Who Repairs a Shared Chimney Stack?

On a semi-detached house or a terrace, the chimney stack often rises from the wall between two homes, with flues from both sides running up inside it. The brickwork, the cap, the pots and the lead tray where it passes the roof slope all belong to the same structure, so a fault in one part can affect both houses. A loose pot on your side can let rain into your neighbour's flue.

That makes it hard to repair only one side. The mortar joints are continuous across the whole stack, and scaffold is needed to reach it. A roofer asked to fix the half above your roof will usually say the other half needs looking at too, since a stack that is repointed on one side and crumbling on the other is still at risk.

Begin by working out what is wrong and which side it shows on. Open joints, a leaning top or loose pots can be spotted from the ground. Our answer on signs your chimney needs repair lists what to look for before you knock on the door, and photos taken from your own garden are a good thing to bring.

No fixed percentage decides who pays what, so treat the split as something to agree rather than assume. Many neighbours simply share the cost of the stack itself equally, since it serves both homes, and each pays for anything that only affects their own side, such as flashing along their own slope or a pot over their own flue.

Put the agreement in writing, even if it is a short email. Say what work is planned, who will arrange it, how the bill will be divided, and how extra repairs found after the scaffold goes up will be handled. A single scaffold shared across both homes costs less than two separate visits, and our answer on scaffolding for chimney repair explains the access side.

If your neighbour will not engage, do not climb onto their roof or enter their property without permission. Write to them with the photos and the date. A letter shows you tried, and it matters if the matter escalates. Where a fall of brick or a leaning stack puts people at risk, tell the council's building control team, and have a roofer make the stack safe.

Ask each roofer who quotes for one total price that you can both see.

Work on a stack that stands on a shared wall can come under party wall rules, which require you to give your neighbour formal notice before certain building work. Whether a simple repoint or a new cap triggers a notice, and whether taking the stack down does, is a matter for a party wall surveyor. We cannot give you legal advice, so please ask before work begins.

The same applies to consents. Taking out a chimney breast always needs Building Regulations approval, and removing one from a party wall also needs a party wall notice to the neighbour. Lowering or removing a stack above the roof may also need a planning check, and conservation areas and listed homes have extra rules. Our answer on planning permission to remove a chimney goes through those steps.

Keep copies of any notice, reply and plan. A buyer's solicitor may ask to see them years later, and they are far easier to find in one folder than in an email search.

For a shared stack the survey should cover both sides of the roof. A roofer needs access to both homes' loft spaces, or at least both gardens, to look at the stack from every angle and to check for damp on the chimney breast below. Brown stains on the plaster are the clue a roofer looks for.

The written price should name the whole stack and which items are shared, so each household can see its part without a dispute later. As a national guide, Checkatrade's April 2026 chimney repair table puts repointing at £300 to £1,000 and a cap at £180 to £520. A shared stack can sit anywhere in or beyond those figures once scaffold and flashing are counted, so check whether VAT is inside any price you are shown.

One roofer working across both roofs also avoids the dispute that arises when two separate firms leave a half-finished stack. Both households get the survey photos, and a single written price follows, so nobody is guessing what the neighbour was told. More on stack work generally is in our chimney repairs hub.