Step 2. The floor boards

Fix the 8 floorboards (#2) to the three under floor skids (#1) with 75mm (3") galvanized nails. Ensure the finished floor dimensions are 780mm x 1200mm (31-1/4" x 48"). The three under floor skids should be evenly spaced with two each side and one in the middle.

Step 3. The front and rear frames.

Nail the front and rear frames together comprising of top and bottom plates (# 3) and studs (# 4). Overall frame dimensions of both front and rear frame should be 450mm high and 780mm wide (18" high and 31-1/4" wide).
Ensure the placement of the intermediate studs allow enough gap for the doorway. See diagrams for reference. Stand and fix the front and rear frames in place at each end of the floor.

Step 4. The side frames.

Fix the 2 sidewall top plates (#5) in place. See diagrams for reference.