Mystery Damp Patch

[saz84]

Hi

We have a single storey room at the front of our house. It is pretty old (pre 1800 ish) and we have a resident damp patch in one of the corners which has been there since before we bought the house.

We had an injection DPC done on buying and as the damp appears to start about 4ft up I am assuming it is not rising damp. The outside walls are rendered however the internal floor depth is below outside floor level.

It is getting worse and as well as damp on the walls (which comes first) it is now spreading onto the floor being soaked up and carried by the wooden carpet holder things so the carpet is now ruined.

What we have tried so far is....
1. Unblock the drain next to the offending spot and installed a proper soakaway replacing a cosmetic one which was there before.
2. Replaced the lead on that side of the roof so water cannot run into that corner under the tiles.
3. Replaced corroded brickwork (I think above wallplate) and replaced roof felt.
4. Tried a dehumidifier to dry out the patch.
5. All offending plaster was knocked off and replaced when DPC was done. Damp came back straightaway in fact I don't think the plaster ever had chance to dry out properly.

Next plan of action is to replace the guttering but there is no sign of leakage and the surrounding bits of wall seem to be quite dry outside - I have checked in the rain!

There was an elder tree trying to grow in the old render (painted black) along the bottom of the wall in that drain I mentioned earlier - is there any way this could be growing up in the brickwork causing some kind of capilliary movement of water?

Does anyone have any thoughts? We are stumped - if anything the problem has got worse since the lead was replaced about 4 months ago.

Any advice or suggestions would be welcome - I have often looked on this site for help on various matters and have always found someone has a good idea!!!

Sara

 

[Burnerman]

Do you think you could post up some pictures for us, Sara?
your problem could be porous stone, or worse....
John

 

[saz84]

I'll do my best.....

 

[saz84]

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I hope these work - the walls are red brick, double skin with no cavity. The outer wall was rendered 1920's and rendered again 1980's.

 

[Burnerman]

Obviously I can only offer a wild guess but I'd be targetting the roof area in the corner - I think its time to get those slates off and see whats happening beneath. I think somehow that water is penetrating down the middle of the brickwork - alas a difficult thing to cure when there's no cavity.
Its been a great move to sort out that downcomer too, although the damp seems to be starting way above that.
Good pics and thanks - how about a couple more of the roof and guttering on that corner?
John

 

[JohnD]

I'm thinking leaking pipe. in an old house there can be old pipes, iron or lead, which have been hammered shut and plastered over. It can also be a modern leaky pipe, from basin or radiator, or shower/bath waste.. If the floor is that wet I doubt is in rising or penetrating damp. Tell us what is in adjoining or above rooms.

have a careful look at gutters and downpipes near that wet patch, but unless it has been quite rainy recently, I still think plumbing leak.

Pull away that bed and see what is behind it. Pull off some plaster at the highest point of the wet patch and see what you find.

If you have a flat roof above, then all other bets are off. Flat roofs leak.

 

[saz84]

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Looking under the wallpaper - wet flaky plaster. When we took it off before - wet bricks underneath. It has only started making the floor wet in the last year. Under the carpet you see the damp starts in the corner and radiates out following the carpet runners. There are a couple of random small patches in the middle of the wall but you can't really see them on a photo. You can see from photos there was once a doorway in the middle of the wall which must have been bricked but long before our time.

 

[JohnD]

have a look in the loft

let's have a closer look at that lead.

 

[saz84]

Sorry JohnD - about the surroundings!

We use it as a lounge. Multifuel burner and 1 radiator. We open windows. Floor level is 3" below rest of house which is 2 storey this one room is only 1. The only pipe we know of used to lead to a well round the back - this has been disconnected. There could be anything in there! The inside of the roof area above is as dry as a bone - even around that corner!

 

[saz84]

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[JohnD]

if you tip a bucket of water slowly into that gutter, where does it go?

 

[saz84]

It's raining at the minute - I'll have a go later

 

[JohnD]

that gutter pic is adjacent to the damp patch, it it? Test it with a big spirit level.

buy a bottle of food colouring next time you're out shopping, in a colour that will be easily visible on the damp patch. Put some in a watering can and pour it onto the edge of the roof where the lead is. I have a feeling...

 

[Burnerman]

There's a fair bit of water wash on that gable end picture (no.3, second set).
Although the water table stones look ok, I'm wondering if there's any penetration through there.
Assuming the guttering is ok!
John

 

[saz84]

Water wash may have come from when the mortar was drying out - the lead goes all the way under the stone and overlaps the other side by 2" so water 'shouldn't' be able to get through?

Waiting for funny colours to appear on the inside - might take a few days......