Hi! I have a couple of projects lined up for this year and I will ask for advice on one of these soon. First though is my request for advice about my 'Warm' flat roof that was installed last year in the summer. Last week we had frost for the first time this year, and when I looked out of my bedroom window I could see every screw hole outlined in the frost, and upon closer inspection, I could see that each screw site beneath the GRP waterproof covering had sunk by about 2 to 3 mm. As the sun slowly heated the roof and water started to form, these dips became full of water and then eventually the warming of the screws and their expansion (I Assume), returned the GRP to its normal evenness and no visible signs of the screws. It is frosty again today and the same thing has happened. I am very worried about all of this, as to my thinking, if this happens regularly with cold weather, and possibly the reverse happening in the summer, every screw hole site will finally break down the GRP which is not designed to move like this and will eventually split and allow water through each hole. I have told the roofer about this, but he said that he has never heard of this sort of thing happening , I think that he just used long metal screws, but will not know for sure until I see him.
I would be grateful for any advice as to how I should handle this situation. Prof.