Random wet patch halfway up internal wall after storm

WIAWSNB

That pic doesn't appear - what size is it?

What is it stored on - phone or PC? It should be possible to make a copy, and resize it to, say, 2 or 3MB. (Not sure what MSE will handle, but I suspect over 5MB could be a cut-off.)

WIAWSNB

Other possibility not to be discounted, tho' very unlikely - where does that radiator's pipe go to? Is it under the floor?

Is your CH a sealed system with a pressure gauge on the boiler? If so, is the pressure steady?

Skint_yet_Again

The radiator pipe goes under the floor. Not a sealed CH system. Radiator recently bled and CH topped up per instruction book. Just a small amount of blue water came out when bled into a container. None went on the wall and radiator has been operating normally. Boiler recently serviced. No wet patch on the wall until the storm. No wet or water on or under the windowsill or around the double glazing.

I’m on my phone and I can see all photos I’ve posted. 🤷‍♀️ Not sure I will post full photos of inside or outside my house. Thank you for all your help so far.

pseudodox

If it is a cavity wall there could be a tie between the two skins onto which some fallen debris/dislodged mortar has got stuck & caused a conducting bridge for water that is finding it's way down the cavity maybe from the roof or leaky gutter. Other than chisel out an external brick or two don't know how this can be determined.

Skint_yet_Again

trying again hopefully you can see photo 2025

Skint_yet_Again

https://forums.moneysavingexpert.com/discussion/comment/82186404#Comment_82186404

When the window is removed next year will we be able to see into the cavity?

Skint_yet_Again

Previous owners cavity wall certificate shows installed 2012 but doesn’t say which walls.

stuart45

It's possible some water is getting in under the frame where the mortar has moved out slightly beyond the cill drip. Nowadays you can see into the cavity with a borescope, although not not easy when the cavity is filled.

If it is mortar on a tie, you can knock a couple of bricks out to clean it. Repairing the mortar under the cill would help.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82186413#Comment_82186413

Yes, you should be able to.

Tbh, it isn't a serious damp patch, and - personally - I'd just wait until the window is removed. Hopefully the cause will be obvious, and easy to sort. Any damage to the plaster should be very easy to repair afterwards.

You say, "Previous owners cavity wall certificate shows installed 2012", so I presume by that you mean that CW insulation has been installed? If so, almost certainly it will include that wall - it is an external wall after all.

Some types (perhaps all?!) of added CW insulation can - likely will - allow a bridge to damp if the outer skin is breached, so it has to be kept in good condition. Your brick pointing looks pretty ropey in places, so that would be my first suspicion. But I wouldn't assume anything until you can check the actual cavity, and it's fortunate that the damp patch is so close to the window. I would personally want to know the cause - whether simply poor pointing, or a compromised tie, for example - before effecting a repair.

Skint_yet_Again

Thank you all for your advice. I will speak with my neighbour and make a plan. As the window is being replaced next year I now know what to look out for and check is done at that time. For now short term I think I will feel happier trying to stop further water ingress by patching under the cill.

Is it worth also using the stormdry masonry protection cream £39.99 to seal the bricks or shall I wait and see what happens after patching?