I have 19/32" OSB as a subfloor (2nd floor) and joists are spaced at 18 -19". It seems like somebody was saving on materials.
I am planning to install hardwood and as per the hardwood installation instructions the subfloor should be at least: 3/4" OSB or 5/8" plywood with the spacing between joists 16" or less. Now the question, what's my options for reinforcing the subfloor?
Using 1/4" plywood, glue and screws on top of the OSB????
Any other ideas besides replacing existing OSB?
Ok, I will install 1/4" plywood.
Do I need to get exterior grade plywood or regular?
1/8" gap between the sheets is enough?
I guess I will need to orient the sheets perpendicular to the existing OSB subfloor sheets, which will be parallel to the joists?
Regular plywood will be just fine. you are correct, you will want to lay the new ply perpendicular to the existing plywood and make sure you overlap and joints. This would also be a good time to screw the existing subfloor down really well if it isn't already.