Hi,

I have a flat garage roof that has started to leak. It currently has
chipboard beneath the felt, which has started to expand and rot. So I need
to totally replace the roof, replacing chipboard with 18mm WBP ply, then 3
layers of felt (2 underlay 1 top)
Now my question is, the 1st layer of underlay, should I nail it to the ply
boards, stick it, or leave it free moving. I read this website
http://www.diydata.com/projects/flatroof/flatroof.htm that says to nail the
felt every 6" (using proper felt roofing nails), however I was talking to
our 2 builders/maintenance contractors at work and they said if you nail it,
when the felt expands, it rips, so you should just lay it on, and not
nail/stick it.

Who is right?

Any help greatly appreciated!

Cheers

Ben

"Thanks to God, I am Still an Atheist"