Last edited 20 May 2025

External wall

Brick wall.jpg

Approved document C, Site preparation and resistance to contaminants and moisture, suggests that a wall is: 'Any opaque part of the external envelope of a building that is at an angle of 70° or more to the horizontal.'

An external wall is a wall forming the external enclosure of a building.

Approved document B, Fire Safety, Volume 2, Buildings other than dwellinghouses (2019 edition), suggests that the external wall of a building includes all of the following:

This definition is also found in the Building Regulations 2010 and this is referenced by The Higher-Risk Buildings (Key Building Information etc.) (England) Regulations 2023.

NB RICS property measurement, 2nd edition, published by the Royal Institution of Chartered Surveyors (RICS) in January 2018, defines an external wall as: ‘The external enclosure of a Building, which comprises the area between the Internal Dominant Face and the outside of a Building.’

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