Non-ResidentialNewBuild 4.3.3TimberFrameWallsTimber frame walls Timber frame design 360 Sales 0844 800 0135 Technical Advisory Centre 01744 766666 4.3.3 Non-residential new build:

Non - Residential New Build4.3.3 Timber Frame Walls

August 2008: Issue 1

4.0Non-residential new build

Non-residential New Build

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Introduction find online pageSolution optimiser and pathfinder 358Design considerations 360

Design Details 588

Timber Frame Walls Contents

find online page

Single layer – insulation between studs Tf01 588

Single layer – insulation betweenstuds with service void Tf02 590

Insulation between studs andinsulated lining Tf03 592

Insulation between studs and insulationto exterior of sarking (full-fill) Tf04 594

Single layer blow-in insulation Tf05 596

Insulation between studs and insulationto exterior sarking (partial fill) Tf04 594

Single layer – insulation between studsProduct*: Crown FrameTherm rangeDescription: Glasswool insulation between 140mm studs with or withoutlow E breather membrane

Page No: 588

Single layer – insulation between studs with service ductProduct*: Crown FrameTherm rangeDescription: Glasswool insulation between140mm studs with low E service void andwith or without low E breather membranePage No: 590

Timber frame wallsSolution optimiser and pathfinder

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4.3.3 Non-residential new build: Walls

Timber frame construction offers a method of construction which is engineered, energyefficient, sustainable and quality assured.With a huge supply of plantation timberreadily available in the UK and Ireland thisform of construction is environmentally friendlywith extremely low ‘embodied energy’. The benefits of timber frame construction are being extended to an increasingrange of non-domestic building types, such as schools, hotels and health care facilities.

Knauf Insulation provide solutions for a range of timber frame systems, givingoptions relating to the preferred method of construction and the required levelof thermal performance in line with Building Regulations.

Elemental U-value requirement

Timber frame wallsConstruction compatibility with Part L2A

Knauf Insulation solution

Insulation between studs with insulated liningProducts*: Crown FrameTherm rangeand Polyfoam LinerboardDescription: Glasswool insulation between 140mm studs with XPS insulated plasterboardPage No: 592

Tf03

Tf01

Area weighted average max

U-value for compliance England

and Wales and Northern Ireland

U-values 0.26 0.25 0.24 0.23 0.22 0.21 0.20 0.19 0.18 0.170.29 0.28 0.270.32 0.300.33 0.31 0.150.16

Tf02

Insulation between studs and to exterior of sarkingProducts*: Crown FrameTherm rangeand Crown DriTherm Cavity Slab rangeDescription: Glasswool insulation between 140mm studs and glasswool cavity slab insulation to exterior of sarking partially filling the cavityPage No: 594

Single layer – blow in insulation between studsProduct*: Perimeter PlusDescription: Glasswool blow in blanket system between 90mm studs

Page No: 596

Single layer – blow in insulation between studsProduct*: Perimeter PlusDescription: Glasswool blow in blanket system between 140mm studs

Page No: 596Tf05

Insulation between studs and to exterior of sarkingProducts*: Crown FrameTherm rangeand Crown DriTherm Cavity Slab rangeDescription: Glasswool insulation between 90mm studs and glasswool cavity slab insulation to exterior of sarkingfully filling the cavityPage No: 594

Tf04

Tf04

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4.3.3Non-residential new build: Walls

Elemental U-value requirement

Timber frame wallsConstruction compatibility with Part L2A

Knauf Insulation solution U-values 0.26 0.25 0.24 0.23 0.22 0.21 0.20 0.19 0.18 0.170.29 0.28 0.270.32 0.300.33 0.31 0.150.16

KeyU-values achievable by constructions within this document.

* Recommended Knauf Insulation product(s). Other products may be applicable.

Find online. Visit www.knaufinsulation.co.uk and key in construction code to find the most up to date information on your chosen solution.

Pb01

Area weighted average max

U-value for compliance England

and Wales and Northern Ireland

Tf05

Timber frame wallsTimber frame design


4.3.3 Non-residential new build: Walls

Off-site timber frame fabrication in progress

OverviewInsulated external timber frame walls can providebetter insulation performance than masonry wallsof comparable thickness.

Timber frame is also widely recognised as themost environmentally friendly constructionmethod – a construction with extremely low‘embodied energy’. This is the energy required tomanufacture a building component or material,deliver it to site and install or construct. In thisrespect timber frame performs much better thanstandard masonry construction. Timber frameoffers unique advantages to home owners,builders and contractors:

• Construction is faster

• A wide range of U-values can be achieved depending on Building Regulations and the required level of thermal performance.

• Excellent thermal efficiency

• Potential for easy future renovation

• Pre-fabrication enhances quality control due to off site manufacture, thereby reducing the risk of on-site workmanship problems.

• Relatively light weight requiring reduced footings and foundations compared to masonry construction.

Timber frame construction offers a method of construction which is engineered, energyefficient, sustainable and quality assured. It fulfils a 21st century agenda, offering amethod of construction which is engineered,energy efficient, sustainable and qualityassured. With a huge supply of plantationtimber readily available in the UK andIreland this form of construction is sustainableand environmentally friendly.

The importance of condensation controlA vapour control layer is essential on the ‘warm’side of the insulation to reduce the risk ofcondensation forming within the timber frame.The vapour control layer may be incorporatedwithin the plasterboard or installed separately.Joints should be as few as possible and sealed,with special care taken around penetrations forservices.

A breather membrane on the outside of thesheathing is also necessary to protect againstwater penetration whilst allowing water vapour toescape.

As a rule of thumb, the vapour resistance of thematerials on the ‘warm’ side of the insulationshould have at least five times the vapourresistance of the materials on the ‘cold’ side of the insulation. Or, calculations should becarried out to assess the risk of interstitialcondensation by referring to BS 5250: 2002.

In some timber framed systems, such as the Twin Insulated, the insulation in the cavitymaintains the timber frame above the dewpointtemperature thus reducing the condensation riskeven further. If in doubt call the Knauf InsulationTechnical Advisory Service for a freecondensation risk calculation.

Timber frame and fire performanceA half hour fire resistance in domestic externalwalls is required by the Building Regulations.Timber frame walls with mineral wool insulationare ideal for meeting this requirement.

In most timber frame constructions, cavity barriersmust be used to divide up the external cavity inorder to reduce the risk of fire spread. In the TwinInsulated system, cavity barriers are notnecessary because the cavity is completely filledwith non-combustible mineral wool insulation (thishas been tested and assessed by TRADA Technology Ltd (report RD92061)– available on request from Knauf Insulation).

Twin Insulated CrownFrameTherm and CrownDriTherm Cavity SlabThis system is unique to Knauf Insulation and hasbeen developed to meet demand for higherinsulation values in timber frame construction.It consists of a standard timber frame wall on theinside, a cavity fully or partially filled with CrownDriTherm Cavity Slab and an outer leaf ofbrickwork cladding. The system can be used inany type of building up to three storeys.

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4.3.3Non-residential new build: Walls

1) Single Layer - insulation between the studs

External brick outer leaf

Clear cavity

Knauf Breatheline

Sheathing

Crown Frametherm Roll/Slabbetween timber studs

Vapour control layer

Plasterboard


Clear cavity (part fill shown)

Crown DriTherm Cavity Slab

Knauf Breatheline

Sheathing



Plasterboard


Clear cavity

Knauf Breatheline

Sheathing


Polyfoam Linerboard

2) Double layer - insulation between the studsand an insulated dry lining

3) Twin Insulated - insulation between the studs and in the external to sarking

Three methods for insulating timber frame construction

Cutting Crown FrameTherm to size to friction fit between narrowly spaced timber studs

design detail finderKnauf Insulation solutions for these types of construction can be found on pages 588-597

Timber frame wallsSingle layer – insulation between studs


6.2.2 Design details: Timber frame walls

Advantages� Low cost

� Lightweight and easy to cut

� Much faster to install than rigid foam boards which require very accurate cutting

� Sized to fit tightly between standardstud widths without any cutting on site

� The insulation is compressible, where cutting isrequired cut the insulation slightly oversize andfriction fit between the timber studs therebypreventing cold air penetrating through jointsbetween the insulation and the timber

� The insulation is fitted in one process

� Completely fire-safe non combustible product

� Improves acoustic insulation of the walls

� Crown FrameTherm is a Zero ODP and ZeroGWP insulation product

� The manufacture of Crown FrameTherm products has a very low impact on the environment

A vapour control layer is stapled to the studsacross the inner face of the wall before fixingthe plasterboard. The vapour control layershould be free from holes. Any gaps should bemade good, tears repaired and overlaps andapertures for services effectively sealed.Particular care is necessary around electricalboxes.

Knauf Breatheline or other standard breathermembrane, or low emissivity breathermembrane should be stapled or nailed to the sheathing board at maximum 500mmcentres. It should be lapped so that each joint is protected, with upper layers lapped over lowerlayers to shed water away from the sheathing.Horizontal laps should be at least 100mm wideand the membrane should extend below thelowest timber member. Vertical laps should beat least 150mm and be staggered.

Typical constructionInner leaf comprising 12.5mm plasterboard,vapour control layer, Crown FrameThermRoll/Slab between studwork, plywoodsheathing and Knauf Breatheline, breathablemembrane. A 50mm cavity separates the timberframe from the outer leaf, typically of brick.Other cladding options, such as tile hangingand timber boarding can also be utilised.

InstallationKnauf Insulation products are dimensioned tosuit studs 90 or 140 mm at standard 600mmcentres. The nominal thickness of the insulationshould not be greater than the nominal studdepth.

Crown FrameTherm Roll/Slabs are friction fittedbetween studs at standard centres and are selfsupporting. Generally, two slabs fully fill thespace between sole and head plates forstandard floor to ceiling height.

ProductsCrown FrameTherm Roll/Slab is a lightweightglass mineral wool available in both slab androll form and a range of thermal conductivities.Its manufacture has a very low impact on theenvironment and is classified as Zero ODP andZero GWP*

Knauf Breatheline is a breathable membranewith a polypropylene non-woven coating onboth sides.

* Ecohomes and Code for Sustainable Homes classification

Tf01

Brick outer leaf

Cavity

Knauf Breatheline

Plywood sheathing

Crown FrameTherm between timber studs


12.5mm plasterboard

Knauf Breatheline

589

6.2.2Design details: Timber frame walls


Typical specificationExternal wall panels to be insulated betweenstuds using Crown FrameTherm 43*/40*/38*/35*/32*/Slab*......mm thick

(*Delete as appropriate).

Insulation to be cut as necessary and frictionfitted between studs.

The breather membrane stapled*/nailed* to the sheathing and extending below thelowest timber member(*delete as necessary).

Cavity barriers and fire stops should beinstalled as required to meet the BuildingRegulations.

Alternatively, refer to NBS clause P10/210.

Table 41: Typical U-values for prefabricated timber framed walls

Product U-values (W/m2K)

Thickness Breather Masonry Tile/timber clad(mm) membrane outer leaf outer leaf

Crown FrameTherm 32 140 (90+50) Knauf Breatheline 0.26 0.28

90 Knauf Breatheline 0.37 0.40140 (90+50) Low E breather 0.24 0.27

90 Low E breather 0.32 0.38

Crown FrameTherm 35 140 Knauf Breatheline 0.27 0.29

90 Knauf Breatheline 0.38 0.42140 Low E breather 0.25 0.28










90 Low E breather 0.37 0.44Notes: The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Studs assumed to be 38mm wide at600mm centres (allowances for sole plates etc, give a 15% bridging area for the timber). Stud depth is taken to be the sameas the thickness of insulation specified. Thermal conductivity of timber studs is 0.120W/mK. Ventilated low emissivityairspace assumed to increase the R value of the cavity to 0.29 Wm/K and unventilated low emissivity airspace assumed toincrease R value of cavity to 0.44 m2K/W as specified in BR443. Higher values can be achieved with proprietary products.Please contact Knauf Insulation Technical Advisory Centre for calculations that include specific products.

Performance

Thermal performanceCrown FrameTherm Slab 43 – 0.043 W/mK.

Crown FrameTherm Roll 40 – 0.040 W/mK.

Crown FrameTherm Slab 38 – 0.038 W/mK.

Crown FrameTherm Roll/Slab 35 – 0.035 W/mK.


Table 41 gives U-values for typicalprefabricated timber frame walls insulated withCrown FrameTherm products.

Fire performance Crown FrameTherm is classified as EuroclassA1 to BS EN ISO 13501-1.

Building Regulations state that external walls indomestic construction shall achieve half hourfire resistance. In tests and assessments carriedout by TRADA Technology Ltd in accordancewith BS 476: Part 21: 1987, different timberframe external walls incorporating CrownFrameTherm provided the required fireresistance.

Brick outer leaf Crown Cavity Barriers

Timber frame separating wall,Robust detail E-WT-1 shown

Crown FrameTherm betweentimber studs

Vapour control layer behindplasterboard

Typical junction of external and separating wall

Timber frame wallsSingle layer – insulation between studs with service void



Advantages Lightweight and easy to cut

Much faster to install than rigid foam boards which require very accurate cutting

� Sized to fit tightly between standardstud widths without any cutting on site

� The insulation is compressible, where cutting isrequired cut the insulation slightly oversize andfriction fit between the timber studs therebypreventing cold air penetrating through jointsbetween the insulation and the timber

� The insulation is fitted in one process

� Completely fire-safe non combustible product

Improves acoustic insulation of the walls

Crown FrameTherm is a Zero ODP andZero GWP insulation product

The manufacture of Crown FrameTherm hasa very low impact on the environment

Service ducts provide both a void for services and insulation value

Providing a service duct increases thelikelihood that the vapour control layer willremain complete when services are fitted

Knauf Breatheline should be stapled or nailed to the sheathing board at maximum 500mmcentres. It should be lapped so that each joint isprotected, with upper layers lapped over lowerlayers to shed water away from the sheathing.Horizontal laps should be at least 100mm wideand the membrane should extend below thelowest timber member. Vertical laps should beat least 150mm and be staggered.

Performance

Thermal performanceCrown FrameTherm Slab 43 – 0.043 W/mK.

Crown FrameTherm Roll 40 – 0.040 W/mK.

Crown FrameTherm Slab 38 – 0.038 W/mK.


Crown FrameTherm Roll/Slab – 0.032 W/mK.

Table 42 gives U-values for typicalprefabricated timber frame walls insulatedwith Crown FrameTherm products.

InstallationKnauf Insulation products are dimensioned tosuit studs at standard 600mm centres. Thenominal thickness of the insulation should not be greater than the nominal stud depth.

Crown FrameTherm Roll/Slabs are friction fitted between studs at standard centres and are self supporting. Generally, two slabs fully fill the space between sole and head plates for standard floor to ceiling height.

A low emissivity vapour control layer is stapledto the studs across the inner face of the wallwith the low emissivity side facing internally.50x25mm vertical timber battens are nailed to the timber studs before fixing theplasterboard. The vapour control layer shouldbe free from holes. Any gaps should be madegood, tears repaired and overlaps sealed withaluminised tape.

ProductsCrown FrameTherm Roll/Slab is a lightweightglass mineral wool available in both slab androll form and a range of thermal conductivities.Its manufacture has a very low impact on theenvironment and is classified as Zero ODP and Zero GWP*



Typical constructionStandard timber frame construction, with a brickouter leaf and a low emissivity vapour controllayer to the inner face of the timber frame. A service duct is formed by nailing 50x25mmtimber battens to the timber frame before fixingthe 12.5mm plasterboard internal lining.

Other cladding options, such as tile hangingand timber boarding can be utilised.

Tf02

��

Cavity

Knauf Breatheline orlow emissivity

breather membrane

Plywood sheathing


��

12.5mm plasterboard

Knauf Breatheline

Service void formed by timber battens

Brick outer leaf

Low emissivityvapour control layer

591



Typical specificationExternal wall panels to be insulated betweenstuds using Crown FrameTherm43*/40*/38*/35*/32*......mm thick(*Delete as appropriate). Insulation to be cutas necessary and friction fitted betweenstuds.

The breather membrane stapled*/nailed* tothe sheathing and extending below the lowesttimber member (*Delete as appropriate).

Form service void with 50x25mm timberbattens as shown on the drawings.

Cavity barriers and fire stops should be installed as required to meet the BuildingRegulations.

Alternatively, refer to NBS clause P10/210

Table 42: Typical U-values for prefabricated timber framed wall with insulation between the studs and a service void


Including a 25mm low emissivity service void

Thickness Breather Masonry Tile/timber clad (mm) membrane outer outer

leaf leaf


90 Knauf Breatheline 0.33 0.35














90 Low E breather 0.39 0.37Notes: Low emissivity values taken from BR443. Thermal conductivity of timber studs is 0.120 W/mK.

Fire performance Crown FrameTherm is classified as EuroclassA1 to BS EN ISO 13501-1.

Building Regulations state that external walls indomestic construction shall achieve half hourfire resistance. In tests and assessments carriedout by TRADA Technology Ltd in accordancewith BS 476: Part 21: 1987, different timberframe external walls incorporating CrownFrameTherm gave the required fire resistance.

Brick outer leaf

Knauf Breatheline orlow emissivitybreather membrane Crown Cavity Barriers

Timber frame separating wall,Robust detail E-WT-1

Crown FrameTherm betweentimber studs

Servicevoid

Low emissivityvapour control layer

Typical junction of external and separating wall

Timber frame wallsInsulation between studs with insulated lining



Advantages� Improves U-values of walls, within

same stud depth

� Between stud insulation is lightweightand easy to cut

� Much faster to install between studs than rigid foam boards which require very accurate cutting

� Sized to fit tightly between standard stud widths without any cutting on site

� The insulation is compressible, where cutting is required cut the insulation slightly oversize and friction fit between the timber studs thereby preventing cold air penetrating through joints between the insulation and the timber

� Improves acoustic insulation of the walls

� Crown FrameTherm are Zero ODP and Zero GWP insulation products

� The manufacture of Crown FrameTherm products has a very low impact on the environment

Knauf Breatheline should be stapled or nailed tothe sheathing board at maximum 500mmcentres. It should be lapped so that each joint isprotected, with upper layers lapped over lowerlayers to shed water away from the sheathing.

Horizontal laps should be at least 100mm wideand the membrane should extend below thelowest timber member. Vertical laps should beat least 150mm and be staggered.

PerformanceThermal performanceCrown FrameTherm Roll 40 has a thermalconductivity of 0.040 W/mK.

Crown FrameTherm 32 has a thermalconductivity of 0.032 W/mK.

The insulation element of Polyfoam Linerboardhas a thermal conductivity of 0.030 W/mK andthe plasterboard has a thermal conductivity of0.19 W/mK.

Table 43 gives U-values for typicalprefabricated timber frame walls lined internallywith various thicknesses of Polyfoam Linerboard.

Typical constructionA 90mm deep timber frame stud wall infilledwith Crown FrameTherm and faced internallywith Polyfoam Linerboard and externally withplywood sheathing and Knauf Breatheline. Theuse of an insulated plasterboard laminateimproves the thermal performance and reducesthermal bridging through the timber studs. A50mm cavity separates the timber frame fromthe outer leaf, typically of brick.

InstallationKnauf Insulation products are dimensioned tosuit studs of 90 or 140mm at standard 600mmcentres. The nominal thickness of the insulationshould not be greater than the nominal studdepth.

Crown FrameTherm is friction fitted betweenstuds at standard centres and is self supporting.Subsequently, Polyfoam Linerboard is screwedto the timber frame at maximum 150mmcentres. The boards are taper edged andshould be finished using standard dryliningtechniques.

ProductsCrown FrameTherm Roll/Slab is a lightweightglass mineral wool available in both slab androll form and a range of thermal conductivities.Its manufacture has a very low impact on theenvironment and is classified as Zero ODP andZero GWP*

Polyfoam Linerboard is a laminate of Polyfoamhigh performance 100% ozone friendlyextruded polystyrene, rigid board insulation and 9.5mm plasterboard.



Tf03

Brick outer leaf

Cavity


Knauf Breatheline

Sheathing board


Polyfoam Linerboard

Knauf Breatheline

Table 43: Typical U-values for prefabricated timber framed walls with an internal lining

Insulation product U-values (W/m2K)

Polyfoam MasonryInsulation between Thickness Linerboard outer Tile/timber cladstuds (mm) thickness (mm) leaf outer leaf

Crown FrameTherm 40 140 36/9.5 0.22 0.23140 25.5/9.5 0.23 0.25140 17.5/9.5 0.25 0.27

90 36/9.5 0.28 0.29

90 25/9.5 0.31 0.33

90 17.5/9.5 0.33 0.36

Crown FrameTherm 32 140 36/9.5 0.20 0.21140 25.5/9.5 0.21 0.22140 17.5/9.5 0.22 0.24

90 36/9.5 0.25 0.27

90 25/9.5 0.28 0.30

90 17.5/9.5 0.30 0.32Notes: The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Studs assumed to be 38mm wide at 600mm centres (allowances for sole plates etc, give a 15% bridging area for the timber). Stud depth is taken to be the sameas the thickness of insulation specified. Thermal conductivity of timber studs is 0.120 W/mK

593



90mm Crown FrameTherm between timber studs

Polyfoam Linerboard

Flexible sealant at perimeter of Polyfoam Linerboard to minimise air leakage

100mm Crown Acoustic Joist Rollbetween floor joists

Crown Cavity Barrier

Knauf Breatheline

Typical specificationExternal wall panels to be insulated betweenstuds using Crown FrameTherm 40*/32*mmthick (*delete as necessary). Insulation to be cutas necessary and friction fitted betweenstuds.

The wall panels to be lined internally withPolyfoam Linerboard, ......mm thick withintegral 9.5mm plasterboard screwed to thetimber studs at maximum 150mm centres.

Knauf Breatheline stapled*/nailed* to thesheathing and extending below the lowesttimber member (*Delete as appropriate).Cavity barriers and fire stops should beinstalled as required to meet the BuildingRegulations.

Alternatively, refer to NBSclauses: P10/210 and K10/205

Fire performanceCrown FrameTherm is classified as Euroclass A1to BS EN ISO 13501-1

Building Regulations state that external walls indomestic construction shall achieve half hourfire resistance. In tests and assessments carriedout at Trada Technology Ltd in accordance with BS 476: Part 21: 1987, different timber frameexternal walls incorporating Crown FrameThermgave the required fire resistance. To meet thehalf hour requirement using PolyfoamLinerboard it will be necessary to line the wallwith 12.5mm plasterboard before installing thePolyfoam Linerboard.

Typical junction of external wall and upper floor

Note: In order to prevent plasticiser migration, PVC insulated cables and pipes should be installed in service conduits orwrapped in aluminium foil faced tape.



Timber frame wallsInsulation between studs and to exterior of sarking

Advantages� Very low U-values can be achieved

� No need for firestopping (full-fill)

� Utilises non-combustible Euroclass A1 insulation throughout

� Partial fill system accepted by NHBC

Crown FrameTherm and Crown DriTherm 37 are Zero ODP and Zero GWP insulation products

� The manufacture of Crown FrameTherm and Crown DriTherm 37 products has a very low impact on the environment

� Crown FrameTherm is compressible and canbe cut slightly oversize to friction fit between the studs preventing cold air penetrating through joints

This will require longer than normal wall ties witha clip to hold the Crown DriTherm Cavity Slab37 back to the timber frame wall. Small cavitybarriers should be installed to the full width of thecavity. Crown DriTherm Cavity Slab 37 isinstalled to the same standard as for full-fill, butshould be fully clipped back to the timber framewall.Note The NHBC will accept this form of constructionproviding a 50mm residual cavity between the CrownDritherm Cavity Slab 37 and masonry outer leaf ismaintained.

PerformanceThermal performanceCrown DriTherm Cavity Slab 37 has a thermalconductivity of either 0.035 or 0.037 W/mK. Crown FrameTherm 35 has a thermalconductivity of 0.035 W/mK.Crown FrameTherm Roll 40 has a thermalconductivity of 0.040 W/mK.Crown FrameTherm Roll 32 has a thermalconductivity of 0.032 W/mK.Fire performanceCrown FrameTherm 40/35/32, and CrownDriTherm Cavity Slab 37 are classified asEuroclass A1 to BS EN ISO 13501-1.Building Regulations state that external walls indomestic construction shall achieve half hour fireresistance. In tests and assessments carried outTRADA Technology Ltd in accordance with BS 476: Part 21: 1987, different timber frameexternal walls incorporating Crown FrameThermRoll/Slab gave the required fire resistance.

The instructions to be found in British Board ofAgrément Certificate 95/3212 apply to the useof Crown DriTherm Cavity Slabs in masonrywall constructions and can therefore be deemedrelevant to this application. The BBA Certificatedoes not cover the specific use of Crown DriThermCavity Slab 37 in timber frame walls. Installation sequence – full-fillThe timber frame is erected in the normalmanner. The sequence and methods are thesame as for conventional timber frame exceptthat small cavity barriers are omitted from thecavity, as Crown DriTherm Cavity Slab 37 is non-combustible and therefore performs thefunction of a small cavity barrier. CrownDriTherm Cavity Slab 37 should fully fill thespace between the external cladding and thetimber frame. Adjacent slabs should always beclose butted leaving no gaps. Any mortardroppings or other debris lying on the top edgeof a slab, must be removed before installing thenext row above. The construction sequenceensures there is no cavity into which debris canfall to an irretrievable position. Adoption ofthese principles will ensure that any rainwaterpenetrating the outer leaf is not transmitted tothe timber frame.Note that the NHBC will not accept this form of constructionon projects where their guarantee is required.

Installation sequence – part fillThe timber frame is erected in the normalmanner. The sequenced method is the same as for conventional timber frame except that awider cavity than normal is used.

ProductsCrown FrameTherm Roll/Slab is a lightweightglass mineral wool available in both slab androll form and a range of thermal conductivities.Its manufacture has a very low impact on theenvironment and is classified as Zero ODP andZero GWP*Crown DriTherm Cavity Slab 37 is a semi-rigid,non-combustible glass mineral wool slabcontaining a water-repellent additive. Itsmanufacture has a very low impact on theenvironment and is classified as Zero ODP and Zero GWP*Knauf Breatheline is a breathable membranewith a polypropylene non-woven coating on both sides.* Ecohomes and Code for Sustainable Homes classification

Typical constructionInner leaf comprising 12.5mm plasterboard,vapour control layer, Crown FrameThermbetween studwork, 9.5mm plywood sheathingand Knauf Breatheline. Cavity between timberframe and outer leaf either fully or part filledwith Crown DriTherm Cavity Slab 37. Outerleaf typically of brick. InstallationThe installation of Crown FrameTherm, vapourcontrol layer and Knauf breatheline are thesame as for solution Tf01. If a service void is tobe included then refer to Tf02. The principlesfor installing Crown DriTherm Cavity Slab 37 ina twin insulated wall are essentially the same asfor installation in a masonry cavity wall whenthe inner leaf is constructed first.

Tf04

Brick outer leaf

Crown DriTherm Cavity Slab

Knauf Breatheline

Plywood sheathing



12.5mm plasterboard

Knauf Breatheline

595



Flexible sealant between plasterboard and floor to minimise air leakage

Crown DriTherm partially filling the cavity

Insulation should be in contact with underside of floor

Ventilated sub floor

Typical specificationTwin insulation full-fill system:External wall panels to be insulated betweenstuds using Crown FrameTherm 40/35/32*......mm thick

(*Delete as appropriate)

Insulation to be cut as necessary and frictionfitted between studs. The breather membranestapled*/nailed* to the sheathing andextending below the lowest timber member(*Delete as appropriate).

Cavity formed between internal and externalleafs to be fully filled with Crown DriThermCavity Slab 37......mm thick. The lowest runof wall ties to be located at 600mm centreshorizontally. Ties thereafter to be at 450mmcentres vertically and at 600mm centreshorizontally. All work to be in accordancewith manufacturers instructions.

Twin insulated part fill system:Frame and breather membrane as above, then:

Crown DriTherm Cavity Slab 37......mm thickto be fitted against the breather membraneon the face of the sheathing and held backusing insulation retaining clips fixed to thewall ties.

The lowest run of wall ties to be located at600mm centres horizontally. Ties thereafter to be at 450mm centres vertically and at600mm centres horizontally. All work to bein accordance with manufacturersinstructions.

Cavity barriers and fire stops should beinstalled as required to meet the BuildingRegulations.

Alternatively, refer to NBSclauses: P10/210, F30/10,150 and F30/12, 155

Table 44: Typical U-values for Crown Twin insulated wall – partial fill


Crown DriThermTimber studs Thickness Cavity Slab Masonry Low e filled with: (mm) thickness (mm) outer leaf service duct

Crown FrameTherm 32 140 50 0.19 0.17

90 50 0.24 0.21


90 50 0.24 0.22


90 50 0.26 0.23

Table 45: Typical U-values for Crown Twin insulated wall – full-fill


Crown DriThermTimber studs Thickness Cavity Slab Masonry Low e filled with: (mm) thickness (mm) outer leaf service duct


90 100 0.19 0.17


90 100 0.19 0.18


90 100 0.20 0.18Notes: The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Studs assumed to be 38mm wide at 600mmcentres (allowances for sole plates etc, give a 15% proportional area for the timber). Stud depth is taken to be the same as thethickness of insulation specified. Thermal conductivity of timber studs is 0.120 W/mK. Unventilated low emissivity airspace inservice void assumed to provide R value of 0.44 m2K/W as specified in BR443. Higher values can be achieved with proprietaryproducts. Please contact Knauf Insulation Technical Advisory Centre for calculations that include specific products.

Typical junction with timber ground floor



Advantages� Low cost

� Installed by approved contractor

Perimeter Plus is a Zero ODP ZeroGWP insulation product

The manufacture of Perimeter Plushas a very low impact on the environment

Brick outer leaf

Knauf Perimeter Plus netting layer

Sheathing board

Knauf Perimeter Plus blowinginsulation

Timber frame wallsSingle layer blow-in-insulation blanket system

Tf05

A vapour control layer is stapled to the studsacross the inner face of the wall before fixingthe plasterboard. The vapour control layershould be free from holes. Alternatively, avapour check plasterboard can be used. Any gaps should be made good, tears repairedand overlaps and apertures for serviceseffectively sealed. Particular care is necessaryaround electrical boxes.

Knauf Breatheline or a low emissivity breathermembrane should be stapled or nailed to thesheathing board at maximum 500mm centres.

It should be lapped so that each joint isprotected, with upper layers lapped over lowerlayers to shed water away from the sheathing.Horizontal laps should be at least 100mm wideand the membrane should extend below thelowest timber member. Vertical laps should beat least 150mm and be staggered.

Crown DriTherm Cavity Slab 32Crown DriTherm Cavity Slab 32 can be usedwithin the cavity in the same manner as shownin Tf04, page 594.

U-values for partial fill solutions are shown inTable 47, opposite.

Typical constructionInner leaf comprising 12.5mm plasterboard,vapour control layer, Knauf Perimeter Plus Blow-in-Blanket System consisting of thePerimeter Plus netting layer and Knauf PerimeterPlus blowing insulation blown betweenstudwork, plywood sheathing and KnaufBreatheline, breathable membrane. A 50mmcavity separates the timber frame from the outerleaf, typically of brick. Other cladding options,such as tile hanging and timber boarding canalso be utilised.

InstallationThe Perimeter Plus netting layer is stapled acrossthe entire wall area creating discrete cavities ofeach stud void. A hole is then cut in the nettingjust large enough to accommodate the nozzle of the Perimeter Plus Blow-in-Blanket System. The nozzle is inserted into the cut and the cavityis filled with Perimeter Plus blowing insulation.The Perimeter Plus Blow-in-Blanket Systemincludes sensors that determine when the cavityhas been filled to the required density and cutsoff the flow automatically. Continue filling all thecavities until the entire wall area is insulated.

ProductsKnauf Perimeter Plus TM blowing insulation is anunbonded glass mineral wool which is blowninto the cavities between the frame in timberframe construction. It requires no mixing on siteand is dry when installed, adding no water tothe building. Its manufacture has a very lowimpact on the environment and is classified asZero ODP and Zero GWP*.

Knauf Perimeter Plus blowing insulation is theinsulation component of the Knauf PerimeterPlus Blow-in-Blanket System. This system isinstalled by a network of nationwide approvedinstallers. The Blow-in-Blanket system alsoincludes an insulation netting layer that retainsthe insulation in the frame cavity during theblowing process and before the wall is linedwith the vapour control layer and plasterboard.

Crown DriTherm Cavity Slab 32 is a lightweightrigid slab of glass mineral wool with a waterrepellent additive. It is manufactured to fit between wall ties atstandard spacings. Its manufacture has a verylow impact on the environment and is classifiedas Zero ODP and Zero GWP*


597



Typical specificationExternal wall panels to be insulated between studs using Knauf Perimeter Plus Blow-in-Blanket System. The breathermembrane stapled*/nailed* to the sheathingand extending below the lowest timbermember (*Delete as appropriate).

Cavity barriers and fire stops should beinstalled as required to meet the BuildingRegulations.All external walls to be insulated duringconstruction by partially filling the cavitieswith Crown DriTherm Cavity Slab 32 ......mm thick.

The first run of wall ties to be located at600mm centres horizontally (at a level to bedecided by the specifier). Subsequent runs ofwall ties to be at not more than 900mmcentres horizontally, or as otherwise requiredby the structure, and at 450mm vertically.

All work under construction must be protected overnight and during adverseweather conditions in accordance with BS 5628: Part 3: 1985.

Alternatively, refer to NBS clause: F30/10,150

Table 46: Typical U-values for timber frame walls with Perimeter Plus Blow-in-Blanket system


Thickness Breather Masonry Tile/timber clad(mm) membrane outer leaf outer leaf

Perimeter Plus 90 Knauf Breatheline 0.38 0.42140 Knauf Breatheline 0.27 0.29200 Knauf Breatheline 0.21 0.2290 Low E 0.34 0.42140 Low E 0.25 0.29200 Low E 0.20 0.22

Notes: The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Studs assumed to be 38mm wide at600mm centres (allowances for sole plates etc, give a 15% bridging area for the timber). Stud depth is taken to be the sameas the thickness of insulation specified. Thermal conductivity of timber studs is 0.120 W/mK. Ventilated low emissivity airspaceassumed to increase the R value of the cavity to 0.29 m2K/W and unventilated low emissivity airspace assumed to increase R value of cavity to 0.44 m2K/W as specified in BR443. Higher values can be achieved with proprietaryproducts. Please contact Knauf Insulation Technical Advisory Centre for calculations that include specific products.

PerformanceThermal performanceKnauf Perimeter Plus blowing insulation has athermal conductivity of 0.034 W/mK.

Crown DriTherm Cavity Slab 32 has a thermalconductivity of 0.032 W/mK.

Table 46 gives U-values for typicalprefabricated timber frame walls insulated withthe Knauf Perimeter Plus Blow-in-Blanket System.

Table 47 gives U-values for typicalprefabricated timber frame walls insulated withthe Knauf Perimeter Plus Blow-in-Blanket Systemand Crown DriTherm Cavity Slab 32.

Fire performanceKnauf Perimeter Plus Blowing Insulation andCrown DriTherm Cavity Slab 32 are classifiedas Euroclass A1 to BS EN ISO 13501-1.

Brick outer leaf Crown Cavity BarriersKnauf Breatheline

Timber frame separating wall,Robust detail E-WT-1 shown

Knauf Perimeter Plus blowinginsulation

Knauf Perimeter Plus nettinglayer and vapour control layer

Plasterboard

Table 47: Partial fill U-values


Timber Crown DriTherm Breather Service Masonry Tile/timberstud (mm) Cavity Slab 32 (mm) membrane void outer leaf outer leaf

Perimeter Plus 90 50 Knauf Breatheline n/a 0.23 0.2565 Knauf Breatheline n/a 0.21 0.2275 Knauf Breatheline n/a 0.20 0.2185 Knauf Breatheline n/a 0.19 0.19

140 50 Knauf Breatheline n/a 0.19 0.1965 Knauf Breatheline n/a 0.17 0.1875 Knauf Breatheline n/a 0.16 0.1785 Knauf Breatheline n/a 0.15 0.16

90 50 Knauf Breatheline Low E 0.21 0.2265 Knauf Breatheline Low E 0.19 0.2075 Knauf Breatheline Low E 0.18 0.1985 Knauf Breatheline Low E 0.17 0.18

140 50 Knauf Breatheline Low E 0.17 0.1865 Knauf Breatheline Low E 0.16 0.1675 Knauf Breatheline Low E 0.15 0.1685 Knauf Breatheline Low E 0.14 0.15

www.knaufinsulation.co.uk

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Knauf Insulation Ltd.PO Box 10Stafford RoadSt HelensMerseysideWA10 3NS

Customer Service (Sales)Tel: 0844 800 0135Fax: 01744 612 007email: [email protected]

Technical Advisory Centre (TAC)Tel: 01744 766666Fax: 01744 766667email: [email protected]

LiteratureTel: 08700 668 660Fax: 0870 400 5797email: [email protected]

August 2008: Issue 1

Ref: KB57908

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