STANDARDS for Conversions and renovations - …

1 STANDARDSforConversions and renovationsApril 2005 editionEffective from July 2005 Conversions and RenovationsCONTENTSC lause PageINTRODUCTION1 Technical RequirementsR1 R63 Procedural flowchart6 Survey of existing buildingC17 Design StandardC27 Completed workC37 Building RegulationsC48 Insured guarantees/warrantiesC58 Wood rot and beetle infestationC68 Vermin and pest infestationC79 FoundationsC89 Basements and structural waterproofing (tanking)C910 Drainage below groundC1011 Ground floorsC1111 WallsC12 C15 12 Chimneys and fluesC1616 Upper floorsC17 & C18 16 Staircases, stairways and landingsC1917 Pitched roofsC2017 Flat roofs and balconiesC2118 Roof drainageC2219 Framed buildingsC23 & C24 19 Doors, windows and glazingC2520 JoineryC2620 Floor, wall and ceiling finishesC2721 ServicesC28 C33 21 Painting and decoratingC3422 External worksC35 C39 22 Provision of informationC40 & C41 23 APPENDIX AUseful contacts and relevant publications24 APPENDIX BSurvey(s) of existing buildings26 IntroductionNHBC STANDARDS for Conversions and RenovationsEffective.

2 July 2005 April 2005 editionINTRODUCTIONC onversions and RenovationsPURPOSEThe STANDARDS for Conversions and Renovationsprovide guidance on the type of project that will be acceptable to nhbc , the scope of the survey(s)and work that will be ARE Conversions AND renovations ? Conversions and renovations are projects that involve work to existing buildings or parts of existing buildings. Examples include: the conversion of industrial or commercialbuildings into housing the conversion of an existing residential buildinginto flats the addition of an additional storey to an existing building the renovation of an existing residential STANDARDS APPLY?New work that forms part of the conversion orrenovation should be carried out in accordance with the nhbc conversion or renovation work should becarried out in accordance with these STANDARDS forConversions and STANDARDS for Conversions and Renovationscurrent at the time work is started, shall (S)The builder should arrange for survey(s) of thebuilding to be carried out in accordance with ClauseC1 before applying to nhbc for Buildmark copy of the survey report(s), including any specialistreports, should accompany the application forBuildmark cover.

3 The reports will be used to establishif the project is acceptable for Buildmark may impose specific requirements for the project, which must be complied with as acondition of providing Buildmark relies on the details supplied by the builderwhen it accepts a project for Buildmark of a project does not absolve the builder from obligations under the Rules andBuildmark in respect of any defects, whether or not they are located in parts of the building coveredby the reports or nhbc s specific REQUIREMENTSThe Technical Requirements are printed in red. They are mandatory and MUST be met by the Requirements R1 to R5 inclusive are the same as those in the nhbc StandardsChapter Introduction to the STANDARDS andTechnical Requirements .Technical Requirement R6 relates specifically to the STANDARDS for Conversions and STANDARDSThe Performance STANDARDS are printed in dark blueand will assist builders in meeting the TechnicalRequirements.

4 By meeting each PerformanceStandard the Technical Requirement will be STANDARDS of performance will beacceptable ONLY if, in the opinion of nhbc , the Technical Requirements are met and the standard achieved is not lower than the stated Performance on how the Performance Standard may bemet is printed in light is based on normal construction proceduresand recommended practices that have been shown tobe satisfactory and acceptable over to the scope of buildings which could beconsidered for conversion or renovation , the guidancemay need to be varied for particular cases. nhbc willconsider other methods proposed to meet specificrequirements, subject to consultation and irregularities in the existing background andfinish, beyond normal building tolerances, may beacceptable for Conversions and there may be disagreements on howTechnical Requirements and Performance Standardsare to be interpreted.

5 Such cases are usually resolvedthrough further consultation, failing which, nhbc willexercise its right to STANDARDS for Conversions and RenovationsPage 1 of 31 April 2005 editionEffective: July 2005 INTRODUCTIONC onversions and RenovationsTESTINGTo establish whether the existing building or parts ofit are adequate it may be necessary to carry out tests,both on the structure and materials that are to beretained. These tests (where required) will be at thebuilder s on the structure to be retained shall be inaccordance with European or National STANDARDS asappropriate. Where suitable tests are not specified inEuropean or National STANDARDS , then builders may be required to obtain the services of a specialist todetermine materials, reclaimed or retained materials shall comply with Technical Requirement , CODES OFPRACTICE AND OTHERAUTHORITATIVE DOCUMENTSW here the STANDARDS for Conversions andRenovations refer to: nhbc STANDARDS European STANDARDS British STANDARDS Codes of Practice Authoritative documents or Technical approval certificationthe documents shall be the editions current at thetime the work is started unless otherwise agreed byNHBC in STANDARDS for Conversions and Renovationscontain references to authoritative documents.

6 These references are not exhaustive and nhbc will consider recommendations from otherauthoritative ON USEThe Technical Requirements, Performance Standardsand Guidance do not form a complete specificationand should not be used as such in 2 of 31 nhbc STANDARDS for Conversions and RenovationsEffective: July 2005 April 2005 editionINTRODUCTIONC onversions and RenovationsR1 Statutory requirementsWork shall comply with all relevantBuilding Regulations and otherstatutory requirements relating to the completed construction workIn England, Wales and the Isle of Man, nhbc will generally accept work that accords with the relevant Approved Documents and their supporting documents. Exceptions would be where nhbc has a higher standard or where there is doubt as to whether the recommendation in the Approved Document is appropriate to aparticular Scotland and Northern Ireland, account shall be taken of the relevant Building STANDARDS and Regulations and rules of StatutoryAuthorities primarily cover matters of health and safety.

7 Matters affecting durability andserviceability also need to be STANDARDS do not apply to: health and safety matters relating to building operations handling and use of certain building materials planning Design requirementDesign and specification shall provide satisfactory performanceAccount shall be taken of:(a) The land quality, including:(i) climate(ii) topography(iii) geology and ground conditions(iv) contamination(v) workings below ground(vi) previous use of the site(vii) any other aspect, on or adjacent to the site,which could affect the appropriate, the land quality will have to bedetermined by a person acceptable to builder shall ensure that the work complies with the Technical Requirements(b) The structural adequacy of the works. The design,with appropriate factors of safety, shouldsatisfactorily allow for loads during and afterconstruction and for their transfer to thesupporting structure, or foundation, withoutundue movement, including:(i) self weight(ii) all imposed loads, including wind loads(iii) construction loads.

8 (c) The geographical location of the site, including:(i) climate(ii) topography(d) The position of the dwelling on the site, especiallywith reference to the dwelling s exposure to theweather, including exposure at early stages in the development of a site, even if it is eventuallyprotected by structures built later.(e) The position of building elements within theconstruction works, including the inter-relationshipof materials and constructions.(f) The security of the Materials requirementAll materials, products and buildingsystems shall be suitable for theirintended purposeThe structure of the home shall, unless specificallyagreed otherwise in writing with nhbc , have a life of at least 60 years. Individual components andassemblies, not integral to the structure, may have a lesser durability and need planned maintenance,repair or replacement during that account shall be taken of the use and location of materials, products and building systems in relation to: durability of both the structure and individual components and assemblies geographical location position on the site position within the , products and building systems will normallybe acceptable if they comply with the following:(a) MATERIALS AND PRODUCTS USED FOR CRITICAL FUNCTIONSF unctions critical to performance are: structure, fire resistance, weatherproofing,durability, thermal and sound insulation, services including heating appliances and STANDARDS for Conversions and RenovationsPage 3 of 31 April 2005 editionEffective.

9 July 2005 TECHNICAL REQUIREMENTSC onversions and RenovationsTECHNICAL REQUIREMENTSR3 (continued)Any of the following are acceptable:(i) performance in accordance with STANDARDS set by nhbc ,or(ii) where no nhbc standard is set, compliancewith the relevant British Standard or equivalentEuropean Technical Specification approved by aCommittee for Standardisation, provided they are used in accordance with the relevant Code of Practice,or(iii) compliance with STANDARDS not lower than those defined in a relevant British Standardspecification or equivalent, provided their use is accepted by nhbc ,or(iv) satisfactory assessment by an appropriateindependent technical approvals authorityaccepted by nhbc , including: British Board ofAgr ment (BBA), Building Research Establishment(BRE) or a body authorised under Annex 4 to the Construction Products Directive,or(v) use of materials and products in accordance with well established satisfactory custom andpractice, provided that such custom and practice is acceptable to nhbc ,or(vi) acceptance, in writing, by nhbc that the quality and use is satisfactory.

10 (b) MATERIALS AND PRODUCTS USED FOR NON-CRITICAL FUNCTIONSC ompliance with the above acceptance criteria for critical functions or strictly inaccordance with manufacturers recommendations for the specific use.(c) RECLAIMED MATERIALSR eclaimed materials may only be re-used with theprior agreement of nhbc . Independent certificationof suitability may be required.(d) PROPRIETARY BUILDING SYSTEMSR eference should be made to R3(a), (iv).(e) TIMBER DURABILITYR eference should be made to Chapter Timberpreservation (natural solid timber) (each section).NoteEquivalents to British STANDARDS or technical approvalsauthority shall be those accepted in the requirementAll work shall be carried out in aproper, neat and workmanlike mannerThe Builder shall ensure that:(a) the conditions of the materials, products and the completed work are satisfactory(b) appropriate precautions are taken to prevent damage(c) account is taken of the following.