Damp Problem - I'm not sure what to do...

[JoeS]

I'm sorry for asking a question like this on here...but i know there are some great experts on all things building and construction.

Have a downstairs toilet which is a brick lean to which leads from the bathroom (part of the main house). There is a good extraction fan which is now running (Although was broken for a few months, my son didn't tell me). We've owned the house 5 years. Careless children tend to shower with the door to the bathroom open - the walls of the toilet are often very wet with condensation after someone takes a warm shower during winter.

The toilet has always been abit damp - its a single skin brick build lean to which was originally the outdoor bog. But with a coat of eggshell, very occasionally in the winter we give the walls a bleachy wipe down and never had any more issues. We never really had any problems in the bathroom either although my moisture meter always shows walls are a bit damp in the winter, but in summer they dry out. We've never had paint peel or mold form. An ambient moisture detector in the bathroom/toilet shows moisture is at 83% at 18 degrees this evening - the walls throughout the bathroom/toilet show moisture using a pin moisture meter (in masonry mode) at about 19-20% versus 15-18% in the rest of the house. The single skin toilet wall shows a reading of about 24% but the paint never comes off the wall...and It's an ancient single skin lean to.

In February last year I noticed under the bathroom rail that the towels sit on that the emulsion paint was bubbling (adjacent to the toilet!) so decided to scrape it off, give it a coat of zinsser and then a coat of eggshell. I assumed wet towels had just made things quite humid under there, and that a coat of paint would fix it. I was pleased with my work...

...but this paint has almost immediately bubbled.

And alarmingly the wall that joins the bathroom to the toilet has now started going completely furry with salty damp patches of soft plaster which are a little yellowy/brown. The damp meter but the reads at 26-27% on this wall all the way upto about 6 feet where the reading goes back to 22-24% of the rest of the bathroom. This doesn't seem to be a drastic difference to be, but i know these pin moisture meters aren't that reliable.



I've been next door to check what is going on the adjoining wall – which is also a bathroom, but they have no issues or obvious leaks, I checked under their bath, everything was dry.

What i cant' work out is why this wall (which makes up the doorway) seems to much damper than everywhere else in the bathroom. It is an internal piece of wall, there is no water supply, the damp appears to be coming from the ground. Is it caused by this being where the warm air from the bathroom meets the cold air of the toilet? It seems unlikely considering that this problem also seems to be occuring on the bathroom side of it. Could a damp course have failed on an internal wall like this? I suspect not having the heating on now for probably a year hasn't helped... the rest of the house gets blasted by the log burner when it's cold.

Can anyone suggest what I should be doing here? Thanks so much, Joe.

 

[Adam W.]

Have you checked the drain from the toilet ?

Edit:

And the buried plumbing for the radiator.

 

[MARK.B.]

Looks to be rising damp and that area of wall has become saturated with water,you need to find the source of the water,is there any pipework under the floor in or near that area that may have developed a small leak ?, is the brickwork/pointing on the external wall in good order?,are there any drainage pipes leaking?. until you can dry out the wall and keep it dry you are wasting your time/effort and money by painting as paint will always peel off a wet/damp wall and can also seal the damp in preventing it from drying.

 

[Woody2Shoes]

I would be checking roofs and gutters. Especially where the leanto roof joins the main back wall. Rising damp is hugely less likely than falling damp!

 

[rogxwhit]

It seems to me to resemble a classic case of condensation dampness. It's a big cold bridge area to the main house and would be better if it could be insulated - perhaps externally - walls and roof? But eliminate any flashing / tiling / gutter problems first.

 

[JoeS]

Roof really looks fine on the lean to and the pointing also doesn't make any sense...the damp is definitely coming from the bottom, the wall is much drier at the top. I'll have another look at where the lean to joins the house, but i just don't think it makes sense.

Perhaps the radiator pipes are the source...or even the toilet waste pipe...but that will require ripping up the tiles That will be fun and hugely expensive. Unless there is some magical way i don't know?

Thanks for all your replies gentlemen - this is a great resource here.

 

[baldkev]

If i understand it correctly, that internal wall is coming off a single skin external wall?
If so, is there any vandex or attempt at waterproofing to stop it being wet?

 

[Bingy man]

I’d echo the above posts and check all external drains and manholes ( foul and storm water. Gutters / down pipes and external pointing . Are you on a lead water main ? Is it shared with your neighbours? Again as above any pipe work in solid floors is at risk of corrosion and of course water can travel a long way and show up a long way from the source. Your damp course is likely no more than a bit of old slate laid along the course of bricks be it double or single. There are many concrete floors laid on ash infill with no damp course whatsoever. You need to find the root cause of the problem then work out how to put it right-good luck .

 

[sawdust1]

Also check external ground level to see if higher than inside.

 

[owen]

If you can't find any o causes, hack off the plaster, tank the wall with a waterproofing slurry, build it out with renovating plaster then skim coat over the top.

 

[Woody2Shoes]

Is the part worst affected actually a boxed-in section of vertical soil pipe run? If so, plumbing related?

 

[Jameshow]

If it's only come up recently and not previous winters then I'd suggest a leak. You need to find and isolate the leak otherwise any other works will be futile.

 

[JoeS]

Is the part worst affected actually a boxed-in section of vertical soil pipe run? If so, plumbing related?

I thought that might be it...but actually the boxed in section of soil pipe is next to that section. The problem is...there just isn't any way of doing this non destructively... i suppose lifting the tiles might be the cheapest and easiest thing to do first. I never liked them anyway hahaha. Don't think i can stomach it this year.

 

[MikeJhn]

If the moisture meter high reading is 6ft up the wall it is most definitely not so called rising damp, does the boxed in section of wall have a soil or rainwater pipe inside it, if so a leak from that may be the problem.

You will note I said "so called rising damp" reasoning, rising damp does not exist, it is almost always other problems, gutters or splashed rainwater from a hardstanding below the wall, one I investigated was a blocked surface water drain in the road outside the building that passing vehicles splashed water onto the wall, but that was extreme with the road close to the building, inevitably its gutters, downpipes or a buried service pipe leaking.

 

[Bingy man]

I’ve just been to see a issue quoted as (-rising damp) , house has been re plastered with no signs of damp elsewhere- turns out the bathroom is next door and the house has been unoccupied for several months . Traced the problem to the shower which is piped from the loft with the hot/cold buried in the wall behind the shower- it’s been leaking for years but has only just showed up - the wall is now saturated with water and I’m fitting a new temporary shower as the bathroom will have a full makeover next year . So as said above find the root cause and go from there.

 

[Adam W.]

I thought that might be it...but actually the boxed in section of soil pipe is next to that section. The problem is...there just isn't any way of doing this non destructively... i suppose lifting the tiles might be the cheapest and easiest thing to do first. I never liked them anyway hahaha. Don't think i can stomach it this year.

As I said up thread, look at the plumbing as it's an internal wall with plumbing close to it.

Pressurise the heating system.......If the pressure falls, you've got a leak. If it doesn't fall, you haven't got a leak and you can rule that out.

As for the drain, that initially requires looking at the joint between the white plastic pipe coming from the toilet spigot and its connection to the drain, which means taking out the toilet, extracting the white pipe and doing a visual inspection. No digging required for these two initial inspections.

 

[redhunter350]

I have not read all the posts but it seems to me there may well be several points to look at, single skin wall -- this needs a damp repellant medium applied on the outside, is there a damp course to prevent rising damp ? if not a chemical one can be added very successfully. Also as some did mention the buried plumbing needs checking out.
If you need damp proofing its worth contacting these folk or their recommend agents/partners, there is a local contractor who has done work for us several times over the years and all very successful -- to far away from you but contact the parent company for advice on local agents Home - Sovereign
Home this helps

 

[dgs2001]

Redhunter350, please stop thinking Rising Damp.
Quite simply "Rising Damp" is a myth.

In order to work out likely cause there are a several questions to go through -
1) Prior to the damp first appearing, was this room just like it is now (new paint aside)?
2) Has anything changed in this room and or adjacent spaces? (Anything means Anything no matter how unconnected it may seem! (ie have some slabs been put down outside along the single skin wall)
3) Is your heating system a 'sealed system' or an open vented system? - If open vented have you checked the small tank in the loft to verify its not constantly trickling water into the system, if sealed system have you had to top it up lately?
4) Once these questions are answered then a temperature/humidity meter may be handy to record what's going on in the space.


As others have said this is highly likely to be caused a plumbing leak or an incidental occurrence adjacent but elsewhere

Hope this helps focus your efforts and finding the problem.

 

[Adam W.]

Snip/ Redhunter350, please stop thinking Rising Damp.
Quite simply "Rising Damp" is a myth.

/snip

Except where you have a wall/floor without a functioning DPC/DPM, then you get moisture from the ground being transmitted to the wall/floor.

It's not as cut and dry as people are led to believe.

 

[Lard]

You will note I said "so called rising damp" reasoning, rising damp does not exist, it is almost always other problems,

Quite simply "Rising Damp" is a myth.

The pair of you both missed out some very important words there.....ie "in my opinion".

During my working years both I, and colleagues, investigated hundreds of cases with external damp/internal condensation issues. In our opinions many of these WERE and many of these were NOT rising damp but all of us, being level headed persons (employed to undertake such roles) were not conceited enough to flat-out ignore the possibility.

I also look forward to reading your proof of 'flat earth' and other narrow minded beliefs. In my personal opinion I believe it's all nonsense but I'm always up for listening to any well presented argument and, in my opinion, you shouldn't either.