So I've cleaned the roof board and I have my foam backed material. Now I need advice on glue. I got 1 litre of Selley Kiwk Grip waterbased contact adhesive (not spray). Did you guy who have done it, apply some on both surfaces, let tack, and push together? Or did you only apply glue to the cardboard? Just let it stay wet and put together, and let dry over a day? Any advice would be appreciated. Cheers guys.