Last edited 05 Jan 2017

Approved Document D

The first set of national building standards was introduced in 1965. Now known as the building regulations, they set out:

The 'approved documents' provide guidance for how the building regulations can be satisfied in common building situations. There is no obligation to adopt the solutions presented in the approved documents, the building regulations can be satisfied in other ways.

Part D of Schedule 1 to the Building Regulations requires that, 'If insulating material is inserted into a cavity in a cavity wall, reasonable precautions shall be taken to prevent the subsequent permeation of any toxic fumes from that material into any part of the building occupied by people.'

Approved Document D - Toxic Substances, provides guidance for complying with Part D. This relates the use of urea formaldehyde (UF) foam.

Approved document D suggests that '…insulating materials which give off formaldehyde fumes (either when used or later in normal use) may be used to insulate the cavity in a cavity wall where there is a continuous barrier which will minimise as far as practicable the passage of fumes to the occupiable parts.'

It provides the following technical solution:

A cavity wall may be insulated with UF foam where:

  • the inner leaf of the wall is built of masonry (bricks or blocks); and
  • the suitability of the wall for foam filling is assessed before the work is carried out in accordance with BS 8208-1:1985 Guide to assessment of suitability of external cavity walls for filling with thermal insulants. Existing traditional cavity construction; and
  • the person carrying out the work holds (or operates under) a current Certificate of Registration of Assessed Capability for the work he is doing; and
  • the material is in accordance with the relevant recommendations of BS 5617:1985 Specifications for urea formaldehyde (UF) foam systems suitable for thermal insulation of cavity walls with masonry or concrete inner and outer leaves; and
  • the installation is in accordance with BS 5618:1985 Code of practice for thermal insulation of cavity walls (with masonry or concrete inner and outer leaves) by filling with urea formaldehyde (UF) foam systems.

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