Damp patch on wall

trevorbayliss · 18 Mar 2020

I have a damp patch on a wall in the dining room. Behind this wall is the stair cupboard and this is where the water feed for the house comes in. So i took up the boards in there expecting to find the water pipe has been leaking.

It is all bone dry behind there and i hope the photos show this.

So i am thinking maybe this discoloration is due to condensation.

The dining room and kitchen are open plan and i think the lady who lives in the house is not using the kitchen hood to extract the water vapour from the cooker area.

What do people think ?

KenGMac · 18 Mar 2020

trevorbayliss, good evening.

In the last image posted [the one with the floor joist] have you checked the joist end? in the image posted there "Appears" to be a lot of very damp looking material on this joist? this [could] be indicative of a rising damp issue??

The wall plate is also a very dark colour [possibly] indicating rising damp??

Do both of the above test "firm" when probed with a screwdriver or similar penetrating tool?

Ken.

^woody^ · 18 Mar 2020

That stain is from a leaking pipe, or a leaking joint spraying mist. It may not be constant.

It's certainly not a condensation stain.

trevorbayliss · 18 Mar 2020

Thanks Ken

When you say wall plate i wonder if you mean the last floor board. Because there is another board running really close up against the wall. Looking at the photo again i am even wondering if the wall is built on this board. I will check next time i am there.

The staining on the joist is i think from past leakage from the water meter. I remember i had an issue with this a while back.

The wall lower down around the meter doesnt feel damp. So i was thinking it cant be rising damp. However, this might be the issue.

I have my own dryzone gun, so can easily drill into the mortar line and injection some of the special silicone.

trevorbayliss · 18 Mar 2020

^woody^ said:
That stain is from a leaking pipe, or a leaking joint spraying mist. It may not be constant.

It's certainly not a condensation stain.

Thanks Woody.

So maybe there is some issue when the water is being drawn in the house. Say when the shower is on. The meter may well be leaking from some point. I will need to go back and test this out.

bobasd · 19 Mar 2020

OP,
a few things:
1. the damp staining behind the cabinet looks (as above) like a leak result, esp with the corona.
2. but the damp stains on the other side of the wall (pic 1.) look like rising damp?
3. why not slide the cabinet out and pic the wall behind it.
4. all stained plaster should be hacked off and replaced with a 4:1 sand & lime render mix.
5. a 22mm(3/4") pipe goes thro the wall with the cables: can you investigate that pipe, in the wall and on the other side of the wall, for leaking? where does this pipe rise to the first floor?
6. why not replace the 1/2" lead supply with MDPE pipe?
7. the meter pipework is not clipped to the brickwork.
8. why not ask the elec forum about your bonding connection - i'd favor jumping the meter & strap clipping the bonding to the lead pipe but they may disagree?
9. my opinion of all injected chemicals is pretty low but it will do no harm if you do inject.
10. you would perhaps need to inject at skirting board/FFL on both sides of the wall.

^woody^ · 19 Mar 2020

bobasd said:
with the corona

It needs isolating

KenGMac · 19 Mar 2020

That last post of yours Woody could go viral??

trevorbayliss · 21 Mar 2020

I took off the plaster yesterday and injected with some dryzone cream.

I dont think this is rising damp, but rather the stop tap which i notice has been dripping.

If it has been dripping its been doing it for 4 years at least.

Only started to get this issue last year i think.

Anyway i have left the wall to dry for a bit and have put some paper around the stop tap.

I have tightened the nut on the stop tap and the dripping has stopped. I will need to google how to service these types of taps.

KenGMac · 21 Mar 2020

On very rare occasions, A drip can turn into a fine spray, when the external mains water pressure rises such as during the night when the draw off is reduced greatly??

just a thought?

Ken

bobasd · 21 Mar 2020

no matter how the moisture is getting to the wall its penetrating to the other side, and rising up about 1m?
you only got what "issue last year"?

OP,
i gave you 10 possibilities you've responded to three of them?

trevorbayliss · 21 Mar 2020

The issue developed last year = staining being visible on the wall.

Lead = happy with it

yes maybe need to secure it better.

electrics all ok with sparky.

trevorbayliss · 27 Jul 2020

Update:

I am going back to this house to do some plastering. I am doing it in lime base and lime top coat. Hopefully this will allow the wall to breath. I cant say i have found the source exactly.

anyway i have a similar issue on an external facing wall in this house. Not as bad, but still there is an issue developing.

In relation to the internal wall in the photos above this wall is about 1.2m away and at right angles to the internal wall. Externally there is a flower bed and the soil is below damp course. The pointing is pretty crappy and the bricks have been painted red in the past. So this week i am going to be ripping out the pointing on this side of the house as i think it does need doing longer term.

I have 2 photos showing what this issue is. The damp patch is just in the photo and doesnt extend to the left behind the sofa. The external photo shows where the damp is inside. The sofa starts roughly where the air vent is. I havent checked the air vent for blockages. Maybe i need to do that.

Any comments appreciated.

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Damp patch on wall

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