EWI to Existing Parapet Eaves [Version ID #168]

Author details

Original Author:Admin Organisation:

Detail summary

A detail for External Wall Insulation, designed to deal with potential cold bridge at eaves - where new or existing loft or roof insulation meets external wall insulation. Where there is a limited overhang at the existing eaves, an integral gutter is required to enable water run-off. Here the EWI is brought up to form a verge, which is then capped with a Stainless steel gutter.

Technical description

Section detail. EWI to existing wall. Up to eaves, existing overhanging with loft insulation joined to EWI.

All guttering to BS EN 12056-3, clauses 3–7 and National Annexes. Collection and distribution of rainwater: Complete, and without leakage or noise nuisance. Reference should be made to Approved Document H (drainage and waste disposal) and Document F (ventilation)

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 breathable membranes to loft and eaves insulation to To BS EN 1928. Durability to EN 1297/1296.

All insulation to be continuous to avoid thermal bridging. Loose laid mineral wool insulation to BS EN 13162, EN 16001 and to conform to BS EN 13501-1 for fire.

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

  • Insulation to Eaves (rigid) [RF06c]

    Phenolic Foam. / Thermal conductivity: 0.023W/m2k. / Thickness: 50mm. / Width: cut to suit rafters. / Installation: Continuous with roof insulation, no gaps, to avoid cold bridging. Friction fit between rafters.

    Contractors choice

  • Breather Membrane [RF06c]

    Sealed to phenolic foam insulation and dressed to drainage point at the end of each run of guttering to allow water to exit construction.

    Green Building Store / Reference: Solitex UM

  • Stainless steel gutter [RF06c]

    Flashing at junction between flat roof verge and external wall insulation. Profile as drawing. To BS 460, and BS EN 12056-3, clauses 3–7 and National Annexes. \ Profile as drawing. \ Size as per drawing- to suit existing roof dimensions and cover depth of external wall insulation. Ensure provides adequate capacity for rainwater discharge from roof. \ Thickness 1.2mm. \ Joins to be avoided where possible. If required must be fully welded and tested. Could be glued and blind riveted subject to approval. \ Self finished Stainless steel grade 304. \ Setting out: to falls. \ Welded stop ends required. \ Fixed as manufacturers recommendations. \ Test on completion.

    Contractors choice

  • Breathable membrane to loft insulation [FL01]

    Laid over top of loft insulation to prevent thermal bypass - joints to be lapped and taped. sd value : 0.01m

    Tyvek \ http://construction.tyvek.co.uk/Tyvek_Construction/en_GB/products/wall/housewrap.html \ Tyvek Housewrap

  • Loose laid loft insulation [FL01]

    Flexible formaldehyde free glass mineral wool. \ 85% (minimum) to BS EN ISO 14021. \ Thermal Conductivity : 0.040 W/mK. \ GWP 0. \ Insulation cover should be even and continuous, right to the eaves. Ensure meets any eaves insulation and/or internal wall insulation to prevent cold bridge at eaves without blocking any ventilation paths required to loft space/ roof space.

    Knauf \ www.knaufinsulation.co.uk \ Reference: Knauf Earthwool loft roll 40

  • Double/Single-sided air seal tape [DP09b/a]

    Tape for junctions critical to air-tightness. 60mm (typical). \ Accessories: ORCON F sealant and TESCON PRIMER RP (for use on rough/old surfaces to assist adhesion)

    Pro Clima \ http://www.greenbuildingstore.co.uk/page--pro-clima-airtightness-tapes-options.html \ TESCON VANA/ TESCON PROFIL (single sided) \ Contega L (double sided)


  1. Admin - 2015-03-27 16:21:59

    Preview image and .pdf file updated.

  2. Admin - 2015-03-27 12:26:20

    Woodfibre EWI added to parts list. Air sealing to ceiling added to parts list. codes amended to match drawing.

  3. Admin - 2015-03-23 15:02:08

    General formatting. Technical description updated and installation sequence revised. Parts list updated with codes and suppliers links.

  4. Admin - 2015-03-12 15:58:51 [Displayed version]

    Intro and technical description updated and expanded. BS and Approved doc information added. Parts list added.

  5. Admin - 2015-03-03 15:12:57

    Preview image updated. Parts list added.

  6. Admin - 2015-02-26 15:36:58

    First Version

Leave a comment


  1. For those who have seen the Earth from space, and for the hundreds and perhaps thousands more who will, the experience most certainly changes your perspective. The things that we share in our world are far more valuable than those which divide us.

    User name

Leave a comment


A total of 14 users have left feedback about this detail.

Share your thoughts about this detail with other users:

Feedback summary

  • 80% of users found this detail easy to implement.
  • 50% of users found it easy to source skills for this detail.
  • 60% of users found this detail hard to understand.
  • 100% of users found the overall cost for this detail to be low.
  • 90% of users found materials for this detail easy to source.