EWI corner detail to perpendicular wall, with opening for door

Author details

Original Author:Admin Organisation:Retrofit Pattern Book

Detail summary

Detail for external wall insulation system to a perpendicular wall, with an opening for a new door/window. This detail applies where the opening size may be adjusted in order to accommodate the new EWI to the existing wall.

Technical description

Plan detail. Corner EWI to perpendicular wall containing opening door. Existing door opening to be reduced and existing door replaced. Air seal to internal face and finishing detail to new opening.

Suggested Installation sequence:

  1. Measure critical distances on site before ordering window/ door.
  2. Install door or window.
  3. Install external wall insulation.

Installation: by system manufacturer, or a contractor approved by the system manufacturer.

  • Weathertight under all anticipated conditions.
  • Capable of resisting all dead loads and design live loads, including impact and wind loads, and accommodating all thermal movements without damage.


Materials/ Surfaces: Do not use frozen materials and do not apply materials to frost bound surfaces.

Adhesives/ Mortars/ Renders: Do not apply when air temperature is at or below 5 °C on a falling thermometer or below 3 °C on a rising thermometer, or when temperature of the air or wall surface is above 30 °C and the surface is not protected. Temperature of the work: Maintained above minimum level recommended by manufacturer until adhesive/ mortar/ render has fully hardened.

Newly rendered surfaces: Protected against rain and snow by covering when precipitation occurs. Coatings damaged by rain or frost: Replace.

Reference Specification:

For guidance on step access or opening sizes for new and existing doors : Please refer to Approved document M (access to and use of buildings).

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.


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/substrate: Before work- remove any existing loose material from external wall and prepare in accordance with manufacturer's requirements. Substrate to be structurally sound, adequately true and level, dry, free from contamination by dirt, dust, efflorescence or other deleterious substances, and in a suitable condition to receive specified coatings.

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.

Existing Services

Gas Meters and Inlets: Gas meters and inlets to be left in-situ. Insulation to be fitted round them as closely as possible, whilst ensuring they are still properly ventilated. Care should be taken when excavating close to gas mains.

Soil Pipes: An assessment of the condition of soil pipes should be undertaken prior to external wall insulation being undertaken. Assume soil pipes will remain in situ unless agreed in by contract administrator. However in some cases pipes may need to be replaced/ moved. Any changes to existing pipework to be agreed in writing by the contract administrator before work starts.

Rainwater Pipes and Waste Water Drainage: Rainwater pipes and waste water pipes will be moved to the outer face of insulation as standard, and swan-necked back into gulleys where possible. Any work additional to this should be agreed in writing with the contract administrator.

Parts list

  • EWI (Woodfibre), with 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
    Web: http://www.backtoearth.co.uk/

  • Single-sided air seal tape [DP09a]

    Tape for junctions critical to air-tightness.

    • Location: see detail drawings - generally critical junctions for air-tightness. Size: 60mm (Single sided).
    • Accessories: ORCON F sealant and TESCON PRIMER RP (for use on rough/old surfaces to assist adhesion)

    Back to Earth: Tel: 01392 861763.
    Web: http://www.backtoearth.co.uk/
    Product reference: TESCON VANA/ TESCON PROFIL - 2 release tapes (single sided)

  • Replacement Triple glazed Timber Patio Doorset [GD11]

    • Type: Triple glazed Timber Patio Doorset.
    • Target U-value: 1.1 W/m2K.
    • Size: As existing.
    • Configuration: Inward opening, double.
    • Security: Locking with security measures to Secured by Design standard
    • Material: FSC 100% Redwood.
    • Finishes:
    • Interior : Clear timber.
    • Exterior : Painted or stained factory finish.
    • Drip rail: Aluminium.
    • Air-tight installation: Install windows 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).
    • Glazing unit: triple
    • Glazing type: As standard, unless agreed by contract administrator.
    • Handle type: Locking
    • Handle colour: tbc.

    Green building store.
    Tel: 01484 461705
    Reference: Ecocontract Secondary Doorset.

  • Sealant To External Door Frames [GD11]

    Silicone, colour TBC. Convex profile.

    Contractor’s choice.

  • Threshold/cill [GD11]

    Hardwood with mobility threshold seal. To interface with EWI.

    Contractor’s choice

  • Woodfibre EWI accesssories [EW01]

    • Corner bead for render reinforcement at external corners.
    • Adhesive render edging strip for air-tight seal around doors.

    As EWI manufacturers/suppliers.


  1. Admin - 2015-04-29 13:51:27 [Displayed version]

    Technical description format changes.

  2. Admin - 2015-04-29 13:49:49

    DWG file uploaded. Parts list contact details for GD14 and EW01 amended.

  3. Admin - 2015-03-27 16:41:10

    Preview image and .pdf file updated.

  4. Admin - 2015-03-24 15:00:18

    General formatting. Technical description expanded with additional clauses. Parts list updated with suppliers links. Woodfibre accessories added to parts list.

  5. Admin - 2015-03-13 13:23:15

    Parts list updated to revise errors.

  6. Admin - 2015-03-13 13:19:28

    Version 2. Introduction updated. Technical description revised and expanded. Parts list added.

  7. Admin - 2015-02-27 17:17:54

    Version 1

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