Permitted development in Harrow

Single-storey rear extension up to 3m deep (attached house) or 4m (detached); side extension up to half the original width; loft conversion up to 40m³ (terraced) or 50m³ (semi-detached); single-storey outbuilding within the curtilage; replacement windows and doors. All subject to material match, eaves setback (20cm), and not facing a highway.

No. Permitted Development rights apply only to houses (Class C3 dwellings). Flats and maisonettes require full planning for almost every external alteration.

Yes — significantly reduced. In a conservation area: side extensions and two-storey rear extensions are not PD; cladding is not PD; chimney removal needs planning; roof additions are restricted.

An LDC is a formal confirmation from the council that your proposal is lawful PD — recommended before building, useful when selling. Costs around £103 for council fees + drawings. We prepare LDC applications as a fixed fee.

Yes. Building regulations are entirely separate from planning. Permitted Development removes the planning requirement only — you still need building control sign-off for structure, insulation, fire safety, drainage, and ventilation. We deliver both planning and building regs drawings.