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Building Regulations

  This page details some of the technical specifications set out in the latest Building Regulations with regard to spray foam insulation, attic insulation, home insulation, and loft insulation.

Technical Specification

  Spray foam is a CFC free blown polyurethane rigid foam, spray applied to the underside of tiles and slates.
  Spray foam is suitable for use as a repair and stabilising system on slate or tiled pitched roofs suffering from the effects of nail corrosion. The anchorage originally supplied by the fixing nails is replaced by the adhesive properties of the foam.
  Damaged, dislodged or missing slates or tiles must be replaced prior to the installation of spray foam to ensure that the risk of subsequent water penetration is kept to an absolute minimum.
  Test Data indicates that the adhesive properties to a slate or clay tile roof are sufficient to withstand the expected wind loads, thermal cycling and minor structural movements likely to occur in practice.
Slates and tiles treated with spray foam will be less prone to damage by impact due to the foam distributing the forces.
All available evidence, including the examination of the product’s performance in use, suggests that the life of a slated or tiled roof will be extended by at least 20 years.

Maximum U-Value (W/m2K)


Foam Depth (mm)


Foam Depth (mm)

Room in Roof (New Build) 0.20 115 0.16 130
Room in Roof (Loft Conversion) 0.30 75 - -
Pitched Roofs 0.16 85* 0.16 85*
Flat Roofs 0.25 85 0.16 135
Walls 0.35 60 0.25 75
Floors 0.25 50 0.22 60
Windows/Doors/Rooflights 0.20/2.00 - 1.80 -
* Calculation based on unventilated loft space with 100mm mineral fibre at ceiling level
  For the full set of 2005 Building Regulations visit

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