A clear, honest guide to the planning rules for loft conversions in London.
The majority of loft conversions in London qualify under Permitted Development Rights — a set of rules that allow homeowners to make certain changes to their property without a full planning application. However, there are a number of important circumstances in which planning permission is required, and understanding these before you start is essential.
Under Permitted Development, the maximum volume you can add to a roof without planning permission is:
These volumes include all roof additions to the property — not just the current project. If a previous owner added a dormer, the volume used counts against your remaining PD allowance.
Yes. A conservation area designation doesn’t prevent a loft conversion — it means that any visible addition requires a full planning application. Rear dormers in conservation areas are regularly approved; the key is design quality and an architect experienced with conservation area applications.
An LDC is a formal confirmation from your local authority that your proposed works comply with Permitted Development rules. We recommend obtaining one even when planning permission isn’t required — it provides legal certainty if you come to sell your property.
Standard planning applications in London typically take 8–12 weeks for a decision. We submit the application and manage all communications with the planning authority on your behalf.
We discuss your specific planning risk in detail at the free survey. Where applications carry material risk, we advise on the position before you commit to the project. We have an excellent track record of securing approval on first application.
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