Legend Insulation zone Blue text Air tightness barrier (note: this can also act as a vapour control layer) Guidance on thermal continuity Red text Guidance on air tightness Values used in psi calculations Material λ-values used in calculations (W/mK) Plasterboard 0.21 Insulation (generic) 0.04 Plywood sheathing 0.13 Brick outer leaf 0.77 Mineral wool insulation 0.044 Concrete block 1.13 (dense) protected Concrete block (lightweight, high strength) 0.19 Timber frame 0.13 Concrete floor beam 2.3 Concrete screed 1.15 Render (cement/sand) 1.0 Gypsum plaster 0.4 (1000kg/m3) Concrete roof tiles 1.5 EPDM membrane 0.25 Timber battens 0.13 Timber flooring 0.13 Chipboard 0.13 Floor joists 0.13 Aluminium 160 Steel 50 Stainless steel 17 Glass 1 Sarking felt 0.23 Insulation board 0.022 Masonry: Cavity Wall Insulation: Partial Fill Isometric cut-away view Plasterboard Service void / protection zone for air tightness membrane (optional) Air tightness barrier Insulation supported within secondary timber stud frame Inner leaf (block shown) Insulation Wall ties Cavity Outer leaf (render on block shown) General guidance notes Alternative constructions 1. The thermal resistance of cavity insulation needs to be greater than that used in the inner leaf insulation, to reduce the risk of interstitial condensation. 2. Different constructions can be used to provide an outer leaf but check that there is sufficient ventilation provision to prevent moisture from being trapped within the wall. Sealing membrane junctions 3. All membranes should be taped, stapled or bedded in adhesive as identified by manufacturer. Repair all tears in membranes before commencing next stage of work. Psi-value calculations 4. For details of all thermal conductivity values of materials used in the psi-value calculations, see also Appendix B of the Introduction. Detail 2.00
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 2. Check that roof insulation butts against the cavity wall insulation, with minimum of 50mm overlap at narrowest point 3. Install cavity barrier at the top of the wall. Ventilation gap equivalent to 5mm minimum continuous opening at ridge is required where the roof pitch is greater than 35 or the roof span is more than 10m 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Proprietary cross flow ventilator to maintain minimum 25mm air gap Timber batten to provide fixing for plasterboard sheet Ventilation gap equivalent to 10mm minimum continuous opening is required where roof pitch is above 15 or ventilation gap equivalent to 25mm minimum continuous opening is required where the roof pitch is below 15 Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material in wall and ceiling Insulation between the studs in addition to the cavity insulation. This insulation to be tightly fitted against the wall, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.02 and 2.21 for other junctions using this roof construction Psi value = 0.0392W/mK Pitched Roof: Ventilated Roofspace - Eaves Detail 2.01
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 2. Ensure that roof insulation butts against the gable wall 3. Install cavity barrier at the top of the wall. 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Cavity insulation continued full height of gable or to the top of the loft insulation Insulation between the last truss and the gable wall Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Timber batten to provide fixing for plasterboard sheet in wall and ceiling Insulation between the studs in addition to the cavity insulation. This insulation to be tightly fitted against the wall, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.01 and 2.21 for other junctions using this roof construction Psi value = 0.0918W/mK Pitched Roof: Ventilated Roofspace - Gable Detail 2.02
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 2. Ensure that roof insulation butts against the gable wall 3. Install cavity barrier at the top of the wall. Minimum 50mm ventilation path over insulation 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Insulation between joists and covering cavity insulation Cavity barrier giving 30 minute fire resistance - thin calcium silicate board or similar across top of wall Note: this construction is typically used where there are habitable rooms within the roof construction Where two insulation types are used together see supplementary guidance Timber runner to provide fixing for plasterboard sheet in wall and ceiling Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.04, 2.05 and 2.22 for other junctions using this roof construction Psi value = 0.0206W/mK Pitched Roof: Ventilated Rafter Void - Gable Detail 2.03
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 2. Ensure that roof insulation butts against the cavity wall insulation, with minimum of 50mm overlap at narrowest point 3. Install cavity barrier at the top of the wall Rigid insulation used as sarking Insulation to be vapour permeable Vapour permeable membrane (with a vapour resistance of not more than 0.25MN.s/g) Ventilation gap equivalent to 5mm minimum continuous opening is required at ridge to batten space 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Lap roof and wall insulation minimum 150mm thickness at narrowest point Proprietary over fascia ventilator Ventilation to batten void Timber batten to provide fixing for plasterboard sheet Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Note: this construction is typically used where there are habitable rooms within the roof construction in wall and ceiling Alternative air barrier - parge coat of plaster finish on blockwork Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.03, 2.05 and 2.22 for other junctions using this roof construction Psi value = 0.034W/mK Pitched Roof: Ventilated Batten Void (warm roof) - Eaves Detail 2.04
1. Ensure that insulation layers are fitted perpendicularly, to cover junctions 2. Ensure that roof insulation butts against the gable wall 3. Install cavity barrier at the top of the wall. 50mm ventilation path over insulation 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Vapour permeable membrane (with a vapour resistance of not more than 0.25 MN.s/g) Insulation between joists and inner face of the wall Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Note: this construction is typically used where there are habitable rooms within the roof construction Where two insulation types are used together see supplementary guidance Timber runner to provide fixing for plasterboard sheet in wall and ceiling Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.03, 2.04 and 2.22 for other junctions using this roof construction Psi value = 0.0552W/mK Pitched Roof: Ventilated Batten Void (warm roof) - Gable Detail 2.05
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 2. Ensure that roof insulation butts against the gable wall 3. Install cavity barrier at the top of the wall. turned up edge of roof insulation, lapped with roof waterproofing layer and sealed Eaves - fix full height blocking piece and tightly fit insulation into void and under deck Membrane roof construction 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Verge option - tightly fit insulation into void over wall and under deck to maintain thermal continuity Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Vapour control layer in ceiling Timber runner to provide fixing for plasterboard sheet Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling 2. A vapour control layer is required at ceiling level, to prevent moisture from entering into the roof construction 3. The option shown here includes a vapour control layer and insulation as part of a membrane roof construction. Similar details could be used for a profiled metal decking roof but consult with manufacturer regarding ventilation requirements. Roof - 9.500(m²K)/W Psi value = 0.0695W/mK Timber Flat Roof Detail 2.06
1. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 3. Ensure that roof insulation butts against the gable wall 4. Install cavity barrier at the top of the wall 1. Check that any air tightness barrier used in the ceiling overlaps with the layer in the wall Compressible filler Roofing membrane to be taken minimum 150mm above finished roof level turned up edge of parapet, lapped over top of blockwork and sealed Membrane roof construction in wall and roof Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check ventilation paths are clear before installing insulation above the ceiling 2. A vapour barrier is required at ceiling level, to prevent moisture from entering into the roof construction 3. The option shown here includes a vapour control layer and insulation as part of a membrane roof construction. Similar details could be used for a profiled metal decking roof but consult with manufacturer regarding ventilation requirements. Roof - 9.500(m²K)/W Psi value = 0.0811W/mK Timber Flat Roof with Parapet Detail 2.07
1. Check that there is no debris in the cavity 2. Install cavity barrier around opening 3. Install insulation in the window reveal Cavity tray with minimum upstand of 140mm and stop ends 1. Install window to overlap with outer leaf of wall finish. Alternative: If window lines through with the bottom of the opening in the external finish, some means of preventing a direct line of air infiltration will be required 2. Install air tightness seal between the inside face of the window and the structural finish of the window opening. 30 minute fire resisting proprietary insulating cavity barrier with integral DPC - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Sealant at window frame If position of window head is lower than or level with the underside of the lintol, a larger compressible filler will be required to stop up a potential air infiltration route Insulate the window reveal Air tightness tape Sealant to back of frame Insulation to be tightly fixed back to inner leaf of wall Vapour control layer Lintol - any type Compressible fill Detail shows window fixed to plywood frame set into window opening Note: the timber batten in window reveal is shown smaller than actual size, to allow the membrane corner strip to be seen 1. Alternative internal finish at window reveal - use insulation backed plasterboard General notes 2. The window head and jamb details shown have used a plywood box lining around the window opening in the internal leaf of the wall, to allow for window fixings. Alternative details are possible but the continuity of insulation and air tightness should be considered. Insulated plasterboard - 1.591(m²K)/W Psi value = 0.1302W/mK Lintel at Window Head Detail 2.08
1. Check that there is no debris in the cavity 2. Install cavity barrier around opening 3. Install insulation in the window reveal 30 minute fire resisting proprietary insulating cavity barrier with integral DPC Sealant at window frame 1. Install window to overlap with outer leaf of wall finish. Alternative: If window lines through with the external jamb, some means of preventing a direct line of air infiltration will be required 2. Install air tightness seal between the inside face of the window and the structural finish of the window opening. Air tightness tape and sealant to back of frame Insulate the window reveal Detail shows window fixed to plywood frame set into window opening Psi value (jamb) =0.2224W/mK Psi value (cill) =-0.02W/mK Compressible filler between window and cill Solid cill acts as cavity closer. If pressed cill is used, a 30 minute fire rated thermally insulated cavity closer will be required DPC lapped behind cill and below window 30 minute fire rated thermally insulated cavity barrier Jamb detail Air tightness tape and sealant to back of frame Insulate the window reveal Windows and Doors - Jambs and Cills Air tightness barrier in wall Note: the timber battens in the window reveal and cill are shown smaller than actual size, to allow the membrane corner strip to be seen in wall Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps Cill detail 1. Alternative internal finish at window reveal - use insulation backed plasterboard General notes 2. The window head and jamb details shown have used a plywood box lining around the window opening in the internal leaf of the wall, to allow for window fixings. Alternative details are possible but the continuity of insulation and air tightness should be considered. Insulated plasterboard - 1.591(m²K)/W Detail 2.09
1. Use a perimeter strip of insulation where the concrete slab abuts the concrete blockwork wall 2. Ensure that insulation level in external wall overlaps with the insulation at the floor slab Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant below timber floor finish 1. Check that any air tightness barrier used in the wall overlaps with the layer in the floor The wall insulation installed below the wall dpc must be fit for purpose with regards to water absorption External ground level Psi value = 0.0744W/mK Ground Bearing Floor: Insulation Above Slab Damp proof membrane above or below slab 20mm strip of perimeter insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK around slab and any screed 1. Check that concrete slab is level and clear of debris before fitting the insulation at floor level 2. If a screed finish is used instead of a timber floor, use a strip of perimeter insulation with a minimum R value of 0.75 m²/kw for the depth of the screed Alternative detail 3. Using lightweight blockwork (e.g. with λ value of 0.19W/mK) to improve the thermal performance at the junction where the external wall and ground floor constructions meet will change the psi value Insulated perimeter strip - 0.455 (m²k)/w Floor - 3.864 (m²k)/w Detail 2.10
1. Use a perimeter strip of insulation where the concrete slab abuts the concrete blockwork wall 2. Ensure that insulation level in external wall overlaps with the insulation at the floor slab Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant 1. Check that any air tightness barrier used in the wall overlaps with the layer in the floor The wall insulation installed below the wall dpc must be fit for purpose with regards to water absorption External ground level Damp proof membrane 20mm strip of perimeter insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK around slab and any screed 1. If a screed finish is used instead of a timber floor, use a strip of perimeter insulation with a minimum R value of 0.75 m²/kw for the depth of the screed Alternative detail 2. Using lightweight blockwork (e.g. with λ value of 0.19W/mK) to improve the thermal performance at the junction where the external wall and ground floor constructions meet will change the psi value Insulated perimeter strip - 1.136 (m²k)/w Floor - 3.864 (m²k)/w Psi value = 0.175W/mK Ground Bearing Floor: Insulation Below Slab Detail 2.11
1. Use a perimeter strip of insulation between the floor joists and blockwork wall 2. Ensure that insulation level in external wall overlaps with the insulation at the floor construction Minimum 50mm strip of insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK should be installed between wall and the last joist Use air tightness tape at junction of air barrier in wall and floor. Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant Air tightness barrier below timber floor finish 1. Check that any air tightness barrier used in the wall overlaps with the layer in the floor External ground level Solum Floor joist ends supported on joist hangers or using scarcement wall Insulation directly under flooring - supported on netting draped over joists and stapled at the required depths Damp proof membrane Sub floor ventilation should be provided, minimum 1500mm² per run of external wall or 500mm² per m² of floor area 1. Check that all ventilation paths are clear before installing the floor insulation Alternative detail 2. Using lightweight blockwork (e.g. with λ value of 0.19W/mK) to improve thermal performance at the junction where the external wall and ground floor constructions meet will change the psi value 3. If there are concerns about damaging the air tightness membrane in the floor finish during construction, an additional services void can be created using timber battens on top of the floor joists Insulated perimeter strip - 1.136 (m²k)/w Floor - 5.455 (m²k)/w Psi value = 0.0978W/mK Timber Suspended Ground Floor Detail 2.12
Design stage 1. Install thermally insulated cavity barrier in line with separating wall 2. Check that there is no debris in the cavity Cavity barrier giving 30 minute fire resistance - ensure cavity barriers are not breeched by inappropriate insulation material 1. Check that any air tightness barrier used in the internal wall overlaps with the layer in the external wall Minimum specification of 8kg/m2 gypsum based plasterboard required if 13mm plaster not used, to comply with acoustic requirements Air tightness layer, 13mm plaster shown 1. Check that insulation is fitted tightly to concrete block wall at corner junctions For more information on acoustic details see guidance in Section 5 of the Technical Standards Psi value = 0.0508W/mK Separating Wall Detail 2.13
1. Check that there is no debris in the cavity Vapour barrier lapped over corner junction and taped to surface of floor construction Design stage 1. Check that any air tightness barrier used in the external wall is secured onto the floor slab 2. If plaster is use as an air tightness barrier seal over junction at floor with barrier tape below timber floor finish lapped over corner junction and taped to underside of floor construction Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps Alternative air barrier - parge coat of plaster finish on blockwork 1. Check that insulation is tightly fixed into the studs adjacent to the floor junction, leaving no gaps Separating floors require to comply with Section 2: Fire and Section 5: Noise Psi value = 0.0541W/mK Concrete Separating Floor Detail 2.14
1. Check that there is no debris in the cavity lapped over corner junction and taped to air tightness barrier Air tightness barrier corner strip lapped over top of joists and joist hangers 1. Check that any air tightness barrier used in the internal wall overlaps with the layer in the floor or ceiling Alternative: If the air tightness barrier is installed onto the face of the blockwork wall and runs continuously through the floor construction, infill any gaps where floor fixing is made to external wall Minimum 50mm strip of rigid insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK should be installed between joists Joists shown supported on joist hangers Air tightness barrier to be continuous behind joists in wall Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps Alternative air barrier - parge coat of plaster finish on blockwork 1. Check that insulation is tightly fixed into the studs adjacent to the floor junction, leaving no gaps Insulated infill strip - 1.136(m²K)/W Psi value = 0.0109W/mK Timber Intermediate Floor Detail 2.15
1. Ensure that insulation is tightly fitted to the back of the masonry wall Air tightness barrier in wall (plaster option shown) Use air tightness tape at junction of air barrier in wall and floor. Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant Air tightness layer below timber floor finish 1. Check that any air tightness barrier used in the wall overlaps with the layer in the floor 2. Consider gluing joints between floor boards Insulation directly under flooring - supported on netting draped over joists and stapled at the required depths Solum Damp proof membrane Sub floor ventilation should be provided, minimum 1500mm² per run of external wall or 500mm² per m² of floor area 1. Check that all ventilation paths are clear before installing the floor insulation Alternative Detail 2. Lightweight thermal blockwork can be used in the separating wall to improve the thermal performance but this will also reduce the acoustic performance of the wall. If this alternative is used then additional elements will be required to meet Section 5 of the Technical Standards. Internal Wall - 1.136 (m²k)/w Floor - 5.455 (m²k)/w Psi value = 0.2365W/mK Ground Floor / Separating Wall junction - Timber susp. floor Detail 2.16
1. Ensure that insulation is tightly fitted against the separating wall Tape corner strip of air tightness membrane over wall / floor junction Air tightness barrier in wall (plaster shown) Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant Minimum 50mm strip of insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK should be installed between wall and the slab in floor 1. Check that there are no gaps between the wall and floor constructions 2. Check that any air tightness barrier used in the wall overlaps with the layer in the floor Damp proof membrane 1. If a screed finish is used instead of a timber floor, use a strip of perimeter insulation with a minimum R value of 0.75 m²/kw for the depth of the screed Alternative Detail 2. Lightweight thermal blockwork can be used in the separating wall to improve the thermal performance but this will also reduce the acoustic performance of the wall. If this alternative is used then additional elements will be required to meet Section 5 of the Technical Standards. Insulated infill strip - 1.136 (m²k)/w Floor - 3.864 (m²k)/w Psi value = 0.2736W/mK Concrete Ground Floor/ Separating Wall: Insulation Below Slab Detail 2.17
1. Ensure that insulation is tightly fitted against the separating wall Tape corner strip of air tightness membrane over wall / floor junction Air tightness barrier in wall (plaster option shown) Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant Minimum 20mm strip of insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK should be installed between wall and the slab in floor 1. Check that there are no gaps between the wall and floor constructions 2. Check that any air tightness barrier used in the wall overlaps with the layer in the floor Damp proof membrane 1. Check that concrete slab is level and clear of debris before fitting the insulation at floor level 2. If a screed finish is used instead of a timber floor, use a strip of perimeter insulation with a minimum R value of 0.75 m²/kw for the depth of the screed Alternative Detail 3. Lightweight thermal blockwork can be used in the separating wall to improve the thermal performance but this will also reduce the acoustic performance of the wall. If this alternative is used then additional elements will be required to meet Section 5 of the Technical Standards. Internal Wall - 1.136 (m²k)/w Insulated infill strip - 0.455 (m²k)/w Floor - 3.864 (m²k)/w Psi value = 0.2822W/mK Concrete Ground Floor/ Separating Wall: Insulation Above Slab Detail 2.18
1. Ensure that there are no gaps between floor slabs or between the top of the wall and the underside of the floor slab. 2. Ensure that the insulation is tightly fitted to the top of the floor slab. Air tightness barrier in wall (plaster option shown) 1. Check that any air tightness barrier used in the internal wall overlaps with the layer in the floor or ceiling Cavity barrier is used in to prevent thermal bypass.use dense insulation or proprietary cavity barrier in sleeve 5mm minimum resilient flanking strip to be used at floor junction. See Technical Standards Guidance Notes for Section 5 for details If membrane used, seal onto top of screed. If render or plaster used as airtightness layer, add a corner strip of membrane to cover junction before applying finish Air tightness barrier lapped over corner junction Air tightness barrier in wall (plaster shown) 1. Check that concrete slab is level and clear of debris before fitting the insulation at floor level Separating floors require additional layers and components to comply with Section 2: Fire and Section 5: Noise Psi value = 0.0133W/mK Concrete Separating Floor / Separating Wall junction Detail 2.19
1. Check that there are no gaps between the floors and the separating wall. Air tightness barrier in wall (plaster shown) Seal between the wall and floor membrane with a flexible sealant or seal the gap between skirting board and floor using a flexible sealant 1. Check that any air tightness barrier used in the internal wall overlaps with the layer in the floor or ceiling Alternative: If the air tightness barrier is installed onto the face of the blockwork wall and runs continuously through the floor construction, infill any gaps where floor fixing is made to the wall Air tightness barrier in to be continuous behind joists Air tightness barrier in wall (plaster shown) See general guidance notes Psi value = 0.1053W/mK Timber Intermediate Floor / Separating Wall junction Detail 2.20
1. Install a cavity barrier at the top of the wall 2. Ensure that insulation layers in roof are fitted perpendicularly, to cover junctions 1. Check that there are no gaps between the top of the masonry wall and the underside of the roof 2. Check that the air tightness barrier used in the ceiling overlaps with the layer in the wall Minimum 50mm strip of rigid insulation with thermal conductivity (λ value) not exceeding 0.025 W/mK should be installed between wall and the last joist Cavity barrier is used in to prevent thermal bypass.use low or soft density insulation wrapped in plastic or membrane in wall and ceiling For more information on acoustic details see guidance in Section 5 of the Technical Standards 1. Check ventilation paths are clear before installing insulation above the ceiling Roof - 9.500(m²K)/W Note: See detail numbers 2.01 and 2.02 for other junctions using this roof construction Psi value = 0.2008W/mK Pitched Roof: Cold Roof / Separating Wall junction Detail 2.21
1. Install a cavity barrier at the top of the wall 2. Ensure that insulation layers are fitted perpendicularly, to cover junctions Minimum 50mm ventilation path over insulation 1. Check that there are no gaps between the top of the masonry wall and the underside of the roof 2. Check that the air tightness barrier used in the ceiling overlaps with the layer in the wall Cavity barrier giving 30 minute fire resistance - ensure cavity barrier is not breeched by inappropriate rigid sheathing insulation material Cavity barrier is used in to prevent thermal bypass.use low or soft density insulation wrapped in plastic or membrane Separating walls require additional layers and components to comply with Section 2: Fire and Section 5: Noise Where two insulation types are used together see supplementary guidance Air tightness barrier in wall and ceiling (plaster shown on wall) Note: this construction is typically used where there are habitable rooms within the roof construction 1. Check ventilation paths are clear before installing insulation above the ceiling Internal Wall - 2.045 (m²k)/w Roof - 9.500(m²K)/W Note: See detail numbers 2.03, 2.04 and 2.05 for other junctions using this roof construction Psi value = 0.2247W/mK Pitched Roof: Ventilated Batten Void/ Separating Wall junction Detail 2.22
1. Check that there is no debris in the cavity. 2. Check that there are no gaps in insulation fitted at the corner junction in the cavity 1. Check that any air tightness barrier used in the external walls overlaps at the corner Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check that insulation is tightly fixed into the studs at the corner junction, leaving no gaps Plan view Psi value = 0.0607W/mK Wall Junction Detail 2.23
1. Check that there is no debris in the cavity 1. Check that any air tightness barrier used in the external walls overlaps at the corner Insulation between the studs in addition to the cavity insulation. This insulation must be tightly fitted, leaving no gaps 1. Check that insulation is tightly fixed into the studs at the corner junction, leaving no gaps Plan view Psi value = -0.0826W/mK Wall Junction - Inward Corner Detail 2.24