The short answer
Often, yes. A tall or leaning stack can be taken down to a safer height, then capped and made watertight. The catch is the flue. If an open fire, stove or boiler still uses it, the stack needs enough height to carry fumes clear of the roof, so lowering it can cause problems. A disused flue is far simpler. Check planning with the council and ask about Building Regulations before work starts.
When a chimney stack can be shortened, what it means for a working flue, and which consents to check before a roofer starts.
Why a stack gets lowered
Stacks are usually reduced for one of three reasons. The top courses may have decayed, with open joints and loose brick, so the safest repair is to take the weak part off rather than rebuild it to the same height. Or the stack may be tall and slim and leaning in the wind, with the weight sitting too far above the roof line. Or the owner simply wants a shorter, tidier stack with a good cap.
Access comes from scaffold or a proper working platform. Bricks are lifted off course by course, scraped clean if they are going back, and re-laid at the new height. Fresh mortar, new flaunching round the pots (the sloping collar that holds them and sheds rain) and a cap or cowl finish the top. Where the lower part of the stack is cracked or leaning, taking it down further may be better than patching, and our page on the leaning chimney stack explains how to judge it.
A roofer should show you photos of the stack from above before agreeing the new height.
The flue decides how low you can go
A chimney is a pipe for taking fumes out of the house, and the height affects how well it does that. If the flue still serves a boiler, a gas fire, a stove or an open fire, cutting the stack down could let smoke or fumes blow back or hang near a window or the roof. For a flue in use, the right height depends on the appliance and the shape of the roof around it, and it is a question for the person who installed or services the appliance.
Do not shorten a working flue on a guess. Ask the engineer who services your boiler or stove what height the appliance needs, and get it in writing before the stack comes down.
A flue that has gone out of use is simpler. It can be capped and vented so damp does not build up inside it. Our answer on venting a capped chimney explains the top and bottom vents.
If the old flue has a gas liner, say so at the survey, because the liner may need cutting back neatly or replacing.
Planning and Building Regulations checks
A shorter stack alters the roofline, and that is where planning comes in. Permitted development Class C covers some roof alterations to a house, but its limits mention chimneys and flues, so do not take it for granted. Write to your council's planning team first. In Crawley that means Crawley Borough Council; other towns have their own council or planning authority.
The checks are tighter in a conservation area, which counts as article 2(3) land, and where an Article 4 direction may remove extra rights. A listed home needs listed building consent for anything that changes its character, and a tall stack is often a large part of that character, so the conservation officer should hear about it before the scaffold goes up.
Building Regulations approval is always needed if a chimney breast is removed, because the breast is structure. Lowering just the stack above the roof is lighter work, but ask your building control body whether they want a notice, and let your insurer know about the change, as it alters the outline of the house.
At the survey we put these same questions to the council and the appliance engineer where needed, and the answers go in with your written price.
Cost and what to ask for
As a national guide, Checkatrade's October 2026 chimney removal guide gives about £260 to £340 per metre of stack removed, with around £1,800 as a whole project. Its April 2026 chimney repair guide puts a new cap at £180 to £520. These are yardsticks, not a quote, because the height, the number of pots and the scaffold needed change the figure a good deal.
Scaffold is usually the largest single item on a stack job, as the stack sits at the top of the building. If other work shares the same access, such as repointing or new flashing, the price per task falls. Our answer on scaffolding for chimney repair sets out when a tower is enough.
Before agreeing, ask what the new height will be and why, what becomes of the flue, how the pots will be fixed, and whether VAT and scaffold are inside the figure. If you want the whole stack gone rather than shortened, the chimney repairs hub leads on to stack removal. Photos of the stack come first, then a single written price.
More on this in Chimney Repairs in Crawley
Two height questions
Is a shorter stack safer in high wind?
A shorter, solidly built stack puts less weight high above the roof, so there is less to blow over. But safety also depends on the state of the brick and mortar below. A short stack built on weak, open joints is no better, so the lower courses need to be checked and repaired during the same visit.
Do I need to tell my insurer or a buyer?
It is sensible to tell your insurer about changes to the roof outline, and a buyer's solicitor will ask for any paperwork on structural work. Keep the written price, the photos from the survey and any reply from the council together in one folder, so the history of the stack is easy to show.