How to Build a Tiny House – Part 6: Installing Wood Floors

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Wood Floors for Comfort

Some structures–A-frames, tree houses, and gazebos–depend on floors for support. Others do not need floors because they rest on a concrete slab or below-ground footings. But you can cover bare ground with gravel or sand. To provide a dry and ventilated surface for walking or for storage, a wood floor may be desirable.

Two Types of Floor: For a permanent floor, build an understructure as shown. For a removable floor, build portable deck modules, called duckboards, which rest on the ground or on a slab.

Make the deck surface from pressure treated 2-by-4s or 2-by-6s spaced 1/8 inch apart for good drainage. The boards are normally nailed to 2-by-6 or 2-by-8 joists spaced 16 inches on center.

If a floorboard is cupped, install it hollow-side down to help prevent water from pooling on the floor.

Laying a Permanent Wood Floor

1. Building the Understructure.

Attach 2-by-8 beams to the outsides of the posts with 3/8-by-3 1/2-inch lag screws.

Mark joist positions every 16 inches along the beams.

With 2 1/2-inch galvanized common nails, attach 3/4-inch plywood nailing cleats to the posts level with the beams so the cleats will support the deck boards.

Secure joist hangers to the beams with joist hanger nails (left), then attach the joists to the hangers.

From joist lumber cut bridging boards to fit between joists. Fasten the bridging with 3 1/2-inch nails, offsetting the boards for ease of nailing.

2. Fastening the Floorboards.

Notch floorboards with a handsaw, as necessary, to fit around the posts.

Fasten the first row of boards flush with the beam edge and extending at least 2 inches beyond the understructure, driving two 3-inch nails at each joist position.

Nail down the rest of the floor, spacing boards 5 inch apart. Extend each row at least 2 inches beyond the understructure. Center any end-to-end joints between boards over a joist.

To ensure the edge of the last board is flush with the beam, adjust the spacing between the last 3 feet of boards (right)–or trim 1/4 inch off the edge of one or more boards–as necessary.

3. Trimming the Board Ends.

Mark the ends of the boards with a chalk line.

Align the blade of your circular saw with the chalk line, butt a 1 -by-3 against the base plate, and tack the strip to the deck boards as a cutting guide.

Trim the first 12 inches with a handsaw–the power saw’s motor will keep the blade from reaching any closer to the post–then cut along the chalk line with a circular saw (left) until the saw contacts the far post. Keep the saw base plate flush against the cutting guide throughout.

Finish the job with a handsaw.

Putting Together a Portable Platform

Making Duckboard Decking.

Measure the length and width of your structure and calculate the quantity and size of duckboards you will need. The usual size is around 3 to 4 foot square.

Build an understructure by butt-nailing pressure-treated 2-by-4s with 3 1/2-inch nails.

Face-nail 2-by-6 boards onto the frame, spacing them 1/4 inch apart.

Adjust spacing of the last few boards so that the outermost board fits the end of the frame precisely.

For further instructions, see How to Build a Tiny House.

Reprinted with permission from Jay Schafer’s DIY Book of Backyard Sheds & Tiny Houses: Build Your Own Guest Cottage, Writing Studio, Home Office, Craft Workshop, or Personal Retreat by Jay Schafer and published by Skills Institute Press LLC and Four Lights Tiny House Company, 2013. Buy this book from our store: Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses.

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