Rising damp on internal wall, concrete floor

[SusanMoore]

I've started decorating in my living room and notice that the skirting in the middle of one of the internal walls has started to rot. The wallpaper peeled off really easily, and I could see faint water stains up to about a foot above the ground. The plaster seems sound.

I've had one guy in to give a quote. He pointed out a pale blue/green section of plaster on the wall and said this was a special treatment used for damp - so the people who lived here before me must have had problems in the past and had had work done.

He also reckoned that this blue/green plaster stuff wasn't very effective. He quoted me 1200 pounds for knocking all the plaster out up to about a metre (this section of wall is about 5 metres wide) and redoing it with some special anti-damp stuff (I didn't really understand how this is different to the bluey green plaster that was already there, but he reckoned it would be a much more effective solution).

I'm waiting on some other quotes, but thought I'd best read up so I know what the next bloke who comes to give a quote is talking about ... but now I'm even more confused.

I read that the rising damp could be if something (eg plaster) was breaching the damp proof course ... but do internal walls have DPC? I thought it was just external walls?

If the plaster is sound, does it really all need to be taken our and re-done? It's definitely not crumbling away.

What's the best way to treat something like this? I've been reading about putting damp proofing membrane on that part of the concrete floor, with about an inch going up the side of the wall. I've also read about some sort of anti-damp sealant that you put along near the bottom to stop the damping rising any further up.

Any help please?

 

[JohnD]

show us some photos.

your problem is that you have some water appearing. You need to find the source and fix it. Popular sources are paving or flowerbeds above the DPC on outside walls, overflowing gutters, leaking pipes.

Water pipes commonly run under the floor, from where the outside stopcock used to be, to where the kitchen sink used to be.

How old is your house?

Do you have a water meter?

 

[SusanMoore]

Thank you so much for answering. Here's some photos.

It's a 1960s semi, no no water metre.

My hall and kitchen are on the other side of the wall. I've checked them, but no sign of damp. I don't *think* there are any heating pipes in that bit of wall (I tried working out by following where the radiators go). Not sure if there's any chance of there being pipes in/under the concrete floor?

 

[vinn]

Did the damp man suggest the cause of your damp and its history?
Your pics show signs of damp on two walls.
The skirting and the plaster do suggest that previous remedial repairs have taken place.

You should remove the plaster back to masonry to a height of 1m along both walls.
Re-plaster with a render mix of 3:1 sand & lime.
Break render contact 50mm above the floor.

Post close-up pics at the skirting levels on the other side of the walls in the kitchen and hall.
Do you have any suspended wood floors in the house?

The DPC injection fashion nowadays is for injecting tubes of chemical Dryzone for instance - its simple to do for a DIY'er.
Is it any good, does it work? Be my guest, I dont know.
You might have a physical DPC thats been bridged by the old plaster.
But I think your problems stem from rising damp coming up at the edge of the concrete slab.

The S&L render will give you 20yrs trouble free from damp signs to the decorative finish.

 

[SusanMoore]

Hi, thanks for the reply. No, the damp map just scanned around with a hand held metre. It was much damper at the bottom than further up, and he seemed confident it was rising damp.

So it would be the sand + lime plaster until 50mm from the bottom, then that 50mm gap at the bottom they'd fill with the DPC injection stuff? Would it matter if the skirting went higher than that 50mm? ie would the damp be able to work its way up the skirting and into the wall? Would there still be a problem with the carpet or bottom of the skirting getting damp if it was touching the concrete floor? (not that the carpet seems damp at all)

 

[vinn]

The new treated skirting has to go higher than 50mm. The skirting can be kept off the floor by a few mm's.
Only you on site can determine the state of the floor but I'd just go ahead & relay the carpet, & keep an eye on it.

 

[JohnD]

so it's an internal wall.

1960's, solid floor.

Do you suppose the incoming water main runs in the floor on that room, or in the adjacent hall and kitchen? Pipes are certain to go to the kitchen, on a route from wherever the external stopcock is.

Have a look at the concrete floor in the adjacent rooms. you may have to lift floor coverings.

Can you think of a source of water other than the plumbing? For example is your house built on a hill so water runs down it? Or in a dip subject to flooding? Or next to a stream?

 

[SusanMoore]

I got my neighbour to take a look and he's pretty sure there are no water pipes round that part of the wall.

Another man came to give a quote and reckoned 500 for the same work - knock the plaster out up to 1 metre, put in an air membrane, plaster over, inject some DPC cream into the foot of the wall.

But then a third man took a look and said the problem was that the plaster was touching the ground, so bridging the DPC. He said I should just chisel out the plaster to leave an inch gap from the ground and the problem would be solved - the plaster higher up didn't need replacing because the damp was only quite mild.

So today I got my son to do that and I'm even more confused now. There's a layer of something black and rubbery. I thought it must be the damp proofing but my son thinks maybe its the remains of the black tiles that they have under the carpet. Either way it's crumbling out. I can also see bits of thin plastic sheeting poking out ... I wonder if the previous owners of the home had put this down to try to fix it on the cheap?

 

[Bri6]

Please have a look at this site and he also has some videos on the subject of RISING DAMP which he advocates there is no such thing. Don't get riped off with damp proofing that may make matters worse.No, i haven't used them or work in the industry i was just intrigued when I watched some of his videos.
http://www.heritage-consulting.org/

 

[SusanMoore]

Yep, I'm aware of his videos on youtube. He comes across as a bit of a nutter, although I'm not completely discounting his claims. It certainly seems to be true that a lot of companies make a lot of money from damp work, but I don't buy the idea that it's some big global conspiracy.

It also doesn't explain why I have dampness at the base of my wall that can't be explained by any leaking pipes or condensation.

 

[JohnD]

can't be explained by any leaking pipes

...that you know of.

 

[SusanMoore]

Yes, very true, but I'm relying on the advice of 5 different people who've inspected it and don't think this is the issue.

 

[JohnD]

were any of them trying to sell you "damp proofing" treatments?

The water must be coming from somewhere. If you can find the source and stop it, you won't need damp proofing.

 

[Turnsnip]

I just had to have a lot more than that done as a condition of my mortgage on a house I just bought. £985 it cost for a PCA registered company to do everything bar remove and refit the skirting with the guarantee the lender wanted.

I was very sceptical until a load of plaster came off with a length of skirting along the internal wall (no water pipes anywhere along that side) and the brickwork behind was full of salt and soaking wet to the touch. Clearly rising damp is a thing but will these silicone injections do anything about it? I think the main fix is probably the porous plaster they use which allows the wall to breathe and moisture to escape.

We will see.