Are these Pipes the likely culprit of this damp patch

21 Feb 2014
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United Kingdom
Short version: Ripping out very old kitchen, a particular cupboard ground level has always smelled damp inside, its wooden sides were its legs and it fell apart when i messed with it, it was very damp damaged on one side in particular, images attached. Wall behind it is obviously very damp in the corner, next to the main water main and stop tap, and where the pipes go into and under a concrete floor to the other side of the room where the provide hot and cold water to sink, washing machine and dish washer. Wall has salty deposits on it, im guessing its been this way for some time?

a bit more detail, the damp point is a join between an extension and the main house, in the inside corner of an L shape, however, the kitchen side of the corner is damp, but the dining room side of the L is dry this makes me think that its less likely the damp is from the outside, as if water was pooling in the corner outside surely it would get both walls? the dining room sits on a raised wooden floor, which is clean and dry looking at it but i cant see the wall. the kitchen floor has been filled in with concrete which spans into the extension part. The extension is 2 story and there is no sign of damp from the roof in the bedroom upstairs but ive yet to properly inspect it, but the roof looks in good shape, ive been up there and inspected it in the summer, not that i'm any kind of expert. Also the ground level is defo below the damp course. although im sure that doesnt always stop it.

there is no other damp along that wall or along the floor only near the pipes, but the damp does seem to be off to the right of the pipes, not surrounding the pipes, but i suppose the bits surrounding the pipes were ventilated where as the bit thats damp was covered by the old kitchen which could explain it, anyway, take a look at the pictures?

im fitting a new kitchen soon and dont really want to fit over damp walls, which is one reason i need to cure it, also im having all the pipes except for the mains pipe moved and they will go through the ceiling instead of the floor, due to me moving the boiler. so im hopeful it will dry out, How will i know its drying out as ive seen mention in other threads of removing the plaster.


Pipes on the left of the image
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the below image shows the damp patch line, you can just see where it drys out below the wallpaper, which just fell off the below.
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you can see the white stuff on the wall in the area
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here is the context of the location, just has a wall knocked down near the pipes, but the damp predates any of this work

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If you are interested in investigating further then roll the sheet vinyl back and pic the floor at the pipes.

Taking the pipes thro the ceiling would work - use plastic pipes. But first consider least disruptive way of doing it, and insulation.

Remove all damp affected plaster - also hack 50mm off all plaster thats in concrete floor contact.

Remove the full length of the skirting if units are to go along that wall.

Why not post pics of the outside wall at that inside corner?
That's a long post, but generally you can get leaks or condensation issues from pipes in that location.

Leaks should be self evident.

Condensation will cause more general dampness to walls, floors and the cupboard backs. Pipes should be lagged to prevent this.
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Here is a pic the last time you could see outside, i built a deck this year in that area, the wall under the patio door looks wet, but thats because we had literally just pulled back 3 - 4 inches of ground to dig down. you can see ive set a paver on concrete in that corner (top left of image) to set the deck on top of.

the Paver and concrete were set on top of compacted hardcore which is 300mm or more deep. the centre of the image is all hardcore due to poorly laid block paving. which is about 50 to 100mm deep. there is a patch of soil on the left of the image that used to be a flower bed.

the pavers and concrete are all below the damp proof course. the deck may sit slightly above it i forget tbh but its angled to the right of the image into the soil and is in a fairly sheltered area.

the floor level of the kitchen would be about 3 bricks up from the top of the paver

this was built 21st april 2015 so im pretty sure this work hasnt caused the damp as the cupboards have always smelled damp since i moved in the year before july 2014.

of course looking back now, i probably should have put a barrier between the paver/concrete and the wall, but as it was below the damp course i didnt think it would be required


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1. neither main wall nor extn wall appear to have cavities - is this just the pics? Because a common cause of damp is a bridged cavity - ie a cavity with rubble above the DPC.
There appears to be too much crystal salts for an only condensation cause.

2. The cu pipe with the isolator appears to be the rising main - is this the case?

3. The DPC's on extn and house are at different levels. Can you post a pic of the inside corner join brickwork?

4. If you lift the vinyl, and the wood floor covering in the next room (carpet?) and pic there, maybe it would help?

5. No DPM is showing from under the slab?

6. was the wall you removed a single brick wall?

FWIW: no air bricks can be seen below the slider? How are the suspended floors ventilated?
OK so further investigations tonight and answers to the above questions

1. yeah its just the photos they both have cavities, the wall taken out was a single brick wall, which hasnt exposed either cavity in the picture.

2. yeah that's the rising main, it comes in at a strange angle from under the cavity floor, no moisture or water underneath it, looks very dry in there

3. picture 3 below is a closeup of the corner, the level the bricks are at there was some kind of membrane between the bricks, not sure if that was a DPC as it was at floor level.

4, ok so ill go through the lifting of the vinyl picks below, carpet lifting is pic 4, took some lifting but all looks dry wood is dry.

5. not sure what you mean?

6. yeah removed wall was single brick

ok so pics explained,

pic 1, i tore a bit of the vinyl up it was all wet underneath not stuck down, ground wet to touch.
pic 2, this is hot and cold water feed to the kitchen sink going back into the concrete slab and under the floor, im guessing its not insulated.
pic 3, rising main coming in at funny angle from under the cavity floor.
pic 4, lifting the carpet
pic 5, lifting the vinyl more, stickier to the right harder to lift the vinyl, less moisture
pic 6, tore up more of the vynl to the midle of the room, found this spot,
pic 7 and pic 8 show this in more detail, the whole path of the pipe is damp and especially this bit
pic 9, shows the marks on the underside of the vinyl that i pulled up

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is everyone happy this is the cause, looks pretty likley?

FWIW, never noticed but looks like the ventilation may be covered at the back, ill look into this as if its covered i can dig it out, they will be uncovered if present at the front of the house as the front of the house sits quite a bit further out of the ground
Thanks for keeping up.

The cause does indeed appear to be leak(s) in the slab. Irrelevant now if you intend to cut and abandon the pipes as they enter and leave the slab channel. If you think it worthwhile you could blow out any residue water from the pipes as you abandon them?

Perhaps manipulate the rising main in closer to the corner and swing the isolator into a friendly position. Lag & clip.

Check that the external stop-tap is accessible & works.

The green stuff on the pipes eg. rising main, is a result of condensate forming due to v. cold water hitting warm air. Its no big deal. But, as suggested above, lag all your pipes esp. under any floor.

pic 4. if you lift some of the top course bricks in the very middle of the pic and expose the tail of a joist down there, it might be worth you examining it for fungal decay.
Given that the top course will have to be lowered to flow one floor into the other you might examine all the joist tails?

5. The kitchen extention concrete floor should have been laid in a DPM envelope and the edges of the membrane sheet should be visible above the concrete surface at the bottom 100mm of the walls.

FWIW: crawl under the house, if possible, and examine the woodwork, the ventilation & the wet or dry condition of the oversite.
hi ree, sounds good ill report back here with some more pics or various bits, I have a feeling there maybe no DPM, I think the raised floor is above a concrete slab as opposed to soil or stone which i believe some can be. So for the part of the kitchen where they filled in the raised floor they may have just poured on top of the slab.

I think i will probably end up pulling up the old pipes, the cement above appears to have collapsed anyway, so i may as well fill the channel in properly.

my only concern is that this morning the surface seems to have dried out quite a bit, the house was very warm last night, would you expect the surface moisture in concrete to look less even if if was wet? parts of it are still damp but not all of it. the plaster on the wall also looks to have dried out a little more.

it does worry me that if it does dry out before removing the pipes im not going to know if i have in fact found the real cause. but im not sure how i can approach it, perhaps i should dig the concrete above the pipes out now and inspect them?

Last night

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This morning

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I understand your concerns but consider that the damp floor surface has been exposed to heat and fresh air/ventilation, and know that its bound to dry up pretty quickly.

Why not cut back and remove as much of the vinyl sheet as possible - leave the floor open, and safer.

You could also rake out the pipe channel and see whats there?

All damp salt contaminated plaster must be removed.

If you dont have a membrane then you'll have to think twice when doing the next floor covering.

AAMOI: have you investigated the joist tails - sometimes these seemingly separate things are connected.
ill defo investigate the joists and post some pics for you in the next few days, unfortunately didn't get chance lastnight.

ill dig up the channel as soon as i get a chance, and take a look in there

plenty of mess at the moment as there is a rewire going on
found a pretty big leak lastnight was enough to hear it, have bandaged it for the time being but plumber booked to do a whole bunch of work in the next few days. I put some thick rubber inside the clip to seal it, which seems to have done the job. i imagine there are more leaks around there too

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Hi, sorry to hear that your troubles continue - you might be better off getting the plumber to replace all the copper pipes with plastic - including the incoming main if its not in plastic already.

The good news is that these things are being revealed now, and not later with a finished kitchen.

Just saying: i cant make head nor tail of your video - probably me.

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