Chimney Repairs South Wales › Aberdare › Guide
Damp on or beside a chimney breast is one of the most common calls we get in the Cynon Valley. The wet upland weather is partly to blame, but the damp nearly always has a particular route in, and finding that route is the key to fixing it properly.
The usual causes
On older terraces, the commonest cause is water getting in at the top of the stack: cracked flaunching, open joints, or a pot that has come loose. Water runs down inside the brickwork and shows up on the breast, often in the bedroom or the loft. Other causes include failed flashing where the stack meets the roof, a blocked or unventilated flue, and condensation in an unused chimney. Flashing has its own page, so we only mention it here.
What you can check from inside
Look at the chimney breast in the bedroom and the loft. Note whether the stain is brown, whether it appears after rain and whether it spreads, since that helps us tell a roof fault from condensation before we even visit. Do not climb up to look at the stack. Check from the ground and from inside the house, and call us for a proper look at the roof and the chimney.
- Does the patch get worse after heavy rain?
- Is the stain brown or yellow with a tide line?
- Is there white salt on the plaster?
- Is the loft side of the breast wet or stained?
Why an unused flue causes damp
An old flue that has been blocked off with no airflow can trap moisture. Water in the brickwork carries salts to the surface, and the plaster blisters and stains. Without ventilation the chimney never gets the chance to dry out. Capping and ventilating an unused flue lets it breathe while keeping the rain out. Do not light or use any flue that has had water or damp problems until it has been properly checked by someone qualified.
How we trace and repair it
We inspect the stack, flaunching, pots and the roof around them, then the loft side of the breast. When the cause is clear, we repair it: new flaunching, replacement pots, a cowl or cap, or rebuilding the stack if the brickwork is failing. Once the source is sealed, the wall needs time to dry before it is redecorated. We tell you what we find, and the decorating afterwards is a separate job for you or your decorator.
- Stack and flaunching inspected from a ladder or tower
- Pots, cowls and joints checked
- Loft side of the breast checked for staining
- Repair carried out, then the wall left to dry
When to get it looked at
Damp that returns after rain is a roof or stack fault until proved otherwise. The longer it is left, the more water gets into the timbers and the ceiling plaster, and the bigger the eventual repair becomes. Call us as soon as you notice a stain growing. We give free, no-obligation quotations across the Cynon Valley, and we will tell you honestly whether the stack is the cause or something else is.
Need a chimney looked at in Aberdare? See chimney repairs in Aberdare, or for the lead and mortar side of it, chimney flashing repairs and chimney repointing and repairs.
More Chimney Guides for Aberdare
Common Questions
Can I just paint over a damp patch on the chimney breast?
Painting over it hides the stain but not the cause, and the damp usually comes back through the paint. Find and repair the source first, let the wall dry, and only then redecorate.
Does damp near the chimney always mean the roof is leaking?
No. Condensation in an unused flue and salts in old brickwork can cause staining without any open leak. That is why we check the stack, the flue and the roof together before recommending any repair.
How long will the wall take to dry after the repair?
It depends on how wet the brickwork became and the time of year. In a damp valley house it can take a while. We will tell you when we have seen the wall, and the plaster should be left alone until dry.
Get a Chimney Looked At in Aberdare
Tell us what the roof is doing in Aberdare and we will look at it. Call 07766 547309, message us on WhatsApp or use the form below.