Floor

FLOOR RESOURCES:

It is critical that the floor framing is square BEFORE the first piece of floor sheathing is installed. Also, other important notes:

The long dimension of the floor sheathing should be installed perpendicular to the direction of the floor joists.
Subsequent courses of panels should have joints staggered by 4 feet.
The tongue of the first course of floor sheathing plywood should be pointed outward; the tongue should be removed if the dimension of the floor sheathing allows for it.
The rigid insulation underneath the floor sheathing will be installed so the long dimension of the insulation is parallel to the joists (so that they are at right angles to the floor sheathing plywood.

Subfloor Installation: Gluing, Placing, and Nailing Subfloor (A short video illustrating the way subfloor panels are oriented and installed relative to the joists). Deviations from the video that we will follow:

We will not be using glue (since this tiny shelter is designed to be moved around anyway).
The subfloor will not be nailed down -- instead 3" screws will be used to accommodate the 1" thick rigid floor insulation.
We will not gap each panel to be 1/8" away from each other. The subfloor plywood will serve as the finish flooring in the tiny structure for its durability. Gaps are to be minimized for sanitary purposes.

Squaring the Floor Frame

Before doing anything else, use a tape measure to measure each overall diagonal. If the two numbers are not equal, the floor frame is not square. Use a sled hammer as necessary to square the structure first before applying any plywood. In you get it square, you might need to temporarily attach some wood (with screws) across the corners to keep it square.

Insulation

Lay down the first full-size piece of rigid foamboard insulation in one of the corners where the floor will be. Use 8D nails to tack this sheet in place temporarily. The screws from the subfloor sheets of plywood will hold it more securely later.

From the first sheet you can measure the other pieces. Make sure joints in adjacent courses of insulation do not line up on the same joist or other structural member. The purple lines in the picture show properly staggered joints..

Sub Floor Plywood

Use 3 pieces of tongue and groove plywood and 3 inch screws (T25 star bit) to screw in the plywood. The impact drill is recommended. The full piece of plywood should be sufficient but it might need to be cut slightly to land halfway on a joists. ALL JOINTS MUST LAND ON FLOOR JOISTS!! The other piece should just be cut in half, but of course check the measurements. If the board is warped place the board on the insulation and get some group members to stand on it. If the board is not in position it is better to put it in place with a sledgehammer while there is still weight to counteract the warp. If you need to use the hammer use a 2x4 to distribute the blow a bit so it doesn't destroy the edge of the plywood. Be careful with this material. This will be the final floor. One side of the plywood should have fewer knots and this side should be faced up. The tongue of one board should FULLY engage into the groove of its neighbor.

Use the track saw to cut the plywood to line up with the floor joists. Measure twice, cut once.

Make sure the plywood seams don't match the insulation seams but still alternate big and small pieces so that joints in adjacent courses of plywood DO NOT land on the same floor joist. Be sure that the tongues line up with the grooves of the sheets and that there is full engagement.

Use the 3" screws (T25 star bits) to secure the plywood to the floor and rim joists. Screws should be spaced 12" on centers in the field, and 6" centers on all edges (where you can). When the seams line up alternate screw locations from one board and its neighbor to minimize the risk of screws interfering with one another.

Use the track saw to cut off any excess plywood.

Front Porch Decking

Make sure flashing is installed around the door before you start decking !!! You won't be able to install it afterwards.
Measure and precut the 2x6 decking boards first. Each board should hang over the front floor joist by at least 1/8".
Pre-drill six holes in each board to line up with the three floor joist locations. These holes should be big enough to allow the screw to pass through BUT NOT THE HEAD OF THE SCREW.
Space the boards evenly across the porch so that the gap between all boards is consistent. Often a nail or screw can serve as a good spacer.
Make sure the front edge of all boards are aligned and even before screwing each board down using six 3" screws.

Use the Chop Saw to cut the boards to length (use a stop block for efficiency). Measure from the purple insulation to the front face of the front rim joist. (measure from multiple locations as it may not be square).

Lay the boards across the exposed floor joists. (DO FLASHING FIRST) Make sure when you do this that the gaps between each board are equal.

Secure each board using six screws.

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