Retrofitting Historic Buildings - Westminster City Council

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Floor insulation (suspended timber floors)Does BuildingRegs applyYes whereinsulation isexposed to theground or airbuildingregulationsapplies.Does Part L1B require this?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requires improvementsto the whole of thermal elements,such as floors where renovationwork is taking place on morethan 50% of the surface of thatelement.Note: buildings which are:1. listed2. in conservation areas3. of architectural andhistorical interest, referredto in a local authoritydevelopment plan,4. of traditional construction.will not be required to undertakeworks which would prejudice theappearance and character of thebuilding. This would depend onthe existing floor. EnglishHeritage have producedguidance on applying part L tohistoric buildings xvPermissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaHigh – it makessense to dothis when floorboards arebeing lifted orreplaced dueto the cost anddisruption.Low risk, but careneeded when liftingfloorboards. Ensureair bricks are notcovered byinsulation ascirculating air isneeded to preventdamp and rot.Internalalterations of anunlisted propertyin a conservationarea don’t requireplanningpermission.May requirelisted buildingconsentdepending onexisting floor.Unlisted outside aconservation areaPermission notrequired.18
Heat loss through the floor amounts to around 15% for theaverage house. Simple draught-proofing of gaps between floorand skirting and between floorboards with sealant can beundertaken relatively easily and at low cost (around £20).Suspended timber floors on the ground floor, typical for manyolder properties can be insulated to improve thermal comfort.This will be quite straightforward if there is a cellar or crawlspacebelow, but without this, floorboards can be lifted and insulationinserted underneath, supported by netting. This should be to thedepth of the joist only and should not block air bricks. Careneeds to be taken when lifting boards to minimise damage.Avoid blocking airbricks when draughtproofing or wheninsulating, and take care to maintain cross ventilation beneathsuspended timber floors to avoid rotting floor timbers. Considerthe potential loss of historic fabric (floorboards/skirting/doorsurrounds/doors) that may occur if insulation increases floorheight.Advantages: Underfloor insulation can save around £50 per yearon energy bills and improve thermal comfort, with draughtproofing saving around £15 per year.Disadvantages: This will be fairly disruptive as it will requirerooms to be emptied, and floorboards to be lifted, which risksdamaging the floor. For this reason it is sensible to takeadvantage of any opportunity to insulate, for example if existingrotten floorboards are being replaced.Risks: Incorrectly installed insulation which blocks air bricks andreduces air circulation beneath a floor may result in damp andcondensation problems. The risks inherent in lifting floorboardsmay be too great in a listed building where one of the featuresfor which it is listed is a particularly attractive floor. Some historicbuildings may also contain historic pugging, which is a coarsemortar between joists and beneath floor boards to deadensound.Costs: Generally although the capital cost of insulation is nothigh, there is significant disruption and cost in having floorslifted. The cost of lifting floorboards properly can be around£25/m 2 while the cost of the insulation itself is only around £5/m 2Floorinsulation(suspendedtimber)UnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer toESTwebsite forlatest info 16Unlisted 80m 2 £875 £917 £896 50-100%building 17When to do this: Floor insulation is disruptive therefore it is bestdone as part of a whole house refurbishment, or whenfloorboards are being lifted or replaced, for example to install oraccess heating pipes below. When it is carried out ensure thatgaps are sealed such as under skirting boards and where waterand gas pipes are located to minimise draughts.19
Page 1 and 2: Retrofitting Historic Buildingsfor
Page 3 and 4: ContentsIntroduction 4Limitations o
Page 5 and 6: This guidance will be of most use t
Page 8: Article 4 DirectionsFor some buildi
Page 12 and 13: competent person’ scheme exists.
Page 14 and 15: MeasuresThis section outlines measu
Page 16 and 17: Installing insulation in existing r
Page 20 and 21: For further information see:• Fac
Page 22 and 23: Solid wall insulation can be a way
Page 24 and 25: For further information see:• Fac
Page 26 and 27: Solid wall insulation can be a way
Page 30 and 31: Advantages: This can improve the th
Page 32 and 33: Disadvantages: It can be more expen
Page 34 and 35: A significant amount of heat is los
Page 36 and 37: Boiler upgradeDoesBuildingRegsapply
Page 38 and 39: Heating controlsDoesBuildingRegs ap
Page 40 and 41: Micro Combined Heat and Power (CHP)
Page 42 and 43: Ground source heat pumpsDoesBuildin
Page 44 and 45: Air source heat pumpsDoesBuildingRe
Page 46 and 47: For further information see:• ‘
Page 48 and 49: Solar PV panels convertenergy from
Page 50 and 51: Solar thermal panelsDoes BuildingRe
Page 52 and 53: Living roofDoesBuildingRegsapply?Is
Page 54 and 55: Case Study: 15 Passmore Street, SW1
Page 56 and 57: Case Study: The Flagship HomeArchit
Page 58 and 59: SummaryMeasureUnlisted, within acon
Page 60 and 61: Westminster’s Planning PolicyThis
Page 62 and 63: Notes and References1 Westminster H
Page 64 and 65: 35 Town and Country Planning (Gener

Retrofitting Historic Buildings - Westminster City Council

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