Cl/SfB (27.9) Tn6 a comprehensive technical guide

1 Technicalguidea comprehensiveto the specification ofwarm and coldpitched roofsCl/SfB( ) No. FM45117 ISO 9001apg5419 APG 5419 04/05 The Haugh, Blairgowrie,Perthshire, PH10 7 ERTelephone (01250) 872261 Facsimile (01250) Proctor GroupPartnerships in action (below)A. Proctor Group sHead Office-The HaughBlairgowrie, PerthshireGROUP LTDGROUP LTDtwoTHE A. PROCTOR GROUPThe A. Proctor Group has, for over 40 years, beenserving the Construction Industry with an extensiveportfolio of technically advanced Thermal, Acousticand Membrane commitment to develop a complete membranerange covering Breather Membranes, Vapour ControlLayers and Gas Control Membranes has resulted ina unique exclusive partnership with two of the UK slargest and most respected and Low Nonwovens have now addedRoofshield to Frameshield and Cladshield, the UK stop brands in the Timber Frame and IndustrialCladding Sisalkraft, based in Strood, Kent are theonly UK manufacturer of reinforced polyethylenebarriers to a carefully determined specification forvapour control layers and gas barrier nationwide technical specification team, togetherwith Tecline Advice Service.

2 Ensure a professionalresponse to the industry s requirements. A nationalnetwork of distribution outlets ensures prompt andeffective HISTORYIn 1987 Don and Low Nonwovens commencedmanufacture of spun bond polypropylene materialsat their plant in Forfar, 1996, a third expansion of the plant wascompleted and this 20 million complex nowproduces some of the most technically advancedtextiles and membranes in the products and services provided by Don andLow Nonwovens meet the toughest process andquality standards required by Total QualityManagement and Agr ment Certification inconstruction DEVELOPMENTR oofshield is the result of a 5 year intensive Researchand Development programme. The need for awaterproof, breathable underlay becameincreasingly apparent during the 1980 carefully monitored critical path has been followedfrom identification of market requirements toproduct design, manufacture, laboratory testingand extensive field into a variety of roof constructionsincluding the warm roof, cold roof, timber boarding,sarking and metal cladding.

3 Give Roofshield anunrivalled pedigree in pitched roofing ProctorContents Conventionally Ventilated Cold RoofsThe need for a breather MembraneCase studiesThermographyInstallationNot all breather membranes are the sameTypical Roof ConstructionsGeneral ConstructionsRoofshield detailsRidgesVerge and Sloping ValleyPipe penetration and EavesRoom in the RoofLoft Hatches and ServicesCondensation Risk AnalysisMembrane Information SheetRoofshield SpecificationRecent Projectspages 4 - 5pages 6 - 7page 8page 9pages 10 - 11pages 12 -13page 14page 14pages 15 - 18page 15page 16page 17page 18page 18pages 19 - 20pages 21page 22page 23 ROLL SPECIFICATIONT hickness mmWeight 175 g/m2 Roll Length50 or 100 mRoll Width m(Other sizes available to order)Colour Green top surfaceWhite under surfacePACKAGING AND SITE HANDLINGR olls of Roofshield are delivered to site, individuallywrapped in a polythene sleeve.

4 The sleeve is pre-printed with Product Name, Supplier Informationand Roofshield User guide is attached to each may be stored flat or upright on a clean, levelsurface and kept under Proctor GroupfourfiveA Proctor GroupGROUP LTDGROUP LTDC onventionally Ventilated Cold Roofs CONVENTIONALLY VENTILATEDCOLD ROOFSI ntroductionAs Building Regulations have required more andmore insulation in the loft space over the last 20years, central heating and double glazing hasincreased air tightness, therefore the risk ofcondensation within cold roofs has become abigger the water vapour in the building passes throughthe plasterboard ceiling and the insulation of highpermeability it reaches a cold roof space. The air sability to hold vapour is reduced, therefore thereis a risk of condensation forming on roof timberswhich can cause rot, mould growth the vapour has been trapped withinthe roofspace due to underlays of low permeabilityie.

5 Bitumen or 1 .Cold Roof (Traditional) withlow permeability underlayKey Point to Watch:Vapour can only escape byvents provided at eavesand these underlays do not allow the roof to breathe,some form of allowing this vapour to escape hashad to be designed in cold pitched roofs. Thismeans of escape is encouraged by ventilation ateaves, sometimes including the ridge and tile orslate air in and outThe ventilation provides holes in the roof to allowthe vapour to escape at these areas only. Theintroduction of air into the loft can also allow humidityfrom outside the building to be brought inside thebuilding. As well as humidity, cold can be introducedinto the loft which can create freezing pipes in theloft space. The air movement in the loft can alsohave an affect on the effectiveness of the insulationand allow heat from the building to escape at thesedesignated areas (see section on Thermography).

6 Complicated designThe design of ventilation can sometimes becomplicated to ensure the adequate release ofthis vapour. Moisture laden air pockets can beformed in such details as dormers or any protrusionsin the roof. Photograph (1) shows condensationforming on the OSB board within a roof with sucha detail and here the roof has not been adequatelyventilated in this protrusion within an otherwisesimple plan common problem is the installation of tilevents without the underlay being cut, thus renderingthe vents useless, and not providing the requiredventilation and air movement into the term designAssuming that the ventilation has been installedcorrectly, without insulation blocking the vents, andthat no air pockets have been formed, and allprotrusions and penetrations have been adequatelyventilated, and the underlay cut as necessary, thereliance of the roofs performance on the ventilationis still in doubt as it does not necessarily takeaccount of the householders use of the (2)

7 Shows a roof where the homeownerhas built a train set in the roof without theknowledge of the effects on the ventilation. Ascan be seen, mould growth has started on therafters, and this is due to the limited air movementin the roof caused by obstructions which were notoriginally designed stored within the loft can create the sameeffect and prevent the intended designed airmovement and ventilation through the roof of whichthe designer or contractor has no control is also true of blocking the vents with glasswoolto prevent cold air entering the loft space. Thereis no control on this issue and therefore ventilationcannot be relied upon as the sole measure forcontrolling condensation if these obstructionscannot be Ventilated Cold Roofs Picture 2 Mould on rafters evidentdue to misuse of roofspaceby tenant blockingventilationVentilation can spoil the aesthetics of buildingsPicture 1 Mould is evident on TimberBoarding due to vapourunable to escape indormer detailA Proctor GroupThe Need for a Breather Membrane sixsevenA Proctor GroupGROUP LTDGROUP LTDINTRODUCTIONRoof underlays and breather membranes are animportant component of modern pitched correct specification , detailing and installationhelps to minimise the risk of water ingress into thecompleted building.

8 Giving the construction teamgreater confidence that new roofs will be reliableand underlay must perform four functions:1. Secondary drainage layerWind blown rain and snow which finds its waybelow tiles and slates, or through side laps in metalsheets, drips onto the continuous underlay anddrains safely down into the gutter and out of thebuilding. Roofshield performs this Temporary waterproofingDuring construction, and in the event of future damageof slates or tiles, the underlay protects the insulationand building fabric below. Roofshield performsthis Condensation controlWarm moist air which rises up from within thebuilding and into the roof construction, can passfreely through the breathing condensation forms on the underside of theprimary covering, then the drops of water fallingonto the underlay would run down into the performs this is satisfactory for use as a fully supportedor unsupported underlay in tiled and slated pitchedroofs, constructed in accordance to the relevantclauses of BS 5534: Part 1: will resist the loads associated with theinstallation of the has adequate resistance to uplift forceslikely to be experienced in most locations in theBritish Isles and for design purposes, may beconsidered equal or greater in strength to a Type1F reinforced bitumen underlay as defined in BS747.

9 2000. Tests on Roofshield fixed over raftersat 600mm centres with batten centres at 350mmhave shown that the material does not extendunduly or tear around nail holes when subjectedto a range of negative to DIN 4102 Roofshield achieves a B2fire classification and will shrink away from thefire the product is used unsupported, there is arisk that fire can spread if the material is accidentallyignited during maintenance works, eg by a roofer sor plumber s torch. As with all types of sarkingmaterial, care should be taken during building andmaintenance to avoid the material becoming roofs has a current British Board of Agr mentCertificate No. 96/3220 Cold roofs has a current British Board of Agr mentCertificate No. 99/36484. WindThe roofing underlay should provide a barrier tominimise the wind load generated and the windgusts acting on the slates and tiles and preventwind driven snow or dust entering the performs this is a spun bonded polypropylene fabricmanufactured in the UK and used as a breathingunderlay for pitched roofs.

10 It meets the followingbasic criteria:Waterproof Wind resistant Stabilised Rot proof Tear resistant NON VENTILATED COLD ROOFSAs described, traditional ventilated cold roofs havea potential, if not correctly specified, installed andmaintained, to create problems of condensationwithin the A. Proctor Group, over the past two years hascarried out extensive research into the use of DaltexRoofshield breather membrane as the underlay incold roofs without work has been carried out by the BRE(Building Research Establishment) on a cold roofwithout ventilation for over a relative humidity and temperature throughoutthe construction, inside and outside the loft space,has been taken and moisture contents takenthroughout the year to ensure that the timbers moisture content did not this period thetimber was found to bedecreasing in moisturecontent and the roofperforming well.