I have  kingspan TR27 PIR tapered insulation stored under tarps but have noticed some moisture in the packaging....the insulation is for a warm roof. How detrimental is the moisture...are the boards moisture resistant?

It fine 

Most insulation on site is stored outside With little or no covering 

but that's not going in a warm flat roof.

PIR is a closed cell foam with very low moisture absorption. Absolutely no problem with it getting wet, it only needs covering to protect from UV which degrades this type of material.

Apologies for jumping in on this post but we have 14 sheets of Celotex GA4100 that we have stored for 18 months on the upstairs floor in a damp but not wet cottage and every sheet has bowed in the same direction by about 20mm. This was destined for UFH so is now pretty useless. Saint Gobain (Celotex) technical have not been helpful as to the reason why this has happened. I suspect that there are internal stresses from the manufacturing process and over 18 months this has relaxed each sheet in the same direction, even though they were stacked randomely in one pile off the floor and covered with a sheet. So I think moisture does have a long term effect. I'm now talking to Kingspan and Reticel to see what they say.

It isn’t useless, screed will flatten out bowed insulation no problem, lay it crown up so the edges are sitting on the deck and they will soon flatten out

Edited March 16, 20224 yr by markc