New door - retrofit installation into EWI

Author details

Original Author:Admin Organisation:Retrofit Pattern Book

Detail summary

Section detail for a new replacement door with a timber frame box to the existing door reveal installed into existing External wall insulation works; (or installed as part of EWI works: but with insulation installed before door.)

The new door is installed in a softwood box frame, glued or fixed to the new door frame; to the size of the existing opening, in order to replace the existing door. The new door and box frame means the door sits further into the EWI; bringing the door into the buildings thermal envelope, eliminating the need to insulate the existing opening, and therefore reduce thermal bridging around the existing opening.

The door threshold is reinforced with steel angle for structural support, with additional structural insulation over extruded polystyrene suitable for below ground insulation.

Technical description

Section detail. New door to EWI. Threshold and head detail. Door to sit forward of existing door position within frame.

Reference Specification:

Doors: Please refer to Approved document M (access).

Based on specifications of door: Door facings:

  • Laminate: to BS EN 438-1 and -7.
  • Plywood: To BS EN 314, surface appearance to BS EN 636.
  • Hardwood: To BS EN 635-2.
  • Softwood: To BS EN 635-3.

External wood matchboarded doors to BS 459.
Wood framed panel doors:
Timber quality: To BS EN 942.
All adhesives for for wood doors and frames:

  • to BS EN 204 for Polyvinyl acetate (PVAC).
  • To BS EN 12765, class C4 for thermosetting resin.

Fire performance of all doors, Fire resistant doorsets and shutter assemblies:

  • Type testing: To BS 476-22 or BS EN 1634-1.

Smoke control doorsets and shutter assemblies:

  • Type testing: To BS 476-31.1 or BS EN 1634-3.

Intumescent seals:

  • Type testing: To BS 476-23.

Testing authorities to be UKAS accredited.

Single leaf external doorsets to dwellings, security: To BS 8220-1: General to BSI publication PAS 23-1, Specific req. to BSI publication PAS 24.

Safety glazing to door leaves and sidelights to BS 6206 for safety plastics and BS EN 12600 for safety glass. Location: To BS 6262-4. Please also refer to Approved document K for glazing to doors.

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

All injected cavity wall insulation Polyurethane foam: To BS 7457. Injection holes formed neatly. Installation to BS 7456 by installer Approved in accordance with the British Board of Agrément Surveillance Scheme.

  • Pattern: regular.
  • Size: Recommended by cavity fill manufacturer.

Before commencing filling of each wall: form all holes in that wall. Do not damage: Dpcs, cavity trays, flues, etc. Prevent debris from falling into cavity.

Cement: To BS EN 197-1 and CE marked.

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

  • Insulated External Wood Flush Doorset [GD14]

    Insulated glazed/non-glazed timber Doorset.

    • Type: 54mm insulated single leaf door.
    • Target U-value : 1.0 W/m2K
    • Air-tight installation : Install to achieve maximum air-tightness, using appropriate air-tight tape and sealants at all junctions and potential air-leakage points. (expanding PU foam will not be sufficient to achieve adequate air-tightness).
    • Size: As existing.
    • Facings : Manufacturer's standard.
    • Glazing : Factory glazed as required.
    • Finish As Delivered : Factory finished paint system.
    • Ironmongery : Manufacturer's standard, factory fitted.
    • Threshold : Hardwood with mobility threshold seal.
    • Frame : Manufacturer's standard.
    • Handing : As existing.
    • Doorset Fixing : As manufacturer's recommendations.
    • Certification : All timber to be FSC certified.
    • Security : Secured by Design

    Performance Door solutions.. Tel: 01706 370001.
    Fax: 01706 370002.
    Product Reference: Enhanced EcoHomes Doorset

  • Softwood timber frame Boards [GD10]

    • Manufacturer: Contractors choice.
    • Type: Half round edge.
    • Finished size: to suit existing opening.
    • Species: Manufacturers standard.
    • Class: Class 2 to BS 1186-3.
    • Preservative treatment: not required.
    • Finish as delivered: Factory applied priming coat.
    • Fixing: Lost head nails at 30mm centres.
    • Certification: All timber to be FSC certified(or re-used from existing on site).

    Contractor's Choice.

  • Structural Insulation beneath door threshold [EW06a]

    Structurally improved Polystyrene insulation beneath door threshold

    • Thickness: as per drawing. Depth as per drawing.
    • Width: as per door threshold.
    • Thermal conductivity: 0.04W/m2k. GWP: <5.
    • Joints: tight butt joints

    Compacfoam. Product Reference: CompacFoam- 200

  • Mastic bead sealant to Door Frames

    Sealant for air-tightness.

    • Type: Silicone.
    • Colour: as contractors choice.
    • Profile: Convex.

    Contractor's choice.

  • Injected foam insulation

    • Type: Expanding Polyurethane foam: To BS 7457.
    • Installation: To fill gaps between existing opening and new door frame and box.
    • NOTE: not to be used in place of air-tightness works. Appropriate air-tight tape and sealants should be applied at all junctions and potential air-leakage points.

    Contractor's choice.

  • Rolled Support Steel Angles [EW06a]

    • Manufacturer: Contractors choice.
    • Type: 65 x 50 x 5 mm rolled steel angle.
    • Finish as delivered:Hot dip galvanised to BS EN ISO 1461.
    • Spacing: at 1/3 points beneath door threshold.
    • Fixing: Mechanically fixed through compacfoam packer to existing masonry. Fixing to suit existing substrate.
    • Top-plate: Top-plate pre-fixed to upper end of angle to take load of threshold through compac foam insulation.

    Contractor's choice

  • 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

  • EWI for ground level/within splash zone [EW01]

    Extruded Polystyrene (XPS) suitable for below ground conditions and for application of render.

    • Thickness: as EWI.
    • Depth: Minimum 300mm below internal floor level.
    • Thermal conductivity: 0.033W/m2k. GWP: <5.
    • Installation: Cut to fit around compact foam and steel supports to door threshold.
    • Joints: Tight butt joints

    BASF. Product Reference: Styrodur 2800C insulation.

  • EWI Accessories [EW01a]

    • Adhesive render edging strip for render up to edge of window frame.
    • Drip bead for render at door head.

    As EWI manufacturers reccomendations

  • Granular Backfill [EW01]

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

    Contractor's choice


  1. Admin - 2015-04-29 16:44:29 [Displayed version]

    General formatting amendments

  2. Admin - 2015-04-28 16:22:52

    DWG detail file added for download.

  3. Admin - 2015-03-31 09:54:04

    Version 2. Part list updated.

  4. Admin - 2015-03-31 08:16:30

    Version 1. Adding new details with user permissions test.

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