Wandsworth's Housing SPD treats a mid-terrace roof and an end-of-terrace roof as different problems. We look at where your house sits in its terrace before we choose a design.
Photo: Bill Boaden, BY-SA 2.0
The Housing SPD, adopted in 2016, ties its loft advice to policy DMH5. Extensions and alterations are permitted where the extension is well designed and not so large that it dominates the original building, and where a roof extension confined to the rear but visible from the street or public places is sympathetic to the style of the building, not visually intrusive and does not harm the street scene.
Mansards come in two kinds. The SPD notes that few Wandsworth buildings were built with true mansards, and that adding one can be a highly intrusive alteration. It says a mansard-style addition, a single steep pitch with a flat roof, to the rear slope of a mid-terrace house where the roofs are subdivided by party walls is usually acceptable if it cannot be clearly seen from the street. For houses at the end of a terrace or on a corner it says the rear mansard style addition should be avoided, because the change to the gable end would be seen from the street; a well-proportioned dormer set in from the edge of the roof is more appropriate.
The other rule is for terraces under one unbroken roof. It is not appropriate to extend across the full width between new party walls, because those walls would show at the front above an unbroken ridge. There the usual answer is a simple rear dormer set below the ridge, above the eaves and in from the property boundary at the sides.
The 2016 SPD gives a different answer for each position in a terrace.
| Position | What the SPD says |
|---|---|
| Mid-terrace, party-wall roofs, hidden from street | Rear mansard-style addition usually acceptable |
| End of terrace or corner house | Avoid a rear mansard style; use a set-in rear dormer |
| Terrace under one unbroken roof | Simple rear dormer below ridge, above eaves, in from the sides |
| Over a back addition, mid-terrace | Less visible, but bulk and neighbours' amenity still tested |
| Conservation area | Mansards unlikely to be acceptable if visible from public areas |
Wandsworth Council, Housing SPD adopted 2016, paragraphs 4.141 to 4.155.
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Chimney stacks are treated as key features of the historic environment, and the SPD says all stacks and pots in conservation areas should be retained or rebuilt as part of approved roof schemes. A live chimney must terminate at least 600 or 1,000 millimetres above any roof abutting it under the Building Regulations, depending on its position relative to the ridge, so a new roof line can force a rebuild.
Where a party wall is raised, the SPD says the way to do it is 225 millimetre brickwork, which meets the Building Regulations and keeps noise between neighbours down. Eight conservation areas have Article 4 directions: Dover House Estate, Heaver Estate, Latchmere Estate, Putney Lower Common, Roehampton Village, Shaftesbury Park Estate, Totterdown Fields Estate and Wandsworth Common. For example, a house on the Totterdown Fields Estate in Tooting must have the direction read before Class B is assumed.
Wandsworth aims to decide householder applications in 8 weeks, and decided 657 in the year to June 2026 with prior approvals set aside, 597 of them inside 8 weeks.
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Wandsworth's Housing SPD (2016) says mansard-style additions to the rear slope of mid-terrace houses with party-wall roofs are usually acceptable where they cannot be clearly seen from the street.
Source: Wandsworth Council, Housing SPD adopted 2016, para 4.142The SPD pairs mid-terrace mansards with a 70 degree pitched roof, and says a rear mansard style addition should be avoided on end-of-terrace and corner houses.
Source: Wandsworth Council, Housing SPD adopted 2016, para 4.143The SPD says a live chimney must terminate a minimum of 600 millimetres or 1,000 millimetres above an abutting roof, depending on its position.
Source: Wandsworth Council, Housing SPD adopted 2016, para 4.140Wandsworth lists 8 conservation areas subject to Article 4 directions, including Shaftesbury Park Estate, Totterdown Fields Estate and Wandsworth Common.
Source: Wandsworth Council, Article 4 DirectionsWandsworth aims to decide householder and small-scale applications in 8 weeks.
Source: Wandsworth Council, Planning application processWandsworth decided 657 householder applications between July 2025 and June 2026, prior approvals excluded, and 597 of them were decided within 8 weeks.
Source: MHCLG, Planning application statistics PS2, July 2025 to June 2026Class B permits a roof extension of up to 40 cubic metres on a terraced house and 50 cubic metres in any other case.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class BTell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
On a mid-terrace house where party walls subdivide the roofs and the addition cannot be clearly seen from the street, the SPD says a mansard-style rear addition is usually acceptable. At the end of a terrace or on a corner it says to avoid it.
The SPD says a full-width extension between new party walls is inappropriate, because the new walls would show at the front. A simple rear dormer set below the ridge, above the eaves and in from the sides is usually the right solution.
The SPD expects all chimney stacks and pots in conservation areas to be retained or, if necessary, rebuilt as part of approved roof alteration schemes. Restoring a removed stack is welcomed.
Dover House Estate, Heaver Estate, Latchmere Estate, Putney Lower Common, Roehampton Village, Shaftesbury Park Estate, Totterdown Fields Estate and Wandsworth Common. Some cover only part of an area, so check your street.
£765 inc survey (£565 if you supply measured drawings) for a rear dormer. That covers the measured survey, the drawings and the submission, with free revisions until the council decides. Wandsworth's own application fee is separate.
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