Once the cement mix dries, double check if the frame is leveled before adding the remaining six joists. It is recommended to space the joists as shown on Fig. 4. Starting from the edge of the first joist, measure 15-in to the center of the second joist and then the space should be 15-in from center-to-center for the rest of the joists. Use nails or screws to attach the joists. However, you should use screws to insure the foundation frame does not shift and remain balanced.
Once you are done installing the supporting joists, you should have a frame looking like Fig. 5.
Using the 4-ft x 8-ft standard plywood, cut them as needed to install the shed floor. You may notice, after installing the plywood, that only one layer of flooring does not feel sturdy. No worries! A double flooring has been accounted for in the materials. Do NOT install a second layer of the plywood yet. You may install a second layer once the wall frames are built and attached to the foundation.
See a compiled drawings of all figures used for planning the foundation, or continue to building back side frame.
