IWI to upper floor with perpendicular joists [Version ID #234]

Author details

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Detail summary

IWI detail through an existing timber floor, where the existing floor joists are perpendicular to the wall to be insulated. Design for an Internal wall insulation system with intelligent membrane. N.B. Continue across intermediate floors, ensuring continuous insulation, vapour-control and air-tightness layers.

The detail provides information on the packing of joist ends in wall, and air-tightness measures, in order to prevent cold-bridging at junctions between IWI and internal upper floors.

Technical description

Section detail. IWI Upper floor, with access from above. Perpendicular joists. IWI continuous between floors. Taped and sealed all edges.

SUGGESTED INSTALLATION SEQUENCE:

Before installation: Remove all timber fixtures: Skirting, Picture Rails, Dado Rails etc. Remove curtain rails. Remove electrical socket/ telephone/cable socket outlets. Re-fix/renew all removed once insulation complete.

1.) Remove wallpaper and plaster if necessary, any fixings and skirting board. 2.) Lift floorboards adjacent to wall to allow access to floor void and joists. 3.) Stuff joist ends with off cuts of flexible woodfibre insulation. 4.) Fix IWI to reach ceiling below. 5.) Intelligent membrane and plasterboard with skim continued into floor void. 6.) Seal round joists as it penetrates. 7.) Fix floorboards and skirting boards and make sure of air-tightness

REFERENCE SPECIFICATION:

All Expanded polystyrene insulation (EPS): To BS EN 13163. All fixings manufactured in accordance with BS1210. Mineral wool (MW): To BS EN 13162; reaction to fire rating to: BS EN 13501-1

All vapour control layers/ air tightness layer to durability requirements of EN 13984.

Please refer to Approved documents: B (fire safety): B1 section 1 (material alterations)/ B2 section 3 (internal fire spread), and Appendix A (material properties). Doc L: Section 5 and 6 of L1B; including all relevant amendments. Ensure existing joists meet requirements in Approved document A (structural) before starting works.

Parts list

  • Internal Wall Insulation System (95mm) [IW02]

    Earthwool Eco batt insulation. N.B. Continue across intermediate floors, ensuring continuous insulation, vapour-control and air-tightness layers. \ Thickness 95mm\ Target u-value: 0.3W/m2k. Thermal conductivity: 0.033W/m2k/ 0.130W/mk. GWP<5. \ Fixing: In accordance with manufacturer's recommendations. Supports: EcoStuds - XPS and OSB uprights.

    Knauf \ ThermoShell Internal Wall Insulation System

  • Single-sided air seal tape [DP09a]

    Tape for junctions critical to air-tightness. 60mm (typical). \ Accesssories: 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 (2 release tapes)

  • Double-sided air seal tape [DP09b]

    Tape for junctions critical to air-tightness. 85mm (typical). \ Accesssories: 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 \ Contega SL.

  • Vapour Control Layer [IW02]

    Intelligent breather membrane. \ Fixing: Laps And Edges: Sealed with vapour-tight adhesive tape. At junctions with party/partition walls, lap under insulated plasterboard. At floor and ceiling junctions ensure is appropriately sealed.

    OPTION 1.) Pro-clima \ http://www.greenbuildingstore.co.uk/page--pro-clima-interior-membranes-options.html \ Reference: Intello membrane \ OPTION 2.) : Knauf \ http://www.knaufinsulation.co.uk/media/1080123/kine1491dat-thermoshell-vapour-control-layer-datasheet.pdf \ Thermoshell Vapour Control layer

  • Plasterboard and fixings [IW02]

    Plasterboard components to be installed with IWI system. Knauf Moistureshield/ Wallboard/ Denseshield. Knauf Drywall screws

    To IWI manufacturers recommendation.

  • EcoStud insulated supports IWI system [IW02]

    Vertical supports for IWI batts. Thermally engineered composite of high performance extruded polystyrene bonded to Oriented Strand Board 3 (OSB 3)supports to IWI sheets. Expanded polystyrene insulation (EPS): To BS EN 13163.

    Knauf Insulation. \ http://www.encon.co.uk/sites/default/files/products/downloads/datasheet-ecostud.pdf \ Reference: EcoStud for Solid walls. (Used in conjunction with Earthwool EcoBatt.)

Revisions

  1. Admin - 2015-04-30 09:30:01

    General formatting changes. DWG file updated.

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  2. Admin - 2015-03-30 11:54:15

    Preview image and detail pdf updated.

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  3. Admin - 2015-03-29 10:44:36

    Air tightness sealant and loose insulation to joist ends added to parts list.

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  4. Admin - 2015-03-26 16:57:16

    Target u-values added.

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  5. Admin - 2015-03-26 16:55:28

    General formatting. Introduction revised and updated. Technical description updated with approved documents and additional notes. Parts list updated.

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  6. Admin - 2015-03-16 15:17:56

    Version 3- Technical description updated.

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  7. Admin - 2015-03-16 14:51:56 [Displayed version]

    Version 3- Introduction updated. Technical description revised with Approved doc and BS information. Parts list updated with relevant codes.

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  8. Admin - 2015-03-03 16:16:58

    First version

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