EWI to clipped eaves with hidden gutter [Version ID #430]

Author details

Original Author:Admin Organisation:

Detail summary

A detail for external wall insulation to deal with potential cold bridging 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 hidden gutter is required to enable water run-off; to facilitate this the EWI is brought up to form a verge, which is then capped with a stainless steel gutter.

Target values:

Psi Value: 0.0778 W/mK

Technical description

Section detail. EWI to existing wall. Up to eaves, clipped, with new/ existing loft insulation join to EWI.

Suggested Installation Sequence:

Preparation of roof and loft space: Remove any existing loose material and prepare in accordance with manufacturer's requirements.

Any alterations to cabling, existing ventilation, drainage, and other fixtures affected by work to be agreed with contract administrator prior to work being undertaken. Prior to start on site inspect the form and condition of the roof internally and externally, especially any structural timbers; institute repairs and/ or additional works necessary to make the structure suitable to receive works.

Installation:

  1. Carefully remove minimum 750mm of tiles or slates, putting to one side for reuse. Note positions of existing roofing battens.
  2. Remove roofing battens to at least 600mm up the roof from the existing eaves. Roll existing membrane back but do not cut.
  3. Insert rigid insulation (FAB RF06)between rafters, allowing at least 125mm from the edge of insulation board to the next batten position up the roof.
  4. Fix external wall insulation (FAB EW01)- cut to fit to eaves insulation and cut back to form gutter parapet.
  5. Install breathable membrane/ roof underlay [RF06c] approx 500mm up roof slope from front edge of EWI. Pin in place to rafters with galvanised clouts at upper edge. Dress over EWI outer layer so as not to protrude beyond the front face.
  6. Insert stainless steel gutter system over the top of the breather membrane/ roof underlay and EWI as shown on drawing. Fix in place with self drilling fixings to every third rafter at inner upper edge.
  7. Roll original membrane back over new stainless gutter to lap new gutter by 200mm. If required replace roofing battens in original locations up to approx 600mm above bottom edge of gutter. Dress the existing membrane over this reinstalled batten. Insert last batten at approx 350mm up from the edge of the gutter.
  8. Roll the original membrane over the top of the polycarbonate vent strip.
  9. Replace slates/tiles, dressing last slate/tile so as to be just below the upper edge of the gutter.
  10. Install loft insulation (FAB RF01) - making sure it meets the back of the eaves insulation (FAB RF06c)

Reference Specification:

:

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.

For all works to existing roofs refer to Approved document C (resistance to contaminants and moisture), with reference to Section 2, and section 6.

Reference should be made to Document H (drainage and waste disposal). Approved Document F (ventilation) should be referred to with regards to ventilation to existing roofs and over eaves ventilation. Document L1b should be referred when working on existing dwellings, with particular attention to sections 5 and 6 regarding material alterations. Document L2b should be referred to with existing buildings other than dwellings.

Notes:

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

  • 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.

  • Ventilation path /Eaves vent strip [RF06c]

    • 12mm Polycarbonate sheeting equivalent to 10mm continuous ventilation gap.
    • OR: ventilator strip to allow airflow under roof whilst preventing ingress of insects and small birds.

    Contractor's choice

  • Breathable Membrane [RF06c]

    Roof underlay. 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. Tel: 01484 461705. Email: info@greenbuilding store. Web: http://www.greenbuildingstore.co.uk
    Product Reference: Solitex Plus

  • Stainless Steel Gutter system [RF06c]

    Flashing at junction between flat roof verge and external wall insulation. To BS 460, and BS EN 12056-3, clauses 3–7 and National Annexes.

    • Manufacturer: Contractor's choice.
    • Profile: As drawing.
    • Gauge: 1.2mm min.
    • Jointing: Joints to be avoided where possible. If required must be fully welded and tested. Could be glued and blind riveted subject to approval.
    • Size: Contractor's choice- to suit existing roof dimensions and cover depth of external wall insulation. Ensure provides adequate capacity for rainwater discharge from roof.
    • Finish as delivered: Self finished Stainless Steel grade 304.
    • Setting out: To falls.
    • Fasteners: as manufacturers recommendations.
    • Accessories: As welded stop ends.
    • Testing: Test on completion.

    Contractor's choice

  • Insulation to Eaves (rigid) [RF06c]

    • Manufacturer: Contractor's choice.
    • Phenolic foam.
    • Size: 50mm thickness
    • Width: cut to suit rafters.
    • Length: 750mm PLUS distance to eaves board or 200mm (whichever smallest).
    • Thermal conductivity: 0.023W/m2k.
    • Installation: Continuous with roof insulation, no gaps, to avoid cold bridging. Friction fit between rafters from inside loft, being careful not to damage existing roof membrane or structure or block existing ventilation paths.

    Contractor's choice

  • Insulation to Eaves (Flexible) [RF06c]

    • Woodfibre offcuts from external wall insulation.
    • Installation: Insert into gaps between wall plate/top of wall and rigid insulation to ensure continuity and avoid air movement.

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

  • Softwood battens (for replacment slating) [RF06c]

    • Size: 50x25mm timber battens.
    • Grading: Fully factory Pre-graded.
    • Preservative treatment: Required- contractor's choice.
    • Certification: All timber to be FSC certified \ Preservative treatment required.
    • Fastening: Galvanized steel nails, sized to penetrate 40 mm (minimum) into rafters.

    Contractor's choice.

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

    Tape for junctions critical to air-tightness.

    • Location: see detail drawings - generally critical junctions for air-tightness. Size: 60mm (Single sided)/ 85mm (double 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) \ Contega SL (double sided)

  • Replace Roof tiles/Slates:

    Type: As existing. Colour: As existing. Size: As existing. Minimum Headlap: As existing. Fixing: Obtain and comply with tile manufacturer's full fixing specification for project. Features: As existing.

    Contractor's choice.

  • Loose laid loft insulation [FAB L01a]

    Flexible formaldehyde free glass mineral wool. Should be laid continuous to eaves: level, covering all parts of the ceiling to meet any eaves/ internal wall insulation to prevent cold bridge. All service holes sealed, debris removed before laying insulation. Eaves ventilation should be unobstructed. Any electric cables overlaid by insulation should be sized accordingly. Where water cistern platforms located on ceiling joists: Insulation below omitted.

    • Recycled content: 85% (minimum) to BS EN ISO 14021.
    • Thermal Conductivity: 0.040 W/mK. GWP 0.
    • Thickness to 400mm

    Knauf Reference: Knauf Earthwool loft roll 40

  • Sealing to ceiling edges [DP03]

    • Location: all ceilings.
    • Description: Seal all ceilings and repair any cracks in plastre to ensure no air leaks.
    • Product: Standard decorators caulk

    Contractor's choice.

Revisions

  1. Admin - 2015-11-03 16:30:31

    Edited the notes

    |
  2. Admin - 2015-04-29 09:17:25

    DWG file updated. Back to earth contact details added for EWI. Formatting changes to Parts list

    |
  3. Admin - 2015-03-27 16:12:16 [Displayed version]

    Preview image and .pdf file updated.

    |
  4. Admin - 2015-03-27 11:19:19

    Parts list updated so concurrent with detail drawing. DP03 added to parts list.

    |
  5. Admin - 2015-03-27 11:14:12

    Parts list updated so concurrent with detail drawing. DP03 added to parts list.

    |
  6. Admin - 2015-03-23 16:01:08

    General formatting and error reduction.

    |
  7. Admin - 2015-03-23 15:02:23

    Parts list updated- loft insulation added. General formatting and error removal.

    |
  8. Admin - 2015-03-23 12:01:43

    Introduction/summary updated. Technical description revised and updated with British Standards and Approved docs. Links added. Parts list updated: reformatted and links added.

    |
  9. Admin - 2015-03-23 11:59:19

    Introduction/summary updated. Technical description revised and updated with British Standards and Approved docs. Links added. Parts list updated: reformatted and links added.

    |
  10. Admin - 2015-03-23 11:58:52

    Introduction/summary updated. Technical description revised and updated with British Standards and Approved docs. Links added. Parts list updated: reformatted and links added.

    |
  11. Admin - 2015-03-13 18:00:06

    Updated with additional titles and codes. Installation sequence added.

    |
  12. Admin - 2015-03-12 12:10:40

    Version 6- Title, description and technical description updated and expanded. BS and Approved doc information added. Parts list added.

    |
  13. Admin - 2015-03-03 11:26:17

    Preview file updated

    |
  14. Admin - 2015-02-27 12:48:00

    Preview image updated

    |
  15. Admin - 2015-02-27 12:47:23

    Preview image updated

    |
  16. Admin - 2015-02-27 12:14:52

    version 2- .dwg file updated

    |
  17. Admin - 2015-02-26 14:15:27

    First version

    |
Leave a comment

Discussion

  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


Feedback

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.