Which roof construction is safest!

[BigGitt]

If you are going to have roof tiles, which construction is safest? Applies to 45 degrees. Felt paper+sheathing+air gap/masonite+insulation+plastic+gypsum? Or plastic like Ähus? Or masonite+air gap/masonite... What should be used for rafters? Wood, e.g., 45x220, or lightweight beams? What on the inside? Gypsum? OSB? Paneling? Plastered styrofoam?

 

[FredrikR]

Purchased roof trusses that someone has calculated and constructed should be in a good position.
What do you mean by the safest regarding the roofs?

 

[BigGitt]

Avoid mold! And all other moisture damage.