Roofing Advice
Chimney Repointing: Warning Signs and What's Involved
Chimney mortar erodes over time, particularly in Ayrshire's wet climate. Catching it early prevents more serious and expensive repairs.
Many older Ayrshire properties have chimney stacks that need periodic maintenance. Repointing — raking out old, deteriorated mortar and replacing it with fresh mortar — is one of the most important jobs you can do to protect both the chimney and the roof around it.
Warning Signs Your Chimney Needs Attention
Visible crumbling mortar
Look at the mortar joints between the bricks. If they're visibly crumbling, recessed or missing in patches, the chimney needs repointing.
Cracks in the chimney stack
Vertical or horizontal cracks in the brickwork — as opposed to just the mortar joints — indicate more serious movement or deterioration that needs investigation.
Damp patches on chimney breast inside
A chimney breast that feels damp to touch or shows staining on interior walls is often caused by water penetrating a poorly pointed chimney stack from the top.
White staining (efflorescence)
White crystalline deposits on brickwork are caused by salts leaching out as water moves through the masonry. It's a sign water is getting into the brickwork.
Staining from chimney flaunching
The flaunching is the cement mortar around the base of the chimney pots. If it's cracking or spalling, water can get into the top of the stack.
Missing or failing flashing
Lead or aluminium flashing seals the joint where the chimney meets the roof. Failed flashing is one of the most common sources of roof leaks and needs prompt attention.
What Does Repointing Involve?
Chimney repointing typically involves:
- Safe access to the chimney via scaffolding
- Raking out old deteriorated mortar to an appropriate depth
- Applying fresh mortar with the correct mix for the masonry type
- Finishing to match existing joints where possible
- Checking and replacing flashing and flaunching as needed
Mortar mix matters
Using the wrong mortar mix is a common mistake. Cement-rich mortar that is harder than the bricks will cause the bricks to crack rather than the mortar joints — which is much more expensive to repair. A properly mixed lime or hydraulic lime mortar is generally appropriate for older Scottish properties.