EWI to just below ground with plinth and ventilation detail [Version ID #176]

Author details

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Detail summary

EWI to below ground floor level with a detail for a periscopic vent installed through the EWI to ventilate a basement or cellar. Required where existing air-bricks to sub-floor void will be blocked by floor insulation works. Periscopic vent should ensure continued clear air-path to sub-floor, to ensure adequate ventilation.

Technical description

Section detail. EWI to ground level detail. Insulation just below ground level.Junction of Woodfibre EWI system to 400-200mm external perimeter insulation suitable for below ground use + drainage layer. Periscopic air ventilation to below ground under suspended timber floor. Insulation to suspended ground floor to depth of rafters.

Perimeter insulation suitable for below ground use and drainage layer. To BS EN 13164

Air bricks in external walling: To BS 493, Class 1.

Rainwater drainage: please refer to approved document H, section H3, rainwater drainage for guidance. Drainage layer: Granular infill free from excessive dust, well graded, all pieces less than 75mm in any direction, minimum 10% fines value of 50 kN when tested in a soaked condition to BS 812-111. In one layer no more than one of the following: Crushed rock (other than argillaceous rock) or quarry waste with not more binding material than is required to help hold the stone together/ Crushed concrete, crushed brick or tile, free from plaster, timber and metal. / Crushed non-expansive slag / Gravel or hoggin with not more clay content than is required to bind the material together, and with no large lumps of clay. /Well-burned non-plastic colliery shale. /Natural gravel. /Natural sand.

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.

Parts list

  • Air Bricks And Wall Ventilators [FL011c]

    Plastics air brick, colour to match existing finishes, cranked sleeve to suit and wall ventilator. Re-use existing airbricks where possible. \ Work Size: As existing brick/blockwork. \ Outer Face Position: Flush with wall face. \ Spacing: Maximum 2m centres to provide 1500mm2 of clear opening per 1m run of external wall; unless otherwise agreed.

    Contractors choice.

  • External Wall Insulation (Woodfibre), rendered finish [EW01]

    For use on solid and hard to treat cavity walls. Composite woodfibre board. UdiTherm SK back board, Diffutherm NF (T&G, renderable) top board. \ Fixed mechanically to substrate in accordance with manufacturers recommendations. \ 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. \ Thermal conductivity: 0.045W/m2K. GWP 0.

    Unger \ www.unger-diffutherm.de \ Reference: UdiFRONT. \ Render: UDI Perl

  • External Perimeter Floor Insulation [FL01]

    Extruded Polystyrene (XPS) to BS EN 13164. Suitable for below ground conditions and for application of render. \ Thickness as external wall insulation. Depth: 600mm below internal floor level or to footings. Tight butt joints. \ Thermal conductivity: 0.033W/m2K. GWP<5.

    BASF \ http://www.plasticsportal.net/wa/plasticsEU~en_GB/portal/show/content/literature/styrodur \ Reference: Styrodur 2800C.

  • Woodfibre EWI adhesive [EW01]

    Adhesive for use at joint between perimeter/ plinth insulation and external wall insulation.

    Unger \ www.unger-diffutherm.de \ Reference: Udi Dispersion Adhesive

  • Woodfibre Insulation Between Floor Joists [FL01]

    Woodfibre Insulation. \ Thickness 200mm. \ Friction fit between joists to ensure air-tightness- cut batts approx 20mm wider than opening between joists. Supported by Polyester webbing drawn underneath insulation at approx 600mm centres, fixed to joists.

    Unger \ www.unger-diffutherm.de \ Reference: UdiFLEX

Revisions

  1. Admin - 2015-04-29 11:44:20

    PArts list updated with Back to Earth contact details. DWG file uploaded.

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  2. Admin - 2015-04-29 11:43:52

    PArts list updated with Back to Earth contact details. DWG file uploaded.

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  3. Admin - 2015-03-27 16:29:06

    Preview image and .pdf file updated.

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  4. Admin - 2015-03-27 13:03:39

    FL03 updated in parts list

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  5. Admin - 2015-03-24 10:01:09

    Single-sided air seal tape added to parts list.

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  6. Admin - 2015-03-23 17:23:45

    General re-formatting. Technical description updated with installation experience. Part list updated.

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  7. Admin - 2015-03-13 09:45:43

    Parts list updated.

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  8. Admin - 2015-03-12 17:25:03 [Displayed version]

    Parts list code updated.

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  9. Admin - 2015-03-12 17:23:58

    Version 2; Introduction, technical summary updated. Parts list added.

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  10. Admin - 2015-02-27 15:43:29

    Version 1

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