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  1. Roof Insulation for Increased depth Rafters

    Detail for the internal installation of woodfibre insulation to an existing roof; where existing rafters are not deep enough to allow 200-250mm insulation to be installed. In this detail the existing rafters are extended with additional timber to fit insulation to the required depth.

    To be used only where a suitable vapour-permeable roofing membrane is present above. (check brand and sd value upon inspection of roof).

    Target U-value : 0.18W/m2K

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  2. Roof Insulation- Existing membrane LR

    Roof insulation to existing rafters, where the existing roofing membrane below tiles/slates is a Low Resistance (LR) membrane. [See Technical Description for definition as of BS 5250: 2011]

    Insulation in plane of rafters where existing roof membrane is low resistance vapour permeable. Need to ensure adequate ventilation behind insulation.

    Insulation boards and proprietary basecoat finish with vapour control render applied to inside face of insulation.

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