Damp stone wall / concrete infilled floor

[Ian Tinkler]

Hi all,

I've just purchased a c1850's stone built cottage, with 1980's brick extension. There is extensive damp in the older stone part (low on walls, to 1ft up). No visible DPC. Although there are issues with guttering, high ground levels, stack etc. that I will fix, strangely the external walls in the same room are dry( suggests to me levels are not the main cause). The walls immediately around the fireplace is also dry (so stack may be OK).. There is also damp on an internal brick partition built inside the old stone part of the house (suggests water penetration from rain is not the main problem). It's been gypsum plastered over in a lot, although there seems to be some lime patches left (whiter colour) but these are still damp.

Since the usual causes seem ruled out, at least as prime causes, to me, this hints at another prime cause of the damp: the concrete floor poured into the old stone part of the house. The concrete floor itself seems bone dry. However, it may be preventing ground moisture escaping, except at one point - the join between the stone wall and the concrete.

My theory is that the moisture is being wicked up this join - and there is moisture in the ground under the concrete and there is nowhere else for it to go. Gypsum plaster / non breatheable paints have made things worse.

Obviously the main solution is ventilation / lime plaster + breathable paint. However, to my untrained eye the walls seem very wet and this alone may not solve things alone - it's a risk it won't work and I'd rather get it right first time.

I have 2 questions
1) Is my theory plausible, or am I talking *******s.

2) If I'm not talking *******s, is there a solution to stop water moving from under the concrete floor into the more porous stone, that doesn't involve removing the entire concrete slab. The less intrusive and expensive the better. I won't get a chemical DPC or concrete render to 'block' the damp. I don't want to damage the wall or cause the damp to reappear higher up at a later date. Anyone with any experience of this? Can you describe what the options are.
Edit: pics here:
https://www.diynot.com/diy/media/albums/a-damp-house.26913/
Thanks so much in advance!

Ian

EDIT: Turns out the party wall is brick, no visible DPC. Internal wall with most damp also brick. Stone walls to front and rear (external) both damp but dryer.
Humidity level in air was 75%. A day with the heating and dehumidifier took it down to 55%. Exposed bricks with plaster off visibly drying after a day.
It may have been empty for up to 3 years according to neighbour. Agent said 8 months... would explain it being a bit cold and damp.

 

[bobasd]

why not post pics of the damp areas inside the cottage and pics of the outside?

would also help you if you read the Related Threads at the bottom of this page, and at each of their pages - and used the search button.

 

[Ian Tinkler]

would also help you if you read the Related Threads at the bottom of this page, and at each of their pages - and used the search button.

I have read them. They are not the same. If you can find one with the same exact circumstances as mine, please could you share the link.

Thanks!

 

[Ian Tinkler]

why not post pics of the damp areas inside the cottage and pics of the outside?

Fair point, didn't know I could do that. Will do, cheers.

 

[Ian Tinkler]

Pics are in this album, thanks in advance!
https://www.diynot.com/diy/media/albums/a-damp-house.26913/

 

[JohnD]

you can copy and paste pictures into your thread.

 

[bobasd]

thank you for the photos. perhaps you will do as johnD suggests?
you would help yourself if you stopped talking about whats to be done and simply said whats wrong - if you know whats to be done then why come on here?
does the new extn have cavity walls.
are there chimney breasts on the ground floor?
can you show pics of the high areas of ground level?

carefully remove the skirting and hack off the plaster to a height of about 1m in all suspect areas.
lift and remove any damaged flooring.
can you gain access to crawl under the floor? traps are often under the stairs.
are there air bricks venting the suspended flooring?
do you intend to rip the kitchen out?
if the carpet is going then rip it out now - to expose the flooring.

 

[JohnD]

Since the usual causes seem ruled out

nope.


there is such a lot of water showing that I suspect a leaking pipe under the floor. Do you have a water meter?

 

[Ian Tinkler]

thank you for the photos. perhaps you will do as johnD suggests?
you would help yourself if you stopped talking about whats to be done and simply said whats wrong - if you know whats to be done then why come on here?
.

Fair points. I didn't know the photos can be in the post. I just wanted to say what I was going to do so as not to waste people's time with answers like 'have you checked the gutters'
I don't know what needs to be done - I think I did suggest I may be talking *******s

are there chimney breasts on the ground floor?
can you show pics of the high areas of ground level?

carefully remove the skirting and hack off the plaster to a height of about 1m in all suspect areas.
lift and remove any damaged flooring.

1 chimney breast, there were 2, another 1 was removed c1980.
Getting on with the plaster now. It's actually a brick party wall and a brick internal wall that are by far the dampest. Turns out it's only stone on the front and back walls and they are comparatively dry (still damp).

can you gain access to crawl under the floor? traps are often under the stairs.
are there air bricks venting the suspended flooring?
do you intend to rip the kitchen out?
if the carpet is going then rip it out now - to expose the flooring.

No - solid concrete floor, not suspended. No air bricks visible. 1 blocked vent, plus evidence of another at the back where a stone has been re-placed. Surveyor reckons was ventilation for the fire but blocked up.
Carpet - yes done, kitchen is going but that bit of damp is at the end. Kitchen is in the modern part, fairly sound apart from one small bit.

Thanks for the help - I'm not being sarcastic about the stuff above - appreciate the tips on forum etiquette, I'm just new here

Cheers!

 

[Ian Tinkler]

nope.


there is such a lot of water showing that I suspect a leaking pipe under the floor. Do you have a water meter?

I've ordered a resistance based one yes - I really hope it's not that since that's my budget gone on digging up concrete.
The damp is quite widespread, not localised in one place. Neighbours house is a mirror image, turns out they have damp in exactly the equivalent walls, to the same extent. They furthest apart walls that are damp from them to me are about 10m. I'm hoping if it was a pipe, it might be worse in one place? Or could it spread evenly over a large area?

Thanks for the advise, really appreciate it.

 

[JohnD]

If you replace a pipe, the new one does not have to follow the same route as the old. For example, you may have access past the side of the house.

Your concrete floor might not be very thick or very strong.

What do you mean by "a resistance one?" I mean a water meter that measures the water flowing from the watermain into (or under) your house.

Have you got a stopcock outside the house?

 

[bobasd]

so, all the floors are solid?
the wood flooring is laid on solid concrete?
is the wood flooring staying or going?

now you have removed skirting, and begun to hack off - is there anywhere in the property where can you see the edge of a plastic sheeting membrane (DPM) just behind the skirting?
any damp is damp - whether its light damp or wet damp its damp. thing is to find out why its damp.
chimney breasts and the wall where a c/breast was removed, and the hearth areas in front of them (if the hearths still exist) need pics.

when the kitchen is gone then more pics of the kitchen walls.

 

[Ian Tinkler]

If you replace a pipe, the new one does not have to follow the same route as the old. For example, you may have access past the side of the house.

Your concrete floor might not be very thick or very strong.

What do you mean by "a resistance one?" I mean a water meter that measures the water flowing from the watermain into (or under) your house.

Have you got a stopcock outside the house?

Sorry I confused water meter with damp meter. Yes there is a water meter - I misunderstood. So check if the water meter is moving even with all the water off right?

Stopcock is inside.
Will see what the water meter is doing and get back to you. Will read tonight and again tomorrow pm and see if we've used any water with taps off.

Nice one
Thanks

 

[Ian Tinkler]

so, all the floors are solid?
the wood flooring is laid on solid concrete?
is the wood flooring staying or going?

yes, parquet on solid concrete. Bitumen bonded, now loose as the bitumen has degraded.
Going - some rot and woodworm in the edges. Most of it seems OK, will store it for now and decide.

 

[JohnD]

clean the meter and illuminate it with a torch.

if it is the type with a glass window, look at the window. Can you see an air bubble? Is it moving round and round?

Movement indicates water flow. If it moves even when you stop using water, you have a leak downstream of the meter.

A leaking drain will not show.