Step 4. Make the floor
Make the floor up on the ground, to the dimensions as shown in the floor plan.

Use the off-cuts from the floorboards to make the trapdoor as shown in (step 8)

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Step 5. Stand the front and rear frames and place the floor
Stand the front frame a and back frame c upright. You will need help or temporary braces and/or props to hold each end frame vertical while you bolt the lower and middle cross members for wall c and d in place. Leave the top cross members d1 and c1 off until the floor has been lifted in place.

The floor will sit on the frame cross members and will not need further fixing.

The top cross members d1 and c1 can then be bolted in place.

Make sure all the horizontal frame members are level and all the vertical members are plumb (upright) and that the structure is square, and then...... add (nail on) all the braces d6, b6 and c6 except for one of the c6 braces on the ladder side (this brace is in the way of a bolt hole and can be added when the ladder is in place).

Fix the beam d3 in place ensuring the font and rear walls are parallel. The beam can be fixed to the collar ties a4 and b5 with nails and then further secured with metal galvanized strap nailed to both beam d3 and collar ties a4 b5

Step 6. The roof
On the topside of each rafter make a mark every 100mm (4").

Commence fixing the roof boards to the rafters beginning at the bottom and working up to the top. Nail through each overlap into the rafters. Ensure the top of each board is on a mark and that the ends of each board overhangs the front and rear frame equally.

Do one side of the roof first and then make up the middle rafters which are two pieces of 70x45x1200 (1 1/2x 2 1/2x 48") bolted together at right angles. Next slide the middle rafters over the beam and clamp into place until nailed. (See pictures).

Now fix the roof boards to the other side of the roof.