Leak Through Fibreglass Roof!?

[coofercat]

Hi all,

I'm after a bit of advice on where problems might be on a fibreglass roof + lantern we have. It seems to be leaking when it rains a fair bit, although I can't see any obvious cracks or holes. Any advice on possible areas to look into some more, or maybe treatments or whatever that might help would be much appreciated.

We have a fibreglass roof over a kitchen extension, and it has a large lantern in the middle of it. The roof has a slight slope on it, although there's a fairly constant puddle at the end where the gully out is (roofer claims this is normal?). The whole roof is about 6M long, by maybe 2.5M wide.

Recently, we've had signs of water in the ceiling below (over the door, actually), but at the opposite end of the roof (the "high" end, no pools there). I've been up and had a good look around - it gets moss off the house in some quantity, so I've cleaned all that off, and cleaned down the surface a bit too, but that doesn't seem to have stopped the leak.

On the roof itself, I noticed a few things, so took some snaps:
- A wide view of the "inside" of the roof, against the lantern: https://flic.kr/p/2ijLnw9
- A close-up of the inside: https://flic.kr/p/2ijPXgw
- A wide view of the "outside" of the roof, against the parapet wall: https://flic.kr/p/2ijNNcL
- A close-up of the outside: https://flic.kr/p/2ijNNjQ
- Lastly, a bit of flaky covering I found: https://flic.kr/p/2ijLnKk

On the "inside" wall, I found the flashing to have a couple of mm movement, and in a couple of places I was able to push it back in a bit. On the outside, I had a look under the "lip" and can see a bit of a gap up there. I can't see any obvious cracks or holes anywhere in the actual fabric of the roof, although it does look like the grey covering has flaked off in a couple of places. I presume the white material underneath is the actual fibreglass...?

We first noticed a leak shortly after the crazy storms we had just before Christmas (and it wasn't too bad, so I just cleaned it up and treated it). It's leaked since though, so it seems to be something pretty "reproducible" now.

Just ahead of getting someone to look at this, has anyone got any ideas of where problems might lurk? I figure it's going to be pretty handy for me to know a bit about this before we get someone to take a proper look at it.

Any ideas, help or advice much appreciated!

[toolbox]

Worth doing a temp fix on that flaking bit and see, just some Denso tape which can be removed and the sticky mess it leaves cleaned off with white spirit.
Sticky and Sh**y stuff to work with cut with an old hacksaw blade snips will not work lay over and smooth down with your hands, you can wear disposable gloves if you have sensitive skin (Health and safety warning box ticked!) but frankly I find bare hands best then clean my hands and tools with white spirit.

[coofercat]

That's a good idea - I don't have any denso around, so I'll look to get some in. I guess some duck tape would suffice until I can get the denso on there - I'll give that a whirl.

I was sure that the rain we've had over the weekend/monday would re-dampen the interior plaster, but actually, I can't see any evidence of it. At worst, I'd say that maybe some patches which were wetter may not be drying as fast as the other bits - which may indicate a small amount of new water, or might not indicate anything at all. There's more rain forecast this weekend, which gives it a bit of extra time to dry out, which might make spotting a problem easier.

As an aside, I was interested in how this was constructed, and found this: https://www.fibreglassdirect.co.uk/fibr ... -kits.html (beware the music, but the video is pretty nice)

[toolbox]

Interesting video I had always imagined it to be several layers thick like a car body or canoe. Certainly a lot more flimsy than I thought!