- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 06 Nov 2020
Approved Document D
- What qualifies as 'building work' and so fall under the control of the regulations.
- What types of buildings are exempt.
- The notification procedures that must be followed when starting, carrying out, and completing building work.
- Requirements for specific aspects of building design and construction.
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:
- 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.
 Find out more
 Related articles on Designing Buildings Wiki
- Approved documents.
- Approved document C
- Approved document G.
- Approved document L.
- Approved document M.
- Approved document P.
- Approved document Q.
- Approved inspector.
- Building control body.
- Building regulations.
- Cavity wall insulation.
- Northern Ireland building regulations.
- Scottish building standards.
- The Building Act.
- Welsh building regulations.
Featured articles and news
IHBC resource offers improved consistency.
New laws to ‘retain and explain’ historic statues.
The principles and art of the possible. Book review.
From horse and cart to hypermarket.
How elements and processes work together in a systems approach.
CIOB offers digital guide to proactive methods of working.
Tech will drive professional development in fields tied to infrastructure.
The idea for the structure emerged from the architect's dream.
Changing air tightness requirements prompt testing and revisions.
Government takes steps to revise building safety legislation.
Product can be 'grown' into bricks or used as a self-healing building material.
Anticipating COVID-19's continuing construction disruptions.