Options for new window to EWI, for single brick reveal, retrofit [Version ID #219]

Author details

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Detail summary

Two alternative options for new window installation to a single brick reveal; alternatives to the reveal detail to sit at the head of the window, with either no subframe or reveal; or with a timber studframe and stainless steel reveal.

For use on Victorian single brick reveals; where original window was originally sat behind and larger than structural opening in outer face of existing masonry wall. Window retrofitted from the outside after completion of insulation.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area. The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required).

Technical description

Section details. EWI to new replacement window, on box into former window location. New triple glazed window to replace existing. Additional reveal works to preserve character of original window. Windows should be installed from outside, with insulation fitted tight up to box and appropriate air-tightness work undertaken as shown on detail drawing.

Care should be taken during the installation to ensure the continuity of insulation and air-tightness at the junction between window, existing wall and external wall insulation.

Parts list

  • Air-tight adhesive/sealant [DP09c]

    Air-tight adhesive/sealant. \ Location : as per drawing - critical junctions for air-tightness around windows.

    Pro Clima \ http://www.greenbuildingstore.co.uk/page--pro-clima-airtightness-adhesives-options.html \ ORCON F \ Primer/ accessories: TESCON PRIMER RP.

  • Structural insulation joining piece [EW04a]

    Compac foam Structural insulation piece pre-fixed to window and frame mounting. Size as drawing.

    Compac foam \ http://www.compacfoam.com/12-what-is-compacfoam.html

  • EWI (Woodfibre) System With 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

  • New Timber frame, triple-glazed windows [GD01]

    Eco-Contract Ultra Outward Opening Casement Windows.\ Thermal Performance (overall u-value) : 0.79W/m2K.\ Air-tight. Size: As schematic.\ Opening Pattern/ Configuration : As existing (unless otherwise stated on schematic).\ Sash/Frame Material: FSC 100% Redwood.\ Drip Rail : Aluminium. \ Finish - Interior: Factory finished paint/varnish system.\ Finish - Exterior: Factory finished paint/varnish system. \ Glazing Unit : Triple, Argon Fill, 44mm. \ Glazing Type: as standard triple glazed unless stated: Light transmission : 72%. \ Solar factor (g): 52%. \ Handle Type: Manufacturer's standard, factory fitted. \ Security: Secured by Design.\ Accessories: Egress Hinges and Child Safety Restrictors. \ Guarantees: Manufacturer's standard.

    Manufacturer: Green Building Store. \ www.greenbuildingstore.co.uk \ Tel: +44 (0)1484 461705. \ Reference: Eco-Contract Ultra Outward Opening Casement Windows


  1. Admin - 2015-04-29 15:54:00

    Intro/summary updated to link detail to EW01-W-RP-RF2. Parts list contact details amended to include back to earth contact details on EW01. DWG file uploaded.

  2. Admin - 2015-03-27 17:43:42

    Preview image and .pdf file updated.

  3. Admin - 2015-03-25 12:37:12

    General re-formatting. Introduction text revised. Technical description updated with links to approved docs and additional specification notes. Parts list updated with suppliers links. Stainless steel cill added to parts list.

  4. Admin - 2015-03-13 17:20:57 [Displayed version]

    Technical description and parts list updated.

  5. Admin - 2015-03-10 10:41:13

    First version

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