I don't know if this is the right place to put this - but I need help and apparently nowhere else has this issue.

I'm trying to make literally just a house and the roof will not fade. The tiny little tile at the top fades because I can assume the game is classing that as the roof but that isn't helping anyone see inside is it? I need the actual roof itself to fade, why isn't it?

I've thrown the opacity all over the place to try and sort it and nothing has worked. Why is this happening?