2 2 pitched roofs rafter level

8/12/2019 2 2 Pitched Roofs Rafter Level

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Section 2.2Pitched Roofs Rafter Level

Between rafters only

Product: Earthwool Rafter Roll orEarthwool Flexible Slab Pr01/02

Between and below rafters– existing roofProduct: Earthwool Rafter Rolland Knauf PIR Laminate

Between engineered timberraftersProduct: Earthwool Rafter Roll

Pr04

Pr05

Between and below rafterProduct: Earthwool Rafter Roll andKnauf PIR Laminate

Pr03

Between and above raftersProducts: Rocksilk Pitched Roof Slaband Earthwool Rafter Roll

Pr06

Between and in front oftimber studs

Products: Earthwool Rafter Rolland Knauf PIR Laminate Pr07/08



79Technical Advice and Support Centre 01744 766666 www. knauf insulation.co.uk

2.2Pitched Roofs - Rafter Level

79

Between rafters only Product: Earthwool Rafter Roll or Earthwool

Flexible Slab

See page: 80Pr01/02

Between engineered timber raftersProduct: Earthwool Rafter Roll

See page: 84

Pr04

Knauf Insulation solution U-values 0.23 0.22 0.21 0.20 0.19 0.18 0.17 0.16 0.15 0.130.14 0.12 0.110.26 0.25 0.24 0.10

Between and below rafterProduct: Earthwool Rafter Roll and Knauf PIRLaminate

See page: 82

Pr03

Between and above raftersProducts: Rocksilk Pitched Roof Slab andEarthwool Rafter Roll

See page: 88

Pr05

Between and below rafters – existing roofProducts: Earthwool Rafter Roll andKnauf PIR Laminate

See page: 86

Pr06

Between and in front of timber studsProducts: Earthwool Rafter Roll andKnauf PIR Laminate

See page: 90

Pr07/08

Solution optimiser and pathfinder

0.27 0.280.290.30

Key

Thermal insulation achievable by constructions within this document. Find online. Visit knaufinsulation.co.uk and key in construction code to find the

most up to date information on your chosen solution.Pb01

2 . 2





PerformanceThermal performanceEarthwool Rafter Roll has a thermal conductivityof 0.032 or 0.036 W/mK.

Earthwool Flexible Slab has a thermalconductivity of 0.035 or 0.037 W/mK.

Fire performanceEarthwool Rafter Roll and Earthwool FlexibleSlab are classified as Euroclass A1 to

BS EN 13501-1.Refurbishment of existing roofsThis is a valid solution for the refurbishmentof an existing roof where the roof tiles and rooftile underlay are not being removed. In thesecircumstances a continuous 50mm ventilatedairspace must be maintained between theinsulation and the roof tile underlay.

Typical specificationThe whole area of the pitched roof to beinsulated with Earthwool Rafter Roll/Earthwool Flexible Slab*…mm thick, frictionfitted between the rafters. The insulation to bepushed over the wall plate at the eaves tolink up with the wall insulation.(*Delete as appropriate)

Alternatively, consult the National

Building Specifications, Standardversion clause/clauses…P10/140 and 310……………

Knauf Insulation specification clauses can bedownloaded from knaufinsulation.co.uk/nbs

Plasterboard

Counter battens

LR underlay

Vapour control layer

Earthwool Rafter Roll /Earthwool Flexible Slab

Typical section

81

Table 7 - Typical U-values of roofs with insulation between rafters

Product Thickness U-values

(mm) (W/m2K)

Earthwool Rafter Roll 250 (2 x 125) 0.15

225 (100 + 125) 0.16

200 (2 x 100) 0.18

175 0.22

150 (2 x 75) 0.24

U Value Competency Scheme

CERTIFICATE CS/1001-2

Note: Rafter sizes assumed to be 38mm wide at 600mm centres (6.3% bridging) and the same depth as the insulation.

Pr01

Table 8 - Typical U-values of roofs with insulation between rafters

Product Thickness U-values

(mm) (W/m2K)

Earthwool Flexible Slab 250 (2 x 100 + 50) 0.16

230 (140 + 90) 0.17

200 (2 x 100) 0.20

180 (2 x 90) 0.22

170 (100 + 70) 0.23

U Value Competency SchemeCERTIFICATE CS/1001-2

Notes: Rafter sizes assumed to be 38mm wide at 600mm centres (6.3% bridging) and the same depth as the insulation.

Pr02

2 . 2



82 Technical Advice and Support Centre 01744 766666 www. knauf insulation.co.uk

2.2 Pitched Roofs - Rafter Level

Pitched roofs – rafter levelBetween and below rafters

Earthwool Rafter Roll

• Friction fitting between raftersensures rafter space is fully filledthereby preventing air infiltration

• Low U-values can be achieved, even with shallow rafters

• Product is compression packed toreduce transport related CO2 emissions


• Non-combustible with a Euroclass A1 reaction to fire rating

• A+ Generic BRE Green Guide Rating

• Zero Ozone Depletion Potential (ODP)

• Zero Global Warming Potential (GWP)

ProductsEarthwool Rafter Rollis made from glassmineral wool and formed into rolls which arelightweight, flexible, resilient and non-combustible, its manufacture has a very lowimpact on the environment.Knauf PIR Laminate is comprised of 9.5mmtaper edged plasterboard bonded to apolyisocyanurate (PIR) board*.*Knauf PIR Laminate is available from Knauf Drywall.

Typical constructionA pitched roof of timber rafters with tiles orslates on battens. Either with counter battensif a LR underlay is pulled taught and insulationis to the full depth of the rafters, or alternativelywithout counter battens if it is draped and theinsulation stops at least 10mm below the top ofthe rafters. Insulated with Earthwool Rafter Rollbetween the rafters and lined internally withKnauf PIR Laminate.

InstallationA LR underlay is pulled taught and laid directlyover the rafters. 50x32mm counter battens arenailed into the rafters with minimum penetrationof 38mm into the rafter, alternatively, helicalfixings can be used with a minimum penetrationof 35mm into the rafter.

Tiling battens are nailed into the counterbattens. Finally, the roofing tiles or slates arefixed, to the manufacturer’s recommendations.

Friction fit Earthwool Rafter Roll between therafters. The insulation should be butt jointed andcontinuous with the wall insulation to avoidthermal bridging.

Finally, Knauf PIR Laminate is nailed or screwedto the underside of the rafters at maximum300mm centres at least 12mm in from theboard edge.

The fixings should be long enough to penetrateat least 25mm into the rafters. The boards arefinished using standard drylining techniques.

With service voidWhere a service void is provided, nail a foilfaced PIR/PUR board to the rafters and tape allthe board joints and joints where the boardabuts walls, roof windows and other intrusionswith self adhesive aluminised tape to completethe vapour control layer. The vapour controllayer formed by the PIR/PUR insulation boardand the tape should form a complete, unbroken,barrier to the warm side of the insulation. Thevapour control layer should be linked to the airbarrier in the external walls.

Nail 50mm wide timber battens through thePIR/PUR board into the rafters. The battens tobe a minimum of 25mm deep but to suit therequired depth of the service void. Afterinstalling first fix services, nail plasterboard tothe timber battens. The boards are finishedusing standard drylining techniques.

Pr03

LR underlay


Knauf PIR Laminate

82

NEW BUILD REFURB





LR underlay

Knauf PIR Laminate


12.5mm plasterboard


The PIR content of Knauf PIR Laminate has athermal conductivity of 0.022 W/mK, theplasterboard facing has a thermal conductivityof 0.210 W/mK.

Acoustic performanceEarthwool Rafter Roll meets the specification fora mineral wool insulation required for thecontrol of flanking sound as described inAppendix A of Robust Details.Fire performanceEarthwool Rafter Roll is classified as EuroclassA1 to BS EN 13501-1.

Refurbishment of existing roofsThis is a valid solution for the refurbishment ofan existing roof where the roof tiles and rooftile underlay are not being removed. In thesecircumstances a continuous 50mm gap mustbe maintained between the insulation andthe roof tile underlay which is vented at theeaves and ridge.

Typical specificationThe whole area of the pitched roof to beinsulated with .....mm of Earthwool RafterRoll, friction fitted between the rafters. Thewidth of the insulation should be appropriateto the spacing of the rafters.(*Delete as appropriate)

Knauf PIR Laminate thickness ......mm nailedor screwed to the rafters at maximum 300mm

centres and finished using standard dryliningtechniques.

Alternatively, consult the NationalBuilding Specifications, Standardversion clause/clauses…P10/140 and 310……………


Typical section

83

Table 9 - Typcial U-values with insulation between and below rafters

U-values (W/m2K)

Product Thickness Knauf PIR Laminate (mm)

(mm) 35 50 65 75


250 (2 x 125) 0.12 0.11 0.10 0.10

225 (100 + 125) 0.13 0.12 0.11 0.11

200 0.16 0.14 0.13 0.12175 0.18 0.16 0.14 0.13

150 (2 x 75) 0.18 0.16 0.15 0.14

125 0.21 0.18 0.16 0.15

100 0.24 0.21 0.18 0.17


Note: Rafter sizes assumed to be 38mm wide at 600mm centres (6.3% bridging) and the same depth as the insulation.

2 . 2






• No special fixings are requiredallowing fast installation

• Product is compression packed toreduce transport related CO2 emissions


• Non-combustible with a Euroclass A1 reaction to fire rating




Pitched roofs – rafter levelBetween engineered timber rafters


ProductsEarthwool Rafter Rollis made from glassmineral wool and formed into rolls which arelightweight, flexible, resilient and non-combustible, its manufacture has a very lowimpact on the environment.

Typical constructionA pitched roof of engineered timber rafters withtiles or slates on battens. 8mm plywood sarkingfixed to the top of the rafters with a LR underlaylaid across the plywood. Insulated with

Earthwool Rafter Roll between the rafterssupported by plywood fixed to the upper edgeof the lower flange of the engineered timberrafter and lined internally with a vapour controllayer and plasterboard.

Install the vapour control layer to the lower faceof the plywood support pieces and across thelower edge of each engineered timber flangetaping all joints to ensure its integrity ismaintained. After first fix services have beeninstalled finish using standard dryliningtechniques.

If the insulation is fitted from below then theplywood sarking board, a LR underlay, counterbattens, tilling battens and slates or tiles arefixed as above. Friction fit Earthwool Rafter Roll(in layers if necessary) between the rafters. Theinsulation should be butt jointed and continuouswith the wall insulation to avoid thermalbridging. Install the insulation support piecesand fix the vapour control layer to the lowerface of the plywood support pieces and acrossthe lower edge of each engineered timberflange taping all joints to ensure its integrity ismaintained. After first fix services have beeninstalled finish using standard dryliningtechniques.

InstallationThe insulation is fitted from above or belowonce the roof is watertight.

If fitting from above fix the ply wood supportpieces to the upper edge of the lower flange ofthe engineered timber rafter making sure thetimber fits tightly to the sides of the web of therafters. Friction fit Earthwool Rafter Roll betweenthe web and upper flange of the engineeredtimber rafter to the full depth, in layers ifnecessary. The insulation should be butt jointed

and continuous with the wall insulation to avoidthermal bridging.

Fix the 8mm plywood sarking board to the topof the rafters. A LR underlay is laid directly overthe plywood sarking board and 50x32mmcounter battens placed on top of a LR underlaydirectly above the rafters and nailed into therafters with minimum penetration of 38mm intothe rafter – alternatively, helical fixings can beused with a minimum penetration of 35mm intothe rafter. Tiling battens are nailed into thecounter battens and the roofing tiles or slatesare fixed to the manufacturer’s

recommendations.

Pr04

LR underlay


Plasterboard

Counter battens

8mm plywood support for insulation

8mm plywood sarking

84

NEW BUILD REFURB





LR underlay


Earthwool Rafter Rollbetween rafters

8mm ply sarking

Counter battens

Service void formed in depthof lower flange

12.5mm plasterboard

Typical specificationThe whole area of the pitched roof to beinsulated with Earthwool Rafter Roll, ofthickness ...... mm friction fitted between theengineered rafters. The width of theinsulation should be appropriate to thespacing of the rafters.

Staple a vapour control layer to theunderside of the rafters and seal all joints.

Nail 50x25mm timber battens to the raftersto form a service void. Nail foil backedplasterboard to the timber battens.

Alternatively, consult the NationalBuilding Specifications, Standardversion clause/clauses…P10/140 and 310……………


Typical section


Acoustic performanceEarthwool Rafter Roll meets the specification fora mineral wool insulation required for thecontrol of flanking sound as described inAppendix A of Robust Details.

Fire performanceEarthwool Rafter Roll is classified as EuroclassA1 to BS EN 13501-1.

85

Table 10 - Typical U-values for roofs with Earthwool Rafter Roll between engineered rafters

U-values (W/m2K)

Product Thickness Service void Low E service void

(mm)

Earthwool Rafter Roll 200 (2x100mm) 0.18 0.17


Note: Rafters assumed to be 58mm wide, 241mm deep with 9.5mm web, spaced at 600 centres, with no bracing between the raft

2 . 2





Pitched roofs – rafter levelBetween and below rafters – existing roof



• Low U-values can be achieved, evenif the existing roof has shallowrafters

• Product is compression packed toreduce transport related CO2emissions

Knauf PIR Laminate

PerformanceThermal performanceEarthwool Rafter Roll has a thermal conductivityof 0.032 or 0.036 W/mK.The PIR content of Knauf PIR Laminate has athermal conductivity of 0.022 W/mK, theplasterboard facing has a thermal conductivityof 0.210 W/mK.Fire performanceEarthwool Rafter Roll is classified as EuroclassA1 to BS EN 13501-1.

Knauf PIR Laminate is faced with 9.5mmplasterboard which is non-combustible.

InstallationEarthwool Rafter Roll is friction fitted (in layers ifnecessary) between the rafters, taking care toleave a 50mm ventilated gap above theinsulation.The rolls should be butt jointed and continuouswith the wall insulation to avoid thermalbridging.

Finally, Knauf PIR Laminate is nailed or screwedto the underside of the rafters at maximum300mm centres at least 12mm in from theboard edge. The fixings should be long enoughto penetrate at least 25mm into the rafters. Theboards are finished using standard dryliningtechniques.

ProductsEarthwool Rafter Rollis made from glassmineral wool and formed into rolls which arelightweight, flexible, resilient and non-combustible. Its manufacture has a very lowimpact on the environment.Knauf PIR Laminate is comprised of 9.5mmtaper edged plasterboard bonded to apolyisocyanurate (PIR) board*.*Knauf PIR Laminate is available from Knauf Drywall.

Typical constructionA pitched roof of timber rafters with tiles orslates on battens on an HR type underlay.Insulated with Earthwool Rafter Roll between therafters and lined internally with Knauf PIRLaminate.

There must be a continuous 50mm gap abovethe insulation (installed between the rafters)which is vented at the eaves and ridge. This isthe most popular method for insulating anexisting roof when a loft is converted tohabitable accommodation.

Optional timber spacer battens tomaintain ventilation space above insulation


Knauf PIR Laminate

Pr05

50mm clear ventilation spacebetween underlay and insulation


HR type underlay drapedbetween rafters

86

REFURB

Earthwool Rafter Roll• Non-combustible with a Euroclass

A1 reaction to fire rating• A+ Generic BRE Green Guide Rating







50mm ventilation path

Roof insulation to link with wall insulation

Knauf PIR Laminate

Sealant to reduce air leakage

Air barrier

Typical specificationThe whole area of the pitched roof to beinsulated with Earthwool Rafter Roll ......mmthick, friction fitted between the rafters, witha continuous 50mm ventilation space abovethe insulation. The width of the insulationshould be appropriate to the spacing of therafters.

Knauf PIR Laminate of thickness .....mm with

integral 9.5mm plasterboard nailed orscrewed to the rafters at maximum 300mmcentres and finished using standard dryliningtechniques.(*Delete as appropriate)

Alternatively, consult the NationalBuilding Specifications, Standardversion clause/clauses…P10/140 and 310 andK10/245……………


Typical section


87

Table 11 - Typical U-values of pitched roofs with insulation between and below rafters

Product

ThicknessU-values (W/m2K)

Knauf PIR Laminate (mm)

(mm) 35 50 65 75

Earthwool Rafter Roll 150 (2 x 75) 0.19 0.17 0.15 0.14

125 0.21 0.19 0.16 0.15

100 0.25 0.21 0.18 0.17

85 0.27 0.23 0.20 0.1875 0.30 0.25 0.21 0.19


Notes: Existing rafters assumed to be 50mm wide at 600mm centres (8.3% bridging) and the same depth as the insulation plus the airspace. A 50mmventilated airspace is required between Earthwool Rafter Roll and the existing HR roof tile underlay.

2 . 2





Pitched roofs – rafter levelBetween and above rafters

Earthwool Rafter Roll and Rocksilk Pitched Roof Slab


• Rock mineral wool layer aboverafters provides support to the roofstructure and reduces impact ofthermal bridging

• Earthwool Rafter Roll is compressionpacked to reduce transport related

CO2 emissions

Earthwool Rafter Roll and RocksilkPitched Roof Slab

• Non-combustible with a Euroclass A1reaction to fire rating




The fixings are to be installed at no greaterthan 400mm centres along the battens.

From below, Earthwool Rafter Roll is simplyfriction fitted between the rafters so that it is indirect contact with the Rocksilk Pitched RoofSlab, with no air gaps between the two layersof insulation.

To avoid a thermal bridge at the eaves, RocksilkPitched Roof slabs should be cut to shape to linkthe roof and wall insulation.

A continuous vapour control layer should befixed to the underside of the rafters.

PerformanceThermal performanceRocksilk Pitched Roof Slab has a thermalconductivity of 0.038 W/mK.

Earthwool Rafter Roll has a thermal conductivityof 0.032 or 0.036 W/mK.

Typical constructionA pitched roof of timber rafters with tiles orslates on battens and counter battens and a LRunderlay. Insulated with Rocksilk Pitched RoofSlab laid over the rafters and Earthwool RafterRoll, friction fitted between the rafters.

InstallationA timber stop rail is fixed to the ends of therafters. Rocksilk Pitched Roof Slab is fittedstarting from the timber stop rail, with all slabstightly butted together.

Rocksilk Pitched Roof Slab should be laid acrossthe rafters with staggered joints. The slabsshould be cut to length to match the centres ofthe rafters.

A LR underlay can be installed either below thecounter battens (as shown above), or above thecounter battens. When installed above thecounter battens the LR underlay should bedraped by no less than 10mm.

Counter battens should be fixed through theRocksilk Pitched Roof Slab boards using spiralfixings such as Helifix Inskew 600 or BuildexRG, with a minimum penetration into the rafterof 35mm.

ProductsEarthwool Rafter Roll is made from glassmineral wool and formed into rolls which arelightweight, flexible, resilient and non-combustible, its manufacture has a very lowimpact on the environment.

Rocksilk Pitched Roof Slab is a compressionresistant, water repellent, rock mineral woolslab specifically developed for over rafter(sarking) insulation, its manufacture has a verylow impact on the environment.

Pr06

LR underlay

Rocksilk Pitched Roof Slab

Counter battens

Earthwool Rafter Roll12.5mm plasterboard


88

NEW BUILD REFURB





Typical specificationInsulation laid over rafters to be RocksilkPitched Roof Slab, ......mm thick. All slabstightly butted together and with staggeredjoints. A LR underlay should then be laid overthe insulation with the edges lapped.

The insulation and underlay to be held inplace by 50 x 32mm counter battens fixedthrough the slabs, into the rafters. Tiling

battens to be nailed into the counter battens.Earthwool Rafter Roll......mm thick, to befriction fitted between the rafters. The widthof the insulation should be appropriate to thespacing of the rafters.

Alternatively, consult the NationalBuilding Specifications, Standardversion clause/clauses…K11/695 and P10/140 and310……………


Acoustic performanceEarthwool Rafter Roll meets the specification formineral wool insulation required for the controlof flanking sound as described in Appendix Aof Robust Details.

Fire performanceEarthwool Rafter Roll and Rocksilk Pitched RoofSlab are classified as Euroclass A1 toBS EN 13501-1.

Counter battens

LR underlay

Roof insulation to link with wall insulation


Seal to reduce air leakage

Rocksilk Pitched Roof Slab

Vapourcontrol layer

Air barrier

Typical section

89

Table 12 - Typical U-values of pitched roofs with insulation between and over rafters

Product

ThicknessU-values (W/m2K)

Rocksilk Pitched Roof Slab (mm)

(mm) 50 70

Earthwool Rafter Roll 200 0.16 0.15

175 0.17 0.16

150 (2 x 75) 0.18 0.17

125 0.21 0.18

100 0.24 0.21

85 0.26 0.23



Notes: Rafter sizes assumed to be 38mm wide at 600mm centres (6.3% bridging) and the same depth as the insulation.

2 . 2





Pitched roofs - rafter levelDwarf attic walls

Earthwool Rafter Roll and Earthwool Flexible Slab

• Friction fitting between studs ensuresstud space is fully filled therebypreventing air infiltration

• Low U-values can be achieved withshallow studs

• Earthwool Rafter Roll is compressionpacked to reduce transport relatedCO2 emissions

Earthwool Rafter Roll and EarthwoolFlexible Slab

• Non-combustible with a Euroclass A1reaction to fire rating




ProductsEarthwool Rafter Rollis made from glassmineral wool and formed into rolls which arelightweight, flexible, resilient and non-combustible, its manufacture has a very lowimpact on the environment.Earthwool Flexible Slab is a multi-purpose,flexible, rock mineral wool slab designed to befriction-fitted between timber studs, itsmanufacture has a very low impact on the

environment.Knauf PIR Laminate is comprised of 9.5mmtaper edged plasterboard bonded to apolyisocyanurate (PIR) board*.*Knauf PIR Laminate is available from Knauf Drywall.

Typical constructionA timber stud dwarf attic wall insulated withEarthwool Rafter Roll or Earthwool Flexible Slabbetween the studs and lined internally withKnauf PIR Laminate.

When an existing pitched roof (with an HRunderlay) is being converted into habitableaccommodation with insulation at rafter level a50mm ventilated rafter airspace must bemaintained between the insulation and the HRunderlay. The 50mm ventilated airspace mustnot be compromised by the installation of thedwarf attic wall.

InstallationEarthwool Rafter Roll or Earthwool FlexibleSlab (the same depth as the studs) is frictionfitted between the timber studs. The insulationshould be butt jointed and in contact with thesole, head plate and timber studs forming thedwarf attic wall. Timber battens (25mm x38mm) should be fixed on the cold side of theattic wall studs as a secondary measure tomaintain the position of the insulation betweenthe studs, alternatively staple mesh to the backof the timber studs, access permitting.

A vapour control layer is then installed to theface of the studs which in turn is overlaid withKnauf PIR Laminate which is secured with eithernails or screws to the studs at maximum300mm centres and at least 12mm in from theboard edge. The fixings should be long enoughto penetrate as least 25mm into the timberstuds. The boards are finished using standarddrylining techniques.

PerformanceThermalEarthwool Rafter Roll has a thermal conductivityof 0.032 or 0.036 W/mK.Earthwool Flexible Slab has a thermalconductivity of 0.035 or 0.037 W/mK.The PIR content of Knauf PIR Laminate has athermal conductivity of 0.022 W/mK and theplasterboard has a thermal conductivity of

0.210 W/mK. AcousticEarthwool Rafter Roll and Earthwool FlexibleSlab provide a high level of sound absorptionand can significantly improve the acousticperformance of dwarf attic walls.FireEarthwool Rafter Roll and Earthwool FlexibleSlab are classified as Euroclass A1 to BS EN13501-1.Knauf PIR Laminate is faced with 9.5mmplasterboard which is non-combustible.

Pr08Pr07NEW BUILD REFURB

EarthwoolRafter Rollor EarthwoolFlexible Slab

Vapour controllayer

Knauf PIRlaminate

Plasterboard

EarthwoolLoft Roll

EarthwoolAcoustic Roll





Typical specificationEarthwool Rafter Roll*/Earthwool FlexibleSlab*……mm thick to be friction fittedbetween the timber studs. The whole area ofthe wall to be overlaid with a vapour controllayer which is stapled to the timber studs.

Knauf PIR Laminate of thickness……mm withintegral 9.5mm plasterboard nailed orscrewed to the timber studs at maximum

300mm centres and finished using standarddrylining techniques.

(*Delete as appropriate)

Alternatively, consult the NationalBuilding Specifications, Standardversion clause/clauses…P10/210 and 310 andK10/205……………


Table 13 - Typical U-values of dwarf attic walls insulation between and over studs

Product

ThicknessKnauf PIR Laminate

ThicknessU-values

(mm) (mm) (W/m2K)

Earthwool Rafter Roll 100 65 0.18

100 50 0.20

100 35 0.23

75 65 0.20

75 50 0.23

75 35 0.27

Earthwool Flexible Slab 100 65 0.18

100 50 0.21

100 35 0.25

70 65 0.21

70 50 0.24

70 35 0.29



Notes: Studs assumed to be 38mm wide at 600mm centres with 0.13% bridging. Thermal conductivity of timber studs is 0.13W/mK. Anadditional R-value of 0.50 m2K/W has been included to account for the pitched roof airspace behind the dwarf attic wall as defined and detailedin BR 443.

Pr08

Pr07

Typical sectionVapour control layer

Knauf PIR Laminate


Earthwool Loft Roll

Counter battens

LR underlay

Seal to reduce air leakage

2 . 2



Knauf Insulation Ltd Customer Service (Sales) Technical Advice and Support Centre LiteraturePO Box 10 Tel: 0844 800 0135 Tel: 01744 766 666 Tel: 08700 668 660Stafford Road Fax: 01744 612007 Fax: 01744 766 667 Fax: 0870 400 5797St Helens Email: [email protected] Email: [email protected] Email: [email protected] www.knaunsulation.co.ukWA10 3NS

2 2 pitched roofs rafter level

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