Do I need planning permission for external wall insulation?

Sometimes. SEAI says external wall insulation may need planning permission in some cases. Cavity and internal insulation do not.

SEAI’s rule, in its own words

The wrap may need planning permission in some cases.
“In some cases, the installation of External Wall Insulation on your house may require planning permission.” SEAI: Individual grants: Homeowner Application Guide, read 25 Sept 2026
Cavity and internal insulation do not.
“Planning permission is not required for internal or cavity insulation.” SEAI: Wall insulation grant, read 8 Jun 2026
You may also need an ESB Networks service alteration.
“You may need an ESB Networks Service Alteration as part of external wall insulation works.” SEAI: Wall insulation grant, read 8 Jun 2026
On a protected structure, any works that affect its character need permission.
“Planning permission is also needed for all works that affect the character of a protected structure.” Source: Fingal County Council: protected structures, read 25 Sept 2026

Each quote links to the SEAI page it is from, read on 26 September 2026. Whether a grant is paid is SEAI’s decision on your application.