Three season porch with flat roof deck. Heard of Lockdry?

I am in the process of adding a three season porch on my home. I live on a golf course and would like the roof to be flat and use the roof as an additional deck. It will have access from the second story master bedroom. A local contractor suggested using lockdry as the roof.

Has anyone tried this material for a flat roof? I am open to all suggestions what is the best roof that can also be used as a deck. The roof will be 16 x 26.

i would put a roof on 1st,lay out extra material in line to put sleepers,then put that over the sleepers,i wouldn`t trust it by itself