I'm needing input on what size floor joist and side boards i should use on a pole barn shop loft 8'x40' standing on 5"x5" post spaced every 10'.I was thinking about 2"x8"s just not sure and spacing apart.I'm only going to build shelves up there to store a bunch of small stuff i dont use often, nothing of significant weight.The shelves will all be built out of 2"x4"s. Any help would be much appreciated.Thanks