5.2 Suspended ground floors

Also see:

9.3

5.2.9 Thermal insulation and thermal bridging

Suspended ground floors shall be insulated in accordance with building regulations to minimise thermal transmission through the floor and using materials suitable for the location and intended use.

Insulation should be installed to ensure that any risk of thermal bridging is minimised, especially at junctions between floors and external walls. Thermal bridging precautions include:

  • extending cavity wall insulation below floor level
  • providing perimeter insulation to floors.

Insulation below cast in-situ suspended ground floor slabs should be:

  • placed on a suitable, compacted and even substrate
  • of a material with low water absorption
  • resistant to ground contaminants
  • strong enough to support wet construction loads
  • compatible with any DPM.

Insulation for timber floors may be either insulation quilt or rigid insulation.

Cavity wall insulation should extend below the floor insulation level.

Insulation for use above suspended concrete floors should be in accordance with Chapter 9.3 ‘Floor finishes’.

Particular attention should be paid to ensuring thermal bridging is addressed at door openings.

Last updated: 2nd January 2024

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