Solving kitchen floor damp

[turnpike]

Hi all,

I'm trying to sort out a damp problem in my kitchen but have found a few different possible causes and I'm not sure which to put at the top of my list, or if I'm missing anything.

The main issue is damp concrete floor at one end of kitchen (if it is not allowed to breath), and two corners of the room where a couple of bricks look permanently damp.

The plasterboard (dot and daub) on the effected wall was touching the concrete floor and was damp up to about a meter. There was a condensation problem too. I've had a radiator added and will also put an extractor fan in.

The concrete floor has a thick plastic sheet under it on most edges, but along the effected wall I can't see it. The floor is higher than the DPC of the outer cavity wall. I can't see if the plastic sheet is linked with the cavity wall DPC. The drive outside is one row of bricks lower than the DPC.

When I pulled up the old vinyl tiles and the cheap lino, the floor was damp in one 2 metre squared area. It has dried out but damp patches appear if you leave something on the floor.

The worst area seems to coincide with where the kitchen sink was, where the old lead pipe water mains comes in and the gutter outside.

The bricks outside the kitchen show signs of salt and damp. I don't use the gutter anymore which has all the salty white marks above it.

I don't want to just inject a damp proof course or use liquid dpm on the floor until I know where the damp is coming from.

This is what I'm considering:

1. Stihl Saw a channel in drive along side outside wall and fill with gravel.

2. Remove stone box (8" by 8") around soil pipe and check for leaks and/or replace.

3. Remove random bit of cement around other drain pipe (bathrrom and guttering) and check for leaks and/or replace.

4. Inject damp proof chemical in affected area

5. Replace all drain pipes or just sections to begin with.

6. Replace lead water pipes (want to do this anyway. I have a second supply with it's own meter so suspicious of leaks where that joins).

Does anyone have any ideas of suggestions? Sorry for fairly lengthy post but trying to mention everything I've found so far.

Photos (worth a thousand words) to follow.

 

[JohnD]

you mention a lead pipe so I guess you have an old house.

the concrete floor you has has a plastic DPM under it so must be more modern

If it was a bodged job the DPM might not be lapped up high enough to isolate the floor from the ground and the wall. Most people know how to do it properly though.

I would suspect a leaking pipe in the floor.

However, if it has been covered with vinyl or something it might just be that it has never had the chance to dry off. Take up the vinyl and put some sort of loose matting down so the floor can breath, give that a try.

I am just a householder but, as it happens, I had a 1920's house where the kitchen floor was wet in one corner. As this was under the leaky sink the surveyor assumed it was just caused by that. However we later discovered the old water pipe was pinholed in the concrete floor under the sink. Later still we found the yard gulley immediately outside, for the kitchen sink, was broken and leaking and the ground and wall were saturated

A pinholed water main can often be heard by the faint but continuous hiss, which stops if someone turns off the outside stopcock. Young children may be able to hear it as they have better ears. You can also test for it using a glass of water under the tap. I will try to find a description already written of how to do that.

edited

here we are
//www.diynot.com/forums/viewtopic.php?t=50437

//www.diynot.com/forums/viewtopic.php?t=74661

//www.diynot.com/forums/viewtopic.php?t=69805

 

[turnpike]

View media item 7090128 - Outside wall. I hacked at the cement a bit in a suspect area but stopped when I realised I'd need a stone saw to do the job properly. Stone "box" around soil pipe looks like a bodge? Bricks stay damp during dry weather. This is where the damp corner in kitchen is. Also roughly where water pipe goes in below.

View media item 7091129 - Messy pointing.

View media item 7092130 - Soil pipe and gulley. Gulley not going to be used anymore.

View media item 7093131 - Drains for bathroom and guttering. Damp from this corner appears on inside (inner leaf) cavity wall.

View media item 7094132 - Iron? pipe worse for wear.

View media item 7095133 - Hopper

View media item 7096134 - Damp bricks near water mains and in line with the damp shown on photos 128, 129 and 130

View media item 7097135 - Damp bricks on internal wall close to damp shown on photos 131, 132 and 133

 

[turnpike]

Thanks John. Really helpful. I've had the old tiles up for nearly 2 months now. The situation has improved but I still think there are two corners where a couple of bricks stay damp. The floor gets damp if you leave something not breathable on it. I will give it more time though as you say.

 

[JohnD]

your pictures are too small.

If you go to your album you will see a link called
DIYnot BBCode:
which looks like
[net]24560/980_73500751.jpg[/net]
and if you paste this into your post you will get a thumbnail like
View media item 653and if you right-click on it you can open the pic full-size



see also
//www.diynot.com/forums/viewtopic.php?t=129539

p.s. You very likely have cracked or broken iron or clay pipes or bends under that concrete. It looks wet. Dig it up and have a look.

 

[turnpike]

Photo links fixed.

Ok so current plan is to cut a channel out from drive along side wall and also clear away what looks like the bodge job of cement around both pipes. It does seem too much of coincidence that both damp walls inside are next to the drain pipes.

Cheers.

 

[PerryOne]

The concrete outside needs to be cut back about 15 inches and dug out to make a french drain. French drains are merely trenches filled with clean stones, the rain hits the stones and disappears, whereas rain hitting the ground will bounce up and make the wall wet above the dpc. The top of the stones needs to be 6 preferably 12 inches below the dpc.The wall should be painted with silicone to shed the rain and allow the wall to breath and dry out.

The internal concrete floor, can be painted with waterproof floor paint and dusted with sharp sand to provide a key for a thin self levelling cement based coat. It is likely that the people fitting the slab could not be bothered to continue the dpm and seal the area under the sink. Having wrote that, it may well be that there is no dpm under the slab merely a strip of plastic round it on three sides.

The plasterboard should be ripped off and the wall studied for rising damp, or water/rain penetration. The fact that the damp has risen to three feet above floor level, indicates rising damp, that can support itself to a height of four feet. Sealed in it will rise higher. It is likely that the floor is bridging the dpc and making the wall wet. Cutting the slab back along the wall and installing a dpm may well solve the problem.

It can take a year or more to be certain that a damp problem has been solved, sometimes there can be more than one problem, do check that the roof, chimneys and guttering are all working properly.
Go up in the loft with a bright light and check the rafters and joists are not showing signs of damp, especially check any fibre glass insulation that may be used to hide a leaking roof.

A cream dpc may well solve part of the problem , make sure its inserted as close to the floor as possible. Keeping in mind that the wall will still be damp below the cream line.

 

[JohnD]

interesting points, PerryOne, but you seem to be skipping over what I consider the first thing to do, which is tracking the cause of the wet and rectifying it.

The cause is very likely to be cracked gullies and/or leaking pipes. No amount of damproofing chemicals will help repair them.

 

[turnpike]

Thanks.

I'll try creating a french drain and digging around old downpipes to check for leaks and consider replacing. If I replace the surface water and guttering drain which goes into the hopper, I'm guessing there's a better way to do that now rather than an overloaded always blocking up hopper..?

I'm also considering removing a couple of bricks and clearing out any debris in the cavity near affected areas.

 

[swbjackson]

The concrete box is a typical bodge when the collar on the soil pipe cracks. Before spending any money on french drains and the like you need to sort out the soil stack and downpipe. It's no coincidence that the damp is occurring where they are located.

Mike

 

[Symptoms]

Pike - I'm with swb on this one. First tackle the 'easy stuff' - take a look at that hopper head and what's being discharged into it. Bath discharge, basin discharge, rainwater downpipe from main building, gutter discharge from extension roof and maybe (but it's not clear from the pic) discharge from garage roof. The condition of the CI pipe looks suspect so it could be that you're getting leakage from poorly sealed joints (hopper head & low-level socket), cracks to the pipe or pin-hole corrosion at the rear of the pipe. You could be getting water running down the back of the pipe, hitting the lugs on the lower socket and bridging to the wall.

Pin-hole corrosion is often overlooked as a cause of this type of problem 'cos the holes are at the rear of the pipe (caused by lack of paint protection over the decades 'cos it's difficult to get a paint brush around the back). This type of damage goes un-noticed as the only sign that they exist is when the pipe is full of water (who goes out in the rain to examine pipes?). Hydraulic pressure in the pipe forces a very, very fine jet of water to spray through the holes thus wetting the wall. As a result the wall will always be wet (jet at bath time, jet maybe when the basin empties, jet when it rains).

 

[turnpike]

Thanks for all your suggestions so far.

I decided to try to investigate the damp near the soil pipe and gulley first. I've not been able to spot any water coming down the pipe and am assuming it is a leak within the concrete box and joint between the pipe and ground collar.

Symptoms: I think you may well be right re: the hopper pipe as I can see greenish leak marks on it from a couple of feet up. It also looks like the water is spashing over the top of the hopper. I've never seen this come close to happening but I can see the evidence. I'll look into that more once the other main damp is fixed.

I've removed what I think was a concrete bodge box and found that the iron soil pipe was "hanging" inside a clay collar which was above ground level. The clay suround and joining cement? material between it and the pipe didnt look in good condition. I've broken some of the above ground level clay circle now as a result of removing the concrete it was encased in. I'm not sure my timing of a sat afternoon was great for this job!

I'm happy with doing this as the concrete box around it was bridging the dpc and right up against the wall near the damp anyway.

The whole area looked wet so I think theres a 50% chance this is where the water is from. If it isn't this then it may be deeper.. the lead water main supply which I am looking into getting replaced.

I've got a Marley Soil to Drain adapter to reconnect the pipe and clay but looks like I'll have to remove the bottom section of iron pipe to get the adaptor on.

View media item 7268
View media item 7269
I've cleared the upper layer of stone driveway from around the whole clay pipe since these photos. The affected area ground level is now 2 or 3 inches lower and the correct 6 inches from dpc and has started to dry out well.

 

[turnpike]

It's been a while but I will post some updates/photos on how I'm doing with the damp problem.

Perry, regarding "rising damp"ness. It only looked like that on the plasterboard. The walls weren't wet up to a metre, just the plasterboard (and that was wrongly touching the floor. Does that change things? However, this one side of the floor does get damp if you leave anything non porous on it.

It's occured to me that the plastic showing on 3 sides could mean that the one edge against the external wall is in fact correctly lapped into? or up to the wall dpc? In other words, maybe not seeing the plastic sheeting coming up on the side of the concrete floor which contacts the external wall may mean it has been correctly fitted?

I know for sure there were condensation problems. If I decide to go with plasterboard again I'm thinking vapourcheck on battens as opposed to dot and dab. Perhaps I should be going for proper cement plaster with additives for damp/salt etc? Doing that seems drastic as it would be much harder to remove if problems came back.

I've cut a channel outside along the wall but only 2 inches lower as there is yet another layer of slabs and what appears to be clay drainage making it difficult to go lower.

I'm going to repoint bricks in damp areas and take the opportunity to remove a couple and try to check for cavity debris.

I've replaced the downpipe and hopper with plastic. It was definitely part of the problem as the pipe stopped above the ground level and the join was just a dollop of cement which was in contact with the water and the wall. The pipes leading into the hopper were also directed badly and overshooting. The cast iron was very old, rusty and leaky anyway. I've also dug up the soil pipe ground area (photos above) and found it was indeed causing damp via the cement bodge box which joined it and the wall. The pipe didn't even reach down enough to go into the clay. I'm replacing the last section with plastic and an adaptor.

I've got the water company coming to look at the replacement of the lead water supply pipe. It needs doing anyway (based on test results of water quality).

I'm considering using a liquid dpm on the concrete floor but then again it seems to me I should just go with concrete and quarry tiles to let it breathe. I'd like to have a wooden floor but I can live without it if it's more sensible to do something breathable and which won't be damaged by water. Any thoughts?

Cheers!

 

[turnpike]

Replaced downpipe and hopper.
View media item 7653
Replaced section of soil stack. The clay bend starts straight away after ground level and the whole bend is cracked badly so I guess I will need to repair? with some sort of sealant or have the whole thing taken out.

View media item 7652