Loft
conversions
in Swiss Cottage, NW3

Across the Fitzjohns/Netherhall streets, pitched roofs are largely of plain clay tile in dark grey or red, over walls of red and London yellow brick.

Eton Avenue's houses generally have two storeys plus an attic level, roofed in red clay tiles.

King Henry's Road reads differently: its townhouses show parapets and repeated chimneys in an even rhythm, and dormers are rarer.

On Maresfield Gardens the heights change from one house to the next, which makes the roofline step up and down.

Camden's design guide for the streets west of Finchley Road points out roofs originally clad in clay tile rather than slate, and brick-fronted houses crowned with turrets or cupolas.

Adamson Road, part of the Belsize Conservation Area, shows what can go wrong: the statement records many paired stock-brick villas at its western end altered with unsympathetic dormers and mansards.

Sources: Camden: Fitzjohns/Netherhall Conservation Area Character Appraisal and Management Plan (December 2022), Camden: Belsize Conservation Area Statement (agreed 20 November 2002), Camden: Elsworthy Road Conservation Area Appraisal and Management Strategy (adopted 14 July 2009), Camden: Swiss Cottage Conservation Area Design Guide (updated June 2026), Camden: Belsize Conservation Area Statement (agreed 20 November 2002)

National guidance puts roof extensions in conservation areas outside permitted development, so a dormer anywhere in the conservation areas round Swiss Cottage needs a planning application.

For those areas, Camden's Home Improvements guidance looks for dormers that leave more slope showing than elsewhere, stay subordinate to the roof, and are proposed only where the stair gives over 2m of headroom.

Its preferred dormer finishes are the traditional ones: timber, lead and hanging tile.

In Belsize, which takes in Eton Avenue, further rear dormers are normally allowed if carefully designed, but not where a group of roofs is still largely unaltered.

Houses on King Henry's Road fall under the Elsworthy strategy, which rules out intrusive dormers and fundamental changes to the roofline.

Sources: MHCLG: Permitted development rights for householders, Technical Guidance (September 2019), Camden Planning Guidance: Home Improvements (January 2021), Camden: Belsize Conservation Area Statement (agreed 20 November 2002), Camden: Belsize Conservation Area Statement (agreed 20 November 2002), Camden: Elsworthy Road Conservation Area Appraisal and Management Strategy (adopted 14 July 2009)

Top-floor flats have no householder permitted development rights, and west of Finchley Road Camden's factsheet makes every new rooflight on a flat, back or front, a matter for planning permission.

Find out whether the void above is demised to you: LEASE says the landlord's permission may be required before you alter anything.

Where the roof belongs to the freeholder, we draw what the licence application needs and agree a route for the roofers through the shared hall and stairs.

Sources: MHCLG: Permitted development rights for householders, Technical Guidance (September 2019), Camden: Swiss Cottage Conservation Area, what the new planning measures mean for you (Article 4(1) factsheet, 1 September 2010, updated June 2026), LEASE: alterations and home improvements

We start with a survey of the void, the existing stair and the floor below, and our structural engineer marks up which walls can take new loads.

Planning drawings and building control drawings are produced side by side, so the dormer submitted to Camden is the one already sized by the engineer.

On site the slope is opened bay by bay under a temporary roof, and the bedroom beneath is sheeted and boarded before any ceiling comes down.