough 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: 01733 453422.

DARBUILD ENERGY LTD

11 Oakley DriveSpalding

LincolnshirePE11 2BN

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ABoUt PeteRBoRoUGH BUIlDInG ContRol

Peterborough Building Control is the Local Authority Building Control (LABC) service for Peterborough City Council PCC building control are based at the town Hall and are in close proximity to your project. the Peterborough City Council area includes both the ever expanding city core together with the surrounding rural area and villages. Peterborough is also fortunate to have Europe’s largest brown-field development which will eventually include over 8000 new homes and all the associated infrastructure.this sustained development ensures that the building control service has continual involvement with major construction projects including recently a new spectator stand for Peterborough United Football Club,variousextracarefacilities,numerousschool and university buildings including the PeterboroughUTC,moregeneralofficeandcommercialschemes,andinthelastyear alone over 200 apartment units in the London area and the East London University technical College in dagenham.We are keen to promote the LABC Partnership Scheme which enables the Peterborough City Council building control service to carry out the plan check process for construction works throughout England and Wales. Our current business partners include national bodies such as vinci Construction,WorkmanLLPandAgeUK,through to local architects and contractors.Peterborough City Council’s building control office employs a number of qualified buildingsurveyors,aswellasaconsultantstructuralengineer,andarenownedaccessspecialist. the advantages of working with Local Authority Building Control:

• LABCsurveyorsareexperienced,qualified and professional

• Thesurveyorshaveindepthknowledgeof local 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 energy efficient buildings

• Theyarepubliclyaccountable• Theycheckyourplansandinspectthe

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

• Theserviceisnon-profitmaking• TheBuildingRegulationsstandardsare

implementedinawaythatispractical,fair and professional

• Theirtechnicalexpertiseisthebestinthe industry

For more information please visit: https://www.peterborough.gov.uk/council/planning-and-development/planning-and-building/ or call 01733 453422

Peterborough Building Control Town Hall, Bridge Street, Peterborough PE1 1HF

Our offices are open from 9am – 5pm Monday to Friday.

Site visits take place between 10.30am and 3.30pm (approximately).

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


Halo BUILDINGSERVICES

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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.

Peterborough Building Control helps you do that by making sure that your work complies with Building Regulations Standards. the Building Regulations help protect you from poor workmanship and ensure that your project is carried out correctly.

the Building Regulations do not cover quality 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. these are minimum technical standards which have been set by the Government to ensure building work is carried out competently and safely. the Building Regulations cover most aspects of the work to ensure that your finished project isstructurallysafe,comfortable,energyefficient and accessible.

the Building Regulations provide you with reassurance that your work is being carried out to a standard that will ensure your home remains structurally safe. the regulations also 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

“

“Peterborough City Council guide to extending or converting your home 9

GMF BUILdERS 453453

WET ROOMS

BATHING SOLUTIONS

RESTORATION

www.peterboroughwetrooms.co.uk

[email protected]

01406 331332

07761 935792


As a well-established local team (and part of your Local Council) Peterborough Building Control know most of the architects and builders who work locally.Infact,wehaveworked with most of them for many years.

through the LABC Partner Authority Scheme,SussexBuildingControlis‘partnered’ with a number of local charteredarchitects,architecturaltechnologists,plandrawers,contractorsand builders.

these individuals and companies have chosen 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


� New builds

� Extensions

� Loft conversions

� Garage conversions

� Kitchens & bathrooms

08456 808608

07940 [email protected]

Renovating the Past Building the Future

Humphrey Demolition

David Humphrey & Son – Cambridgeshire’s Premier Independent Demolition Contractor.

Based in Gore� eld near Wisbech in North Cambridgeshire, David Humphrey & Son o� er a range of Demolition and other services Nationwide and are the only demolition company in the area to be licensed to recycle waste aggregate.While maintaining the advantages of a small family run business we have surprised many who don’t know us by taking the “Demolition Apprentice of the Year” title twice at the National Construction College, demonstrating our commitment to training and the maintenance of high standards.If you have a project that requires professional demolition services you can do no better than contact us. You’ll be pleased with our price and impressed by our results.

Telephone: 01945 410340 Andrew: 07860 570885 Fax: 01945 410710

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HoW to PlAn YoUR PRoJeCtHoW to PlAn YoUR PRoJeCt Before you begin do your research! take alookattheLABCvideosonYouTube,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. they can also help you find a builder 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. their design department will prepare the 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 Peterborough please visit https://www.peterborough.gov.uk/council/planning-and-development/

planning-and-building/do-i-need-planning-or-building-permission/

otHeR PeRMIssIons YoU MAY neeDListed Building Consent: if your property isalistedbuildingorinaconservationarea,you may require Listed Building Consent. this includes changes to the exterior and interiorofthebuilding,plusalterationsand extensions to outbuildings within the curtilage that were constructed prior to 1st July 1948. Unauthorised alterations to listed buildings are a criminal offence under the Planning (Listed Buildings and Conservation Areas) Act 1990 so please contact the Council’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 under the Party Wall Act. this is a Civil Act and Building Control does not have any enforcing power under the Act. For more information 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. this could include trees protected by a TreePreservationOrder(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.


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.

Peterborough Building Control accepts Building Notice Applications (for minor works) and Full Plans Applications for all other work. If you are extending or convertingyourhome,youshouldmakea Full Plans Application. https://www.peterborough.gov.uk/council/planning-and-development/planning-and-building/apply-for-planning

A Full Plans Applicationthis is recommended for major building work 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 Control Reference Number. the surveyor checks the plans and consults with the designer and once they are satisfied that theworkcomplies,theyissueaBuildingRegulations Approval to the agent. this is known as your decision Notice.

You can start work any time after you receive the Acknowledgement Letter and Building Control Reference number – but it is wise to wait until you receive the decision

Notice. this takes approximately 3 weeks (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 up to 8 weeks.

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 Applicationthis route is best suited to small projects that 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.

Submit your Building Notice Application with a site location plan and payment of the fee.Uponreceipt,Peterborough Building control will issue your Acknowledgement Letter and Building Control Reference number. You can start work 48 hours afteryoureceivethis.Onceworkstarts,a building control surveyor will meet with your builder on-site to discuss your intentions,andagree:• howtheworkshouldbecarriedout• whentheworkwillneedtobe

inspected • whetheranyfurtherinformationwillbe

required e.g. structural calculations or drawings.

Occasionally,withabuildingnotice,customers find that the expected build cost increases because they need to add fire doors,ventilationorinsulationwhichhasn’tbeen considered at the start of the job.

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,Peterborough Building Control will send you a Site Inspection Plan telling which stages of the build they want to inspect. the site inspection plan will be designed around your project. You must give this to your builder so they can contact Peterborough Building Control and arrange site inspections. the surveyor will inspect theworkasitprogresses,askthebuilderto alter something and make sure the work complies with the Building Regulations. If youhaveanyconcerns,wantPeterborough building control to inspect something specific,orwouldliketomeet to discuss the work please email [email protected] or call 01733 453422.

CoMPletIon CeRtIFICAtesWhen your project has been satisfactorily completed and inspected to confirm that it complies with the Building Regulations we will issue a Completion Certificate. this is a legal document which you will need to produceifyouarere-mortgaging,insuringor selling your property.

Please make sure that you contact Peterborough 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

“

“16 Peterborough City Council 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.

these include:

• 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 Peterborough Building Control for advice.

this is separate to the Building Control Process.

selF CeRtIFICAtIon



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this chapter covers some of the technical aspects 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?to decide if your home can be extended you 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 most expensive parts of the build. For domestic extensions trenchfill foundations are commonly used. these should be taken

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.

“


down into firm natural ground and are generally a minimum of 1m deep.

Inareaswithclaysubsoil,treesupto20m away can have a significant effect on foundations which usually means that they needtobedeeper,sometimesasdeepas2.5m. If you are concerned about any trees please discuss with your designer 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 foundationsneedtobedeeper,don’tassume it can be removed as it 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’system may be required. For more information visit www.labc.co.uk and take a look at the LABC Registered Construction details (foundation category).

GROund FLOOR: the ground floor supportsthefloorloading,keepsoutdamp and provides thermal insulation. If your property is within a Radon Protection Zone (or if you’re not sure what this means) please see the section on Radon on page 41 because you 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 have an upstairs. the first floor is generally made up from timber floor joists which span between load bearing walls. they support floor boarding above and plasterboard is then fixed to the underside of the joists to provide a ceiling finish and fire resistance. the size of the floor joists will depend on the span. the floor will also need to include sound insulation - 100mm of sound deadening 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 can often provide you with some storage space. there are two types of roof which 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 size and support of the roof joists and the insulation and ventilation (if necessary

Pitched Roofs: these are generally more substantial structures and finished with roof tiles or slates. the supporting 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 using specialist computer software. this method minimises the carpenter’s time on-site.


Traditional Roofs: A carpenter cuts a traditional roof on-site. the roof structure will 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 individual timbers to size before installing them. this type of roof offers the greatest flexibility in roof shape and is often the only way of roofing complicated extensions especially where the new roof must join onto an existing structure.

the size of the timbers and supporting beams 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 generally 850–1000mm wide so that they are 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 900mm high and any exposed edges of stairs or landings should have balustrading which is also at least 900mm high. the balustrades should be designed so that they can not be climbed and do not have gaps exceeding 100mm.

FiRE PRECAuTiOnS: House fires can kill so it is important to think about how your family would escape in the event of a fire. the most dangerous fires generally occur at night when everyone is asleep so you should consider installing early warning devices such as smoke alarms. the Building Regulations suggest that when your house isextended,youinstallmainsoperatedsmoke alarms on each floor.

to prevent your family being trapped by a fire,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 of at least 0.33m2 and be at least 450mm wide with a cill height of between 800 and 1100mm above floor level.

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,youneedtomakesureyouhavearegular supply of fresh air. to help you do this,theBuildingRegulationsstatethatyourextension should have adequate ventilation such as a window with a ‘trickle vent’ in the

frame that can be opened. the trickle vent is a small slot type vent (usually in the top of the window frame) which can be left open to allow fresh air in. the window should have an openable area equivalent to at least 1/20th of the floor area of the room. If yourextensionhasakitchen,utilityroomorbathroom you’ll need to install an extractor fan in these rooms.

dRAinAGE: you can usually connect the new drainage into your existing systems. there are two types of drainage: foul water and rainwater and they should be kept separate.

Foul drainage is usually discharged through a 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 diameter of at least 100mm to ensure they do not block. they must 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 Water Authority (Anglian Water) may be responsible for the maintenance of the pipes and this could have an impact on your plans so please check with them before proceeding. Rainwater drainage should not be discharged to foul sewers because it can cause flooding. Rainwater should be discharged to soakaways in your garden (make sure they are at least 5m from any building) or to storm water sewers if they areavailable,

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: if you damage a neighbours tree which is protected (ie has a tPO) you could be 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 is going to cover the boiler flueoutlet,youwillneedtomovetheboiler.Any alterations to your heating system should be carried out by a suitably qualified plumber or heating engineer registered with Gas Safe for gas fired boilers or OFtEC for oil 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,youwillneedto insulate the walls and floor to minimize sound transmission. this is generally achieved by placing 100mm of sound


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

ELECTRiCAL inSTALLATiOnS: for most new electrical installations you need to provide building control with British Standard test Certificates. Please ensure your electrical contractor is registered to providethese.Iftheyarenotprovided,Peterborough Building Control can arrange for a test to be carried out. Please ask your Building Control Surveyor about the cost of this service.

GLAzinG: glazing in and around doors and all glazing within 800mm of floor level should be either toughened or laminated glass. this is to protect people from injury.

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 application to us. think carefully about where 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.


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(see page XX)

• planyourextensioncarefully

• employan experienced contractor

the Building Regulations are there to protect you and to ensure that buildings are constructed to a reasonable standard. Your Local Authority Building Control team provide advice and guidance to help you achieve this visit


Windows are a major source of heat loss so 24mm double glazing units incorporating low emissivity glass are generally required. the window area of your extension is limited by the Building Regulations to 25% 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 and heat condensing boilers. New heating systems should have suitable thermostats and controls.



know the feeling?

www.morspacelofts.co.uk

Many houses have a large unused loft space that could be converted into an additional room. this chapter covers some of the technical 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?to decide whether your loft can be converted 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 common since the 1970s and sometimes more difficult to convert as internal walls are not constructed off a foundation. 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 floor and to strengthen therafters,sothebracingsectionsofthetrusses 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. these roofs are less complicated to convert than 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 ceiling joists and rafters. the structure won’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 you to have a reduced headroom of 1.9m over the centre of the stair and 1.8m on the outside edge. For loft conversions where space is very limited and only one room iscreated,aspecialistalternatingtreadstaircase can be used. these are steeper

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

“

“


than 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 event of a fire. the most dangerous fires generally 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. Fire can kill so careful design and planning are 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 all habitable rooms on the first floor have an ‘escape window’.

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.

“


Escape Windows: these are windows that are large enough for you to escape or be rescued from. they need to have a clear opening area of at least 0.33m2 and a clear width of at least 450mm. the bottom of the opening light should be no more than 1100mm above floor level and they should allow 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 your glazing supplier when ordering them.

Creating a Three Storey House: when you convert the loft of a house and create athirdfloor,theBuildingRegulationsrequire additional protection measures. 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 hall with a doortotheoutside.Generally,unlessasprinkler system or alternative fire escape is provided,stairsinthreestoreypropertiescannot finish in other rooms.

Four Storey Houses: if your house already hasthreestoreys,loftconversionsbecomeeven 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.

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. the most common way to provide a high 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 will need to be insulated. this is generally achieved by placing 100mm of sound deadening 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 Standard test Certificates. Please ensure your electrical contractor is registered to provide you with these. If test Certificates arenotprovided,Peterborough Building Control can 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 to 1/20th of the floor area of the room. All new windows must be fitted with highly efficient double glazed units. An extract 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: dormer windows can 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 – depending on size and location. If the side of the dormer is less than1metrefromyourboundary,itwillneed to achieve 30 minutes fire resistance from both sides. this means you will need to include special boards within the construction and this may restrict the use of somematerials,suchastimberboarding,on the outside.

down Lighters: Flush fitting down lighters areverypopularbut,ifyoufittheseitcouldmean that your conversion doesn’t comply with the requirements of the Building Regulations. they require you to have a continuous insulation layer and this can be difficult to achieve if you have limited construction space (particularly in a flat roof). down lighters need space around them 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:

• seekadvicefromanLABCpartnerarchitect(see page 13)






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 consider converting your garage. this chapter covers some 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.?

then seek the advice of a professional designer – see page 13.

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.Somegaragesalready have a foundation that runs across thegarageopeningwhichcanbeused,butyou will need to dig a hole to check. If your garage doesn’t have a foundation under the door,youhavetwooptions:

Option 1. dig a foundation 1m deep or to the same depth as the foundations of the existinggarage,callPeterborough Building Control to inspect it and then fill it with concrete.

Option 2. Install two 150mm deep concrete 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. It is often more aesthetically pleasing to insert a window that is narrower than the garage door opening as a full width window can appear out of proportion.

Option 2. Installalightweight,timberframed panel with a weatherproof external surface and insulation. this can be quicker and cheaper than option 1 and can easily be removedifyou,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 the conversion. there are several ways to 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.

the upgrading scheme will be influenced by 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 a problem. these walls generally have damp proof courses so if your wall is in good condition and is not showing signs ofwateringressorrisingdamp,itwillsimply require insulating and plastering ready for decoration.

there are two options for insulating the wall: 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 a single brick approximately 100mm thick with 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 behind the original wall. this can be done by building an additional skinofmasonrytoformacavitywall,whichcanbeinsulatedasthewallisbuilt,thendrylinedorplastered.Alternatively,an independent timber framed wall can be constructed. the frame should be constructed from treated timber and insulation should be placed between the timberstuds.Oncetheframeisinplace,aninsulated plasterboard finish can be applied ready for decoration.

If your garage was built with 225mm thick 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 considered to be Party Walls. these walls 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. the roof void will need to be ventilated above 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 for gas fired boilers or OFtEC for oil 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.

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 an opening window equivalent to 1/20th of the floor area of the room with a trickle vent at high level. All new windows must be fitted with highly efficient double glazed units. they should have an opener with a clear area of at least 0.33m2 and 450mm wide and big enough for you to escape through if there was a of fire. this is essential 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 house fire. the Building Regulations often require these to be installed when garages are converted to habitable rooms.


Electrical installations: for most new electrical installations you need to provide building control with British Standard test Certificates. Please ensure your electrical contractor is registered to provide these.

Iftheyarenotprovided,Peterborough Building Control 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?to decide if your cellar can be converted ask 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. this is not a simple job and it may undermine the foundations of your or

your neighbour’s house. the floor may also 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 to convert it. this chapter covers some of the technical issues 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 is required to be provided from the cellar. the stair should be designed in accordance with the following guidance.

Width: In the Building Regulations there is no minimum width for stairs but they are generally 850–1000mm wide so that they are 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 the walls. these are normally installed by specialist 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.

to be considered as a secondary fire escape it would need to be fitted with a door or window with a clear area of at least 0.33m2 and 450mm wide. Special fire escape hinges 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 often 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,istobeusedasabedroom you will need to install 100mm of acoustic 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 for gas fired boilers or OFtEC for oil 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.

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 an opening window equivalent to 1/20th of 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 is not possible to get naturalventilation,amechanicalventilationsystem will need to be installed and various package systems are available.

DID YoU KnoW?“all new habitable rooms need to be

ventilated”


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 the amount of heat loss. the walls and floor should be lined with insulating boards and the windows (if installed) should include 24mm double glazing units incorporating low emissivity glass. You will also need to consider the efficiency of any services you install and low energy light fittings should be used where possible. New heating

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

ELECTRiCAL inSTALLATiOnS: for most new electrical installations you need to provide building control with British Standard test Certificates. Please ensure your electrical contractor is registered to providethese.Iftheyarenotprovided,Peterborough Building Control 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 building having a high radon level. these mapscoverEngland,Wales,ScotlandandNorthern Ireland. But even in the areas with the highest chance of a building having a high radon level not all buildings will have high levels. the maps can be viewed at www.UKradon.org.

In the Peterborough area radon tends to be present in the villages to the West of the city centre.

What is a low level?the amount of radon is measured in becquerels per cubic metre of air (Bq m-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?the floors and walls of dwellings contain many 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 in the underlying soil. this small pressure difference is caused by the stack (or chimney) effect of heat in the building and by the effects of wind.

Radon protective measuresthese can be included relatively easily and cost-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.

Full radon protection:inthissituation,thedamp proof membrane (minimum 1200g) 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 damp proof membrane is required. the detailing in both cases will depend on the type of construction used and the positioning of the damp proof membrane,yourBuildingControlSurveyorwill 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 they meet within the wall of the house. this is 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 shouldbeoveratleast3months;theHealth Protection Agency (HPA) can provide detectors for this purpose. If radon levels at your property exceed the currentrecommendedactionlevel,youcan incorporate appropriate protection measures into your building project.

uSEFuL COnTACTS

CentreforRadiation,ChemicalandEnvironmental Hazards

Chilton,Didcot,Oxon.OX110RQ telephone +44 (0) 1235 822622 Fax +44 (0)1235 833891 www.ukradon.org

British Geological Survey

Keyworth,NottinghamNG125GG E-mail: [email protected] telephone: 0115 936 3143 Fax: 0115 936 3276 www.bgs.ac.uk/radon


DISCLAIMER

The information about the Building Regulations is accurate at the time of printing October 2016 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

Building Control Service and Development & Construction Peterborough City Council

Town Hall Bridge Street

Peterborough PE1 1HF

Administration and EnquiriesTel: (01733) 453422 / 453581

Answer phone for use out of office hoursTel: (01733) 453422

Building Control Manager Alistair Reid

Tel: (01733) 453442 Mobile: 07920 160671

Email: [email protected]

Development Management Manager Lee Collins

Tel: (01733) 454421 Mobile: 07920 8208727

Email: [email protected]

Date post:	05-Jul-2020
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GUIDE TO EXTENDING HOME OR CONVERTING YOUR · 2016-12-05 · Thermo Graphic Survey PAT Tes ng...

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