Particle Board Roof Decking?

This was installed on a detached garage. Probably was installed 15 years back, 5/8 inch particle board roof decking. I did a search on this board and did find that at some point there was a type of particle board allowed for roof decking, not sure if it is still around. I am also not sure if this is it. I found something stamped on a board but could not make it out (pic #2). As you can see some of the boards have cracked between the trusses. Anyone have a link or information on this?

Crappy material and they didn’t even use H clips!

With those sheathing cracks it looks like a safety hazard. :shock:

I think back then it was tong and grove

It looks to be MDF board. Used in cheap furniture manufacture. Not suitable for roof loads.

yep I agree

Yep that looks definitely like MDF and IMO it is not even good for furniture manufacture. Only good for crap IKEA or Walmart not offs of decent furniture.
Really hope the OP didn’t walk on that roof.

I did walk on the roof. Took about two steps, felt the sponginess and got right off! Thanks for the help guys.

Best I could come up with, Appears to say underlayment I have never heard that term used with roof sheathing material

Ps. mdf is medium density fiberboard, fairly dense and individual strands of fiber cannot be seen. That is indeed particle board and the particles are press together with a glue binder containing a great deal of formaldehyde. Individual particles are fairly coarse and can easily be seen both on the surfaces and on the edges. Not a suitable material for roofing or any exterior use.

Agreed. That is not MDF. It is particle board for sub-floor underlayment, only that’s not what they used it for…defect for sure.

Definitely not MDF just cheap particle board. Doesn’t particle board underlayment need to be T&G?

My first carpenter job was working for a builder that was using 5/8" particle board underlayment over 1/2" plywood subfloor…no T&G. I distinctly remember carrying that crap upstairs. That is the only time I have seen it, and glad that it didn’t become the norm.