Are you talking about this?
http://www.homedepot.com/webapp/cat...=None&Ntpr=1&Ntpc=1&selectedCatgry=Search+All
Going to be a whole lot more the $400.00 to use that material and it's going to sag between the joist.
If this is a commercial building then I would think you will need to meet fire codes which will require at least one layer of 5/8 fire rock.
http://www.homedepot.com/webapp/cat...=None&Ntpr=1&Ntpc=1&selectedCatgry=Search+All
Going to be a whole lot more the $400.00 to use that material and it's going to sag between the joist.
If this is a commercial building then I would think you will need to meet fire codes which will require at least one layer of 5/8 fire rock.