Odd damp patch on kitch wall noticed after block paving laid

[kman]

Dear forum members,

I have an issue with damp patches on the kitchen exterior wall which do not appear to be related to weather conditions, photos attached below . Usually the pattern is it’s very damp in the morning and then dries off during the day, so I noticed it when leaving for work in the morning, by the time I return it’s fairly dry again. The water marks running down the wall behind the drain pipe aren’t related to this but a previous incident where the drain pipe became disconnected from the guttering hence water was dripping straight onto the wall from the porch above.

I noticed these damp patches a shortly after a block driveway was laid – previously the area was majority grass and the area next to the wall was a soil patch with lots shrubs and herbs growing, so if the issue was there before I would not have seen it. I have had a couple of professionals around but they cannot see a cause and haven’t really been able to help. A drainage company came round to examine the possibly of a water mains leak and concluded it was not, they also checked the drain pipes for blockages and concluded that was ok. A plumber came round to see if there was an internal leak and concluded there was not. The inside wall is not damp.

I have removed the air brick to have a look and couldn’t really conclude anything from that other than the mortar was soft and crumbly. The only next step I can think of would be to lift the blocks around the wall unless anyone has other ideas? Any advice appreciated – this issue has been giving me a headache.
Many thanks.

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Untitled

• kman
• 24 Oct 2011
• 2

Untitled

• kman
• 24 Oct 2011
• 2

Untitled

• kman
• 24 Oct 2011
• 2

 

[datarebal]

is the air brick the right way up? and is the door sealed properly to the brickwork?

 

[jadzy]

Just a guess here, but it looks like on top of these two damp brinks is your damp proof course. think i can just see it in the last photo.

based off that i'd say it was ground water rising up and stopping at the dpc, then coming to the surface of the brick. bit odd it is only happening in that one spot and around the airbrick.

would otherwise be thinking did the blocks bridge the dpc?

 

[HERTS P&D]

Was there a gully there before for the down pipe?

Andy

 

[kman]

is the air brick the right way up? and is the door sealed properly to the brickwork?

The door has just recently been replaced by a glazing company, the issue was also present before the door was changed.

 

[kman]

Just a guess here, but it looks like on top of these two damp brinks is your damp proof course. think i can just see it in the last photo.

based off that i'd say it was ground water rising up and stopping at the dpc, then coming to the surface of the brick. bit odd it is only happening in that one spot and around the airbrick.

would otherwise be thinking did the blocks bridge the dpc?

Correct, the damp stops at the DPC. One of the reasons I removed the air brick was because it looked like the dpc was missing in that section, however it is present but set back about 5-6mm from the edge of the bricks, not sure if that is an issue?

 

[kman]

Was there a gully there before for the down pipe?

Andy

No haven't changed anything to do with the drainage, it's a soakaway and only for the porch roof.

 

[HERTS P&D]

Is the soak away blocked?

Andy

 

[kman]

Is the soak away blocked?

Andy

I had it checked by a builder and he said it was fine, he poured loads of water down the pipe and a string with a weight attched.

 

[noseall]

Those water marks are a result of running water down or into the cavity.

Have you got a condensing boiler that runs for a while in the morning and has a condensate run-off that passes through the cavity?

 

[kman]

Those water marks are a result of running water down or into the cavity.

Have you got a condensing boiler that runs for a while in the morning and has a condensate run-off that passes through the cavity?

Correct the water marks occured from a previous issue when the downpipe became disconnected from the guttering and rain water was falling onto the wall, for a couple of weeks.
The condesing boiler condensate run off is plumbed into the sink soil pipe.

 

[cotswoldbuilders]

How I am looking at it, the damp stains are only on or near the dpc, theres no sign of it rising.
So Im guessing the damp is coming from inside, ie it could be penetrating through the brick work from any where above, as for some reason the dpc level is breached.
When you took the air brick out, did you notice weather the dpc continued across the cavity to the inner wall, if it has you may need to fit weep vents.
That staining looks like its seeping through from dpc level.

 

[joe-90]

Most unexplainable damp problems can usually be traced to interstitial condensation. It affects the bricks below the damp course because they are naturally damp and colder - hence condensation. Basically it is the water vapour from your house condensing as it reaches the outside.

 

[kman]

How I am looking at it, the damp stains are only on or near the dpc, theres no sign of it rising.
So Im guessing the damp is coming from inside, ie it could be penetrating through the brick work from any where above, as for some reason the dpc level is breached.
When you took the air brick out, did you notice weather the dpc continued across the cavity to the inner wall, if it has you may need to fit weep vents.
That staining looks like its seeping through from dpc level.

The dpc did not continue across the cavity to the inner wall. My next line of investigation was going to be the kitchen sink soil pipe. The sink is directly behind that wall the pipe goes into the ground. Also are you suggesting it could be leak anywhere along the front wall, perhaps at roof level? or dodgy pointing etc?

I tried to get advice from a damp specialist and this is what they told me based on the same photos.
"It looks like you may have a leak under the solid floors of the house to cause what is evident in your photos. It may be worth turning on your radiators to see if you have a drop in pressure or failing that, speak to your water provider about putting a dye in the supply to see if this comes out of the brickwork.

It does not look like a rising damp problem which is what we specifically deal with or dampness due to higher ground levels."

 

[cotswoldbuilders]

Is the cavity below the dpc clear, ie not full of rubbish, probably best to cut out a few bricks in the areas where damp is showing, check the cavities are clean and check for any sign of water, like a leaking mains pipe.
If you have a suspended wooden floor lift a couple of boards up.