Chimneys might look like simple structures but they’re actually carefully engineered. That means any repair work needs to be carried out by an expert, who’ll quickly be able to identify which part needs attention.
While a HETAS-registered chimney expert or roofer can repair certain elements, like flues or lead flashings around the breast, a general builder may also be required if you have structural problems. Because of the range of jobs involved, the cost of chimney repair can vary. Your tradesperson will usually quote to fix specific problems based on the time needed, while installing certain new elements like a flue will normally be costed based on a fixed fee.
This guide covers the main elements of chimney repair and provides an average cost for each job. Those costs vary by chimney size – the larger your chimney, the more extensive the work will be. We’ve also included other considerations that you’ll need to factor in, such as the use of scaffolding to carry out the work. Depending on the level of damage to the chimney, the remaining chimney breast and stack may need to be supported while work is taking place. Extra labour and equipment like this will add to the total cost of the project.
The average cost to repoint a medium-sized chimney is £600–£800 (excluding scaffolding).
The cost of repointing a chimney varies depending on the size of your chimney and how easy it is to access, but you can expect to pay between £600 and £800 for a medium-sized chimney that’s easy to access. A damaged chimney can leak toxic gases, including carbon monoxide, as well as exposing areas in your home to extreme heat – creating a fire risk. That’s why it’s important to have regular inspections to make sure your chimney lining is intact.
Cracks, loose render and eroded masonry are all visible signs of damage to your chimney. They’ll happen naturally, with age and deterioration, but if left they can eventually result in structural damage. So, it’s best to get them resolved as soon as you spot a problem.
Any defective masonry should be cut out and replaced, and if brickwork has come loose, then partial rebuilding may be needed. Eroded mortar joints can be repointed and cracked areas of render can be removed and patch repaired. A flue test may be required after the repairs have been carried out to ensure smoke or gas isn’t leaking into your home.
If you need a flue replaced (or a new flue installed) as part of this process, clay lining is a popular and economical choice, but stainless steel is a lot more hardwearing. With chimney linings subject to heat and gas, stainless steel is often a wise choice thanks to its resilience. Installing a flexible stainless steel flue liner and cowl involves removing the chimney pot and flaunching, sweeping the flue, inserting the liner, then adding a cowl and new flaunching.
The average cost of replacing leadwork or lead flashings on a medium-sized chimney is £600–£800 (excluding scaffolding).
Damp patches on walls and ceilings near your chimney breast are signs of a leak around the stack. These leaks could lead to fungal decay in your roof timbers, and eventually serious structural problems with the ceilings in your home.
If your roof tiles are intact, then defective flashings at the junction between the chimney and the roof are the most likely cause of leaks. Sometimes mortar fillets can be applied as a cheaper option instead of lead, but they’re prone to cracking and won’t last as long. That’s why flashings are always best replaced with new leadwork. When fitting new flashings, your roofer will arrange them in a stepped pattern to provide full protection against water and moisture penetration. The lead flashing should then be sealed with new mortar.
The average cost of repairing flaunching and chimney pots is £100.
Gradually, mortar flaunching at the base of chimney pots can begin to crack and disintegrate. Even though chimney pots are heavy, they can be blown over by strong winds and they can also become damaged over time. Tell-tale signs are flaking or cracks in the ceramic on the surface of the pot.
Replacing a chimney pot is a relatively simple job for a professional. They’ll take the pot down and either repair any damaged areas or replace your pot if the cracks have penetrated too deep. If the flaunching has fallen away, loose elements can be cut out and replaced after securing any damaged brickwork.
The average cost to hire scaffolding for chimney repair is £560.
Most chimney repair jobs will require scaffolding. The amount you’ll pay to hire scaffolding depends on how long it’s needed for and the size of the roof and chimney. The cost will go up the longer you need it for and the bigger the roof and chimney. For smaller repairs, a mobile scaffold tower (stretching up to 6 metres) can be used, but this won’t be suitable for bigger jobs. If you need scaffolding to reach up to a gable chimney then costs should be around £400 on average. For ridge chimneys – which are harder to access – a more complicated scaffolding setup will mean an average price of around £1,000.
|General chimney repair costs|
|Chimney pot repair||£90||£100||£150|
|Leadwork and flashing repair||£600||£700||£1,200|
|Scaffolding for chimney repair||£420||£560||£750|
|Chimney breast removal||£1,500||£1,800||£2,700|
|Chimney stack removal||£900||£1,100||£2,000|