For most houses external wall insulation is permitted development, but there are important exceptions. Here is what to check before you start.
External wall insulation adds around 90–120mm to the outside face of your walls and changes their appearance, so it is reasonable to wonder whether it needs planning permission. For the majority of houses in England the answer is no, but the exceptions matter and getting it wrong is expensive.
The general position
On a typical house, cladding or insulating the external walls is usually permitted development, provided the materials are similar in appearance to the existing house. That is why most insulated homes are finished in render or brick slips rather than something visually jarring.
When you do need permission
You will normally need to apply if the property is a flat or maisonette, if it is listed, or if it sits in a conservation area, National Park, Area of Outstanding Natural Beauty or similar designated land, where permitted development rights for cladding are removed. An Article 4 Direction can also withdraw those rights on an ordinary street, so it is worth a quick check with the local planning authority.
Building Regulations always apply
Planning permission and Building Regulations are separate things. Even when no planning application is needed, external wall insulation is notifiable work under Building Regulations because it affects thermal performance, and the detailing around windows, eaves, damp-proof courses and ventilation has to be done correctly. We handle that side as part of the job.
Boundaries and the party wall
If your wall is on or very close to the boundary, the extra thickness may oversail your neighbour's land or a public footpath, which needs their agreement or a small design change. On a semi or terrace, insulating up to a shared boundary can also bring the Party Wall Act into play. We flag any of this at survey stage so there are no surprises.
Thinking about this for your home?
Book a free survey and we will give you honest advice and a fixed written price.
Get a free quote