What the exemption may allow
From 27 July 2026, certain side and rear dormer developments may qualify for a new planning exemption, subject to conditions and restrictions. The intent is to enable well-designed dormers on the private elevations of many houses.
The 30 m³ aggregate condition
The exemption is subject to an aggregate internal volume condition of 30 m³. Any previous attic works count towards that total. Getting the volume right is a design task, not a rule of thumb.
Front dormers
Front dormers typically remain outside the new exemption and continue to need a planning review.
Overlooking and neighbour context
Windows on side elevations can raise overlooking concerns even where the works may fall inside the exemption. Sill heights and glazing specification matter.
Protected Structures, ACAs and specific zoning
Additional controls apply and exemptions are usually more limited. A specialist review is essential.
Building Regulations still apply
The exemption is a planning matter. Structure, fire safety, ventilation and energy performance are still governed by Building Regulations.
When to consider a Section 5 declaration
Where a project is close to the limits or the property is unusual, a Section 5 declaration from the local authority can be a useful step to formally confirm the position.
What this means for your project
Every home is different. Use this guidance to ask the right questions and to shape your brief — but confirm what applies to your specific property with a home survey and appropriate professional input.
Start with a quick check of your attic.
Answer a few simple questions about your home and what you would like to create. We’ll give you an early indication of which conversion route may be worth exploring. A home survey is still required before suitability can be confirmed.
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