Wall Damp Source

[braddock71]

Hi all,
Having a bit of trouble locating the source of a damp patch in a bedroom. Has been like this since we moved in and I thought it would've dried out by now but it hasn't.

As you can see from the layout pic, the most obvious place is water coming from the chimney flashing but I've been up there and checked and I can't see anywhere water would come in from.
This chimney serves as a flue from the boiler and wondering if this could also be a source of vapour? I'm still leaning towards the chimney even though I've been up there and checked (and also one part where it looked possible water could get in, I've pushed some extra lead underneath to make sure. I can take a pic at the weekend.

Am planning on taking off the wall plaster soon and see if the wall is damp behind it (probably). I have a tester and is around 33% or so at the join with the ceiling and is about 1m sq patch (although is semi circular in shape).

To totally rule out the chimney join with the roof, would it be worth putting something temporary around it to determine the source? I've got a dehumidifier in the loft which is collecting water - the wall in there is damp also.

Appreciate any help!

Damp Inside

• braddock71
• 22 Feb 2016

Layout

• braddock71
• 22 Feb 2016

 

[Doggit]

If you check the chimney, I suspect you'll find there's no DPC in it. The chimneys getting wet, and the damp is seeping down into the room below. If you can get up there, then you can use dryzone silicone DPC, and possibly dryzone stormguard for belt and braces. The "does what it says on the tin stuff" only lasts for about a year.

 

[braddock71]

Nice one, thanks for info. Easy to get up there and I have sds drill so I can easily put in dpc. This would be best done above the tiles, maybe one brick up? I'd have to stagger where it joins the roof which should be ok?

 

[braddock71]

Ok, put dryzone in 3 sides of the chimney, 1 brick above the flashing. Dehumidifier doing a good job in the loft so will see if it reduces the dampness and then replaster the damaged bit. Hope it works!

 

[Doggit]

You really need to do all sides of the chimney so you've got a complete ring of DPC. As you do the roof side of the chimney, you work along and up, following the flashing so that the perpendiculars get done as well.

 

[braddock71]

Hi - having put in the Dryzone and some water seal on the chimney, the plaster inside is showing as 25% on my damp meter (from previous 33% as mentioned originally - been measuring same place).
The boiler has now gone so has to be coming from roof, as thought.

I might get the wall boarded up and skimmed (removing old plaster) but don't want that to be damaged so my question is - should the plaster dry out totally in which case I still have a leak?

 

[vinn]

braddock71,
you would do well to post pics of the interior chimney breast area where your two(?) flues start, and photos of the flashing and flaunching on the stack. Plus pics from inside the loft.

You have an external chimney breast - when its flues were in active use any fumes would quickly cool & condense causing possible penetrating damp and salts.
Have all your flues been swept are they all ventilated top and bottom?
Has any flue liner been left in position?

Eventually you will have to hack off all affected plaster, and then render with a sand and lime mix - otherwise the salts will remain & constantly attract moisture.
Dont even consider boarding over salts/water damage.

 

[braddock71]

thanks Vinn - there isn't anything to photo on the inside really, just a hole where the old cast iron flue connected in to the ceiling - is single story (utility room at the back of the garage). 2 flues? just 1, i think.

Probably not been swept but no longer in use - metal cowl on the top, open at the bottom, so well ventilated. flue liner is still in position.

Some pics of the flashing and also one of the wall which has some strange mortar, kind of bubbling and crusty? from the drawing i did of the outside (2nd pic, post 1), this just to the right of the 'e' of the word 'inside'

IMG_20160621_201955

• braddock71
• 21 Jun 2016

IMG_20160621_201943

• braddock71
• 21 Jun 2016

IMG_20160621_201929

• braddock71
• 21 Jun 2016

IMG_20160621_201916

• braddock71
• 21 Jun 2016

IMG_20160621_201904

• braddock71
• 21 Jun 2016

i'll get a pic from inside the loft tomorrow, if needed.
appreciate help!

 

[^woody^]

If that was a problem caused by no DPC in the chimney, then it would have been damp from then it was built.

If it gets wet after rain, and has yellow or brown stains, then its a flashing defect.

If its damp almost all the time, but not spreading, then its a flue issue

Once wet, plaster salts cause misreadings on damp meters

 

[braddock71]

Thanks Woody. I reckon it was a flue issue then from your comments.
I might pull the flue out and cap the chimney at some point so I can check but first I'd like to fix the room.
So pull off affected plaster then render with sand/cement/lime, then reskim be enough? (that's assuming no more damp).

 

[braddock71]

Still got this damp patch and is tough to work out what to do!
We had whole room reskimmed and against my better judgement, I decided that the plasterers knew more than me about what to do so left them to it. Sure enough, this patch hasn't dried out so have chopped it out to see what's happening.

IMG_20160927_194736

• braddock71
• 27 Sep 2016

IMG_20160910_223413

• braddock71
• 27 Sep 2016

The bricks show the chimney (outer skin, just to right of red rod) and where that red puller rod is, there was a bit of a crack which led me to fix the wooden cladding which (as you look from the inside) is left of the brick chimney covering the breeze blocks, brick is the outside skin of the chimney and also to the right of the chimney. Not sure if this is the cause - possible that even a small gap in the cladding would lead to this? Has been filled anyway.
I was thinking it was more chimney as the centre of the patch lines up with it but not so sure now. Have a dehumidifier going to see if the blocks dry out - if they don't, i'm all out of ideas!

appreciate any pointers or advice!
cheers
gary

 

[braddock71]

updated picture in glorious technicolor...

Wall-2

• braddock71
• 27 Sep 2016

 

[Doggit]

It's either the 4th wall that didn't get done, or the chimney needs capping, but it is possible that the wall was so damp, that it's going to take time for the breeze blocks to dry out, but tit could well be the hole in the cladding. You're going to need to investigate further.

 

[braddock71]

thanks for reply.
I did do the 4th wall on the chimney.
Also, the blocks in the loft above this damp patch don't seem to be damp from my reader - they are pretty much the same as other blocks on the other side of the house.
There is salt showing there so am wondering if there was a fairly major leak in the past prior to us moving in which has been fixed, so this is prior damage to the wall and the current damp IS due to the small crack in the wood cladding. If you look carefully at the pic of the flashing on the chimney, you can see some of the mortar is different so might have been patched up to fix the problem.

Thinking I have 2 problems, 1 is fixed (chimney/flashing leak) which damaged plaster and blocks in loft show damp. And the other is due to the cladding crack which I've also fixed.
As I say, if it doesn't dry out now, I've no idea (and don't really want to pull the cladding off unless I really have to - not sure I can take it off without damaging it).