Last edited 12 Nov 2015

Hearth definition

Approved document J, Combustion appliances and fuel storage systems defines a hearth as:

‘…a base intended to safely isolate a combustion appliance from people, combustible parts of the building fabric and soft furnishings. The exposed surface of the hearth provides a region around the appliance which can be kept clear of anything at risk of fire. The body of the hearth may be thin insulating board, a substantial thickness of material such as concrete or some intermediate provision dependent upon the weight and downward heat emission characteristics of the appliance(s) upon it.’


Hearths should be constructed of suitably robust materials and to appropriate dimensions such that, in normal use, they prevent combustion appliances setting fire to the building fabric and furnishings, and they limit the risk of people being accidentally burnt. They should be able to accommodate the weight of a combustion appliance and its chimney if the chimney is not independently supported.

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