Chimney survey and stability report
An assessment of chimney stacks and breasts for leaning, cracking or unsupported construction, common in older houses and after alterations.
About this service
A chimney stability report looks at whether a chimney stack and its supporting breasts are sound and properly carried. Most London houses built before the Second World War have several flues, often shared across a party wall with the house next door. Over a century or more, weather, flue gases and alterations take their toll, and a stack that looks fine from the street can be in poor condition close up.
Two problems come up again and again. The first is leaning, often caused by sulphate attack, where flue gases react with the mortar on one side of the stack and make it expand, so the stack bends away. The second is missing support, where chimney breasts were removed in a ground floor room or bedroom and nobody installed a proper beam or brackets for the masonry left above.
Our report sets out what we found, how stable the chimney is and what we recommend, whether that is monitoring, repointing, rebuilding, removal or new support. It is signed off by a chartered engineer who is a Member of the Institution of Civil Engineers (MICE), so buyers, lenders and solicitors can rely on it. Fees start from £400 + VAT, confirmed in writing before we visit.
When you need it
- A chimney stack is leaning or cracked
- A chimney breast has been removed below and you're unsure what supports the rest
- A buyer or lender has raised concerns
What's included
- Inspection of the stack and visible breasts
- Check of supports where breasts have been removed
- Assessment of stability
- Repair or removal recommendations
How it works
- Background and accessWe ask about the chimney's history, any breast removals and what has prompted concern. We confirm loft access, fee and timing in writing, and whether a drone view of the stack would help.
- Inspect stack and breastsThe engineer examines the stack from the ground, loft and accessible viewpoints, and checks each visible breast for cracking, bulging, damp staining and signs that masonry has dropped.
- Check support below removalsWhere breasts have been taken out, we look at what now carries the masonry above, such as gallow brackets, a steel beam or nothing at all, and whether it is adequate.
- Assess stabilityWe judge lean, mortar condition, flashing and pot loading together, and consider the shared party wall structure, to decide whether the chimney is stable, needs repair or poses a risk.
- Issue the reportYou receive a chimney stability report with photographs and clear recommendations, explaining what is urgent, what can wait and which design service would cover any structural work.
What you receive
Chimney breast removals: why missing support matters in a terrace
A removed chimney breast does not just affect one room. The masonry above, including any upper breasts and the stack, still has weight and must be carried somewhere. Older removals often relied on simple brackets that are no longer accepted for new work without justification, while some have no support at all, leaving masonry hanging on the party wall. Because stacks are often shared, problems can involve the neighbouring house and may bring in the Party Wall etc. Act 1996. Our chimney breast removal guide explains the usual options.
If the report recommends new support or partial removal, the next step is a chimney breast or stack alteration design with calculations for Building Control. Where stack condition at roof level is the main question and scaffold would be costly, a drone roof inspection can provide close-up images first. We will always explain which of these, if any, you genuinely need.
Frequently asked questions
Is a leaning chimney stack dangerous?
Not always, but it should be checked. Many stacks have leaned slightly for decades and are stable. Others are moving because of sulphate attack or decayed mortar and could become unsafe in high winds. An engineer looks at the degree of lean, the mortar condition and whether movement is ongoing before advising on repair, rebuilding or removal.
Do I need building regulations approval to remove a chimney breast?
Yes. Removing a chimney breast is structural work and needs Building Regulations approval, with calculations showing how the masonry above is supported. If the breast is on a party wall, you will usually need to serve notice on your neighbour under the Party Wall etc. Act 1996 as well.
My survey says the chimney breast has been removed. What should I do?
Ask the seller whether Building Control approval was obtained for the removal. If there is no completion certificate, an engineer should inspect to see what supports the remaining masonry. A chimney stability report tells you whether the support is adequate and, if not, what work is needed, which helps with negotiating the purchase.
Are gallow brackets acceptable for supporting a chimney breast?
Gallow brackets were widely used in the past and many remain in place without problems. For new work, Building Control usually expects a designed solution, often a steel beam, unless the brackets can be justified for the specific situation. For existing brackets, an engineer checks their condition, fixing and the load they carry.