EWI corner detail - change of material around corner [Version ID #341]

Author details

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Detail summary

Detail of corner junction between Woodfibre and EPS foam external wall insulation; with an appropriate seal detail at junction. EPS insulation to be used where thinner insulant required.

Technical description

Plan detail. EWI junction at external corner with perpendicular wall, EWI carrying round with change of material over corner. EPS insulation system junction with Woodfibre EWI insulation system. Adhesive to join insulation types with render carried round and over join; mastic seal to edge of join projecting beyond render to fully seal.

Suggested Installation Sequence:

  1. Fix EWI A to existing wall, edge hard up to corner.
  2. Apply adhesive to exposed edge on corner.
  3. Fix EWI B to wall around corner, line edge up with face of Insulation A.
  4. Mastic seal to joint of insulation types.
  5. Corner reinforcement and render over.

Reference Specification:

Expanded polystyrene (EPS): To BS EN 13163. Installed by system manufacturer/ contractor approved by manufacturer to weather-tight installation, to resist dead and live loads inc. impact and wind loads. Do not install in adverse weather conditions.


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.

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.

Windows and doors: Where windows and doors are to be replaced in insulation please refer to contract/window schedules for details. Where windows and doors are to be retained in insulation please refer to relevant detail drawings to show reveal insulation and cills.

Parts list

  • Foam EWI System (140mm), rendered finish [FAB EW02a]

    Vapour permeable expanded polystyrene (EPS) external wall insulation: To BS EN 13163.

    • Thermal conductivity: 0.031W/m2K.
    • GWP: <5.
    • Fixing: Adhesive bedding and mechanical fixing to substrate in accordance with manufacturer's recommendations.
    • Adhesive layer: Baumit openContact - round perimeter of each board and three dabs within on each board.
    • Fixing anchor: Baumit STR U.
    • Basecoat: Baumit openContact.
    • Reinforcement : Baumit openTex.
    • Primer: Baumit openPrimer.
    • Topcoat: Baumit Nanopor Top.
    • Beads/ Trims: Manufacturer's standard.
    • Finish Colour: See schematic.
    • System Guarantee: 25 years - ECO Compliant insurances and guarantees.
    • System Certification: ETAG.

    Baumit: Tel: +44 (0) 333-358 3434
    Fax: +44 (0) 843-557 7666
    Web: http://www.baumitinsulation.co.uk
    Product Reference: Baumit EWI system open.
    Insulation: Baumit open reflect - vapour permeable EPS.

  • 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. Product Reference: UdiFRONT.

  • Woodfibre EWI adhesive [EW01]

    Adhesive for use at joint between perimeter/ plinth insulation and external wall insulation.

    Back to Earth. Tel: 01392 861763
    Web: http://http://www.backtoearth.co.uk/
    Product Reference: UdiSpecial Adhesive.

  • Woodfibre EWI accesssories [EW01]

    Corner bead for render reinforcement at external corners

    As EWI manufacturers/suppliers.


  1. Admin - 2015-04-29 13:23:03

    Intro summary updated. Parts list contact details amended for EW01. DWG uploaded.

  2. Admin - 2015-03-27 16:36:41

    Preview image and .pdf file updated.

  3. Admin - 2015-03-24 15:17:42

    Errors in parts list removed.

  4. Admin - 2015-03-24 14:43:45

    General reformatting. Technical description updated with additional clauses.

  5. Admin - 2015-03-24 13:26:33 [Displayed version]

    General reformatting. Introduction revised. Technical description expanded with additional clauses. Parts list updated with suppliers links. EWI accessories added.

  6. Admin - 2015-03-24 13:26:02

    General reformatting. Introduction revised. Technical description expanded with additional clauses. Parts list updated with suppliers links. EWI accessories added.

  7. Admin - 2015-03-13 12:54:15

    Title update. Intro and technical description expanded and updated. Parts list added.

  8. Admin - 2015-02-27 16:57:38

    Version 1

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