Most sheds are built on fairly level ground. The flat surface makes a better base for a shed foundation. Sometimes, a shed must be built on a slope. That presents a foundation challenge, because the shed floor must be level, meaning the foundation has to be adapted to the slope. A shed on a slope also presents a challenge for construction of an entry ramp. Overcoming that will depend on whether the slope is toward the shed door or away from it. The basic techniques are the same -- building a platform from the ground to the shed floor.
Lay a board from the shed floor to the ground to determine the angle of slope. Use a 2-by-4-inch board set on its edge on top of the shed floor or a sheet of plywood or wide plank butted against the end of the shed. Lay the other end against the ground. Mark the connection on the bottom of a 2-by-4 with a pencil or draw a line with a straight edge along the larger board to show the angle, which will determine the cut needed for framing members.
Install a 2-by-4 ledger board across the shed door about 3/4-inch below the floor, or other depth for whatever flooring will be used for the ramp, typically either plywood or 1-inch planks. Fasten the ledger with 3-inch galvanized deck screws driven with a screw gun into the shed floor frame, preferably at points where floor joists connect.
Build a ramp frame of 2-by-4s, one on each end the width of the shed floor, with side bands and any internal bands required, depending on the width; a standard door, for instance, will require only side bands while a wider door will require some internal braces. Figure the length of the ramp frame based on the type of flooring; for 1-by-6-inch fence planks, for instance, divide the length of the slope by 5 1/2 inches.
Adjust the length of the ramp to conform to the flooring, allowing either plywood or planks to extend beyond the outer end almost to the ground and to extend on the shed side over the end frame and the ledger board, right to the edge of the shed floor. Cut the shed ends of the outer boards to the angle required to fit against the shed. Use a speed square to mark the angle and cut with a circular saw.
Nail the ramp frame together with 16d framing nails, driven with a hammer through the end bands into the sides. Use two nails in each side board. Lay the frame against the ledger board. Support it temporarily with blocks to hold the ramp end against the ledger board. Check the slope angle, the connection points on both ends and make sure the shed door will close properly.
Fasten the ramp frame to the ledger board, once it is properly adjusted, with 3-inch deck screws, spaced about a foot apart. Cover the ramp with plywood -- 3/4-inch for heavy objects, 5/8-inch for a smaller shed -- or 1-inch planks of any width; 1-by-6-inch fence planks make a sturdy ramp. Fasten the plywood or planks to the ramp frame with 2-inch deck screws.