How to Build a Foundation and Frame a Floor for a Garden Shed ...24 Jul 2012 ... If not, persuade the frame a bit with a hammer and a block. The floor of the shed is simply a combination of 2×6 and 2×10 framing lumber: durable and visually interesting. The boards are fastened to the underlying frame with epoxy-coated decking screws. Just like the 4×4 components, these floorboards are likely to be wet from the lumberyard and a bit swollen. I want to install them tight to each other so that when they dry out and shrink, I'm not left with excessive gaps.