EWI Plinth Insulation to below ground [Version ID #173]

Author details

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Detail summary

EWI plinth detail. To ensure watertightness and prevent thermal bridging to zones under an existing floor by providing continuous insulation down the ground level. Woodfibre EWI to stop min. 300mm from external ground level, adhesive fix to XPS insulation carried down to below ground, minimum 300mm below internal floor level.

Technical description

Section detail: EWI to junction with perimeter insulation. Below ground: insulation past ground level. Woodfibre EWI junction to XPS insulation at minimum 300mm above ground level.

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

  • 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 [EW01]

    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

  • Granular Backfill (only where excavation necessary) [EW01]

    20 mm washed and graded aggregate providing 30% voids. Minimum Thickness: As drawing

    Contractors choice

Revisions

  1. Admin - 2015-04-29 11:37:48

    General formatting changes. DWG file uploaded.

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  2. Admin - 2015-03-27 16:26:53

    Preview image and .pdf file updated.

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  3. Admin - 2015-03-23 16:52:44

    General re-formatting. Technical description expanded with installation sequence. Links to suppliers provided in parts list.

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  4. Admin - 2015-03-12 17:05:35 [Displayed version]

    Intro & technical description updated and expanded. BS and Approved doc information added. Parts list added.

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  5. Admin - 2015-02-27 15:20:49

    Version 1

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