Window leak - nobody can figure out where the water is coming in from!!

[SpanielsSunflowersSand]

As per title. I am going insane staring at water coming through the ceiling above the window in my office. Had 4 people out and nobody can work out where the water is coming from.

The water is coming from above the window but all 4 have said it doesn’t look like the water is caused by the window but the roof above also looks fine. We have had new guttering and fascias, and they all look fine too.

Any ideas?

Photo shows the damp coming in which is the same all along the window (doesn’t appear to come from the edge of the window). Brackets are for my blinds.

I cant get to this section of the roof through the attic as it’s a dormer.

Could it be a broken or dislodged roof tile?

All 4 have said the roof looks absolutely fine in that area. I’m really worried there is a leak further up which is trickling down. Is that even possible?

From the shape of the stain, I'd say it's coming in on the corner where the mould is. Probably spreading along inside from there. I can see the gutter is there - could it be something where the gutter is blocked or slow draining so when there's rain it's kind of bubbling up and back under the tiles?

A roofer or joiner might need to open up your ceiling to trace the water backwards. Unless it's a flat roof, water could be trickling down from further up the roof and ingressing at the lowest point.

If it ends up being expensive you can claim the "seek & trace" on your buildings insurance as well as the cost of putting everything back together and fixing the ceiling stain.

We had similar a while back. Turned out to be a faulty gutter ( shared with neighbour) that was angled at not enough of a slope to drain quickly enough in heavy rain. Every time it rained the gutter would overflow and the water would go down behind the fascias, under the roof tiles and work the way down to come out above the downstairs window. Drove me mad for months, had walls repointed, roof checked and all sorts.

Got shared gutter angle fixed and new additional downpipe around the side (end terrace) to cope with excess and problem solved.

I’m going to check the gutter myself. Everyone says it looks fine but I noticed the water coming in the day after next door had their water replaced so it is very possible that they shifted our guttering slightly. I will be so over the moon if it is that because I’ve had visions of having to remove my office ceiling and have be priced up a new window.

It’s too difficult to get on the roof without a big machine so it would cost thousands to even inspect this part of the roof.

Probably condensation if it's not from the roof, would need to cut into the top reveal and see what's going on.

Everyone who has inspected it says it all looks good which is what is causing the frustration really because we seem to keep going around and around in circles. The damp patch was in the corner and is now all along the window.

Apparently the slates look good, the flashings all good too. The guttering and fascias was all fitted brand new. Shared chimney between us and next door removed, etc.

Everyone has said the guttering looks good but now someone has mentioned theirs being at an incorrect angle, I am wondering if next doors window fitter moved it slightly and has caused this issue so that’s something I’m going to check myself tomorrow morning.

I doubt it’s condensation because we don’t have this issue in any of the other rooms in the house. It’s the furthest away from the bathroom which has an industrial fan in it. We have roof vents etc or am I missing something?

Sorry didn't have time to reply properly.
Does it coincide with rain or with cold weather?
The type of condensation that causes things like you have is not really visible as it happens inside the structure of the house.
Imagine a freezing cold coke can you just got out of the fridge, would it be streaming with water if you put it in that room? Even dry seeming rooms can contain a lot of water in the air.
Now imagine the can never warms up and it could be massive, and you can imagine it could appear to be a leak.
It's not super common but it's possible especially if there's an impermeable flat roof above and the ventilation in the roof space is poor.

Has it got worse after a downpour.

Can you let us see a photo from outside? We've had a lot of leaks over the years. One was through the upper seal on the dormer which was weakening. We've just had a new roof and one leak is ongoing. Roofer has come back out twice, assures us he will work it out, but has found on inspection, there was no membrane on neighbours part of the party wall.

If you get constant heavy rain thrashing thrashing the outside elevation, check to feel if it ever feels cold/tacky damp. I wonder if the sealant is starting breakdown/loosen. You could discuss this with roofers who've been out, if not a builder could re-do seal - maybe one that does roof conversions.

I’d say it’s one of the warmest rooms in the house as it’s the smallest and was insulated fairly well when we gutted the place. Windows never condensate for example. It’s a slate roof above and I know we insulated it well as can’t access that bit from the attic. We insulated the floors, ceiling and all external walls. The sun also beams into that room so gets very bloody warm. This last week I’ve had to work with the blinds shut.

When you say sealant, do you mean the silicone around the window?

Is it suspended floor? Could it be one of the pipes running through the joist?

No pipes up there (it’s the ceiling). Going to take the light fittings out and see if I can shine a torch in there too 😂

Some builders/roofers have drones - if it's hard to access, might be worth seeing if you can find someone who can do a drone inspection to get a better look at the details.

Can I see a photo from the outside? Not just directly outside up to the roof could well be the gutter but never j see estimate the power of water to travel a long distance down through walls/the mortar between bricks that's why it's important to look outside at the wall/roof/chimney/flashing

You can’t see anything but guttering! Right pain but going to see if I can get someone with a drone 🤞🏻

Depending on how the dormer has been done, there might be sealant on the side elevation. That's why I was asking for a photo (doesn't have to be close up) to try and see if it's similar to us.

Obviously easier to try and work it out from outside, ie roofing materials can be lifted. If that isn't possible/doesn't show anything, a roofer can cut into your ceiling and at least see where it's coming in.