Learn which chimney mortar defects need attention, when repointing is insufficient and what a useful chimney repair quote should include.
Home›Advice›How Do You Know When a Chimney Needs Repointing?
Roof problems
Illustrative image: open joints need assessment alongside the surrounding masonry.
The short answer
Open, crumbling or missing mortar joints can indicate that a chimney needs repointing. The important distinction is whether the masonry remains secure: replacing mortar does not correct a leaning stack, damaged bricks or failed flashing. A chimney inspection should identify the defect before choosing the repair.
Start with what you can see from inside the property, ground level or a safe window. Do not climb onto the roof, lean out of a window or walk on a fragile covering. These steps give a roofer useful context without putting you at risk.
Photograph the stack from ground level using zoom.
Record fallen mortar, fresh indoor staining and when you first noticed it.
Keep clear of areas beneath visibly loose masonry.
Find previous chimney repair invoices if available.
Look for missing mortar, not just an old-looking chimney
Mortar is the material between the bricks or stones. Deep gaps, pieces falling out and joints that have separated from the masonry deserve attention. A chimney can look weathered without needing every joint renewed, while one exposed face may be much worse than the sheltered side.
SPAB advises that sound pointing should be retained and that softness alone does not justify replacement on older masonry. Ask for photographs identifying the failed areas, rather than accepting that an entire stack needs repointing simply because its colour looks uneven.
Illustrative image: repointing and rebuilding loose masonry are different scopes of work.
Check whether the damp actually comes from the joints
A stain beside a chimney breast is a useful clue, but it is not a diagnosis. The stack also has a top, pots, flashings and a roof junction. Water entering any of these can make repointing appear necessary when another detail is responsible.
Tell the inspector whether staining follows rain, appears in windy weather or continues during dry periods. Ask them to explain which visible evidence connects the proposed work to the indoor symptom. If several defects exist, the quote should distinguish them instead of describing everything as chimney pointing.
Illustrative image: check nearby flashing before attributing damp to pointing.
Older brick and stone chimneys need particular care when choosing the repair mortar. A very hard mix is not automatically a stronger or more durable repair for the chimney as a whole. SPAB explains that unsuitable cement-rich pointing can accelerate damage to traditional masonry.
Ask which mortar is proposed, why it suits the bricks or stone and how sound existing joints will be protected. Matching colour is only part of that decision. The material also needs to suit the building and exposure; a generic mix selected without inspecting the stack is not a meaningful specification.
Cracked or broken masonry, displaced pots, a visibly leaning stack or sections moving apart call for a wider assessment. Adding mortar over the face cannot establish whether the underlying masonry is stable. Keep people away from falling debris and arrange prompt professional attention.
The top of the stack needs checking too. SPAB identifies deteriorated mortar around pots as a possible cause of instability. The inspection should therefore separate joint repairs from pot security, top weathering and roof junction work, with photographs showing why each item is needed.
A useful quotation names the faces or areas to be treated, access arrangements, mortar specification, any replacement masonry and the treatment of nearby flashing. Ask what happens if closer access reveals more extensive damage than was visible from the ground.
Before-and-after photographs should show the agreed areas, including awkward parts behind the stack where possible. Keep them with the invoice. If the original problem was damp indoors, agree how it will be monitored after the repair; immediate redecoration can make it harder to distinguish old staining from renewed water entry.
Preparing for an inspection
Send the property postcode, a safe ground-level photograph and the history of the problem or planned work. Mention access restrictions, previous repairs and any shared parts of the building. Ask what can be established during the visit and what may remain uncertain until work begins.
Questions worth asking before you approve work
Which joints have actually failed?
Is any masonry or pot insecure?
What mortar is proposed and why?
Are flashing and top repairs included or separate?
You should understand the recommended repair, how the roof will be reached and anything the quote does not include. Do not choose on price alone when two quotes cover different work.
Discuss your property with OnPoint RoofCare
For roofing enquiries in Motherwell, Lanarkshire, Glasgow and the surrounding service area, call with your postcode and a brief description of the work. We can discuss the appropriate next step and any further inspection or specialist input needed before a scope is agreed.
Talk to us about chimney repointing
Send the property area and a safe ground-level photograph if you have one. We will review what you have noticed and contact you about the appropriate next step.
