How to Build a Shed Floor

Garden Shed Flooring

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Overview
  • Working Time: 3 hrs
  • Total Time: 4 hrs
  • Yield: 8-foot by 8-foot shed floor
  • Skill Level: Intermediate
  • Estimated Cost: $200 to $400

While a shed might add rustic charm to your yard, it is, above all, a functional structure. And to help the shed function at its best, you'll need sturdy elevated flooring. It helps, too, when that flooring is inexpensive and easy to build.

You can build your own shed flooring from little more than two-by-six lumber, sheet plywood or OSB, and a few extra items and fasteners. As an option, you might want to install a floor covering—a touch that improves the look and adds to the value of your shed floor.

Basic Elements of a Shed Floor

Shed Floor Joist System

At the base of the shed floor is the joist system. This system rests below the subfloor and any optional floor coverings.

  • Floor Joists: These are a series of parallel two-by-sixes spaced 16 inches apart.
  • Rim Joists: These are the two two-by-sixes placed perpendicular to the ends of the floor joists.
  • Foundation Rails: These are the two long boards—often, four-by-six pressure-treated boards set on concrete deck blocks—that were previously installed as part of the shed foundation. The rim joists rest on the foundation rails.

Shed Floor Sheathing/Subfloor

Sheathing is a smooth subfloor that is nailed to the top of the floor joist system. Eight-foot-long sheets of OSB or exterior-grade plywood are commonly used for shed floor sheathing. These large pieces provide smooth, strong flooring and laterally stabilize the joist system.

Depending on your needs and your budget, you may decide to use the OSB or plywood subfloor as the de facto top floor covering. Both materials function well as basic shed floor materials.

Optional Shed Floor Covering

If you'd like to add extra style and utility to the shed, you may decide to add a floor covering.

  • Pine Flooring: Inexpensive tongue-and-groove pine flooring planks can be easily laid down on top of the sheathing. You'll only need to cut the planks to size, then slide the tongues into the grooves. You can even face-nail the planks down to the joists below—no need for nailing or stapling into grooves.
  • Rustic-Grade Unfinished Wood: Rustic or utility-grade hardwood flooring is one of the best-kept secrets of many flooring retailers. Its price is on par with pine flooring, yet it looks much like the higher-grade hardwood you might install in your home. However, you should expect defects and blemishes with this economy flooring.
  • Sheet Vinyl Flooring: What sheet vinyl flooring lacks in durability, it makes up for in ease of installation, its ability to shed water, and its smooth surface. Since sheet vinyl can tear, use it only in light-duty sheds. One section of sheet vinyl flooring can cover most small sheds. To install, you'll only need to staple down the perimeter.

Codes and Permits

Building a shed floor itself as a standalone component rarely creates the need for a building permit in most communities. However, as part of a larger shed-building project, a building permit might be required. Check with your local permitting department.

What You'll Need

Equipment / Tools

  • Circular saw
  • Speed Square
  • Hammer
  • Wood clamp
  • Tape measure
  • Pencil

Materials

  • 2 OSB or plywood sheets, 3/4-inch, each 4-foot by 8-foot
  • 10 two-by-six boards
  • 4 steel framing connectors, 4-1/4-inch
  • Shed floor covering (optional)

Instructions

  1. Mark the Rim Joists

    Working on a flat, level surface, set two of the two-by-sixes on-edge, parallel to each other. Make sure that the ends are flush. Clamp the boards to prevent them from moving. Run the tape measure down the boards and mark every 16 inches with the pencil. Remove the tape measure. Use the Speed Square to transfer the marks across both of the boards.

    Tip

    Most tape measures have diamond-shaped hashmarks at every 16 inches. With this feature, it is not necessary to calculate every 16-inch progression.

  2. Install the Floor Joists on the Rim Joists

    Move the two rim joists about eight feet apart from each other and parallel. Dry-fit seven of the two-by-sixes at a 90-degree angle to the rim joists. Two of the floor joists should be located at each end of the rim joists. Using a hammer or pneumatic nailer, nail the floor joists into place from the back side of the rim joists.

  3. Move the Floor Joist System in Place

    With an assistant, lift the floor joist system onto the foundation rails. Run the tape measure across both diagonal directions of the joist system to check for square.

    If both numbers match, the joist system is square and can be nailed down. If not, the joist system is flexible enough that you and the assistant can adjust it so that it is square.

  4. Attach the Floor Joist System to the Foundation

    Nail the floor joist system down by toe-nailing it directly onto the foundation rails and by using steel framing connectors. Space the framing connectors between each of the floor joists.

  5. Install the Floor Sheathing

    Attach the plywood or OSB sheets to the shed joist system. The sheets should run at 90-degree angles to the joists. Nail the sheets into place on the rim joists and onto the floor joists.

  6. Install the Floor Covering

    If you decided that you would like to install a plank-style floor covering, install it on top of the floor sheathing so that the covering runs perpendicular to the floor joists. Sheet vinyl flooring can run in any direction desired.