So Im working on my next home project and want to turn the space above my garage into a storage space. When I went up there to take a look around I noticed the floor joists were simply just 2x4s as well as the rafters. The garage front to back (Width) is approximately 23ft and side to side (length) is about 24ft. The 2x4 joists are joined together with truss plates. Is sistering the current joists with another 2x4 enough to support a floor using 1/2 inch plywood and light weight storage bins?