Damp on Ceiling help

Brian909 · 27 Mar 2009

Hello,

I have a bit of a problem, I recently bought a house which is around 80 years old.
The house is in general great condition, though I did have around 10 layers of paper to take of in the living room, nightmare.

The situation is -

The living room has be joined or knocked though, there were 2 chimney stacks which have been previously taken away and the ceilings have like 2 concrete squares where they used to be. The walls were fine, re plastered and dry.

1st thing I noticed before replastering was, there concrete square in the ceiling where the chimney stack used to be had sagged a little and it did seem a little damp and I think there may have been evidence of salts on the surface.

I did not really pay attention and had the ground floor re plastered, now it has all but dried out apart from there 2 damp spots about 6 inches across each, where the chimney stack used to be.

I think I know a bit about damp and I just thinking the chimney might need re pointed? Or re concreted or covered to stop the rain coming in?

Any help would be greatly appreciated.

Diyisfun · 27 Mar 2009

I hope the concrete slabs are being supported.

Brian909 · 27 Mar 2009

I dthe know really, the one concreted over chimney in the front room is fine, I had just figured it had sagged a bit with damp or maybe it was just a bad job in the first place? Worth mentioning the bedroom directly upstairs does not have it removed and the wall seems fine, how would I check if it was supported?

Alastairreid · 27 Mar 2009

look here chimney stack removal the chimney head should also be capped off with one of these View media item 9740 to prevent water ingress.

Brian909 · 27 Mar 2009

If the chimneys have been removed in the living room I think it was around 1955. Is it something I need to worry about? Meaning if the work was done correctly, surely if its been ok for this long? Asides from the little bi of damp I mean

PrinceCharles · 27 Mar 2009

Rebuild the fireplaces!!. A perfect solution when one wants to burn ones servants when they outlive their usefullness. Camilla swears by 'em

HRH

Brian909 · 27 Mar 2009

If I was able to lift the floor board/s in the upstairs bedroom, would I be able to see if it was properly supported?

Symptoms · 27 Mar 2009

Brian - typically in the 'old days' a chimney breast in a ground floor room would have been removed and then the stuff above supported, in the ceiling space, with a couple of lengths of cross timbers. Yep, lift the floorboards and look for these in the space. Warning ... often they were omitted and the whole structure would just be left to hang there on a wing and a prayer.

Brian909 · 27 Mar 2009

Best case they are supported and the chimney cap will sort the small damp problem?

Worst case its unsupported and may come tumbling down at some point in the future? At that point 6 inch circle of possible damp problem wont seem so bad at all

Brian909 · 27 Mar 2009

I had a look under the floor boards after work, there look like there are 2 fireplaces in the upstairs bedroom directly above where there missing chimney stacks are downstairs, seems sturdy enough to me, there are a couple of thick beams coming out from the wall, though that maybe just to hold the 1st floor fireplaces up,

Still have a little bit of damp directly underneath where one of the first floor firplaces are, its worrying as thats where the ceiling, concrete sags a little bit.

dave1953 · 27 Mar 2009

Whats been burnt over the years in the ground floor fireplace will have polluted the stack. Condensation within the stack will produce staining etc upon adjacent walls /ceilings , personally I would reduce the entire stack and eradicate the problem.

Brian909 · 27 Mar 2009

costs? ballpark figure?

alittlerespect · 28 Mar 2009

Damp is one of two problems - one no flue cap to stop rainwater entering what is basically a funnel, or if the flue is capped off then there is no ventilation provided and the problem then becomes one of thermal bridging and condensation forming in the void - solution if problem 1 - fit a cap similar to the one proposed by alastairried, or if problem 2 - install an air brick to the chimney stack slightly above the roof line one for each disused flue.

Concrete ceiling slab - from what you have mentioned this does not sound like a pucker job as there was always going to be differential movement between the timber and the concrete. Under normal circumstances a gallows bracket made up of 2" x 2" angle iron would have been rawbolted to the wall to support the underside to the chimney breast from the room above, much the same as the detail shown in alastairrieds attachment. However, from your description reliance has been put on the existing floor joists to take the load - not the brightest of idea's as it was bound to lead to the sort of problems that you are now encountering - possibly the best solution would be to take out the chimney breast and concrete infill to the bedroom, terminate the chimney breast in the loft space with a gallows bracket, and make good to all disturbed areas, but don't go forgetting you still have the issues to do with the damp penetration! May as well treat it all as one job!

Regards

Brian909 · 29 Mar 2009

Thanks for the advice, though the concrete slabseems to be about 5ft long its supported from the ground floor by 2 walls at either end, on top of the slam sits the 2 firplaces on the 1st floor, I may leave as although not ideal I dont really have the money to fix it atm, though I may fix it later.

Im just hoping if its been ok for so long it should be ok for a while yet.

I'll get a good builder round and get him to have a look.

I'll get the chimney pot caps, thanks for your help.

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Damp on Ceiling help

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