External walls in flatsExternal walls in flatsclose

If you want to re-render or replace timber cladding to external walls, the Building Regulations may apply depending on the extent of the work.

Where 25 per cent or more of an external wall is re-rendered, re-clad, re-plastered or re-lined internally or where 25 per cent or more of the external leaf of a wall is rebuilt, the Regulations would normally apply and the thermal insulation would normally have to be improved.

If you want to insert insulation into a cavity wall the Regulations will apply.

The appropriate requirements will be applied to ensure the insulation material is suitable, and that in the case of some foam insulants the risk of formaldehyde gas emission is assessed.

It is advisable to contact an installer who can provide the necessary advice, preferably one who belongs to the relevant Competent Person Schemes.

Learn more on the Planning Portal.

Learn more about insulation.

Safety when working at height.

Safety when working with dust.