Insulation to new window [Version ID #121]

Author details

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Detail summary

New window fitted into EWI with a timber frame for mounting of window into external wall insulation. Used where single brick reveal means original window was originally sat behind and larger than structural opening in outer face of existing masonry wall. 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 detail. EWI to new replacement window, on box into former window location. New triple glazed window to replace existing.

Windows and window boxes should be fitted prior to installation of external wall insulation wherever possible. Ideally installed from outside, with insulation fitted tight up to box and appropriate air-tightness work undertaken as shown on detail drawings. Where this is not possible, windows and boxes can be fitted from inside, with temporary boxing acting as place-holder within the insulation until installation can take place.

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

No parts have been included in this revision of the detail.


  1. Admin - 2015-04-29 15:16:28

    DWG uploaded. General formatting amendments.

  2. Admin - 2015-03-27 17:35:43

    Preview image and .pdf file updated.

  3. Admin - 2015-03-27 14:59:41

    EWI (Woodfibre) accessories [EW01] added to parts list.

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

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

  5. Admin - 2015-03-13 17:37:01

    Parts list: Cill updated

  6. Admin - 2015-03-13 16:18:51

    Title revised to match drawing. Technical description updated. Parts list updated.

  7. Admin - 2015-03-10 10:42:28

    Version 4- title updated

  8. Admin - 2015-03-10 10:11:55

    Version update - Summary updated.

  9. Admin - 2015-03-10 09:42:24

    Version 2 - title changed.

  10. Admin - 2015-03-06 17:29:27 [Displayed version]

    First Version

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