Leak - could be bathroom or roof - who to call?

[Halitosis]

Tapping into the hive knowledge...

We noticed recently that a couple of walls in our kitchen extension are slightly damp near the ceiling - so water ingress is coming from above. Although it's a single story extension (built 10 years ago), there are two bathrooms above and just to the other side of the same walls (now held up by RSJs). There is also (lesser) ingress on the other side of the same wall, so directly below the bathrooms.

I know we've had some heavy rains this week, but I've had a look at the roof tiling and flashing all appears in good order (we have a small flat section of roof directly above the damp walls that is accessible from a bathroom window). Equally, the bathroom seems to be in reasonable order, having re-siliconed the shower enclosure perhaps 2 years ago and all appears intact on inspection.

So, would you call a plumber, a roofer, or someone else I haven't thought of?

Thanks in advance for any suggestions

[sprite1275]

Hard one. Rain bouncing down at a certain angle could bounce back up flashings. I replaced some pushfit right above a damp patch in a bathroom about a year ago.
Bloke wrang me the other day to say the patch had come back.
Cut it out again, checked fittings and seemed fine. Closer inspection was water was getting under a flashing by a dormer window, running down the rafter and dripping right where the pipe fittings were.
Fine for a year but some driving rain found it's way in.

[xxnick1975]

Is it possible to mark the edge of the damp patch, then stop using then bathroom and see if it gets worse or not?

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[bambam]

We had something similar a while back, but not with the possibility of a roof leaking too.
Ours was a damp patch in the ceiling that had 2 bathrooms above it.
We tried replacing the silicon around the shower in one of the them as the first who came out was convinced that was the cause. Anyway, that didn’t work.
In the end, someone cut out the damp part of the ceiling and looked inside - the taps to the basin in the other bathroom were leaking slightly. You would never have guessed as they were the newest part of that bathroom.
Ultimately you might need to cut a patch out and look inside.

[lewie]

Possible to get under the bathroom floor?

[Halitosis]

Thanks gents and some good points to ponder. I’ve taken panels off and looked under a shower enclosure, bath and behind a toilet where all looks dry enough. Unfortunately the bathroom floors are tiled.

Leaning towards it being a roof problem at the moment, but think I’ll monitor it - and the weather - to see if a link exists.

Sod’s Law this occurs just as we’re thinking of selling and moving.

[Kingstepper]

Leak tracing dye?

[lewie]

Get a dehumidifier in and if you’ve no rain might help with fathoming it out
Water is terrible for migrating and traveling down joists
I had a similar problem once and it was driving raining hitting the wall and running behind the pebble dash finish
Could the cover the small section of flat roof with a sheet of DPC - tucked under the flashing and gaffa taped over the edge?
Toolstation sell big sheets for around £10
Might give you an idea of it’s the roof

[MCFastybloke]

Is it possible to mark the edge of the damp patch, then stop using then bathroom and see if it gets worse or not?

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This only works on the waste side,not pressure side.

Rain seems to be in time with leak so suspect roof first. Can you get up to look? own or have a relative with a drone?

If we have dry weather and leak grows then is not roof.