Planning Permission FAQs

Most loft conversions fall under Permitted Development rights and do not require planning permission, provided they meet specific criteria: the additional volume does not exceed 40m³ for terraced houses or 50m³ for detached and semi-detached, no extension beyond the existing roof slope facing a highway, and materials match the original. However, properties in Hampstead Conservation Area and listed buildings require full planning permission regardless.

Within NW London conservation areas (covering much of Hampstead, Hampstead Village, Belsize Park, and parts of St John's Wood), Permitted Development rights are reduced. You cannot change windows, doors, external materials, or roof coverings without approval. Internal works do not require planning permission unless the building is listed. A conservation area consent is needed for demolition. Always check with Camden or Westminster planning before proceeding.

Minor applications (householder applications for extensions and loft conversions) have an 8-week statutory determination period. More complex applications may take 13 weeks or longer. Pre-application advice from Camden Council can significantly improve success rates and reduce the risk of refusal. We recommend budgeting 3–6 months from application to approval for NW3 properties.

Permitted Development (PD) rights allow certain types of building work without a full planning application. PD rights are automatically removed for: properties in Article 4 Direction areas (much of NW3 and parts of NW8), flats and maisonettes, and listed buildings. Camden has applied Article 4 Directions across many conservation areas, meaning that even works normally permitted nationally require local consent.

If your work affects a shared wall or boundary with a neighbouring property, you must serve Party Wall notices under the Party Wall etc. Act 1996. This applies to loft conversions (excavation near boundaries), side extensions, and any work to a shared wall. You must serve notice at least two months before construction begins. A Party Wall Surveyor is often appointed to protect both parties' interests.

Basement conversions are technically Permitted Development in many cases, but almost all basement projects in Camden require prior approval or full planning permission due to significant material amendment. Camden published a Basement Development SPD which imposes strict conditions on depth, drainage, waterproofing, structural impact, and landscaping. Budget for 6–12 months to obtain permission for a basement in NW3.

Solar panel installation is generally Permitted Development if panels are flush with the roof, do not protrude more than 200mm, and do not project above the roof ridge. In conservation areas and on listed buildings, planning permission is usually required and approval is difficult on street-facing slopes. Rear-facing and courtyard installations have a higher chance of approval.