Another roof attachement question

[suckerpunched]

I've read that when applying aluminum over wood on the roof it should float to allow for expansion.....I am using 1/8 birch for my roof, maybe one layer....maybe two....should I glue the first layer directly to the spars or allow it to float????? If I use a second layer,,,,should it float on the first or be glued????
Thanks,,,,,TC

[madjack]

...ALL wood should be glued/fastened securely...on another note, I place my spars on 8" centers and use NO ply underlayment and lay the AL directly on the spars/ribs...I do use 1/8th ply on the hatch..........
madjack

[planovet]

I used one layer of 1/8 birch on my roof. Like MJ said, it should be secured very well. I used a combination of staples and screws along with glue. I then floated my aluminum on top of that.

[suckerpunched]

Thanks for the info.....glued and screwed it will be...............