Masonry cavity walls
What are the regulations and guidance for insulation in masonry cavity walls and which products could be used?
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Most building work being carried out in Scotland must comply with the Building Regulations 2004. The following sections of the Building Regulations should be adhered to when selecting insulation for your project.
Cavities
2.4 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the spread of fire and smoke within cavities in its structure and fabric is inhibited.
Internal linings
2.5 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the development of fire and smoke from the surfaces of walls and ceilings within the area of origin is inhibited.
Spread to neighbouring buildings
2.6 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the spread of fire to neighbouring buildings is inhibited.
Spread on external walls
2.7 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building is inhibited.
Page updated 16/01/2026
In 2022, Regulation 8 was released and sets out the requirements for materials which become part of an external wall cladding system, or specified attachment, on 'relevant buildings'. For more information, take a look at our article on relevant buildings.
The Technical Handbooks (one for domestic buildings and another for non-domestic), give practical guidance on common building situations to meet the requirements of the Building Regulations 2004 for Scotland.
Note that following the guidance in full should be accepted as compliance with the Regulations. However, there may also be other ways to comply with the requirements than those described. The project Principal Designer (during design stages), Principal Contractor (during construction) and relevant consultants (such as Fire Engineers) should be consulted to ensure compliance with the Building Regulations.
Our CPD covers the guidance, regulations and testing for insulation products. It takes a look at essential terminology for understanding how a fire develops and how products need to perform as a fire develops.
