does anyone?

heres another crazy question? can anyone tell me on a flat roof with a built up roof wht that insulation is called that looks like light weight cement and crumbles thats over the metal decking. thanks in advance! sorry no pictures. its whitish and chaalky

Could be gypsum or maybe tectum. However, neither one would require metal deck as a form board normally. Old School s observation as fesco board imho is correct, cause this product was made w/ wood chips and disintegrates when wet.

Sounds like it might be gypcrete which is a misture of gypsum and concrete...it's sometimes poured over just a wire mesh with felt on it around here.

be careful walking on it, check the deck for rusted spots before walking on it.

Jed you take this one :lol: