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    • CommentAuthormarsaday
    • CommentTimeJan 27th 2010
    i have damp again on the chimney breast in the attic bedroom.

    i thought it was the chimney leaking and so redid the pointing last autumn (the pointing was sand and mud so really needed doing) however the damp is coming through again.

    could it be the flashing? it didnt look fantastic, but am not sure it is faulty.

    also would i need to put a vent hole in the wall ? the chimney is used by the gas fire in the lounge so gases will be coming up it.
    • CommentTimeJan 27th 2010
    it could be a number of things, pointing on the chimney, flashings and/or soakers, a dodgy ridge butting up to it, the flaunch could be shot... I'd get a roofer to come and have a look, just to diagnose the problem...

    There should be a dedicated flu coming from the back of the gas fire up to the top of the chimney, should have a proper cap on it aswell - if you're venting straight in to the chimney, leave the house now!

    I'm not sure what you mean by vent hole tho...
    Thought I'd posted, but it didn't 'stick'. Try poss condensation. vapour condenses out within x-year-old flue ?eaten up by combustion gases. Bricks 'suck' and moisture shows on internal plasterwork.
    • CommentAuthormarsaday
    • CommentTimeJan 27th 2010
    the chimney doesnt have a liner. i have pointed the chimney as it was sand and mud. the top is pretty good and it has 2 little metal tops with holes in them.

    vent hole = an air brick. if the chimney isnt lined them i dont think this is a good idea.

    i will take a photo tomorrow. my mate is a builder and we will have a look in due course. i hope it isnt condensation and rather the flashing or soakers.
    Have you only got one flue, or was there a bedroom one too? What I describe relates to unused flues, so N/A if you've only one - sorry! Don't stick an air brick in a 'live' one!!
    Have you roof checked for any breaches, if you find that this isnt the issue than your problem is not rain water getting in.

    Because flue gases from your fire carry water vapour the colder air temperature towards the top of your chimney causes it to condense against the bricks that suck the condensate thats why you can see it in your attic room wall.

    The solution to this is to have your opening from your gas fire lined with stainless steel up to your chimeny, as this will carry the gases outside. To prevent condensation from occuring in the liner you must have the chimney breast insulated with vermiculite. Filling it from the top with bags of the stuff. This will prevent any condensation occuring in your chimney breast.

    Hope it helps
    • CommentAuthorCWatters
    • CommentTimeJan 28th 2010
    Could be any one of the causes already mentioned. Is the chimney open to the sky or does it have some kind or rain cap on the top?

    I think I'd follow amermaj2006's advice and get it properly lined and capped. If you ever plan to replace the gas fire with a wood burner make sure the right type of liner is used. Different grades of stainless steel are used for gas, wood or coal fires. You will need a Hetas approved installer. We found these people very helpful but they may not be local to you.


    Meanwhile I'd get hold of some carbon monoxide alarms, at least for the bedrooms.
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010
    here are some photos of the room and chimney. i think the damp coming through on the small wall is related to the poor pointing on that wall. as to the chimney breast i think the flashing is old and needs redoing, inc soakers.
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010 edited
    corner section next to chimney breast (pointing very poor around here)
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010
    opposite corner, again pointing bad around here.
    • CommentAuthormarktime
    • CommentTimeJan 29th 2010
    I would have characterised that as more "catastrophe" than "damp". :bigsmile:

    flashing looks rough but I've seen similar that has held well. I think you need to do some serious discovery, i.e. open up to see what's happening.
    • CommentAuthortony
    • CommentTimeJan 29th 2010
    I would say that it is all due to condensation.
    From the photos it looks like the flash band is stuck down over the top of the slates on the slope side of the flashing, to my mind this is a bad idea as its trapping water flow that would run off of the slates.
    Like the flashing the flash band should go under the tiles.
    • CommentTimeJan 29th 2010
    I suspect that Tony's right (above). If the the attic room's unheated that would reinforce that conclusion.
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010
    this is the chimney breast
    Thats damp from condensation inside the chimney or condensation inside the room in my opinion.
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010
    in this attic bedroom is a bathroom without a window. it does have a small fan (4") and i wonder if this is the reason for all the condensation.
    • CommentAuthortony
    • CommentTimeJan 29th 2010
    It could also be lack of insulation -- looks like none behind plasterboard stuck to brick walls and possibly fallen off/missing/ bypassed to stud wall?

    lack of heat and possibly the coldest room in the house as well will all exacerbate the problem

    Dehumidifier would be a good investment in the short term.
    • CommentAuthormarsaday
    • CommentTimeJan 29th 2010
    ok, so if i insulate the walls in the corners and the chimney breast, would this solve the problem?

    i am worried that if i insulate these small walls the condensation problem will move elsewhere.

    between the rafters in the ceiling there is polystyrene.

    firstly though i want to point the walls where this damp is appearing and sort the chimney flashing.

    the photo doesnt really show how poor the pointing is, but it does need redoing.
    • CommentAuthortony
    • CommentTimeJan 29th 2010
    I dont think that your flashing is leaking -- the back gutter might be but with all the evidence of condensation it is unlikely.

    I would insulate but as you fear the problem will find the places that haven't been insulated --(hence the dehumidifier)
    • CommentAuthorBrianR
    • CommentTimeJan 29th 2010
    Get a humidity meter into the room ASAP. Any humidity over 50% Rel Humidity is bad news. Kill the mould with Chlorine or some other mould killer - it is a health hazard and the spores get everywhere.

    Assuming this is because of high RH humidity then I would suggest this:

    Buy a dehumidifier - £100 will buy a new one and they will make the room warmer

    Find the source of the humidity
    It may come from a leak
    Is somebody drying clothes inside
    Are the windows not being opened every day
    Is there a nearby bathroom without any extractor fan
    We're about to view a Georgian rubble stone property where another buyers surveyor found damp in a chimney breast and the buyer subsequently backed out.

    I'm assuming that merely repointing won't be enough to address this in the long term (it's going to be hard to spot causes anyway as they've redecorated recently).

    The property has been unoccupied for a while (so presumably unheated) and is built into a slope but I don't think the chimney is on the retaining wall side so I doubt it's hydrostatic pressure.

    Are there any other things to look for, or potential remedies?
    • CommentAuthortony
    • CommentTimeJan 11th 2015
    Send us a photo!
    • CommentAuthorsquirrel
    • CommentTimeJan 11th 2015
    Following advice is from just reading this thread: ask if the chimney has a liner. It really should have, otherwise it's quite a health risk. Check if its used, and how it's capped at the top.
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