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Damp Proofing Question
Damp around chimney breast - chimney has been repointed, reflaunched and releaded
I have for a long time seeked an answer to my problem... yet after several workmen and thousands of pounds spent the problem is still there and now seems to be worse.
The chimney in question has been re-pointed, re-flaunched, re-leaded ...the flaunching and chimney outside brickwork was waterproofed with a brush in liquid and chimney pot had been capped with what was supposed to be a vented cap.
But chimney is near the roof on the inside of the house dripping on the paintwork and is very wet, dripping has a funny consistency almost like oily, same chimney breast on the ground floor appears to have rising damp up to about half a meter to a meter high...but even more strange on the front of chimney breast again on ground floor some yellow patches have appeared and these ones again have like an oily feel to it...when it rains I can hear dripping through the air vents on it both ground and first floor I am so frustrated, I feel cap was probably fitted to tight and it may not be vented because of that so it may have condensation forming from us breathing etc....chimney breast has two pots ...not sure how rain gets in as it drips never cured.
I wanted not to have to spend loads of money more as in total, I must have spent over 2k and had about 4 different people doing things to it I needed for the problem to be diagnosed properly and fixed properly with guarantees. Not sure what to do and who to call or what the problem may be...I heard everything from possible debris inside the stack, rising damp, condensation and rising damp etc etc...anyone out there honest, reliable and not expensive that can tell me anything that may help????
You may struggle to get an answer here mainly because we cannot "see" what the problem is.
There are many questions that need answering before an accurate appraisal can be made for example
1. Is the property in question detached, semi or terrace? The problem may be water ingress from the neighbouring side of the stack where brickwork may be partially collapsed etc
2. What free space in cm2 is there on the upper vent & lower vents ? - It may be too large (letting water in or too small (not allowing sufficient ventillation)
3. Can you categorically say that the tradesmen did the re-pointing, flaunching & flashing properly in the first place?
4. The issue of "oily residue" is easily explained. Any chimney stack that has been used for coal or wood becomes ingrained with oily soot....when the chimney gets damp this will permeate through the plaster - even on chimneys that are in use if they are not regularly "fired up"
5. It is not unusual to find rising damp at the foot of the chimney - they were traditionally not built with damp courses and without sufficient ventilation or with water ingress you will get rising damp.
There are many more questions that need answering before I could give you the definitive answer and drawings, photos etc that show the internal rooms, stack, loft and external roof would be the only way to diagnose the problem.
Answered 10th Oct 2013
I would say Mr Fereli is pretty much spot on ! You do not mention though , if the chimneys are used ? If the chimneys are not used and exclusive to your property then it is often a solution to remove the stack to below the roof level .!
Answered 28th Jan 2015
Can't say about dripping without seeing it first but the rising damp is very common on chimneys best fix for this is trying a chemical injected DPC and/or tanking membrane to a minimum height of 1200mm but if the damp is up to about 1m would probably be worth going up to 1500mm.
Hope this is of some help.
Answered 9th Mar 2018