Chimney Repairs South Wales › Porthcawl › Guide
Damp on or beside the chimney breast is one of the most common reasons people call us in Porthcawl. It can come from the stack itself, from the roof junction, from an unused flue, or from salts in the old brickwork. The fix depends on the source, so tracing it matters more than painting over it.
Where the water usually comes from
Wind-driven rain is a frequent culprit here. If mortar on the stack has weathered or the crown has cracked, water gets into the brickwork and runs down inside the breast. An open pot with no cap lets rain straight down the flue. Flashings where the stack meets the roof can also let water in, though that has its own page.
Signs that point to the chimney
Damp that gets worse after heavy rain or a gale, and dries out in settled weather, usually points to water coming in from outside. Patches near the ceiling suggest the stack or roof junction; patches low down may be rising damp or salts. Check from inside only, and do not go onto the roof. Look at the following.
- Brown or tide-mark stains on the breast, often higher up
- Wallpaper lifting or paint blistering near the chimney
- A musty smell in the room or loft
- Wet patches on the loft timbers around the stack
- White powdery salts on the plaster surface
What about the old fireplace
A chimney that is not in use can hold damp in the flue and breast. With no heat or air movement, moisture builds up and eventually shows on the wall. Salts left from old soot and moisture can also draw damp to the surface. A ventilated cap on the pot and an air vent in the fireplace opening often help, and we advise after looking at the flue.
How we trace and fix it
We look at the stack from the ground, check the loft around the chimney, and then inspect the pot, flaunching and brickwork from a safe platform. That tells us whether the water is entering at the top, through the stack walls or at the roof junction. Repairs might be new flaunching, a cap, repointing, or rebuilding the stack. Plasterwork inside should only be redone once the source is fixed and the wall has dried.
Why not just treat the wall
Damp-proof paints and sealants hide the stain but do nothing about the water. The patch often returns, and meanwhile the timbers in the loft may be getting wet. Fix the cause first, give the wall time to dry, then redecorate. Do not light the fire in a damp or faulty chimney until a proper check has been done.
Need a chimney looked at in Porthcawl? See chimney repairs in Porthcawl, or for the lead and mortar side of it, chimney flashing repairs and chimney repointing and repairs.
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Common Questions
Is a damp chimney breast always caused by the stack?
No. It can also come from the roof junction, a leaking gutter, condensation or salts in old plaster. That is why we trace the source from the ground, the loft and the stack, rather than assuming the chimney is at fault.
Will the damp go away on its own?
Rarely. It may dry in settled weather and return after the next storm. The water keeps entering until the fault is repaired, and repeated wetting can damage plaster and the timbers around the stack.
Can I use the fire if the breast is damp?
We would not advise lighting a fire or stove until the chimney has been properly checked. A damp breast may point to a fault in the stack or flue. Call us for an inspection first and follow a qualified installer's advice.
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