Hello. I have a house built in 1968. Flat metal roof. The roof has started leaking quite badly and I'm planning to use 3 cm insulation boards between the seams and Icopal Mono as a system. Since I will be opening the ceiling to see what damage this leak has caused, I'm unsure whether I should wait to apply the Icopal system now or wait until it gets warmer and first check what the leak has caused from the outside, i.e., remove the metal sheet. Or should I apply it now and deal with the problem from the inside later? I don't want to apply the roof unnecessarily just to tear it up again later. The problem is that I really need to install a new roof immediately due to the heavy rain leaks. Grateful for some opinions.