Insulation to suspended floor, accessible from below. [Version ID #91]

Author details

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Detail summary

Detail for insulation to a suspended timber floor accessible from beneath to increase thermal efficiency and reduce heat loss.

Technical description

Section detail. Floor insulation between joists with air-tightness works. Ground floor- suspended. No ceiling required. To achieve target U-value of 0.2W/m2k.

Preparation: Inspect sub-floor and timbers for signs of damp and rot. Before starting work carry out a survey of any structual timbers, particularly those which enter external walls (e.g. floor joists). 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

Parts list

  • Woodfibre Insulation Between Floor Joists

    Woodfibre Insulation. \ Thickness 200mm. \ Friction fit between joists to ensure air-tightness- cut batts approx 20mm wider than opening between joists. Supported by Polyester webbing drawn underneath insulation at approx 600mm centres, fixed to joists.

    Unger \ \ Reference: UdiFLEX

  • Seal between floorboards- existing ground floor.

    Draught-proof and seal all timber floors to ensure no air-leaks

    Draughtex. \ \ Reference: Draughtex Neoprene Strips

  • Single-sided air seal tape

    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 \ \ TESCON VANA/ TESCON PROFIL (2 release tapes)


  1. Admin - 2015-04-30 11:07:40

    General reformatting. DWG file uploaded.

  2. Admin - 2015-03-30 11:13:01

    Preview image and pdf detail file updated.

  3. Admin - 2015-03-30 10:59:22

    Air seal tape removed, code added to webbing in parts list

  4. Admin - 2015-03-26 13:52:16

    General re-formatting. Introduction and Technical description expanded. Parts list updated with suppliers lists.

  5. Admin - 2015-03-17 10:23:12

    Version 3. Parts list updated and errors removed.

  6. Admin - 2015-03-16 17:03:27

    Introduction and technical description updated. Parts list updated with codes.

  7. Admin - 2015-03-04 15:20:28 [Displayed version]

    First Version

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