L-shaped dormer drawings in Hammersmith and Fulham

Dense conservation areas, narrow streets

The borough publishes 47 conservation areas, and Historic England lists 268 entries. Inside an area, the national rule is: Class B roof enlargements are not permitted development on article 2(3) land.

Much of the borough is terraced housing on narrow streets, where one dormer can be seen from many windows. We draw the view from the neighbours' upper floors, not only the street, because officers consider both.

Small plots and the roof as the only space

Domestic gardens cover just 17.1 per cent of the borough's land, so gardens are small and rear extensions are limited. The roof is often the one place left to grow, and an L-shaped dormer gets the most from it.

The average home costs 738,048 pounds, a move of -9 per cent in twelve months, which is why owners invest in space they already own.

Certificates and the national allowance

Where the house is outside a conservation area, permitted development allows 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume, and the height rule is: No part higher than the highest part of the existing roof. At the junction with a rear addition: Eaves-retention and 0.2 m set-back do not apply where the enlargement joins the original roof to the roof of a rear or side extension.

The borough logged 94 lawful development certificate applications in the latest national return.

Party walls, stairs and structure

Terraced houses almost always share the roof, so the notice rule applies: Party structure notice at least 2 months before work. Stairs must achieve the following: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width).

A loft of this scale also meets the fire rule: New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30). We plan the landing and doors to satisfy it before the roof shape is fixed.

Fulham terraces and the narrow rear outrigger

The classic Fulham terrace has a narrow rear outrigger running along one boundary, sometimes only a room wide. An L-shaped dormer over it is slim, and the stair often arrives at the corner where the two roofs meet. We test the stair position against the head height available there, because the geometry of the corner decides whether the second room is usable.

If the outrigger is too narrow for a bedroom, the L can still serve as a bathroom and landing, which frees the main roof for a larger room.

Why complete submissions matter more here

With only 79.8 per cent of householder cases decided in time in the latest year, delays tend to follow missing information. We run a pre-submission list that covers the location plan, block plan, existing and proposed drawings, the volume calculation and the heritage note where it applies.

A validated application starts the clock, and we chase validation rather than waiting for it.

Daylight and neighbours

Narrow streets mean neighbours' windows sit close to the new roof. We assess daylight to the nearest rear windows by drawing a section through the dormer and the opposite elevation, so the effect on their light is visible. Where a window looks directly at the dormer cheek, we move or shorten the L.

A neighbour who feels informed is less likely to object, so we also prepare a short plain-language note you can hand them with the party wall notice.

Structure of the L

The L carries load over two roofs, and the steel runs along the outrigger as well as across the main roof. We coordinate with your engineer so the beam positions are known before the stair is fixed, because moving a steel after the drawings go in is the costliest change on a loft.

Delivery and next pages

Each set of plans, roof plan, junction sections and elevations is checked by a second MCIAT chartered technologist, and we redraw at no charge until approval.

See loft conversion drawings in Hammersmith and Fulham, house extension drawings in Hammersmith and Fulham, or the Hammersmith and Fulham architectural drawings hub. Nearby, L-shaped dormer drawings in Ealing follow different guidance.