Viewing 13 posts - 1 through 13 (of 13 total)
  • Damptrack World
  • ThurmanMerman
    Free Member

    Grrrrr.

    Any damp experts around? Running out of ideas and all the builders/roofers I’ve deferred to have shrugged.

    Ours is an old house. There is a long-redundant brick chimney breast in the kitchen – and damp is seeping through the wall. The brickwork’s been tanked with tanking slurry, re-plastered, skimmed, and now painted and tiled.

    The chimney stack’s been repointed, all the flashing and roof tiles are sound, and it’s been capped-off with a vented cowl. It does not leak. In the kitchen the hearth has been boarded up and plastered over, with a vent at the base.

    We assume it can only be heavy condensation on the inside – but surely if there’s airflow that’s unlikely?

    Thoughts? Experience?

    bigginge
    Full Member

    Is the ground that the foundation sits in wet and does the brickwork for the chimney stack have any sort of damp course?

    jeffl
    Full Member

    When you say old, how old? Is it cavity wall construction, stone, brick with no cavity etc?

    Also the leaking chimney breast is it an external wall or internal wall. If it’s internal and ventilation is good then I’m at a bit of a loss based on what you’re saying. As it’s a kitchen do you have an extractor fan that vents to the outside world rather than just re-distributing the moist air inside? Where it’s damp is it cold to the touch?

    If it’s an outside wall you mention that the tiles are good and it’s all been repointed, tanked etc. Water’s a proper bugger so it could be tracking down from a point above but quite a distance to the left or right.

    Also if you have a cavity could it have been bridged somewhere? I’ve got a Victorian house with cavity walls. Had damp in a couple of alcoves for years. Over the summer I removed some bricks and pulled out about 60kg of rubble, dust and god knows what else that was bridging the void and allowing damp to penetrate.

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    Nobeerinthefridge
    Free Member

    Is it only vented at the top?

    big_n_daft
    Free Member

    Is the ground that the foundation sits in wet and does the brickwork for the chimney stack have any sort of damp course?

    Very doubtful that it’s rising damp

    Kitchens are humid places, the chimney breast will be cold with all the ventilation, it’s probably condensation. Also may be salts still coming through the chimney breast.

    Pete Ward Heritage House on YouTube will help give you ideas

    perchypanther
    Free Member

    Is it near your washing machine?

    Bear
    Free Member

    Have you got cavity trays fitted in the chimney?

    If you have, then chances are only 1, when you often need 2, depending on how it penetrates the roof.

    Single brick, water will soak through the external brickwork and run down the inside without a tray.

    ThurmanMerman
    Free Member

    Single brick, water will soak through the external brickwork and run down the inside without a tray.

    I did wonder that, as that could be the only point of entry. Think it can only be penetrating through the brickwork on the chimney. Thomson’s water seal??

    The part of the house the chimney’s in is c.1800. It’s a brick chimney in a stone-built house.

    There is good, strong airflow so am at a loss as to how it can be condensation.

    Doubt it’s rising damp as nothing else in the kitchen is damp. It’s a huge patch on the chimney breast 5 to 6ft off the ground and about 3ft wide.

    A thought struck me last night that it *might* be a leaky pipe under the bedroom floor above. That would explain how the plaster is damp when there’s a tanking slurry between it and the brickwork…

    Where’s my jemmy…

    Bear
    Free Member

    Big problem on lots of new build in recent years with chimneys (those that have them). Your chimney would have traditionally been connected to an open fire probably so rain ingress through brick work wouldn’t have been noticeable due the the fire being alight, and almost certainly wouldn’t have had trays fitted.

    ThurmanMerman
    Free Member

    True. There hasn’t been a fire in the fireplace there for 20+ years.

    So: what do we do about a long-redundant chimney that’s wet inside?

    I don’t know enough about the science of ventilation, condensation or the anatomy of chimneys to solve the problem and I’m all out of ideas.

    It’s not a leaking pipe in the room above, either. I’ve just checked.

    Bear
    Free Member

    Lead trays in the chimney, or take it down above the roof and roof over it.

    Vader
    Free Member

    First thing would be to stop more water getting in – has the chimney can got a china-mans cap or elephants foot on it? If so i would do that as a matter of course – without one it’s a large hole pointing skyward. Elephant’s foot £60-80, cheap cap maybe £20. Plus fitting if you can’t get up there yourself – fitting is easy once your’e up though, 10 minute job. I’d probably think about installing an external air brick or vent at the base of the flue.

    It’s conceivable you have something bridging the flue. Id drop an endoscope camera down the flue and see whats going on, you can get one to connect to your smartphone pretty cheap. People stuff all sorts of crap in their flues that they thought was a good idea, cement, rubble, masonry – I’ve seen it all.

    What looks like a well pointed wall can sometimes be the opposite, my day job is more often than not repointing gables and it is very common to find a void where the existing mortar has just not been pushed back into the joint. Driven rain will find it’s way in through the tiniest of cracks, given a chance. A few mm of mortar skimmed over a joint won’t keep the weather out for long.

    redmex
    Free Member

    Old houses with numerous chimney flues ie every room other than the bathroom to separate each flue there is brickwork that bridges from the outside to the inside and possibly capillary action with all this rain causing the dampness or maybe holes in the exterior, Thompson’s water seal will do f all to cure something like that

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