Last edited 20 May 2017

Approved Document C

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.

Approved Document C: Site preparation and resistance to contaminants and moisture, was last published in 2013.

It covers the weather-tightness and water-tightness of buildings, subsoil drainage, site preparation, and measures to deal with contaminated land, radon, methane, and other site related hazardous and dangerous substances.

In terms of resistance to moisture, the regulations state that the building should be protected from harmful effects caused by:

It defines a ‘contaminant’ as ‘any substance which is or may become harmful to persons or buildings, including substances which are corrosive, explosive, flammable, radioactive or toxic’; and lists examples of sites likely to contain contaminants, including:

The content of the Approved Document includes:

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