Expert: Daniel Humphrey - 3/17/2008

Question
I obtained the walls and roof sections from an 8'x17' wood-framed shed that was dismantled.  I want to place it on the already-paved concrete area in my side yard, but this area has a slope of 7.5 inches over 17 feet.  I am concerned about how to set piers on the concrete slope, and how to anchor the piers to the concrete and to the shed floor which is a 2"x4" frame with 1/2 inch OSB.

Answer
Chris,

I think the slope is not great enough to cause the pier blocks to slide. Simply forming up pier blocks, four per side, and pouring them on top of the existing concrete will probably be enough anchor; the concrete you pour will mate to the surface and have a good grip and still be removeable if you want at a later time.

With 2x4 floor joists, you need to support them at midspan as well, since your floor would have a lot of deflection otherwise. The best way to do this is with a 4x4 saddle beam beneath the midspan, supported every 6 feet or so.

I would replace the OSB with plywood at least 5/8" thick, since OSB is not appropriate for a floor--it is too weak and disintegrates easily. If your floor joists are more than 16" OC, use 3/4" plywood.

Dan