Dealing with a damp stone floor/walls

[HeidiHi]

I have recently bought a 1900's mid terrace and have been living in it for 5-6 months now. When we bought the house it had been empty for over 18 months and we knew it had evidence of damp that we felt was largely due to condensation.

Most of the damp has now retreated and all is good. However the kitchen walls are still damp and have shown no signs of improvement.

So far we have tried the following:
- Improving ventilation (keeping windows open and have installed new air bricks)
- Running a dehumidifier 24/7 for a few months in the kitchen
- Lowering the outside ground level so that it is below the internal floor level
- Checking guttering, drainage etc for blockages/leaks
- Checking windowsills for damage etc.
- Re-pointing the brickwork
- Previous owners also had a chemical DPC injected

Nothing has worked so far.

A builder came round for something unrelated and mentioned that it might be caused by the plaster on the walls touching the kitchen floor. I'm not sure if this is true- we haven't checked to see how far the plaster goes behind the skirting (the skirting looks like its made of concrete by the way). The floor is covered in lino. The floor itself looks like stone flags that have been covered in a thin layer of concrete or something (it has been damaged and is now flaking off the stone flags underneath). When i peeled back the lino the floor looked to be covered in hygroscopic salts (which are also on the wall). So my builders theory seems plausible to me.

My questions are, is it plausible and if so what do i do about it?

Builder recommended knocking plaster back to brick, dot a and dab the wall leaving a gap between the internal wall and floor, and laying asphalt or another damp proof membrane on top of the floor.

I know a damp proof membrane will be an effective barrier against the moisture, but will this prevent the stone floor 'breathing' and force the moisture somewhere else and cause problems elsewhere?

Any ideas about what I should do next?

All advice would be greatly received.

Cheers!

 

[dann09]

I take it that this is the kitchen area only?

The exterior ground level should be 150mm below the DPC. Have you located the mechanical (bitumen, slate or lead) DPC on the outside brick face?
Avoid any further injection DPC work.

Internal plaster or render should stop 40-50mm short of any solid floor.

Sand and cement (or even lime putty) shaped skirtings were common in older buildings.

How thick is the external wall(s)? You possibly have a thin cavity.

I would imagine that the essential remedy is to lift the floor, and then re-lay it with cleaned stone flags as the FFL.
Research "how to" on here.

Maybe the wall(s) will have to be rendered in remedial S&C.

Install a powerful ext fan.

The kitchen will have to be stripped for the above work.

Photos of what exists inside and outside would help your cause.

 

[HeidiHi]

Yes the problem is located in the kitchen only, and much worse on the exterior wall than on the interior ones.

The walls are approx 9inches thick (and i think this goes for all the walls in the house, and the kitchen is the only room with a solid floor).

We are renovating the house and were planning on stripping the kitchen anyway.

Here are some pics:

The worst affected wall

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• HeidiHi
• 12 Jul 2013
• 1

The same wall (from inside the base cupboards)

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• HeidiHi
• 12 Jul 2013
• 1

Underneath the lino

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• HeidiHi
• 12 Jul 2013
• 1

Exterior view of the wall (excuse the paint work- not got round to stripping/cleaning the paint off from the previous owners)

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• HeidiHi
• 12 Jul 2013
• 1

Thanks

 

[MIKALAN]

I have recently bought a 1900's mid terrace and have been living in it for 5-6 months now. When we bought the house it had been empty for over 18 months and we knew it had evidence of damp that we felt was largely due to condensation.

Most of the damp has now retreated and all is good. However the kitchen walls are still damp and have shown no signs of improvement.

So far we have tried the following:
- Improving ventilation (keeping windows open and have installed new air bricks)
- Running a dehumidifier 24/7 for a few months in the kitchen
- Lowering the outside ground level so that it is below the internal floor level
- Checking guttering, drainage etc for blockages/leaks
- Checking windowsills for damage etc.
- Re-pointing the brickwork
- Previous owners also had a chemical DPC injected

Nothing has worked so far.

A builder came round for something unrelated and mentioned that it might be caused by the plaster on the walls touching the kitchen floor. I'm not sure if this is true- we haven't checked to see how far the plaster goes behind the skirting (the skirting looks like its made of concrete by the way). The floor is covered in lino. The floor itself looks like stone flags that have been covered in a thin layer of concrete or something (it has been damaged and is now flaking off the stone flags underneath). When i peeled back the lino the floor looked to be covered in hygroscopic salts (which are also on the wall). So my builders theory seems plausible to me.

My questions are, is it plausible and if so what do i do about it?

Builder recommended knocking plaster back to brick, dot a and dab the wall leaving a gap between the internal wall and floor, and laying asphalt or another damp proof membrane on top of the floor.

I know a damp proof membrane will be an effective barrier against the moisture, but will this prevent the stone floor 'breathing' and force the moisture somewhere else and cause problems elsewhere?

Any ideas about what I should do next?

All advice would be greatly received.

Cheers!

IHAVE RESTOREDMANY TERACED IN MY TIME YOULL FINT THE FLAGD LAID ON CINDERS ASPHALTING OVER WIL NOT SOLVE THE PROBLEM WHICH S ORIGINALLY CAUSED BY OVERLAYING AND MADE WORSE WITH LINO REMOVING ALLCOVERING AND LETTING IT BREATH WILL EVENTUALLY CURE LIFTING AND REPLACING THE CINDERS WITH VERMICULITE WHICH IS MOISTURE RESISTANCESHOULD SOLVE IT. WHEN THE FLOOR IS RELAID AND POLISHED ITWILL ADD VALUE AS AN ORIGINAL FEATURE PEOPLE PAY A LOT OF MONEY FOR THIS

 

[jeds]

Depends how much you want to spend but if you are renovating anyway it would be a false economy not to do the job properly. It would be hugely beneficial to insulate the concrete floor but if floors are level into the kitchen you would have to break it up and relay it. That's really only sensible if the floor is screeded which it probably isn't. A surface dpm is the next option. For the walls I would advise hacking off plaster and fixing a thermal laminate board. They can be fixed with adhesive but I would go for a mechanical fix to avoid any de-bonding. That will warm everything up, cut out any condensation and eliminate penetrating dampness as well. No battens or cavity necessary.

 

[HeidiHi]

We pulled up the lino and all the other stuff stuck to the floor this morning.

It looks like this so far

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• HeidiHi
• 12 Jul 2013
• 1

The surface of the flag stones look to have been damaged by the moisture so they are very powdery and flaky now.

Here's a pick of the rest of the kitchen floor that looks like it has been concreted over

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• HeidiHi
• 12 Jul 2013
• 1

Can the concrete be lifted from the floor without damaging the stone?

Presumably the stone floor has always let in the damp but back in the day it would have been kept at bay by draughts open fires and no lino... is it possible to keep it at bay these days? I am not planning to have any open fires, we've got double glazing but could run a dehumidifier.

 

[dann09]

Thank you for the pics,

1. Knock off plaster to window board height all round, and to the right of the window hack off to window head ht.
( FWIW: the window board appears to be dropping from left to right)
( you also have two kinds of skirting which might indicate previous work.)

2. You have stock brick with thin beds and perps - very difficult to point up.
But stock and thin beds makes it difficult for moisture to enter the wall.

3. The injected DPC is useless at that height, likewise the wild rise on the left - perhaps there was high soil there in the past.

4. Clean off all exterior brickwork - dont allow grime to accumulate.
Is that gulley hopper in use?

5. You will have to lift that floor ( no permanent dehumidifier's or wishful thinking) - once you have eased up the first flag it should be relatively easy to lift the remainder. The SLC(?) and screed will break away.
Its difficult to tell if any part of the floor is a true concrete slab - most probably its a S&C screed. But come back here if you run into difficulties.

6. Turning the flags over might reveal a clean, fresh flag face.

7. Stay away from notions of going over the top of the in place floor - dig down and re-lay on a membrane.

8. The insulated plaster board (above) is a good suggestion - but first, hack off, dig out and see what you've got.

 

[HeidiHi]

Thanks all for the very helpful advice.

The gully hopper is no longer in use... It used to be connected to the old bathroom drains but when the bathroom was refitted they drained everything into the soil stack and removed the old pipes.

I've been chiseling away some of the concrete on the kitchen floor so I can see where each stone lies but discovered that I only have stone in part of the floor, the rest of it looks to have been replaced unfortunately. I don't know what with (I'm assuming different layers of concrete). The bottom level is coarse and the top level is finer. In one section there appears to be a tar like layer between the coarse layer and the fine layer (and i can chisel the layers apart relatively easily), but in another section there is nothing between the layers and its much harder to chisel them apart.

Is this tar like stuff asphalt? And why hasn't it been used throughout the floor?

Anyway, unless any of you advise otherwise I think I'll get everything dug up and dug down and get a membrane put down. Then i'll need to decide whether to re-lay the stone floor (i'll need to find replacement stone for the missing bits) or concrete everything.

We are planning on knocking off all the plaster in the kitchen anyway so will follow the advice about replastering/insulating board.

Thanks again everyone!

 

[HeidiHi]

Also, just wondering if anyone would mind explaining why having a DPM underneath the floor is better than a surface one?

I'll be getting people in to do the remedial work for me so I'd like to be a bit more informed about both types so no one pulls my leg.

Thanks in advance!