June Residential Refurbishment Masonry cavity walls

Transcription

1 June 2010 Residential Refurbishment Masonry cavity walls

2 Residential refurbishment 3.0 Residential Refurbishment Masonry Cavity Wall Contents Introduction find online page Solution optimiser and pathfinder 264 Design considerations 266 Design Details 568 find online page Full-fill built-in with glass mineral wool cavity slab (75-300mm) Mc Full-fill built-in with rock mineral wool cavity slab mm) Mc Full-fill with floor glass mineral wool (50-300mm) Mc Masonry cavity partial fill XPS Cavity Board Mc Masonry cavity partial fill glass mineral wool Mc Other masonry details Window and door openings Mc06 586

3 3.3.1 Residential refurbishment: External walls Masonry cavity walls Solution optimiser and pathfinder Knauf Insulation offer a range of products suitable covering both new build and refurbishment of masonry cavity walls. Extensions England, Wales and N.I. Max U-value for replacement thermal elements- England and Wales and Northern Ireland** Extensions Scotland Masonry cavity Construction compatibility with Part L1B Retained cavity wall 0.55 Elemental U-value requirement Knauf Insulation solution U-values Full-fill insulation with built-in glasswool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 75mm cavity with block inner leaf and built-in glasswool cavity slab Mc01 Page No: 568 Full-fill insulation with built-in glasswool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 85mm cavity with block inner leaf and built-in glasswool cavity slab Mc01 Page No: 568 Full-fill insulation with built-in glasswool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 100mm cavity with block inner leaf and built-in glasswool cavity slab Mc01 Page No: 568 Full-fill insulation with built-in glasswool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 150mm cavity with block inner leaf and built-in glasswool cavity slab Mc01 Page No:568 Full-fill insulation with built-in rock mineral wool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 85mm cavity with block inner leaf and built-in rock mineral wool cavity slab Page No: 574 Mc Full-fill insulation with built-in rock mineral wool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 100mm cavity with block inner leaf and built-in rock mineral wool cavity slab Mc02 Page No: 574

4 Residential refurbishment: External walls Key U-values achievable by constructions within this document. * Recommended Knauf Insulation product(s). Other products may be applicable. Pb01 Find online. Visit and key in construction code to find the most up to date information on your chosen solution. **Max U-value for upgraded thermal elements England and Wales and Northern Ireland (Cavity Walls Only) 0.35 W/m 2 K Max U-value for replacement thermal elements- England and Wales and Northern Ireland** Extensions England, Wales and N.I. Extensions Scotland Masonry cavity Construction compatibility with Part L1B Retained cavity wall 0.55 Elemental U-value requirement Knauf Insulation solution U-values Full-fill insulation with built-in rock mineral wool Product*: Earthwool DriTherm Cavity Slab range Description: Full-fill 150mm cavity with block inner leaf and built-in rock mineral wool cavity slab Mc02 Page No: 574 Full-fill with injected glasswool Product*: Supafil Green 37 or Supafil Description: Full-fill 50mm cavity in existing masonry wall with injected glasswool Page No: 576 Mc03 Full-fill with injected glasswool Product*: Supafil Green 37 or Supafil Description: Full-fill 75mm cavity in existing masonry wall with injected glasswool Page No: 576 Mc03 Full-fill with injected glasswool Product*: Supafil Green 37 or 40 Description: Full-fill 100mm cavity in existing masonry wall with injected glasswool Page No: 576 Mc03 Partial fill Product*: Polyfoam Cavity Board Description: Partial fill 100mm cavity with block inner leaf and XPS cavity board Page No: 578 Mc04 Partial fill Product*: Earthwool DriTherm Cavity Slab range Description: Partial fill 100mm cavity with block inner leaf and built-in glasswool Page No: 578 Mc05 265

5 3.3.1 Residential refurbishment: External walls Masonry cavity walls Masonry cavity design Accredited Construction Details Accredited Construction Details (ACDs) have been introduced chiefly for new build housing, but can be applied as good practice when building extensions to existing housing and as a starting point for the design of details for refurbishment work on existing walls. They are designed to limit both: Heat-loss through junctions in the building fabric Air infiltration To avoid excessive heat losses and local condensation problems, it is necessary to ensure there are no substantial thermal bridges or gaps where the layers of insulation occur, especially at junctions and around openings. A limited range of ACDs have been issued for housing. The drawings on this page illustrate typical details for openings in masonry cavity wall construction. Accredited Construction Details can be downloaded from: These details require a proprietary closer to be used at openings for sills and jambs with a minimum thermal resistance of 0.45 m 2 K/W. Polyfoam System Closer and Polyfoam Combi-Closer easily exceed this performance requirement. Details of these products are on page 756. Where there are no Accredited Construction Details for the construction method specified by the designer, other approved details may be used or the heat loss through the thermal bridges and junctions may be calculated. Accredited Construction Details are also designed to reduce unwanted air leakage and so prevent an increase in energy use within the heated part of the building. The Accredited Construction Details assume that the building has an internal air barrier to reduce air leakage. For masonry cavity walls, the air barrier is assumed to be either: A wet plaster finish The block inner leaf, with a parging coat on the block inner leaf, behind a plasterboard finish Plasterboard on dabs, with continuous ribbons or plaster adhesive at the perimeter of each wall area and around openings It is important to provide a flexible sealant at the junction between the air barrier and the wall perimeter and at junctions with window frames. It is at these junctions that a high level of air leakage takes place in traditional construction. Using a flexible sealant at these junctions should result in many more buildings achieving air leakage rates of less than 10 m 3 / m 2 /hr in air pressure tests. Typical Accredited Construction Details Folded lintel detail Jamb detail with insulated cavity closer Maximum thickness of steel lintel 3.2mm Minimum 30mm overlap between window frame and lintel insulation Flexible sealant between plaster finish and frame to limit air leakage At least 30mm overlap between frame and insulated cavity closer Flexible sealant between plaster finish and frame to limit air leakage Polyfoam System Closer No continuous base plate to lintel Sill detail with insulated cavity closer Flexible sealant to sill/plaster junction and window frame/sill junction to limit air leakage Minimum 30mm overlap between window frame and insulated closer 266

6 Residential refurbishment: External walls design detail finder Knauf Insulation solutions for these types of construction can be found ±on pages Ground bearing floor ACD no. MEI-GF-01 Windows doors and lintels ACD no. MEI-WD-01 Seal between wall and floor air barrier with a flexible sealant or seal gap between skirting board and floor using flexible sealant Ensure wall insulation (having a min. R-value of 0.60m 2 K/W) overlaps the window frame/ packing piece Apply flexible sealant to the frame junctions with external render and internal air barrier Insulation to tightly abut blockwork wall Ground bearing floor ACD no. TFW-GF-01 Timber intermediate floor ACD no. TFW-IF-01 Seal between wall and floor air barrier with a flexible sealant or seal gap between skirting board and floor using flexible sealant Seal between the skirting board and floor using flexible sealant Install insulation with a minimum R-value of 0.75m 2 KW around floor perimeter Insulation to tightly abut the inner face of the timber frame soleplate Ensure continuity of air barrier through the floor zone, e.g. solid nogging or header joist 267

7 3.3.1 Residential refurbishment: External walls Masonry cavity walls Masonry cavity design When constructing extensions, all the techniques used in new build work can be applied. The thermal upgrade of existing masonry cavity walls is also easily achieved by installing injected cavity wall insulation. This offers one of the fastest paybacks of all energy efficiency measures. Cavity wall insulation There are three methods of insulating the cavity in a masonry cavity wall. 1) Full-fill: built-in 2) Full-fill: injected 3) Partial fill External brick outer leaf Earthwool DriTherm Cavity Slab (glass) (including 34 and 32) or Earthwool DriTherm Cavity Slab (rock) Blockwork inner leaf Plasterboard on dabs or wet plaster finish External brick outer leaf Supafil Blockwork inner leaf Plasterboard on dabs or wet plaster finish External brick outer leaf Clear cavity Earthwool DriTherm Cavity Slab (glass - including 34 and 32) or Polyfoam Cavityboard Blockwork inner leaf Wall tie with retaining disk Plasterboard on dabs or wet plaster finish design detail finder Knauf Insulation solutions for these types of construction can be found ±on pages

8 Residential refurbishment: External walls Advantages Insulated masonry cavity walls can offer excellent thermal performance when the cavity is utilised as an insulation zone. Masonry cavity is the most widely used form of wall construction in the UK and Ireland. The cavity wall benefits from several features that account for its popularity with designers, developers and builders: Existing empty cavities can be upgraded with retrofit injected cavity wall insulation Flexibility of design, allowing the designer to meet the requirements of clients with widely available materials A wide range of U-values can be achieved and performance tailored to specific performance requirements Cost-effective Traditional method of construction that is understood throughout the industry Masonry cavity design Apart from structural considerations, which are obviously pre-eminent, the correct specification of wall ties is crucial in two additional respects. Firstly it is necessary that the tie does not compromise the performance of the cavity wall insulation with regard to liquid water penetration. Secondly, that the U-value calculation method takes into consideration the number of wall ties per square metre as well as the cross sectional area, and thermal performance of the tie. Refurbishment of an existing property If the property is being refurbished there may be a need to install remedial wall ties, installation is a simple affair conducted from the outside and the wall does not have to be demolished for it to happen. The adaptability of cavity walls has led to a significant evolution from their beginnings with two skins of masonry and an empty cavity, a form of construction offering minimal thermal properties. In contrast, the full and part fill systems used today provide exceptional thermal performance and energy efficiency. Refurbishment projects benefit from the fact that existing empty cavities can be upgraded with retrofit injected cavity wall insulation to dramatically improve the thermal performance of the wall(s). Extension to an existing property If the property is to be extended the new construction should be built subject to the current Building Regulations; close fitting ducts or sleeves should be installed across the wall cavity to serve air bricks and other ventilation openings. Cavity barriers should be installed at junctions with the existing structure and with compartments. In this case stainless steel wire ties can be used for cavities up to 175mm and are recommended because they have a low cross sectional area minimising their impact on the thermal performance of the wall. Where wider cavities are used a two part cavity tie is recommended. These are more robust and have a significant impact on the U-value of the wall. In all circumstances it is recommended that the designer seeks advice from the manufacturer of the wall tie to ensure that the tie selected meets the requirements of the renovation or building work. Recommended solutions The recommended masonry cavity wall system is full-fill, either injected (Supafil) or built in slabs (the range of Earthwool DriTherm Cavity Slabs). These systems not only provide the best U-value to wall width ratio but are also the lowest in cost. Even with dense concrete blocks it is possible to achieve very high thermal performance in a manageable wall width. The systems shown do not require cavity barriers, and both full-fill systems can be installed in buildings up to 25m in height as detailed in their British Board of Agrément Certificates. With formal guarantees against liquid water penetration and a long history of use in housing construction, they offer peace of mind for the specifier, builder and client alike. Full-fill cavity insulation provides the best U-value to wall width ratio and is also the lowest cost option for insulated cavity walls Insulation injected into a clear cavity allows an unobstructed inspection of the open cavity to check on quality of workmanship before the insulation is injected 269

9 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Full-fill with built-in glasswool Advantages 3 Low system width 3 Low cost 3 All products have BBA Certification for all exposure zones 3 Product guaranteed to resist moisture penetration 3 35 year performance heritage 3 Compression fit between slabs prevents moisture penetration and cold bridging at joints 3 Earthwool Dritherm Cavity Slabs are Zero ODP and Zero GWP insulation products 3 The manufacture of Earthwool Dritherm Cavity Slab products has a very low environmental impact Mc01 Plasterboard on dabs Suitable wall tie Blockwork inner leaf Earthwool DriTherm Cavity Slab Brick outer leaf Earthwool DriTherm Cavity Slab Products Earthwool DriTherm Cavity Slab 37/34/32 are a range of lightweight semi rigid or rigid slabs of glass mineral wool with a water repellent additive. They are manufactured to fit between wall ties at standard spacings. Their manufacture has a very low impact on the environment and is classified as Zero ODP and Zero GWP* * Ecohomes and Code for Sustainable Homes classification Typical construction Brick or block outer leaf (which may be rendered), brick or block inner leaf with cavity fully filled with Earthwool DriTherm Cavity Slab. Internal finish of plasterboard on dabs. For buildings from 12m to 25m high, BBA Certificate No 95/3212 imposes additional requirements. For additional information see the BBA Certificate or contact our Technical Advisory Centre on Guarantee All products in the Earthwool DriTherm Cavity Slab range are formally guaranteed for 50 years to resist the transmission of liquid water from the outer masonry leaf to the inner masonry leaf in new external cavity walls and to maintain their original manufactured thermal conductivity at normal building temperatures. Masonry includes bricks, blocks and dressed and reconstituted stone. The guarantee is available by application from Knauf Insulation. Table 34: Typical U-values for fully filled masonry cavity walls U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, plasterboard on dabs Insulation Thickness (mm) Dense block (λ = 1.13) Medium block (λ = 0.51) Lightweight aggregate (λ = 0.34) Standard aircrete (λ = 0.16) Lightweight aircrete (λ = 0.11) Earthwool DriTherm Cavity Slab (3x100) (2x100) (2x85) (2x75) (2x65) Earthwool DriTherm Cavity Slab (3x100) (2x100) (2x85) (2x75) Notes: The U-values have been calculated assuming that all walls are lined with plasterboard on dabs. Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm wide, wall ties assumed to be stainless steel with a cross-sectional area of no more than 12.5mm 2 for structural cavities up to 175mm wide. Above 175mm, the cross sectional area of tie wires is assumed to be 25mm 2. The U-values have been calculated to BS EN ISO 6946: 1997 and BR

10 Design details: Masonry cavity walls Typical wall/ground floor junction Earthwool DriTherm Cavity Slab 37/34/32 Typical specification All external walls to be insulated during construction by completely filling the cavities with Earthwool DriTherm Cavity Slab 37*/34*/32*...mm thick. (*Delete as appropriate) Continuous ribbon of adhesive behind plasterboard and flexible sealant below skirting and floor surface to minimise air leakage The first run of wall ties to be located at 600mm centres horizontally (at a level to be decided by the specifier). Subsequent runs of wall ties to be at not more than 900mm centres horizontally, or as otherwise required by the structure, and at 450mm vertically. Wall insulation to extend a minimum of 150mm below top of floor insulation All work under construction must be protected overnight and during adverse weather conditions in accordance with BS 5628: Part 3: Damp proof membrane Alternatively, refer to NBS clause: F30/10,150 Table 35: Typical U-values for fully filled masonry cavity walls U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, plasterboard on dabs Insulation Thickness (mm) Dense block (λ = 1.13) Medium block (λ = 0.51) Lightweight aggregate (λ = 0.34) Standard aircrete (λ = 0.16) Lightweight aircrete (λ = 0.11) Earthwool DriTherm Cavity Slab (3x100) (2x100) (2x85) (2x75) (2x65) (75+50) (65+50) Notes: The U-values have been calculated assuming that all walls are lined with plasterboard on dabs. Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm wide, wall ties assumed to be stainless steel with a cross-sectional area of no more than 12.5mm 2 for structural cavities up to 175mm wide. Above 175mm, the cross sectional area of tie wires is assumed to be 25mm 2. The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Performance Thermal performance Earthwool DriTherm Cavity Slab has a thermal conductivity of either W/mK or W/mK depending on thickness. Earthwool DriTherm Cavity Slab 34 has a thermal conductivity of W/mK. Earthwool DriTherm Cavity Slab 32 has a thermal conductivity of W/mK. Fire performance All products in the Earthwool DriTherm Cavity Slab range are classified as Euroclass A1 to BS EN ISO Moisture resistance All products in the Earthwool DriTherm Cavity Slabs range contain a water-repellent silicone additive to ensure that no liquid water is able to pass through the slabs and reach the inner leaf of masonry. Tests by the British Board of Agrément confirm that the range of Earthwool DriTherm Cavity Slabs will not transmit water to the inner leaf. Nor will they transmit moisture by capillary action across the cavity or from below DPC level. Vapour resistance All products in the Earthwool DriTherm Cavity Slabs range have negligible water vapour resistance, allowing water vapour to pass freely through the slabs. 569

11 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Full-fill with built-in glasswool Installation sequence Mc01 1 Build up the first stage of one leaf of masonry to include the first row of ties above the commencement of the 2 Position the Earthwool DriTherm Cavity Slab against the masonry, so that the wall tie drips are halfway across the top edge of the slabs. The Earthwool DriTherm Cavity Slab should be cut to course if necessary. Earthwool DriTherm Cavity Slab. Clean Earthwool DriTherm Cavity Slab should be taken below DPC level mortar squeeze from the masonry and (preferably by at least 150mm) to provide edge insulation, with no snots from any ties or cavity tray. risk of capillary action. Earthwool DriTherm Cavity Slab does not wick. Always bring Earthwool DriTherm Cavity Slab to course with wall ties. Installation The thickness of Earthwool DriTherm Cavity Slab and the cavity width should be designed within the tolerances given in Table 36 (right). It is not possible to compress Earthwool DriTherm Cavity Slab during installation because its resilience will be enough to dislodge bricks before the mortar has set. Earthwool DriTherm Cavity Slab should be kept clean and free from mortar droppings. All joints should be closely butted. Any cutting and fitting should be neatly done and not distort the layers of glasswool which comprise the material see Problems to avoid on opposite page. DPCs should be installed to ensure that penetrating water is directed only to the outer leaf. The illustrations above outline technique only, and do not imply that the outer leaf must be built first. Construction practice will vary from site to site. Where design details differ from those illustrated please do not hesitate to contact Knauf Insulation for any clarification required. Wall ties Earthwool DriTherm Cavity Slab is supplied in 1200 x 455mm slabs for use between wall ties at 450mm vertical centres. Standard butterfly, stainless steel wire ties and vertical twist ties are suitable, as are all ties with a positive drip which will penetrate the top edge of the Earthwool DriTherm Cavity Slab halfway across its width. The use of any other type of tie should be referred to Knauf Insulation. Advice should also be sought from the wall tie manufacturer as to the maximum cavity width for which the use of a specific tie is approved. Generally, rows of wall ties should be at 450mm vertical spacing and at horizontal spacings of not more than 900mm or as otherwise required by the structure. Where whole rows of ties are at different vertical spacing, Earthwool DriTherm Cavity Slab should be cut to course, allowing an extra 5mm for compression to form close butt joints. Where extra ties are required, e.g. at the side of openings, Earthwool DriTherm Cavity Slab should be cut and fitted carefully around them. When off-cuts of Earthwool DriTherm Cavity Slab are needed, the slabs can be cut with a long bladed knife or bricklayer s trowel. Further recommendations Above, below and beside openings, where cut strips of Earthwool DriTherm Cavity Slab may be needed, particular care should be taken to fit closely and ensure work is clean and free from debris. At the end of the day s work, or during rain, any exposed Earthwool DriTherm Cavity Slab should be covered. If Earthwool DriTherm Cavity Slab is terminated vertically at an open cavity, a vertical DPC must be fitted up the inside face of the outer leaf to ensure that any mortar droppings on exposed edges do not bridge the cavity. Table 36: Permitted deviations in cavity widths Earthwool DriTherm Cavity Slab size and nominal cavity width Thickness (mm) Permitted cavity deviation (mm) 150 or more -0 or or or or or or or

12 Design details: Masonry cavity walls The following leaf is then built to the top level of the Earthwool DriTherm Cavity Slab. Do not let the second leaf overtake the Earthwool DriTherm Cavity Slab so as to create a trough (but see 5 regarding choice of leading leaf). 4 Proceed similarly with successive stages of the wall. As with normal masonry cavity construction, no mortar should remain in the cavity. Particular care should be taken to keep slab joints closely butted and free from mortar. To facilitate keeping the top edges of slabs clean it is recommended that a cavity board be used. 5 Building may proceed leading with either the inner or the outer leaf. When leading with the inner leaf it is recommended to build a trough not more than one brick deep at horizontal joints in Earthwool DriTherm Cavity Slab. The mortar joint should be struck flush inside the cavity and any mortar droppings must be cleaned off before the next Earthwool DriTherm Cavity Slab is fitted. Problems to avoid Do not push slabs into the cavity. Mortar snots may be dislodged and bridge the cavity. This can happen all too easily where a change in the leading leaf occurs and care should be exercised at such positions to ensure correct application. Do not tear or impale Earthwool DriTherm Cavity Slab. If there are protrusions into the cavity, Earthwool DriTherm Cavity Slab should be carefully cut to fit, particularly where there are extra wall ties around openings. Do not position Earthwool DriTherm Cavity Slab on slabs which have not been cleaned of mortar droppings. When using small off-cuts, the face of the slabs and not the edge, shall be positioned against the wall surface. 571

13 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Full-fill with built in glasswool, extra wide cavities Wider cavities Mc01 With the move towards carbon neutral housing, the use of wider cavities in masonry cavity walls is likely to become much more common. Earthwool DriTherm Cavity Slab and Earthwool DriTherm Cavity Slab can be installed in multiple layers to fully fill cavities up to 300mm wide. Proprietary cavity closers and folded steel lintels are widely available for cavities up to 100mm wide. For cavities over 100mm wide, the choice of proprietary products is more limited. For cavities over 150mm wide, the detailing of openings may need to be altered radically. Jambs Cavities over 150mm wide present particular problems at the jambs. One solution to this is to use a plywood liner to the opening that can also double up as a former for the window frame. The diagrams below indicate this option for a 200mm wide cavity. The plywood box answers solves a number of problems: It closes off the cavity It can be sealed against the inner and outer leaf to limit air leakage It provides an accurate template for the window frame The temporary polythene front cover provides weather protection until the window frame is installed The window frames can be installed after the brickwork is complete reducing the risk of damage from mortar, etc. Typical use of a plywood box as former for window opening Metal anchors used to secure plywood box to outer leaf Polythene sheet to front of plywood box to provide weather protection before window is fixed Temporary bracing to ensure squareness of box WBP plywood box as permanent former for window opening DPC stapled to plywood box Two part wall tie Eaves detail showing installation of window frame in ply box Expanding foam used to limit air leakage Plasterboard finish to reveals The Ancon two-part wall tie Window frame installed 5-10mm proud of plywood box - tolerance gap filled with expanding foam to limit air leakage Sealant and/or timber fillet to seal gap between frame and outer leaf 572

14 Design details: Masonry cavity walls Lintels The use of separate lintels for the inner and outer leaf becomes more common and practical as the cavity width increases. Separate lintels not only avoid the thermal bridging problems of one piece steel lintels, but they also provide the designer with a greater level of design freedom. A concrete or aircrete lintel for the inner leaf is a simple, economic and firesafe option. The lintel in the outer leaf can be anything from reconstituted stone to plain brickwork supported on a steel angle. Wall ties Earthwool DriTherm Cavity Slab is supplied in 1200 x 455mm slabs for use between wall ties at 450mm vertical centres. For cavities up to 75mm wide, stainless steel wire ties are recommended by Knauf Insulation because: Stainless steel has a thermal conductivity of 17 W/mK, compared with 50 W/mK for mild steel Wire ties have a much smaller cross-sectional area than flat metal ties For these two reasons, stainless steel wire ties present a smaller thermal bridge through the cavity insulation than other types of metal wall tie. For cavities up to 175mm wide, double triangle stainless steel wire ties are available up to 300mm long. These ties conform to BS EN as a Type 3 tie. It is recommended that they are embedded 85mm into the inner leaf to help keep the cantilevered section of the tie horizontal during the build. With the use of wider cavities, it is anticipated that other designs of stainless steel wire ties will be developed for cavities up to 175mm wide. For cavities over 175mm wide, Knauf Insulation recommend the use of two part stainless steel ties. These are available from Ancon and Wincro Metal Industries. These ties overcome the problem of keeping a long tie horizontal when built into the inner leaf. However, they have a much greater cross-sectional area than wire ties and their thermal bridging effect must be taken into account when calculating the wall U-value. They are suitable for cavities up to 300mm wide. Typical detail using separate lintels Two layers of 100mm Earthwool DriTherm Cavity Slab Two part wall tie Reconstituted stone lintel Cavity tray Expanding foam between frame and plywood former Concrete inner lintel Plywood former sealed to inner leaf with expanding foam Plasterboard on dabs to soffit Typical detail using separate lintels and rebated window frame Two layers of 100mm Earthwool DriTherm Cavity Slab Cavity tray Two part wall tie Brick soldier lintel DPC and metal angle support for soldier lintel Expanding foam between frame and plywood former Aircrete inner lintel Plywood former sealed to inner leaf with expanding foam Plasterboard on dabs to soffit 573

15 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Full-fill with built in rock mineral wool Advantages 3 Low system width 3 Low cost Mc02 Plasterboard on dabs Earthwool DriTherm Cavity Slab 3 Readily available from local stockists 3 BBA certification for all exposure zones 3 Product guaranteed to resist moisture penetration 3 Compression fit between slabs prevents moisture penetration and cold bridging at joints 3 Earthwool DriTherm Cavity Slab is a Zero ODP and Zero GWP insulation product Suitable wall tie Blockwork inner leaf Earthwool DriTherm Cavity Slab Brick outer leaf 3 The manufacture of Earthwool DriTherm Cavity Slab has a very low environmental impact Products Earthwool DriTherm Cavity Slab is a medium density, water-repellent slab manufactured from rock mineral wool. It is dimensioned to fit between wall ties at standard spacings. Its manufacture has a very low impact on the environment and is classified as Zero ODP and Zero GWP* * Ecohomes and Code for Sustainable Homes classification Typical construction Brick or block outer leaf (which may be rendered), brick or block inner leaf with cavity fully filled with Earthwool DriTherm Cavity Slab. Internal finish of plasterboard on dabs. For buildings from 12m to 25m high, Agrément Certificate No 05/4207 imposes additional requirements. For additional information see the BBA Certificate or contact our Technical Advisory Centre on Guarantee Earthwool DriTherm Cavity Slab is formally guaranteed for 50 years to resist the transmission of liquid water from the outer masonry leaf to the inner masonry leaf in new external cavity walls and to have a thermal conductivity of W/mK at normal building temperatures. Masonry includes bricks, blocks and dressed and reconstituted stone. The guarantee is available by application from Knauf Insulation. Installation Earthwool DriTherm Cavity Slab should be kept clean and free from mortar droppings. All joints should be closely butted. Any cutting and fitting should be neatly done and not distort the layers of rock mineral wool which comprise the product. Damp proof courses should be installed to ensure that penetrating water is directed only to the outer leaf. The installation sequence is identical to Earthwool DriTherm Cavity Slab, as shown on pages Performance Thermal performance Earthwool DriTherm Cavity Slab has a thermal conductivity of W/mK. Fire performance Earthwool DriTherm Cavity Slab is classified as Euroclass A1 to BS EN ISO Moisture resistance Earthwool DriTherm Cavity Slab contains a water-repellent silicone additive to ensure that no liquid water is able to pass through the slab and reach the inner leaf of masonry. Tests by the British Board of Agrément confirm that Earthwool DriTherm Cavity Slab will not transmit water to the inner leaf. Nor will it transmit moisture by capillary action across the cavity or from below DPC level. Vapour resistance Earthwool DriTherm Cavity Slabs have negligible water vapour resistance, allowing water vapour to pass freely through the slabs. 574

16 Design details: Masonry cavity walls Typical wall/ground floor junction Earthwool DriTherm Cavity Slab 37/34/32 Wall insulation to extend a minimum of 150mm below top of floor insulation Continuous ribbon of adhesive behind plasterboard and flexible sealant below skirting and floor surface to minimise air leakage Damp proof membrane Typical specification All external walls to be insulated during construction by completely filling the cavities with Earthwool DriTherm Cavity Slab...mm thick. The first run of wall ties to be located at 600mm centres horizontally (at a level to be decided by the specifier). Subsequent runs of wall ties to be at not more than 900mm centres horizontally, or as otherwise required by the structure, and at 450mm vertically. All work under construction must be protected overnight and during adverse weather conditions in accordance with BS 5628: Part 3: Alternatively, refer to NBS clause: F30/10,150 Table 37: Typical U-values for fully filled masonry cavity walls U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, plasterboard on dabs Insulation Dense Medium Lightweight Standard Lightweight Thickness block block aggregate aircrete aircrete (mm) (λ = 1.13) (λ = 0.51) (λ = 0.34) (λ = 0.16) (λ = 0.11) Earthwool DriTherm Cavity Slab 300 (3x100) (2x100) (2x85) (2x75) (2x65) (75+50) (65+50) Notes: The U-values have been calculated assuming that all walls are lined with plasterboard on dabs. Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm wide, wall ties assumed to be stainless steel with a cross-sectional area of no more than 12.5mm 2 for structural cavities up to 175mm wide. Above 175mm, the cross sectional area of tie wires is assumed to be 25mm 2. The U-values have been calculated to BS EN ISO 6946: 1997 and BR

17 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Full-fill with injected glasswool Advantages 3 Low cost 3 Installed by approved contractor Mc03 Plasterboard on dabs Suapfil 3 BBA certification for all exposure zones 3 Product guaranteed to resist moisture penetration 3 Wall construction quicker than with built-in cavity wall insulation 3 Injected after wall constructed, allowing empty cavity to be checked 3 Supafil 40/Supafil Green 37 are Zero ODP Zero GWP insulation products Suitable wall tie Blockwork inner leaf Supafil 40 / Suapfil Green 37 Brick outer leaf 3 The manufacture of Supafil 40 and Supafil Green 37 has a very low impact on the environment Products Supafil 40 and Supafil Green 37 cavity wall insulation are loose glass mineral wool insulation materials which are injected into existing or newly-built cavity walls. They require no mixing on site and are dry when installed, adding no water to the building. Their manufacture has a very low impact on the environment and is classified as Zero ODP and Zero GWP* Supafil 40 and Supafil Green 37 cavity wall insulation are available only through approved installers fully trained by Knauf Insulation and approved by the British Board of Agrément. A list of Approved Installers is available on request. * Ecohomes and Code for Sustainable Homes classification Typical construction Brick or block outer leaf (which may be rendered), cavity fully filled with Suapfil 40 or Suapfil Green 37 cavity wall insulation, brick or block inner leaf. Internal finish of plasterboard on dabs. Tests by the British Board of Agrément confirm that Suapfil 40 and Suapfil Green 37 cavity wall insulation will not transmit water to the inner leaf. Nor will they transmit moisture by capillary action across the cavity or from below DPC level. Suapfil 40 and Suapfil Green 37 cavity wall insulation have negligible resistance to water vapour, permitting the wall to breathe. Guarantee Knauf Insulation offers a 25 year comprehensive guarantee for new build installations which also covers materials and workmanship. For installation in existing domestic properties, the Cavity Insulation Guarantee Agency (CIGA) offers a 25 year guarantee covering both materials and workmanship. Installation A survey is carried out prior to installation to ascertain the suitability of the building for insulation and to determine the position of flues, air vents, etc. Essential ventilation openings such as those providing combustion air or under floor ventilation, and all flues in the cavity wall, are checked and sleeved, or otherwise modified to prevent blockage by the insulation. An approved cavity barrier is inserted as appropriate to isolate terraced or semi-detached properties and to close any open cavities. A series of 22 or 25mm diameter holes are drilled in accordance with the patterns detailed by the British Board of Agrément Certificate. For new build schemes, the holes are usually drilled through the inner leaf and the insulant installed prior to plastering. For existing buildings, holes are usually drilled through the mortar joints in the outer leaf and are made good by repointing with mortar to match the wall finish as closely as possible. Suapfil 40 or Suapfil Green 37 cavity wall insulation is fed into an approved blowing machine and injected into the cavity under air pressure through a flexible hose fitted with a tapered nozzle. The machine is fitted with a pressure sensor which automatically cuts off to stop the flow of material when the area of wall being insulated is completely filled to the correct density. Vents, flues, etc, are checked to ensure they are free from blockage. Specialised buildings Knauf Insulation together with their approved installers have considerable knowledge and practical experience of installing Suapfil 40 and Suapfil Green 37 cavity wall insulation in various constructions such as: Cornish, BISF and other system-built houses. Knauf Insulation will be pleased to advise on the suitability of any building for insulation. Performance Suapfil 40 and Suapfil Green 37 cavity wall insulation will not deteriorate with age or settle, and will therefore remain effective as an insulant for the life of the building. The operations of all approved installers are rigidly monitored by Knauf Insulation and the British Board of Agrément in accordance with the terms of the British Board of Agrément Certificate. 576

18 Design details: Masonry cavity walls Typical specification Suapfil 40 */ Suapfil Green 37* glass mineral wool cavity wall isulation to be injected into the cavity by an Knauf Insulation/BBA Approved Installer. (*Delete as appropriate) In new construction, cavity injection is usually through the inner leaf before the plaster finish is applied Existing dwelling showing typical drilling pattern Table 38: Typical U-values for masonry cavity walls with injected insulation U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, type: Insulation thickness (mm) Suapfil 40 Dense block (λ = 1.13) Medium block (λ = 0.51) Lightweight aggregate (λ = 0.34) Standard aircrete (λ = 0.16) Lightweight aircrete (λ = 0.11) New cavity walls to receive Suapfil cavity wall insulation by injecting insulation into the cavity should be constructed so that insulation cannot penetrate ventilation ducts or pass through to cavities in adjoining buildings or compartments which are not to be insulated. Close fitting ducts or sleeves should be installed across the cavity to serve air bricks and other ventilation openings. Cavity barriers should be installed at junctions with other properties and compartments, and as required by the Building Regulations. Existing cavity walls to be inspected by the approved installer and all necessary builder s work carried out prior to Suapfil 40*/ Suapfil Green 37* cavity wall insulation being injected. All work to be in strict accordance with the procedures laid out in the relevant BBA Certificate and the Knauf Insulation Operators and Survey & Assessment manuals. Alternatively, refer to NBS clause: P11/40,220 Suapfil Green Notes: The U-values have been calculated assuming that all walls are lined with plasterboard on dabs. Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm wide, wall ties assumed to be stainless steel with a cross-sectional area of no more than 12.5mm 2 for structural cavities up to 175mm wide and 25mm 2 for larger cavities. The U-values have been calculated to BS EN ISO 6946: 1997 and BR 443. Thermal performance Suapfil 40 cavity wall insulation has a thermal conductivity of W/mK. Suapfil Green 37 cavity wall insulation has a thermal conductivity of W/mK. Fire performance Suapfil 40 and Suapfil Green 37 cavity wall insulation are classified as Euroclass A1 to BS EN ISO The installation of Suapfil cavity wall insulation will not adversely affect the fire rating of the wall and will not constitute a toxic hazard in fire conditions. 577

19 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Partial fill with Polyfoam Cavityboard Advantages 3 Very robust product 3 Shiplap joints between boards sheds any water in the cavity away from the inner leaf Mc04 Plasterboard on dabs or Polyfoam Linerboard 3 Retains clear cavity 3 Completely unaffected by moisture Blockwork inner leaf Wall tie with retaining disk Polyfoam Cavityboard partially filling cavity Clear cavity Brick outer leaf Products Polyfoam Cavityboard is a 100% ozone friendly, extruded polystyrene, rigid board insulation. It is lightweight, yet has excellent rigidity and long term effectiveness, even when exposed to moisture Polyfoam Linerboard is a laminate of Polyfoam high performance, 100% ozone friendly, extruded polystyrene, rigid board insulation and tapered edge plasterboard Typical construction Brick or block outer leaf (which may be rendered), cavity, Polyfoam Cavityboard, block inner leaf. Internal finish of plasterboard on dabs or an insulated dry lining, where increased thermal performance is required. British Board of Agrément approval means that in many instances only a minimum 25mm residual cavity needs to be maintained. In more exposed areas, buildings over 12m in height and for dwellings subject to NHBC inspection, a 50mm residual cavity should be maintained. Note that where the structural cavity is over 100mm wide, wall ties should be type 1 to BS 5628, or DD140: Part 2. Performance Compression resistance The rigidity of Polyfoam Cavityboard makes the board easy to handle and less prone to site damage than less robust materials. Moisture resistance The boards are resistant to moisture absorption and can be laid in ground water or up against wet concrete with negligible impact on the performance of the product. The interlocking rebated edge sheds any water into the cavity away from the inner leaf in the unlikely event that it penetrates the face joint between two boards. Thermal performance Polyfoam Cavityboard has a thermal conductivity of W/mK. Fire performance Polyfoam Cavityboard contains a flame retardant to inhibit localised ignition. The use of Polyfoam Cavityboard will not prejudice the fire resistance of the wall. 578

20 Design details: Masonry cavity walls Typical wall/pitched roof junction Roof insulation taken down to link with wall insulation Typical specification Polyfoam Cavityboard,...mm thick, to be located in the cavity of all external masonry cavity walls; residual cavity width to be...mm. Insulation to be retained against the cavity face of the inner leaf of masonry by means of insulation retaining wall ties as manufactured by.... The wall ties to have one of their drip centres half-way across the residual cavity. Clip to secure free end of Polyfoam Cavityboard in place For structural cavities over 100mm, type 1 wall ties must be used Continuous ribbon of adhesive behind plasterboard Cavity barrier of calcium silicate board Polyfoam Cavityboard with clear cavity The first run of wall ties to be located at the bottom level of the insulation (to be decided by the specifier). Ties to be at 450mm centres vertically and a maximum of 900mm horizontally. All work under construction must be protected overnight and during adverse weather conditions in accordance with BS 5628: Part 3: All work to be in strict accordance with this specification and the recommendations contained in Knauf Insulation s literature. Table 39: Typical U-values for partially filled masonry cavity walls U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, type: Alternatively, refer to NBS clause: F30/12,151 Polyfoam cavityboard thickness (mm) Dense block (λ = 1.13) Medium block (λ = 0.51) Lightweight aggregate (λ = 0.34) Polyfoam Cavityboard (with internal finish of plasterboard on dabs) Standard aircrete (λ = 0.16) Lightweight aircrete (λ = 0.11) Polyfoam Cavityboard (with internal finish of 17.5/9.5mm Polyfoam Linerboard) Polyfoam Cavityboard (with internal finish of 36/9.5mm Polyfoam Linerboard on dabs) Note: Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm, wall ties assumed to be stainless steel with a cross-sectional area of 12.5mm 2 for structural cavities up to 175 mm wide. The U-values have been calculated to BS EN ISO 6946: 1997 and BR

21 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Partial fill with Polyfoam Cavityboard Installation sequence Mc04 1 Bring the first leaf to the level of the first row of wall ties and remove any excess mortar. 2 Trim the bottom of the board to fit the space between the bottom of the cavity and the first row of wall ties. Fit the board 3 Build the second leaf up to the level of the insulation board. Adjust retainers so that the board is held firmly against the inner so that the shiplap joint will shed water leaf. Do not let the second leaf overtake away from the inner leaf. Cut small the Polyfoam Cavityboard so as to create notches in the upper edge of the Polyfoam a trough. Cavityboard to accommodate the wall ties. 150mm minimum Installation Polyfoam Cavityboard is supplied in 1200 x 450mm boards. Wall ties with insulation retaining disks must be used. Normally ties are spaced at 450mm vertical centres. Horizontal centres vary according to the width of the cavity and the type of tie used but should not be more than 900mm. Manufacturer s recommendations must be followed. Construction practice will vary from site to site. Where design details differ from those illustrated please do not hesitate to contact Knauf Insulation for any clarification required. Polyfoam Cavityboard should be cut and fitted carefully around openings and to suit wall lengths. The boards can be cut with a long bladed knife, or saw. Avoid thermal bridges by taking the Polyfoam Cavityboard to the back of frames, sills and cavity closers. Also, ensure the wall insulation starts at least 150mm below the top of the perimeter floor insulation and is supported on ties (as shown in step 2). 580

22 Design details: Masonry cavity walls Build up the first leaf a further 450mm, clean off any excess mortar and fit the second row of boards. The vertical joints should be staggered so that they do not line up with the joint in the board below. Ensure that the board is tightly fitted against the row of boards below. There should be at least four retainers per board. 5 Raise the second leaf to the level of the first and repeat previous sequence to completion. As with normal masonry cavity construction, no mortar should remain in the cavity. Particular care should be taken to keep board joints tightly butted and free from mortar. To facilitate keeping the top edges of insulation clean it is recommended that a cavity batten or board be used. Wall tie manufacturers The following manufacturers can supply stainless steel wall ties: Ancon Building Products tel: Stainless Steel Fixings tel: Catnic Profiles tel: Helifix Ltd fixings.co.uk tel: Tecties tel: The Stainless Wire Tie Co tel:

23 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Partial fill with glasswool Advantages 3 Lowest cost partial fill solution 3 Readily available from local stockists 3 BBA certification for all exposure zones 3 Compression fit between slabs prevents moisture penetration and cold bridging at joints 3 Built-in during construction 3 Earthwool DriTherm Cavity Slabs are Zero GWP and Zero ODP insulation products 3 The manufacture of Earthwool DriTherm Cavity Slab products has a very low impact on the environment Mc05 Plasterboard on dabs Blockwork inner leaf Wall tie with retaining disk Earthwool DriTherm Cavity Slab partially filling the cavity Brick outer leaf Clear cavity Earthwool DriTherm Cavity Slab 582 Products Earthwool DriTherm Cavity Slab 37/34/32 are a range of lightweight semi rigid or rigid slabs of glass mineral wool with a water repellent additive. They are dimensioned to fit between wall ties at standard spacings. Their manufacture has a very low impact on the environment and they are classified as Zero ODP and Zero GWP* * Ecohomes and Code for Sustainable Homes classification Typical construction Brick or block outer leaf (which may be rendered), brick or block inner leaf with cavity partially filled with Earthwool DriTherm Cavity Slab 37/34/32. Internal finish of plasterboard on dabs. British Board of Agrément approval means that in many instances a minimum 25mm residual cavity needs to be maintained. In more exposed areas, buildings over 12m in height and for dwellings subject to NHBC inspection, a 50mm residual cavity should be maintained. Note that where cavities are over 100mm wide, wall ties should be type 1 to BS 5628, or DD140: Part 2. Guarantee All products in the Earthwool DriTherm Cavity Slab range are formally guaranteed for 50 years to resist the transmission of liquid water from the outer masonry leaf to the inner masonry leaf in new external cavity walls and to maintain the original manufactured thermal conductivity at normal building temperatures. Masonry includes bricks, blocks and dressed and reconstituted stone. The guarantee is available by application from Knauf Insulation. Performance through the slabs. Thermal performance Earthwool DriTherm Cavity Slab has a thermal conductivity of either W/mK or W/mK depending on thickness. Earthwool DriTherm Cavity Slab 34 has a thermal conductivity of W/mK. Earthwool DriTherm Cavity Slab 32 has a thermal conductivity of W/mK. Fire performance All products in the Earthwool DriTherm Cavity Slab range are classified as Euroclass A1 to BS EN ISO Moisture resistance All products in the Earthwool DriTherm Cavity Slab range contain a water-repellent silicone additive to ensure that no liquid water is able to pass through the slabs and reach the inner leaf of masonry. Tests by the British Board of Agrément confirm that the range of Earthwool DriTherm Cavity Slabs will not transmit water to the inner leaf. Nor will they transmit moisture by capillary action across the cavity or from below DPC level. Vapour resistance All products in the Earthwool DriTherm Cavity Slab range have negligible water vapour resistance, allowing water vapour to pass freely

24 Design details: Masonry cavity walls Typical wall/ground floor junction Clear cavity Earthwool DriTherm Cavity Slab 37/34/32 Wall insulation to extend a minimum of 150mm below top of floor insulation Table 40: Typical U-values for partially filled masonry cavity walls Continuous ribbon of adhesive behind plasterboard and flexible sealant below skirting to minimise air leakage DPM Typical specification Earthwool DriTherm Cavity Slab 37*/34*/32*,...mm thick to be located in the cavity of all external masonry cavity walls. (*Delete as appropriate) The residual cavity width to be 25mm/50mm. Insulation to be retained against the cavity face of the inner leaf of masonry by means of insulation retaining wall ties as manufactured by.... The wall ties to have one of their drip centres half-way across the residual cavity. The first run of wall ties to be located at 600mm centres horizontally (at a level to be decided by the specifier). Ties thereafter to be at 450mm centres vertically and a maximum of 600mm horizontally. All work under construction must be protected overnight and during adverse weather conditions in accordance with BS 5628: Part 3: Alternatively, refer to NBS clause: F30/12,151. U-values (W/m 2 K) for brick outer leaf/cavity/100mm block inner leaf, plasterboard on dabs Insulation thickness (mm) Dense block (λ = 1.13) Medium block (λ = 0.51) Lightweight aggregate (λ = 0.34) Standard aircrete (λ = 0.16) Lightweight aircrete (λ = 0.11) Earthwool DriTherm Cavity Slab Earthwool DriTherm Cavity Slab Earthwool DriTherm Cavity Slab Notes: The U-values have been calculated assuming that all walls are lined with plasterboard on dabs. Block sizes assumed to be 440 x 215mm, mortar joints assumed to be 10mm wide, wall ties assumed to be stainless steel with a cross-sectional area of no more than 12.5mm 2 for structural cavities up to 175mm wide. The U-values have been calculated to BS EN ISO 6946: 1997 and BR

25 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Partial fill with glasswool Installation sequence Mc05 1 A section of the inner leaf is built to a course above the next row of wall ties. Mortar squeeze is removed from the inside of the first leaf. Earthwool DriTherm Cavity Slab is then installed by placing it 2 The remaining leaf is then built-up to the top level of the insulation, ensuring that the designed residual cavity is maintained. The residual cavity should be at least 25mm wide. A 50mm wide against the inner leaf, on the lower ties, and fitting it under the residual cavity is required in more exposed areas, buildings over retaining disk of the upper wall tie. Slabs should be cut to fit round 12m in height and for dwellings covered by the NHBC. The cavity extra wall ties or other protrusions in the cavity. All slab joints must always be kept clean of mortar droppings. The use of cavity including corners should be close butted with vertical joints battens and boards is recommended. staggered. No gaps should be left between slabs. Installation Any thickness of Earthwool DriTherm Cavity Slab may be used in partial fill applications. During installation all joints should be closely butted and kept clean and free from mortar droppings. Any cutting and fitting should be neatly done and not distort the layers of glasswool which comprise the material. Earthwool DriTherm Cavity Slab is supplied in 1200 x 455mm slabs for use between wall ties at 450mm vertical centres. When off-cuts are needed, the slabs can be cut with a long bladed knife or bricklayer's trowel. Construction practice will vary from site to site. Where design details differ from those illustrated please do not hesitate to contact Knauf Insulation for any clarification required. Wall ties and fixing devices Earthwool DriTherm Cavity Slab is designed to be installed using proprietary insulation retaining wall ties and clips. The wall ties should be placed with a drip in the centre of the clear cavity. Advice should also be sought from manufacturers as to the maximum cavity width for which the use of a specific tie is approved vertical spacing, Earthwool DriTherm Cavity Slab should be cut to course, allowing an extra 5mm for compression to form close butt joints. Where extra ties are required, for example beside openings, Earthwool DriTherm Cavity Slab should be cut and fitted carefully around them. 584

26 Design details: Masonry cavity walls Repeat this process up to the top of all walls, or the underside of a cavity tray. The top of all cavities should be closed with a non-combustible board (such as 9mm calcium silicate board) 4 As an alternative to the retaining wall tie and disk, insulation retaining clips can be used to hold the slab in place. These clips penetrate the Earthwool DriTherm Cavity Slab and are pushed into or proprietary non-combustible cavity closer. the joints of green mortar. This type of clip may also be used where it is not possible to secure the insulation in place with wall ties, for example below sills or eaves. The clips should be fixed at Encapsulated cavity stop horizontal spacings of 400mm. Non-combustible cavity closer at top of cavity Insulation retaining disk pushed into wet mortar joint Wall tie manufacturers The following manufacturers can supply stainless steel wall ties: Ancon Building Products Tel Stainless Steel Fixings Tel Catnic Profiles Tel Helifix Ltd fixings.co.uk Tel Tecties Tel The Stainless Wire Tie Co Tel

27 6.2.1 Design details: Masonry cavity walls Masonry cavity walls Window and door openings insulated cavity closers Advantages 3 Insulated cavity closers exceed the requirements of Building Regulations and Accredited Construction Details or restricting thermal bridging 3 Raise temperature at junction reducing risk of surface condensation forming 3 Improve thermal transmittance value (psi value) of opening Mc06 Blockwork inner leaf Earthwool DriTherm Cavity Slab (rock or glass) or Polyfoam Cavityboard Cavity closer Flexible strip to closer acts as backing to sealant Plaster finish covers cavity closer Typical product Pre formed rigid PVC casing containing extruded polystyrene foam or rock mineral wool insulation. Typical construction Insulated closers are located between inner and outer leaves of masonry cavity walls at window and door openings in place of the traditional blockwork return. The closer fully fills the cavity and provides a damp proof barrier between the inner and outer leaves. The casing and the insulation core should be highly moisture resistant and have a flexible strip attached to fit into the rear of door and window frames to act as an extra damp-proof seal. The closers are held in position using proprietary cavity ties or are simply nailed to the blockwork at centres determined by the manufacturer. Insulated closers are readily available to suit 50, 65, 75, 85, 100 and 150mm cavities. Performance Thermal performance Accredited Construction Details require a cavity closer to have a minimum thermal resistance of 0.45m 2 K/W the insulation core of the closer is usually no lesss than 25mm thick which easily exceeds this requirement. Fire performance When contained within a cavity wall behind a plaster or similar finish cavity closers will not prejudice the fire resistance of the wall. Installation The closers are simply cut to length with a normal hand saw. Care should be taken to ensure a tight fit. The jamb closer should overlap the sill closer and butt up to the underside of the insulated lintel. Off-cuts can usually be utilised by simply pushing the insulating foam core upwards so that it protrudes from the end of the plastic casing. The casing of another piece is then slid over the insulating core, joining the two pieces together. Where proprietary ties are used, they are typically installed at 500mm centres and built in as work proceeds. Alternatively, the flanges of the closer can be nailed in position at approximately 450mm centres. 586

28 Design details: Masonry cavity walls Typical jamb detail with full-fill cavity insulation Typical specification Cavity closer sized to fit full cavity width Refer to manufacturers literature or NBS clause: F30/18,180 Window frame to lap Polyfoam Closer by at least 30mm Polyfoam ties help to hold the closer in place during construction 587

29 Knauf Insulation Ltd PO Box 10 Stafford Road St Helens Merseyside WA10 3NS UK Tel: Fax: Ref: KB June 2010 Knauf Insulation Ltd Customer Service (Sales) Technical Advisory Centre Literature PO Box 10 Tel: Tel: Tel: Stafford Road Fax: Fax: Fax: St Helens Merseyside WA10 3NS