Damp problem possible multiple causes - please help!

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Hi all,

I hope someone here can help me sort this problem once and for all. I'll try and explain the problem in as much detail as I can...

I have the ground floor of a 1900 semi and have a damp problem on the outside walls of the two front bedrooms. The construction is solid random stone on the side wall with a render on the outside. Underneath the bay window at the front also has some damp, and from what I can tell that is a combination of two layers of brick (not much of a cavity) and a large block of sandstone under the middle window. On the side walls in both rooms there's a chimney breast with a vent, but they're blocked off upstairs.

When I bought the flat, there was serious problems on the side wall. The plaster was all crumbling off. The solution proposed by the builder was to remove everything back to the brick, then waterproof cement render, then plaster. This was done and seemed fine for a while, then the damp started to come back. It was mainly in the alcove to the right of the chimney breast and under the bay window, and was mostly black mould and some crystallisation, from the floor to about waist height.

My initial thought from the black mould was condensation, as they're definitely cold walls, so I tried a quick fix using some leftover Sempatap from my parents. I applied this under the bay window and round to the chimney breast. This seemed to make a big difference and for the first winter it was fine.

Now however the problem has moved onto the chimney breast it's self, with some of the plaster at the bottom, starting to come away from the brick, and mostly crystallisation with some black mould. On removing the vent on the chimney breast and pocking a stick in there, you can see that there's damp earth filling the chimney to about 10" from the floor. I'm sure that this is bridging to the internal brick and causing the break up of the plaster.

The whole problem is worst in the front bedroom with the bay window, but it's very similar in the second bedroom, but just to a lesser extent.

I've had another builder look at the problem recently and he suggested hacking back to the stone, then bichamin the stone, then waterproof render, then plaster. I'm very wary of this as even if it managed to stop anything that my be penetrating through the wall, I'm guessing that it wouldn't stop any condensation problems, because the walls would still be cold?

My thoughts are to open up the blocked up fireplace and clear out the earth, then hack off back to the stone and brick on the side wall and under the bay window, then put up a drylined wall with insulation behind.

I'm no expert but I've done a fare bit of reading on this subject now, so think I've got a good understanding, but would love some other opinions, before embarking on any work.

I've attached some images of the front bedroom. Sorry for the awful quality and light, I only had my phone.

Any advice will be much appreciated!

Thanks, Robin

 
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The floor is wooden floorboards with carpet.

Some other details... there are two air bricks at the front under the bay window, and two new ones that I added below the alcoves on the side wall. But I don't think they're very affective as they can't really create a through draft under the floor as beyond the two bedrooms the floor steps down and has been replaced with concrete.
 
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Your post is a bit of a jumble. Perhaps you could:

1. Post pics (from a better camera) of the house exterior including ground level shots, c/stack(s), and pics of any mould or wall surface eruptions anywhere in the property?

2. Can you scan or photo a plan view/ footprint of the ground floor, tying-in annotations to each photo. Show the c/breast(s), the conc. floor(s) and all sub-floor vent positions.

3. Can you crawl under your suspended floor? Note that historic replacing of a suspended floor with a slab is indicative of possible similar difficulties in the past. Are the backs of the removed skirting fungal damaged?

4. The c/breast will have to be opened up and at least cleaned out - the debris might be from down the flue, not earth soil. Research recent posts on flues and c/breasts.

5. The c/breast is on a gable wall?

6. Research recent posts ref condensation and rising and penetrating damp. The black spots and crystals are most likely condensation.

7. "blocked off upstairs" - where, in the flat above, or the roof stack? Or totally removed?

8. What the earlier builder suggested was not what i would do, if i understand the situation correctly. But, first, more info.
 
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As a rule, if the "damp" has a brown/yellow stain and an even or wavy line at its edge, and white salts, then its penetrating or rising. Otherwise more probably condensation

If you had condensation on the bay, and fitted sempatap there only, then you wont have solved the problem just moved it to the next cold wall. This may well be the chimney, or it could be something unrelated and to do with that damp ground - or both.

You wont get a definitive answer here or from pictures, and it may need someone visiting to look at it

You need to know the cause or causes before deciding on a solution
 
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Thanks for the reply. I'm not really expecting a solution on here, just some guidance on the best way to proceed really.

From most of the stuff I read online about damp issues, I've very weary of getting a so-called damp specialist in. One that I spoke to recently on the phone wanted £100+VAT to come and look. That's fine if they're top notch and can really identify all the causes and give a complete solution, but it's a lot if they're just going to come in and say "rising damp" and say they want to hack off the plaster to 3 feet and inject! (Their website mentioned rising damp quite a bit).

Any advice on how I can find a reputable person to investigate it properly (in Cardiff if that helps)? And how much, if anything, should I be expecting to pay for the investigation?

Thanks again.
 
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I recently moved into a property where the buildings survey pulled up few sections of amp. Before we moved in we had a damp proofing company have a look and quote to fix it. We then knocked this much off the asking price.

When we actually moved in I paid for an independent damp survey. It cost £225 + VAT for a 4 bed detached. The interesting thing is that the damp works quoted by the damp proofing company are all unnecessary - they had identified rising damp when actually its cracked render on the outside by the plinth that comes up to DPC.

So for me this was £225 well spent - the damp company wanted about £2k to inject an unnecessary DPC, which we knocked off the asking price but don't have to spend. Real cost to repair is more like a few hundred if that.

PM me if you want to know who I used.
 
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tm-surveying.co.uk ( Swansea ) and tawhite@mail.com ( Weston -S-M)
both independent D&T Surveyors.

I earlier asked you a number of questions, and i'm wondering how you are getting on answering them?
 
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Thanks Dan for the questions. I know the post was a bit of a mess, but it was a start! Get on with what I can do and post back. I can't get under the floor without a fair bit of effort at the moment though.

I did have the whole floor up when I bought it though as a lot of the boards where rotten and the space below was full of building waste, pretty much right up to the boards, presumably from when the flat conversion was done. That's all been cleared out now though, but I was expecting that they just dumped stuff in the chimney too, but we'll see when it's opened up.

I'm not sure exactly where the chimney stops, I just know the stack's gone from the roof, but I'll try and check upstairs in the flat above to see if the breast is still there (I expect it is).
 
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Yeah call a damp surveyor at about £10 per minute. :rolleyes:
 
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Choose someone from here www.property-care.org

A local building surveying firm should be able to diagnose and impartially advise on this. But if you choose a surveyor, then specifically state that you expect him to diagnose without referring you to any other specialist. If he can't give you that assurance, then don't use him
 

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