In this article we will look at the regulations and guidance for masonry cavity walls in Approved Document B England, including which Kingspan Insulation products could be used in this application.
The information contained within this article should be used in combination with the full Building Regulations.
Note that complying with the guidance in the Approved Document does not guarantee that building work complies with the requirements of the regulations. There may also be other ways to comply with the requirements than those described in the Approved Document. 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.
What are the fire regulations for insulation in masonry cavity walls in England?
The regulations set out a criteria for ‘relevant buildings’. Relevant buildings are defined in Regulation 7 (4) as:
“(a) a relevant building means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which –
(i) contains one of more dwellings;
(ii) contains an institution; or
(iii) contains a room for residential purposes; and
(b) “above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey”.
Insulation used in masonry cavity walls in relevant buildings above 18 m, must achieve European Classification (Euroclass) A2-s1,d0 or A1.
What guidance does Approved Document B give for insulation in masonry cavity walls in England?
Any insulation used in masonry cavity walls in non-relevant or non-residential buildings above 18 m, or residential buildings above 11 m, could be used when installed within a masonry cavity wall with two leaves of masonry each at least 75 mm thick, with a closed cavity around all openings and a closed cavity at the top of the wall (unless the cavity is totally filled with insulation).
Which Kingspan Insulation cavity wall products could be used in England?
Relevant buildings above 18 m
Kingspan Insulation’s range of phenolic and PIR cavity wall products cannot be used in relevant buildings above 18 m.
Non-relevant and non-residential buildings with a storey above 18 m
All Kingspan Insulation cavity wall insulation products (Kooltherm K106 Cavity Board, Kooltherm K108 Cavity Board and Thermawall TW50) could be used in all non-relevant and non-residential buildings above 18 m to meet the guidance of Approved Document B, provided they are installed within a masonry cavity wall with two leaves of masonry each at least 75 mm thick, with a closed cavity around all openings and a closed cavity at the top of the wall (unless the cavity is totally filled with insulation).
Note – some warranty providers may require specific protection around the closing of cavities. This would need to be investigated for their approval.
Residential buildings above 11 m (up to 18 m)
All Kingspan Insulation cavity wall insulation products (Kooltherm K106 Cavity Board, Kooltherm K108 Cavity Board and Thermawall TW50) could be used in all residential buildings below 18 m to meet the guidance of Approved Document B, provided they are installed within a masonry cavity wall with two leaves of masonry each at least 75 mm thick, with a closed cavity around all openings and a closed cavity at the top of the wall (unless the cavity is totally filled with insulation).
Note – some warranty providers may require specific protection around the closing of cavities, this would need to be investigated for their approval.
Non-relevant and non-residential buildings with storeys below 18 m
All Kingspan Insulation cavity wall insulation products (Kooltherm K106 Cavity Board, Kooltherm K108 Cavity Board and Thermawall TW50) could be used to meet the guidance of Approved Document B.
Residential buildings below 11 m
All Kingspan Insulation cavity wall insulation products (Kooltherm K106 Cavity Board, Kooltherm K108 Cavity Board and Thermawall TW50) could be used to meet the guidance of Approved Document B.
Further information
For further information on the suitability of Kingspan Insulation products please refer to the relevant BBA Certificates:
The following links provide further information on the Building Regulations and guidance for external walls:
