subflooring

[mtCDCcb]

I have a second floor condo that is getting remodeled. I am replacing the carpet and my subfloor is 1.5" of gypcrete over 5/8" plywood. The condo is over 30 years old and the gypcrete is all cracked and flaking off. My contractor wants to replace the gypcrete with 2 pieces of 3/4" plywood glued together. Can he do this? Thanks.

There is a residential unit below. Would the (2) 3/4" pieces of plywood meet the required separation?

[Jerry Peck - Codeman]

My contractor wants to replace the gypcrete with 2 pieces of 3/4" plywood glued together. Can he do this?

Not without first checking with the local building department and Fire Marshal to see what they say. This is because:

There is a residential unit below. Would the (2) 3/4" pieces of plywood meet the required separation?

However, your contractor would need to check for a UL design to see what is allowed, and the entire system (gypsum coating, sub floor, type of wood trusses - if wood trusses, gypsum ceiling below - 1 or 2 layers, etc.

There are some examples here: http://www.gypsum.org/wp/wp-content/upl ... part2.html (scroll down to page 122 to start with), but your contractor would need to verify all the exact particulars as to what exists and the original construction, then select the appropriate UL design, submit that to the building department to find out what they say. My guess is that your local building department is going to want 'someone responsible' (i.e., an architect or engineer) to sign and seal the proposed change, not just accept what you contractor finds on their own. Building departments want, and for good reason too, to have a responsible party for any and all changes, especially when made to a fire-resistive separation component such as a floor-ceiling system.