Penetrating damp

yakyak

Hi All,

I know that this is going to be a long shot before I begin, but I thought I'd post on here to see if anyone has any opinions on what could be wrong before I get a specialist damp expert out. (I think this may be the best case scenario here though)

Basically I have some patches of penetrating damp on my south west facing kitchen wall. I sanded the paint back about 5 months ago, and it demonstrates how bad the patches got. More heavy rain yesterday has caused the problem to start to get worse again. An image is below from this morning:



About 2 years ago, I re-did the kitchen. Where the external door is now, there were 2 external doors where one opened onto another. (Strange I know) All the plaster was removed from around the door, and the internal and external brick leafs were plaster boarded over at the end.

Above the damp patch (white box area) is the turn for the stairs, just to the left of the turn for the stairs is the bathroom. I have had the floorboards up on the stairs and in the bathroom, but can't find any leaks.


A few months ago I re-pointed the brickwork around the door, and applied a breathable water seal to the brickwork. (The top half of the house was rendered 2 years ago)

The next thing I checked was the roof, specifically the guttering. Whilst the gutters were holding a bit of water, they didn't appear to be any obvious problems.

One potential issue may be that the felt under the tiles appeared to be worn in a few places, (frayed at the ends) and basically wasn't reaching right over into the guttering. I could see some of the wooden battens under the felt were very wet when it was raining – I presume that these should be dry?

When re-doing the kitchen one of the workmen told me that under the floor was quite wet when he was replacing the lead mains supply. He said that this could be a number of issues, the water table being one of them. He said though that the dam proof course was working, as there was no evidence of rising damp.

The house also had cavity wall insulation installed prior to me purchasing the house. I have also been running a dehumidifier to try and dry the wal out, but this isn't resolving the issue. (nor drying the wall much)

Has anyone seen anything similar to this or can shed any light on the issue?

Thanks!

Kiran

What does the left hand reveal look like, is that damp too?

Were there two door side by side originally?

Kiran

If they just plasterboarded over the gap between the internal and external skin without an insulated cavity closer that could be the cause.

yakyak

Thanks for the replies. The two doors were side by side originally, I remember each foor having its own yale type lock.

From memory the plasterer just boarded over the brickwork with platerboard and plasterboard adhesive. (The stuff that sets like rock)

Should something have been placed in the cavity? The left hand reveal has evidence of salt marks in the plaster along the plasterers edge/bead.

Would a cavity closer stop moisture travelling from the external leaf to the internal leaf?

Kiran

Yes, they are used to prevent cold bridging. The other thing that I'm wondering about is is there was a cavity closer above both doors, what has happened to the bit which was over the second door (now removed). If it has been cut off and left with an open endmoisture will be tracking down to the left on your photo where the issue appears to be. Have you got weep holes on the outside above the door? If so make sure they are clear and haven't been rendered over.

Sorry to go down so many routes but without seeing it its quite hard to tell

yakyak

Having looked outside there are no weep holes at all. I don't think the installers who fit the door put anything above the old door. I'm presuming the plaster is going to have to come off now as it's got salt in it. The 'white box' area is completley dry and there is no ovidence of water at all, the dampness seems to start below the top of the doorframe.

I'm thinking of removing three or four of the bricks on the outside to try and see whats going on in the cavity. That may prove difficult though as the previous owners had cavity wall insulation installed - I can't find any certificates or reciepts to prove when this was done though...

I'm presuming that the cavity wall insulation is wet through now, and will probably have to be removed....That looks like an expensive job.

Kiran

Without knowing the details of the cavity wall insulation its hard to say however you may be lucky and the fibres used to insulate may be hydrophobic.

You will be able to see into the cavity when the plasterboard is removed especially if there is no cavity closer so no need to remove bricks yet.

The lack of weepholes would mean that moisture in the cavity above the door has nowhere to go so will track along the path of least resistance.

yakyak

The cavity awll was probably done a long time ago, knowing my luck it will be the worst possible type to have, the one which holds water!

Anyway, back on track - I'll remove the UPVC beading around the door frame and will have a look into the cavity. I'll take more pictures and update the thread. Thanks for all of the help so far.

Kiran

Your welcome.

It also depends if the cavity wall insulation was done prior to the old doorway being blocked up, there may be no insulation at all. If there is damp insulation then it may not go back that far and you can remove it from the exposed opening when the plasterboard is removed. You may find, if your budget allows it, an inspection camera (or boroscope if you want the propper name) useful as you can drill a hole through the mortar and see whats going on without major damage. Also nice and easy to patch an 8mm hole in mortar.

Good luck and keep the updates coming.

yakyak

After months of looking at the damp patches, I decided to do something about it - I hacked the plaster and plasterboard off to have a look underneath. It looks like there isn't a leak at all, and the damp patches have shown up due to the lack of a cavity. The bricks are completley dry. Hopefully the images below should demonstrate what I'm trying to explain...



The wall gets hammered by the weather, and I think that the bricks or the mortar must have soaked up some of the heavy rain over the winter and the plaster/plaster board on the inside has just soaked it up. The steel plasterer’s edge was actually rusty when I removed it, so it has probably been building up for a while.

The question is what options do I have now to cover this up and prevent it coming through again? Someone has mentioned waterproof plaster, but I don't know if that goes over plasterboard or not?

Any advice appreciated!

Kiran

The photo shows that they've used bricks to close off the cavity. There will be a cavity behind that brick to the reveal. If the outside of the wall is getting constand rain hitting it then you may want to get the clear paint on damp seal for the outside. When you re board the wall possibly consider a foil backed green board (moisture resistant)