I am planning on installing 5/8'' bamboo flooring in my three story
townhouse. I just ripped up the carpet and pad on the second floor and
discovered the subfloor material is not wood, but rather something that
resembles cement board used for tiling. When I pulled the nails from
the carpet tack strips out, some small pieces flaked off.

Does anyone have an idea of what material this subfloor might be? Is
my guess of cement board correct? I would take a piece of it to home
depot to compare, but just haven't had the time. If it is cement
board, am I correct in assuming that my nail-down job just became a
glue down job?

Thanks in advance,

Joe