The short answer
A terraced house roof can be replaced on its own, but it joins the neighbours' roofs at each end, so the details at those junctions matter most. The Planning Portal publishes a terraced-house roof guide with the same re-roofing test as any house. Party wall rules apply when work is done to the shared wall itself, and scaffold on a narrow front needs planning.
What the Planning Portal terraced-house guide says
The Planning Portal has an interactive guide for the outside of a terraced house, with a roof page on Building Regulations. It applies the same test as for any other house. The portal's terraced-house page says building control is normally not engaged while under 25 per cent of the building envelope and under 50 per cent of the roof is touched. A covering 15 per cent or more heavier, or one with a significantly different fire performance, does bring approval in.
In a terrace the arithmetic runs differently. A mid-terrace house has party walls on both sides, so fewer of its walls are external, and the roof can be a large part of its envelope. A re-roof of the entire slope is likely to pass the 50 per cent mark anyway.
Planning is a separate question. Class C of the permitted development rights is the route for re-covering a house roof, and a dormer on a terrace falls under Class B, which caps the volume at 40 cubic metres for a terrace house. Neither right applies to flats, and a conservation area or Article 4 direction can change the answer. Ask your planning team, which for Farnborough is Rushmoor, before you assume.
Party walls and your neighbours' roofs
The wall between two terraced houses is a party wall, and the roofs meet it. Re-covering your own slope does not normally cut into that wall, so the Party Wall etc. Act 1996 does not come into it. The Act applies when building work touches the shared structure: cutting into the wall, or removing a chimney breast that sits in it.
Section 2(2)(g) of that Act allows a neighbour's projecting chimney breast, jamb or flue to be cut back, with notice given two months or more beforehand under section 3. GOV.UK warns that silence from a neighbour is no consent. Where the two sides differ, a party wall surveyor is appointed, and that surveyor, not building control, is the person for party wall disputes.
The junction with your neighbour's roof is what matters here. The covering, the lead flashing and the verge or abutment where the two roofs meet are shared in effect, even if each side owns its own half. A well-built junction protects both houses, and a failed one can leak into either.
We tell neighbours before scaffold goes up, because workers will be on your side of the wall and they may see the work from their windows. Good notice keeps relations easy and the job moving.
Scaffold on a narrow frontage
Many terraced houses sit right on the pavement with no front garden. Scaffold then stands on the public highway, which Highways Act 1980 s169 treats as needing the highway authority's licence. In Rushmoor and Hart that authority is Hampshire County Council. Hampshire County Council says the scaffold firm applies for its customers, wants ten clear working days, charges £211.90 for the first 2 weeks and £72 for each further 2 weeks, and offers no extensions.
Scaffold at the back is private land and needs no licence, but access can be harder. Many terraces have a rear alley or no side passage, and everything, tiles included, may have to go through the house or be lifted from the front. That affects both the programme and the price.
A narrow pavement has a second problem: pedestrians still need to get past. Wokingham, for one, asks for a footway of at least 1.2 metres to remain, and the scaffolder plans for a walkway or a gantry accordingly.
We plan access at the survey, decide with the scaffolder where each load is hoisted, and ask who is applying for the licence. Our page on scaffolding for a new roof goes into more detail.
Doing a terraced roof in the right order
A terrace usually has a ridge and eaves that line up with the neighbours', and the finished roof is judged by how it sits alongside them. Matching the ridge height and the tile colour to the next house keeps the row looking right, and that is easier to judge on the survey than from a drawing.
The work runs in stages. Scaffold goes up, the covering comes off in sections, the underlay and battens are renewed, and the new covering goes on from the eaves up. Each stage is shorter than on a detached house, because the slopes are smaller, though the junctions take care. A temporary cover goes on before anyone leaves for the day.
Check what your neighbours have done. If the house next door has already been re-roofed in a different material, your choice may be affected by that, and a covering that is much heavier than the old one needs a Building Regulations check first.
You see the photos and hear a plain account of the junctions, with a single written total to follow. See roof replacement for the whole job, and bungalow roof replacement for a contrast in access and structure.
