How to Build a Floor for an Outdoor Shed

Backyard sheds in various sizes and appearances are available at hardware stores.

Whether it's a backyard shed you build yourself, or one from the hardware store, it needs a sturdy floor to hold your valuable yard machines, and protect them from the dirt and moisture. A simple wood frame and floor takes several hours to build and will last for years. Using standard 8-foot stud lengths gives an 8-by-8-foot floor without having to cut any wood.

Things You'll Need

• 7 8-foot 2-by-4-inch wood studs
• 2 4-by-8-foot 1/2-inch plywood sheets
• Paint brush
• Creosote oil
• 2 1/2-inch wood screws
• 1-inch wood screws
• Power screwdriver
• Spray paint
• Shovel
• Carpenter's level
• Contractor-grade weed-control plastic barrier
• Pea gravel

Instructions

Preparing the Frame

1. Paint each piece of wood with a coating of creosote oil and allow to dry.

2. Lay two studs parallel to one another, 8 feet apart and with the 2-inch side facing downward. Lay a stud in the same fashion at each end, just inside the first two studs, making a square.

3. Screw two 2 1/2-inch screws through the flat side of the stud and 3/4-inch from its edges into the end of the corner connecting stud, making a butt joint. Repeat this at each corner.

4. Place three more studs inside the square frame with the 2-inch side facing down, at the 24-inch mark, the 48-inch mark and the 72-inch mark. The ends of the studs should just reach both sides of the frame.

5. Screw two screws from the outside of the frame into the ends of the studs the same as the corner studs, holding them security in place.

6. Lift the frame and move it to where the shed floor will go. If you want the floor to rise about the ground level, then skip the next section.

Digging the Soil

1. Spray paint around the edges of the frame and then lift it up and move it out of the way.

2. Dig out the interior of the spray painted square to a depth of 4 inches.

3. Tamp the soil with a hand tamper until it is well packed down and level.

4. Check the level with a large carpenter's square to ensure that the soil is level across the entire surface. Perfection is not the goal but it should be as close as you can make it.

5. Set the frame back into place.

Laying the Floor

1. Check the level of the frame on all sides with the carpenter's level. If it is not level, then adjust the underneath soil by digging or adding soil at the proper level. Continue to measure the level and adjust the soil until the frame is level on all sides.

2. Pull the frame up from the area and cover the space with a layer of contractor-grade weed-control plastic barrier. Put the frame back into place.

3. Fill in the spaces between the studs with pea gravel to the level of the top of the studs. Drag a free stud over the top of the frame to ensure that the gravel is not reaching above the top level.

4. Place a 4-by-8-foot sheet of 1/2-inch plywood on the frame so that it covers half the frame.

5. Screw a 1-inch screw through the plywood into the frame every 24 inches around the perimeter of the square, and along each interior stud. Repeat the process with the other sheet of plywood, making a complete floor for the shed.

References

• Woodworking Online: Connections
• ToolsInAction.com: Lumber Wood Buying Guide
• Secrets-of-Shed-Building.com: Building a Shed Base for a Plastic or Metal Shed in 8 Easy Steps