Wandsworth, SW18
L-shape dormer loft conversion
An entire new floor, because the roof had two shapes to work with.
Project type
Planning route
Borough
Loft conversion
Permitted development
Wandsworth
The decision that mattered
Look at the back of almost any Victorian or Edwardian terrace in Wandsworth and you will see a narrower section projecting into the garden — the original outrigger, usually built to hold a scullery. It is the reason the L-shaped dormer exists.
A dormer that follows that L gives you two roofs to build across instead of one. On this house that difference is what turned a loft into a floor: two large bedrooms and two bathrooms, rather than the single room and shower a plain rear dormer would have yielded.
As with our side and rear extension nearby, we combined permitted development with a planning application to reach the full size rather than accepting the ceiling of one route.
The second bathroom is the expensive decision
Adding one bathroom to a loft is straightforward. Adding two means routing a second soil connection, more structural work to carry it, and a longer second fix. It is the single biggest variable in a loft conversion after head height, and it is worth deciding early rather than halfway through, because retrofitting it later means opening up work already finished.
Worth knowing if you are planning the same thing
Before anything else, measure from the top of your existing ceiling joists to the underside of the ridge. Around 2.2 metres is the usual rule of thumb for a straightforward conversion. Below that you are into lowering the ceilings in the rooms beneath or raising the ridge, both of which are possible and both of which change the job substantially.
Also plan the staircase before you plan the bedrooms. Where the new stair lands dictates the layout of the floor below as much as the floor above, and it is the constraint people discover last.
Start with a survey, not a guess
If your house is a similar shape, most of the same decisions will apply. We will come and look, and tell you what the building allows before anyone spends anything.
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The layout: before and proposed
Compare the original layout with the project drawings. Select a plan to view it at full size.
Before — existing layout
The property before the proposed work.Proposed layout
The proposed arrangement shown in the project drawings.
Photographs from this job
Bright loft room beneath the roof slope — L-shape dormer loft conversion, Wandsworth, SW18.
Loft shower room — L-shape dormer loft conversion, Wandsworth, SW18.
Dormer seen from the garden — L-shape dormer loft conversion, Wandsworth, SW18.
Rooflight above the new staircase — L-shape dormer loft conversion, Wandsworth, SW18.
Basin and timber vanity — L-shape dormer loft conversion, Wandsworth, SW18.
Study space beside the dormer window — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 7 — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 8 — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 9 — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 10 — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 11 — L-shape dormer loft conversion, Wandsworth, SW18.
Project photograph 12 — L-shape dormer loft conversion, Wandsworth, SW18.