Celotex cavity insulation getting wet!

Hello all

Couldn’t find an exact answer to this in an existing thread… but other sites I had come across suggest that celotex is not supposed to get wet or rather be exposed for long periods eg over 24 hours of rain.

I am having a rear flat roof extension done and the builder is using the 90mm celotex thermaclass cavity insulation securing to the inner leaf using the wall ties and a 10mm residual gap. He has assured me multiple times that it is fine to get wet… and sure enough each time it’s has rained the next day it appears bone dry. It’s been up for 8 days now as the walls were built and kept having to stop due to rain, My concern is that the constant exposure can damage the insulation structure and reduce its thermal performance… or even trap damp in the walls long term - wish I had gone an got some tarps myself to cover it and allay my fears.

The other issue I found is that there are some snots around the wall ties when the brick wall has been built up-could this cause a cold bridging issue in future ?

Again my builder has assured me it’s all fine and I want to just let him get on with it but I just wish I could find info online that would support his claim, which would provide me some reassurance I won’t have issues down the road

Any advice welcome!
Thanks

Check what the Celotex documentation for your product says.

Checking one random PIR product's docs, I read "Immediately after installation the insulation boards must be protected against weather conditions and sunlight."

Yeah I also read that on a celotex product info doc… it’s not had any sunlight but a fair bit of rain over a few days. But doesn’t seem this is common practice that builders I know actually keep it covered if rain is expected. So wondered if it was more the company covering themselves rather than an actual issue… the previous extension I had done few years ago was all mineral wool and that got soaked at the time but never had any issues… wasn’t sure if the same for celotex

Doesn't matter in the slightest