Installing OSB subfloor in garage attic

GatorJoe · 11-21-2009, 10:28 PM

I am in the process of installing OSB as a floor in my garage attic. I intend to use the area for storage. The garage is 24' x 24' and the joists are 2x12's installed 16 inches on center the full width of the garage. While I am not even close to an engineer, this appears to be very sturdy and I would think could hold a moderate amount of weight (typical storage - nothing excessive). Is this a reasonable assumption based on what you see in the pictures provided?

The other important question involves a few random 2x4's that are nailed across the joists. I am guessing that these were put there just to add a little bit of stability. Since I am nailing down OBS throughout, do I need to leave these in place? They just seem to random to be anything required by code.

There is also one 2x4 that is installed vertically between the roof and one of these 2x4's. It is firm but in no means solid when I push on it.

Any thoughts would be appreciated.

Regards,
Joe

**Gary in WA** · 11-22-2009, 01:16 AM

The 2x4's flat on the joists are temporary if you install sheathing . The center 2x4 under the 1x ridge board is temporary when installing the rafters. You can remove them BUT the joists will move so sheet up to them and nail the decking off before removing the flat 2x4's. And you door top track and opener is attached so be careful that the joists will not move during decking.

They are made to carry their own weight and span the distance. They already carry the garage door when open and the opener. You would need to weigh the door and opener to subtract it from the total load they could carry. I would use real ply as it is 15% lighter than OSB.

Be safe, Gary

GatorJoe · 11-22-2009, 11:17 AM

Gary, thank you very much for your input on this issue. You have offered me reassurance that my initial thoughts might be correct. Unfortunately, you are also the third person to question the choice of USB. I'm worried about this, but I went in the basement of my home (built in 2002) and the subfloor above was OSB. The product I purchased to put above my garage was labeled tongue and groove OSB subfloor. Hmmmm.

Regardless, thank you again for your time!