'Rising damp' in chimney breast

katemcf

Hi there. I was wondering if anyone is able to offer an advice, or even better speak from experience, about damp in old houses. My house is 200 years old and made of stone. The external walls are up to 50cm thick, rendered in pebble dash and painted white (probably not very breathable - aware that it probably needs chipping off and lime rendering instead £££££ :eek: )

We have recently noticed damp coming from the bottom of our chimney breast (on an internal wall). The wallpaper has yellowed about 30 cm up from the ground, and paint/plaster in the cavity is crumbly in areas. We also have a bubbled patch of wallpaper just over a metre up. The chimney is not used, and is blocked up and fitted with a vent, leaving only a rectangular hole in the chimney breast.

I had a builder come and take a look, and he wants to inject a damp proof course. I have been researching solutions online, but everything I find says that old stone walls shouldn't be treated with this, so I'm not keen. The only problem is that I can't seem to find a suitable solution, particularly for damp on an internal chimney breast. I keep finding solutions where making sure gutters/drainage etc outside are up to scratch is priority, but this doesn't help when the wall is the adjoining one between my neighbour and myself, as it's obviously not leaky gutters causing it.

This isn't the only damp we have on the ground floor of the house, but at the moment it has been the most destructive. Ideally we need to solve the damp problems in other rooms too, but I just have no idea what the suitable treatment is for an old stone house. I can only find wrong answers, not right ones. (Wrong answers apparently being injecting & electro-osmosis)

We probably don't have the budget to do the whole ground floor right now, and would focus on the chimney breast, but would love to be able to aim for doing the whole house in the next couple of years.

Can anyone offer help with this please? Thanks a lot.

cyclonebri1

Physical damp course, if you trully think it is rising damp.

Many say, I agree, that rising damp is none existant.

Be very careful how you spend your money

katemcf

Ok, well not 'rising damp' then, I don't know the correct terminology. All I know is my walls damp at the bottom...

What other options are there with an internal chimney breast? We ruled out water coming in from above, due to there being no damage anywhere else on the chimney breast (including upstairs) and also there's no dampness at the top of the cavity within the chimney breast. It seems to come from below, not above.

DRP

Presumably the chimney isn't stone? probably brick? so in theory could be injected but probably not required and counterproductive/damaging.

How about knock off the old plaster, let the brick dry out for a bit if it seems damp, then re-render and plaster?

I'm not an expert but i understand the salts from a fire that's in use penetrate the chimney structure and are hygroscopic - causing damp. Therefore need to totally remove and replaster.

It seemed to work for us.

Another thing is to check the subfloor for debris, clear it out, make sure plenty of airbricks are present front and back, with a good flow between rooms (honeycomb walls under te floor).

Sometimes damp in old houses is inevotable, but can be managed & reduced.

phil24_7

Find out where the moisture is getting in first, then work out how to treat it.

Has the water table risen? Is the ground level outside too high or does it slope towards the house? Is there a water leak anywhere? DPC injection will never be 100% effective in stone wall.

Water can also track behind the pebble dash if there are cracks...these cracks can be hard to see in the pebble dash!

Doozergirl

Open the chimney place up again

You'll read what not to do, because old houses work the way they were built and don't take kindly to being changed. The chimneys are designed to be open, not blocked; not even with a tiny vent, considering wall thickness.

Damp prevention is all about ventilation in old houses, unless there is an evident water leak.

Damp patches at the bottom can be caused by the lack of a cap at the top or a lack of ventilation at the bottom. Either way, with walls that thick, I think plenty of venting is essential.

Open it up.

Marktheshark

Sounds like an opportunity for a log fire place to me !

katemcf

Thanks very much for your replies. All points are noted and have fuelled further research. I just needed the right starting points

Like the idea of opening it up again, not really sure why the previous owners would've closed it up anyway. They seemed to try and retain all of the other character features but not the fireplace.

Thank you

phil24_7

Perhaps the flue needs lining due to deterioration so they felt closing them up was better. Perhaps they just didn't like loosing all the heat from the central heating up the chimney!?!?

katemcf

Yep, perhaps. Still seems a shame though

katemcf

Out of interest, do you think installing a wood burning stove would have the same effect on the damp as an open fire? Or would having an actual open fire be more effective?