A terraced house has a roof that looks like part of a single long covering, and in some ways it is. The ridge runs on past each front door, the tiles or slates carry on unbroken, and a leak on your side can show up in a neighbour's bedroom. At the same time, each house is its own property, with its own responsibilities, and the line between them is rarely marked on the roof.
That mix causes most of the questions we hear on terraces. Does the chimney stack belong to you or next door? Can one owner repair a shared valley? What happens to the roof if a neighbour takes out their chimney breast? And who tells whom before a scaffold goes up?
This guide explains where the shared parts of a terraced roof usually are, the joints that leak in this type of house, what the law asks you to do before certain jobs and how we work around a neighbour's roof. Treat it as general guidance, because for ownership or boundary questions the deeds and a solicitor have the final word.
Where your roof ends and next door's begins
On the roof, the boundary follows the wall between the two houses, which is called the party wall. It rises through the loft and finishes at the underside of the roof, or continues above the covering as a short upstand or parapet. If you stand in your loft and look along the ridge, you can often see where the brickwork of the party wall runs up between the rafters of your house and the next.
The covering on each side of that wall belongs to the house it covers. A tile that has slipped on your slope is your repair, and one on the other side is theirs, even though the two are only a metre apart. The ridge is trickier, because it runs across the boundary, and the same goes for a valley, a gutter or a stack that straddles the wall. Who owns and maintains those shared pieces is a legal question that depends on your deeds and title plan, which a solicitor can read for you.
Why it matters in practice
Water does not respect the boundary. A failed flashing at the party wall can let rain into either house, a blocked shared gutter can overflow onto both walls, and a lifted tile at the join can wet both lofts. If you find a leak near the wall, it is worth telling your neighbour early, because they may have signs of the same fault.
Our survey photographs your own side of the roof and tells you what we find at the join. Where the fault sits on the neighbouring slope, we explain what we can see from your side and leave the other half of the repair to whoever owns it. Our page on how to spot and mend a sagging roof covers one of the signs.
Shared chimney stacks and what they need
Many terraces have stacks that sit on the party wall, with the flues of two houses side by side in one tall block of brickwork. Each side has its own pots, but the stack is one structure, and its weak points are shared: the pointing, the flaunching, a sloped mortar bed that seats the pots, and the flashing where the stack comes through the roof.
No other part of the house is so exposed. The stack is the tallest part of the house, it faces wind from every direction, and frost works at its mortar joints each winter. Leaning, loose bricks and open joints can all let water into both homes and send damp patches down the chimney breasts inside. Our page on the shared chimney stack goes into repointing, rebuilding and who pays.
When a neighbour removes a breast
A common source of trouble is a chimney breast taken out of one house on a terrace, because the stack above may then lose some of its support. Before a chimney breast is removed, Building Regulations approval is needed in every case, as the Planning Portal makes clear. If the work touches the party wall, a party wall notice comes into it as well. Where the stack stays, it needs proper support, and a stack left standing on nothing is a serious fault that shows up as cracks and leaning.
If you suspect a neighbour has had work done, or you are buying a terrace and spot a missing breast, mention it when we survey. We trace how the stack is carried and tell you whether it needs attention. The guide to removed chimney breasts explains what we check.
Valleys, parapets and butterfly roofs
Terraces from the Victorian and Edwardian period often use roof shapes that put a gutter in the middle of the building. A butterfly or M-shaped roof has two slopes tilting inwards towards a lead-lined valley gutter between them, with the water leaving through a downpipe at the front or back. A parapet, a low wall that rises above the roof edge at the front or on the party wall, hides the gutter behind it.
These arrangements keep the street elevation tidy, but they are hard places for water to leave. Debris collects in the valley, the lead splits where it is trodden or where it has aged, and the parapet takes in rain through cracked mortar and open copings, the stones or tiles that cap it. The leak then appears in the ceiling of the top-floor rooms, often far from the actual fault. Our guide to parapet wall leaks shows how to separate a coping fault from a lead fault.
Shared valleys
Where a valley gutter serves two houses, a blockage on one side can flood the other. Leaves, moss and tennis balls gather at the outlet, and a gutter that cannot clear fast enough backs up under the lowest course of tiles. Regular clearing is the first defence, and we check the fall of the lead to make sure water can leave.
Lead in a valley is usually laid in a heavier code than on a simple flashing, and it should be dressed with rolls and drips that allow it to move. If it has cracked along its length, the right fix is replacement of the affected lengths, which may cross the party line and need discussion with your neighbour. We photograph the split, so the case for repair is clear to both households.
Party wall notices: what GOV.UK asks you to do
Some roof work on a terrace falls under party wall rules, which exist to protect both owners. GOV.UK sets out the process. Notifiable work includes removing chimneys from a party wall, and the owner has to serve notice on the neighbour between 2 months and 12 months before building starts. GOV.UK adds that silence from the neighbour must not be read as agreement. A written notice is the starting point, and a reply or a dispute process follows.
Not every roof repair triggers a notice. Re-covering your own slope, replacing a few tiles or repairing a gutter on your own side does not usually touch the party wall. Cutting into the wall, rebuilding a shared stack or raising the wall are the kinds of work where the question arises. Which rules apply to your job is a question for the official guidance or a party wall surveyor, so we tell you exactly what we plan to do to the wall and you can check from there.
Building control comes separately
A party wall notice is not the same as Building Regulations consent. Building Regulations approval is a separate matter, and re-roofing has its own thresholds: an application is not normally required when less than 25 per cent of the total building envelope and less than 50 per cent of the roof is affected. On a terrace, a repair that crosses the boundary deserves an early word with your building control body. We go through consent during the survey and deal with the Building Regulations notification when a job needs one.
Notices take time to run their course, so plan a major terrace job well ahead and not mid-leak. An urgent make-safe on your own slope can go ahead while any notice runs.
Access, scaffolding and working next to neighbours
A terraced house usually has no side access, so work on the roof starts from the front or, if there is an alley, from the rear. Scaffold across a terrace front can reach over a neighbour's frontage, and anything that touches the roof or wall of the next house needs their permission. We ask early, and a short conversation or a note through the door saves difficulty later.
Where scaffolding obstructs the footway or road, the Highways Act requires a written licence. West Sussex County Council issues scaffold licences across Worthing and Adur, and its page asks for a minimum of 10 working days from application to erection. The scaffold contractor applies on your behalf. Over in the city, Brighton and Hove issues its own. Allow for that wait in your plans if the repair is not an emergency. MyBuilder gives around £850 to £1,200 for a standard two-storey house scaffold, though the figure varies with the frontage.
Sharing the work and the bill
When a repair benefits both houses, such as a shared valley or ridge, the usual route is to agree the split between neighbours in writing before the work starts. We can price the full length or only your half, and photograph the whole area so each owner sees the fault.
Bear in mind the practical side as well. A long run of ridge tiles in a terrace may need re-bedding in one go to look consistent, and a slate or tile that is no longer made may have to be matched from reclaimed stock. We deal with matching at the survey rather than leaving it as a surprise on the day.
Noise, dust and a weekday on the scaffold affect the neighbours as much as you. A short message from you, before the scaffold goes up, helps keep the terrace on good terms.
How we repair terrace roofs, and what shapes the price
A terrace roof job begins with the cause, and with finding which side of the line the fault sits on, because the answer shapes who has to act. We go into the loft on your side, check the party wall, the chimney, the valleys and any parapet, and photograph what we find. If the wet started on a neighbour's slope, we tell you plainly, because a repair on your side will not cure it, and we show what we saw so you can pass it on.
Several things move the price of a terrace repair: the length of roof involved, the way it is reached and how much sits on a shared part. MyBuilder gives a typical UK range of £150 to £1,500 for a roof repair in general, and minor jobs sit at the bottom of that range while larger structural work goes beyond it. A terrace pushes the figure up or down through access, the need for scaffolding and any work on a shared part. Our roof repair cost guide explains the pattern. We steer you to the least work that will hold.
What you receive
Once we have surveyed, the quote reaches you in writing as a single total, illustrated with pictures of your roof. Whichever quotes you gather, see that scaffolding and VAT are included, because they make a large difference on a terrace. When we leave, the waste goes with us, and the outlets on the shared gutter run are checked so water does not spill down a neighbour's wall.
A leak by a party wall is a job we prioritise, and a wet roof is made safe first. For the wider range of work, see roof repairs.
