Expert: Bruce E. Johnson - 4/19/2009

Question
I have a 3 car garage with a 13' ceiling in a finished garage, 2003 construction. I want to build an 7' loft for storage accross the entire garage which is 29' accross. My plan is to install 2x4s for the frame supported by 3 walls and a 2x4 decending from the rafters every 8 foot. I plan to install 2x4s every 16" to support the floor of 1/2" plywood. Will this structure support 60lbs/sq ft? The area is strictly storage(decorations, plastic tubs, camping gear etc.) I'd like to do this project in three sections starting the first 7'x8' section soon.
Any thoughts?
Thanks,
kg

Answer
Hi kg, if your loft has walls going all the way to the floor of the garage then yes.  If your loft is suspended solely from the existing roof system then no.  Most roof trusses only have a 20-40 pound live load capacity.   Your 2x4 joists should span the 7 feet okay but the 60 psf is a little heavy.  Are you sure that is how much of a load you require?  60psf is much more than you may think.  60 psf means that the area of a 4x8 sheet of plywood would hold almost a ton of weight..I have storage in my attic consisting of the same articles you describe and don't need nearly that much weight capability.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com