Light steel framed walls and floors

6.10.12Insulation

Insulation materials shall be correctly installed, be of a suitable thickness to comply with building regulations and reduce the risk of interstitial condensation.

Insulation should:

  • be inert, durable, rot and vermin proof and should not be adversely affected by moisture or vapour
  • cover the whole external face of the wall
  • extend 150mm below the bottom rail to minimise thermal bridging and maintain a warm frame
  • be tightly butted with joints of rigid board isulation taped, where required by the design.

Foil-faced insulation boards with an integral facing on one side only should be fixed with the foil face on the cavity side.

Table 7: Acceptable insulation material

MaterialRelevant standard
Mineral woolBS EN 13162
FR (flame retardant) grade expanded polystyreneBS EN 13163
FR (flame retardant) grade extruded polystyreneBS EN 13164
Rigid polyurethane foam and polyisocyanurateBS EN 13165
Phenolic foamBS EN 13166
Cellular glassBS EN 13167
Other insulation materialsTechnical Requirement R3

In England and Wales, account should be taken of Accredited Construction Details for Part L.