EWI to lower roof sloping along external wall.
Detail summary
Detail for external wall insulation to an existing roof, either pitched or sloping along the external wall to be insulated.For use where the existing roof tiling or other finish is to be retained, meaning perimeter junction of EWI needs to be sealed and flashed along the length of the junction with the roof.
Detail also indicates junction between woodfibre insulation system and insulation suitable for splash zone. EWI system is cut to slope of lower/projecting roof and flashed over to prevent any gaps in insulation.
Technical description
Section detail. EWI to lower roof. Pitched/sloping in direction of insulation. External woodfibre insulation used in conjunction with 400 - 200mm, rigid, external perimeter insulation suitable for use in a splash zone. Appropriate cap flashings and soakers to be used alongside mastic detail at junction with roof.
Suggested Installation Sequence:
- Remove any existing projecting masonry/render from existing wall.
- Fix external wall insulation.
- Fix supporting bracket.
- Friction fit water resistant insulation in splash zone between external wall insulation and existing roof.
- Fix cap flashings and soakers to base of EWI at existing roof.
- Mastic seal edge.
- Render up to flashing.
Reference Specification:
Guidance should be sought from Approved documents C, section 5 and 6; and Document H, sections 2 and 3 for rainwater drainage.
Perimeter insulation suitable for below ground use and drainage layer. To BS EN 13164. Stainless steel strip flashing to BS EN 10088-2 and BS EN ISO 9445-1 or -2.
Lead sheet: Rolled lead sheet to BS EN 12588. Tolerance (by weight): ±5%. Colour marked for thickness.
Soakers and step flashings (slate or tile roofs): Lead Soakers:
- Length: Slate/tile gauge + lap + 25mm.
- Upstand: 75mm (min)
- Underlap: 100mm (min).
Lead step flashings:
- Length: 1500mm (max).
- End to end joint: laps 100mm (min).
- Cover: overlap to soaker upstands 65mm (min) cover. Lead wedges at every course.
- Fixing: lead wedges at every course.
Step and cover flashings (single lap tile roofs) in sheltered/ moderate exposure locations.
- Length: 1500mm (max).
- End to end joint: laps 100mm (min).
- Upstands 85mm (min).
- Fixing: Lead wedges at every course. Clipped at 500mm (max) centres along free edge.
Single step and cover flashings (single lap tile roofs) in exposed locations.
- End to end joint: laps 50mm (min).
- Cover: Overlap to soaker upstands 65mm (min) cover.
- Fixing: Lead wedges at every step.
Lead cover flashings:
- Length: 1500mm (max).
- End to end joint: laps 100mm (min).
- Upstands: 85mm (min).
- Cover to roof: 150mm (min) and over first tile corrugation.
- Fixing: turned over head of tiles. Clipped at first 500mm (max) centres along free edge. Upstand plugged and screwed to abutment in top third of each length only.
Notes:
Care should be taken to ensure air-tightness. Seal all service penetrations through EWI and existing wall. Lap and tape all membranes around edges of EWI system.
All insulation to be continuous to avoid thermal bridging.
Preparation of external wall: Remove any existing loose material and prepare in accordance with manufacturer's requirements.
Any alterations to drainage and other fixtures, or work to prepare the substrate, to be agreed with contract administrator prior to work being undertaken. Prior to start on site inspect the form and condition of the structural substrate; institute repairs and/ or additional works necessary to make the substrate suitable to receive EWI system.
Existing Services:
Rainwater pipes and waste water pipes to be moved to the outer face of insulation as standard, and swan-necked back into gullies where possible. Any work additional to this should be agreed in writing with the contract administrator.
Soil Pipes: An assessment of the condition of soil pipes should be undertaken prior to external wall insulation being undertaken. Drawing assumes soil pipes will remain in-situ. However in some circumstances in order to do this they will need to be replaced, and in others they will need to be moved. This is to be agreed in writing before start of work.
Parts list
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External Wall Insulation (Woodfibre), rendered finish [EW01]
Composite woodfibre board for use on solid and hard to treat cavity walls.
- Insulation back board: UdiTherm SK.
- Insulation top board: Diffutherm NF (T&G, renderable).
- Thermal conductivity: 0.045W/m2K. GWP 0.
- Base Coat: levelling on substrate: 90% contact required around edge of boards between board and substrate to prevent thermal bypass. If substrate is very uneven, use base-coat material around edge of board to achieve contact.
- Fixing: Fixed mechanically to substrate in accordance with manufacturers recommendations.
- Render/carrier: to manufacturers standard.
- Render: Udi Perl
- Decorative finish: tbc
- System guarantee: 25 years - ECO compliant insurances and guarantees.
- System Certification : ETAG
Unger-Diffutherm. Product Reference: UdiFRONT.
Supplied by: Back To Earth.
Tel: 01392 861763
Web: http://www.backtoearth.co.uk/ -
External Insulation at roof abutment [EW01]
Extruded Polystyrene (XPS) suitable for below ground conditions/use in a splash zone, and for application of render.
- Thickness: as EWI.
- Depth: Minimum 300mm above roof abutment level.
- Thermal conductivity: 0.033W/m2k. GWP: <5.
- Joints: Tight butt joints
Unger-Diffutherm. Product Reference:Reference: UdiFLEX
Supplied by: Back To Earth.
Tel: 01392 861763
Web: http://www.backtoearth.co.uk/ -
Cap flashing and soakers embedded into rigid insulation [RF09b]
H71b lead sheet flashings and weathering. Rolled lead sheet to BS EN 12588.
- Soakers: 1.50 to 1.75mm (code 3) lead sheet.
- installation: Dressed up and bedded into new EWI.
Contractor’s choice
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Woodfibre EWI adhesive [EW01]
Adhesive for use at joint between perimeter/ plinth insulation and external wall insulation.
Back to Earth. Tel: 01392 861763
Web: http://www.backtoearth.co.uk/
Product Reference: UdiSpecial Adhesive. -
Mastic seal
To junction of insulation and existing tiles.
Contractor's choice.
Revisions
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Admin - 2015-04-29 12:09:29 [Displayed version]
DWG uploaded. EW01 roof abutment insulation amended to include "use in splash zone".
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Admin - 2015-03-27 16:34:43
Preview image and .pdf file updated.
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Admin - 2015-03-24 12:29:19
General formatting. Introduction expanded. Technical description expanded: approved document links added. Installation sequence revised. Parts list updated with suppliers links. Adhesive and mastic added to Parts list.
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Admin - 2015-03-24 12:27:09
General formatting. Introduction expanded. Technical description expanded: approved document links added. Installation sequence revised. Parts list updated with suppliers links.
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Admin - 2015-03-24 12:26:17
General formatting. Introduction expanded. Technical description expanded: approved document links added. Installation sequence revised. Parts list updated with suppliers links.
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Admin - 2015-03-13 12:18:28
Version 3. Introduction and technical description updated and expanded. Parts list added.
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Admin - 2015-02-27 16:41:26
Version 2 -Preview image updated
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Admin - 2015-02-27 16:39:29
Version 1
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For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.
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For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.
For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.
- Ease of understanding detail: Easy
- Ease of sourcing materials: Easy
- Ease of sourcing skills: Easy
- Ease of implementation: Easy
- Overall cost: Low cost
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User name
For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.
For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.
- Ease of understanding detail: Easy
- Ease of sourcing materials: Easy
- Ease of sourcing skills: Easy
- Ease of implementation: Easy
- Overall cost: Low cost
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