Cavity wall leak.

ollieu1900

Hey, 

I've got a cavity wall extension which during driving rain leaks onto the ceiling below. I believe the problem is lack of cavity trays on the outer skin. 

Ive had a handful of builders point blank refuse to retro fit cavity trays as it could disrupt the structure. I've got 3 options available from what I understand

1) use a brick seal that allows the brick to breathe. 

2) render over the top (hate this option) 

3) install cladding to reduce water absorption

In an ideal world I would want cavity trays installed but no one is willing to do this. I will keep looking but I always look out for the next south west driving rain so feel abit pressured! 

Cheers 

Grenage

Could you upload pictures?

No sealant is going to allow the bricks to breath, regardless of claims.

ollieu1900

Grenage said:

Could you upload pictures?

No sealant is going to allow the bricks to breath, regardless of claims.

So I'm guessing brick sealer is not a brilliant idea? Many of them make some big claims regarding letting the wall breathe. I Must admit I was skeptical about it ..

 I was leaning towards cladding as it's reversible if it doesn't work and access to the wall is very easy. 

Grenage

I wouldn't touch it, no.  Have you got any pictures of the area?  Is it possible that there are other issues such as bad pointing that are letting the water in?

ollieu1900

Grenage said:

I wouldn't touch it, no.  Have you got any pictures of the area?  Is it possible that there are other issues such as bad pointing that are letting the water in?

I'll try and take photos later and post.

It could be the flashing as the leak was sudden and heavy suggesting a quick rush of water. Penetrating damp would surely be a much slower leak? 

The pointing is fairly good and the area has no drainage problems from what I can tell. 

FreeBear

ollieu1900 said: It could be the flashing as the leak was sudden and heavy suggesting a quick rush of water. Penetrating damp would surely be a much slower leak?

Penetrating damp would only give rise to damp patches internally, If you have water dripping through the wall in heavy rain, this would suggest more than just porous bricks. Faulty flashing would be the first thing to check. Significant cracks in the exterior wall would be another source - By significant, I mean 10mm or wider.

Grenage

Yes sudden and heavy can happen with flashing; I had the same in my last house.  Dry as a bone 98% of the time, then absolute deluge when the rain and wind were right.  Relatively cheap and easy to fix at least.

stuart45

ollieu1900 said:

Ive had a handful of builders point blank refuse to retro fit cavity trays as it could disrupt the structure. 

It doesn't if you know what you are doing. Means coming back for a few days.

ollieu1900

Grenage said:

Yes sudden and heavy can happen with flashing; I had the same in my last house.  Dry as a bone 98% of the time, then absolute deluge when the rain and wind were right.  Relatively cheap and easy to fix at least.

Pretty much as you describe here. 99% of the year it's dry and then the perfect wind/rain combo and I'll have 3 pints of water showing up as a damp ceiling and water dripping through light fixtures. 

Grenage

Get some pictures up and we can advise.  If it is the flashing it should be relatively obvious.

ollieu1900

Grenage said:

Get some pictures up and we can advise.  If it is the flashing it should be relatively obvious.

So I took 3 photos but it's quite dark,

 one shows the flashing. Where it's pushed into the wall I've covered with sealant out of desperation during the winter months. Seems to have reduced it but not eliminated it. 

The other photo shows weep holes present in the top section of the wall. There are none where the flashing is so in simple terms the top half has cavity trays and the bottom half doesn't. (What were the builders thinking?!)

The wall becomes internal lower down so any water penetrating the brick below the cavity trays will run down the back and onto the ceiling if I'm understanding it correctly?