Insulation to suspended floor, thin joists, membrane below. [Version ID #247]

Author details

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Detail summary

Detail of woodfibre insulation laid between existing suspended ground floor joists. Detail applicable where existing joists are too thin to allow minimum 200mm depth for woodfibre installation, additional timber added to bottom of joist to increase depth and fix breathable membrane to underside.

To achieve target U-value of 0.28W/m2k as per Doc L

Technical description

Section detail. Floor insulation between joists with breather membrane below. Accessible from below. To achieve target U-value of 0.2W/m2k.

SUGGESTED INSTALLATION SEQUENCE:

Before start of works: Inspect any structural timbers, particularly those which enter external walls (e.g. floor joists); Inspect sub-floor, and timbers within for signs of damp and rot. Report immediately if any found. If possible record current condition of timbers and moisture content for future reference. Remove any organic matter from sub-floor and floor void. Ensure all existing air-bricks are unobstructed with clear ventilation path

Remove any organic matter from sub-floor and floor void. Ensure all existing air-bricks are unobstructed with clear ventilation path

1.) Check floor void for signs of rot and damp report immediately if found. 2.) Remove below floor obstructions take particular care to remove organic matter eg. timber pieces. 3.) Seal joists/gaps between floor boards from above or below. Ensure all gaps in floorboards are filled. 4.) From below: ensure gap between floor and skirting is sealed with tape/membrane. 5.) Fit any timber to support new ceiling plasterboard to underside of existing joists. 6.) Fit insulation butts between joists. 7.) Install rigid board insulation. 8.) Plaster finish.

REFERENCE SPECIFICATION:

Please refer to Approved documents: B (fire safety): B1 section 1 (material alterations)/ B2 section 3 (internal fire spread), and Appendix A (material properties). Document A (structural safety) should be referred to when fixing/applying loads to existing floor joists or members. Ensure existing joists meet requirements in Approved document A (structural) before starting works. Refer to Doc L: Section 5 of L1B for dwellings; including all relevant amendments.

Parts list

  • Vapour Control Layer [FL01c]

    Intelligent breather membrane. \ Fixing: Laps And Edges: Sealed with vapour-tight adhesive tape. 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 \

  • Seal between floorboards [DP02] & [DP04]

    Draught-proof and seal all timber floors to ensure no air-leaks. Draughtproof neoprene strips between floorboards. Standard decorators caulk to wall/floor junctions and skirting boards /OR: additional draughtproof strips.

    Draughtex. \ www.draughtex.co.uk \ Reference: Draughtex Neoprene Strips. \ Decorators caulk- contractors choice.

  • 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)

  • Woodfibre Insulation Between Suspended Joists [FL01d]

    Flexible woodfibre insulation. \ Depth TBC on site based on depth of existing joist. \ Friction fit between joists to ensure air-tightness (batts cut approx 20mm wider than opening between joists.) \ Thermal conductivity: .004W/m2K. GWP 0.

    Unger \ www.unger-diffutherm.de \ UdiFLEX flexible wood fibre insulation.

Revisions

  1. Admin - 2015-04-30 13:23:14

    Intro/summary updated.

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  2. Admin - 2015-04-30 11:10:49

    General reformatting. DWG file uploaded.

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  3. Admin - 2015-03-30 11:11:39

    Preview image and pdf detail file updated.

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  4. Admin - 2015-03-26 13:26:47

    General re-formatting. Introduction revised. Technical description updated with approved docs and additional notes.Parts list updated with supplier links.

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  5. Admin - 2015-03-17 10:27:08

    Detail updated. errors removed.

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  6. Admin - 2015-03-17 10:23:23 [Displayed version]

    Version 2. Introduction expanded. Technical description updated and expanded with BS codes and approved docs. Parts list update with codes.

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  7. Admin - 2015-03-04 15:47:03

    Version 2- Parts list updated

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  8. Admin - 2015-03-04 15:45:55

    First Version

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