Removal of tanking from cellar to expose stone walls

[Jane]

Hi
I have been removing the tanking render from a wall in my cellar and although the stone is very wet and the mortar has fallen apart in places the wall is starting to dry. Today I have removed the tanking at the bottom section in one area and water is puddling from behind the stone onto the floor. It is only happening in one area although the base of the stone wall is very wet . Will the puddling stop once the stone dries a bit more? I'm a bit devastated as this has been a nightmare to get the tanking off and now the wall leaks!
Any advice would be great please. The cottage I live in was built in 1700s but previous owners tanked all the cellar including the floor and steps down to the cellar. My intention is to lime mortar the stone wall once the tanking is off but I was going to leave the other walls because it is such a job. Thank you Jane

 

[a twig]

There are plenty of others on here with better cellar experience than I have so I will leave your detailed questions to them

If it’s any consolation - the wall was always leaking - you just couldn’t see it before, so you certainly haven’t made it worse as at least it can dry out now when it gets wet, rather than the water being trapped and deteriorating the stone.

Oh and photos always help

 

[Jane]

Thank you for your reply and for cheering me up! I'll upload some photos tomorrow
Jane

 

[Jane]

I have added some photos of the wall and the leaking onto the floor. It hasnt slowed any overnight but as you can see rest of wall is starting to dry slowly! Any advice would be great
Thanks Jane

 

[malcolm]

Removing the tanking was a good plan but it's disappointing you've got running water. I imagine someone put waterproof paint on there and had it flake off and decided that was a damp issue so they concreted the whole thing. The limewash had presumably worked well enough for the previous 300 years. If you were under the water table the floor would be a swimming pool and also they wouldn't have built the cellar in the first place. So that can be ruled out.

The cement would have been waterproof. A lot of water will have built up behind the cement and now it's getting it's chance to make it's way out. I've only experienced damp 12 inches underground which was bad enough but I guess a cellar will have enough gravity to make the water come out as a liquid at the bottom of the wall.

It will probably take a very long time for the walls to find an equilibrium and it's probably too early to be thinking about finding solutions. Can the project be delayed a few days or weeks to let the wall dry and see what happens? Don't worry about it as it will get better now that the concrete has gone and breathable finishes should be fine for another few hundred years or until the next occupant. Tea and Kit-Kats available in the PPUK cafe while the wall either fixes itself or tells you what it needs.

 

[Stevers]

We had water bubbling up like that at the base of a retaining wall in our 'garage'. That turned out to be a leaking drain confirmed one day when soap suds (nothing worse) were spotted, and now fixed by replacing the foul drainage at the back of the house. It could also of course be a leak from a fresh water supply pipe.

Some cellars are tanked because at least part of the floor (for natural and man-made reasons) is now below the water table resulting in hydrostatic pressure against at least part of the walls. It would be interesting to know what the previous owners inherited, and what they were trying to achieve with the tanking they put in, and how that had actually worked out by the time of your ownership.

It's also not impossible for local developments (building/highways/quarrying) to disrupt drainage patterns and render previously dry cellar wet. Information about how your home is set in its surroundings, if there's anything nearby that's changed, and whether it's low lying land with potential for a high water table might be helpful. Also if there are any other cellars nearby, how they're faring.

If there is standing water behind the wall then pointing with NHL mortar is unlikely to be enough to stop the water coming through. I have a leaking fresh water drain coming out of a retaining wall that I repointed all around in NHL mortar and I can confirm that for water retention purposes NHL mortar is much more like a sponge than a plastic bag!

 

[Jane]

Thank you Malcolm and Stevers. I have been working on the wall today and the water seemed to be slowing down and when I put a screwdriver through the gap between stones I couldn't hear sloshing water. However we then had a massive downpour and the water has gushed through again. I think I might need to get a drain checked out - the water coming in is clean.
I live in Co Durham - have you any knowledge of drain inpectors and what I should be looking for in terms of a company? Thank you Jane

 

[Stevers]

We had a broken and blocked rain water drain at the front of the house that we linked to damp floors in our tanked basement when it rained heavily, the floors being limestone flags and not tanked. Fixing the drain made a huge difference. It's a question of identifying all pipe runs round your house and then eliminating them from your enquiries. one by one, by whatever means available. We had the route and condition of a mystery disused drain located by a specialist with a camera and some sort of electronic depth sensor working back from the manhole. Draining into the same manhole the faulty drain had a junction in it (no inspection chamber) and the broken pipe was in a branch that he couldn't reach to inspect.

If you have a water meter in the road, check that it isn't spinning with everything turned off in the house. There are specialist leak detectives who do nothing else but find leaks and fix them. The YT channel https://www.youtube.com/@theleakdetectivemg is one example. His short and tongue in cheek vids will give you examples of pretty much everything that can go wrong with plumbing - quite an eye opener!

From what you've just replied, I suspect your first step should be to have a look at where the water from nearby downpipes go. Is it into a culverted stream in the road like ours does, or is it going into a soakaway that is old, blocked or just too close to the house. If the water from that pipe is diverted well away from the house (you can be creative here) does your leak stop?

 

[worms]

Jane, what is under the floor? It looks as if there may be something visible in one of your pictures. is this the edge of membrane?

 

[Jane]

Hi Stevers and Worms sorry for the delay but haven't logged on for a bit. I have just had a drain survey done but they have not included two gullies which join to main pipe to take away kitchen water, rain from drainpipes etc so I am currently disputing the survey as in my view it should
Include the gullies. All water from downpipes goes through gully to main pipe. The floor does have plastic under it as it also has a ton of concrete on top! The ground in the cellar is heavyclay and so absorbency of water is poor. I am currently taking off next render on wall and I think a section of the floor might need to come up to see underneath. I havepointed all cracks in paving this week and so hopefully this will rule out surface water but it is still leaking quite badly. Do you think it could be water that has just sat behind stones ? The water is clean but strugg.ing to find its source!!
5hank you for your replies
Jane