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Thermal renovations

Renovation of a thermal element (existing dwellings)

A thermal element is a roof, wall or floor which separates a thermally conditioned (heated or cooled) space from any of the following:

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  • the outside (including the ground)
  • an unheated part of the same building
  • a structure exempt from the building regulations, such as a porch or conservatory
  • part of the same building heated or cooled to a different temperature

Renovation of a thermal element means adding a new layer to a thermal element or the replacement of an existing layer, new decorative finishes are excluded.  When the renovation is to be more than 25% of the element concerned, Building Regulations approval will be required.

The purpose of providing insulation when renovating a thermal element is to limit the heat loss through the thermal elements of the building fabric.  This is one way the Government is able to improve the country's existing housing stock to achieve reductions in carbon emissions.

Approved Document Part L1B provides further information and technical guidance.