# Loft conversions in Harrow

Canonical URL: https://mirion.uk/areas/harrow/loft-conversions/

> Hip-to-gable and dormer loft conversions in Harrow: the council's preferred designs, set-back distances, detached-house rules and permitted development.

We convert lofts across Harrow, most often on 1930s semis, where Harrow's own design guide recommends the classic hip-to-gable with a rear dormer.

### What Harrow prefers

Harrow's Residential Design Guide says the preferred roof alteration for a semi-detached or terraced house is to extend a hipped roof to a gable and add a rear roof extension or dormer. To keep it contained within the roof, a rear dormer should be:

- set in at least 500 millimetres from the party wall;
- set in at least 1 metre from the gable end;
- set back at least 1 metre from the eaves, measured along the roof slope; and
- where possible, set down about 500 millimetres from the ridge.

Where there is a pitched rear projection, the dormer should stay 500 millimetres from the valley. Front and side dormers can be objectionable, and dormers should never rise above the ridge or wrap around the hips.

### Detached houses are different

For detached houses, the guide says gabling a hipped roof can be unduly prominent and should be avoided, and that side and rear dormers may be an acceptable alternative. Floor-to-ceiling French doors or windows with railings, creating a roof balcony, should be avoided.

### Permitted development

Many Harrow lofts never need an application: the national limits allow up to 50 cubic metres on a semi-detached or detached house and 40 cubic metres on a terrace, outside conservation areas and where rights have not been removed. Harrow's 30 conservation areas and Article 4 directions are the main exceptions.

Harrow loft conversions: common questions

Does Harrow allow full-width dormers?

With planning permission, Harrow's guide expects rear dormers to be set in at least 500 millimetres from the party wall and 1 metre from the gable end, so a strictly full-width dormer is unlikely. Under permitted development, the national limits apply instead.

Can I gable the roof of a detached house in Harrow?

Harrow's design guide discourages it for detached houses because the result can be unduly prominent, and suggests side and rear dormers. Permitted development may still allow a hip-to-gable, so check the route before deciding.