A level base makes everything else easier: square walls, smoother door fit, and fewer headaches.

1. Choose a firm, well-drained spot. Avoid areas where water pools.
2. Use patio slabs/pavers, or treated timber skids on compacted gravel/blocks to keep timber off soil.
3. Check level in multiple directions with a long spirit level and straight edge.
4. Check squareness by measuring diagonals across the base area.

1. Lay out the two 2400mm rim joists parallel.
2. Fit three ~1724mm joists between them, spaced evenly (~600mm centres).
3. Square the frame by matching diagonals.
4. Pre-drill and screw: two 80–100mm screws per joist end, staggered to avoid splitting.
5. Set frame on the base/skids and check it doesn’t rock. Shim if needed.

floor frame assembled and squared.

1. Cut OSB3 to cover 2400×1800mm. Plan joints to land on joists.
2. Leave ~2mm expansion gap between sheets.
3. Fix with 50mm screws or ring-shank nails every 150–200mm along joists.
4. Optional: treat underside edges/cut ends for extra moisture resistance.

4A. Front wall (door wall — high side)

• Build a 2400×2100mm frame with a centred door opening ~750mm wide.
• Add a header at ~1800mm door height (single 38×63 on edge is typically fine for a small shed).
• Double up studs around the door if you want extra stiffness.

front wall framing with door opening and header.

4B. Back wall (low side)

• Build a 2400×1800mm wall with studs ~600mm centres (corner studs + 3 intermediates).

4C. Side walls (sloping tops)

• Each side slopes from 2100mm (front) down to 1800mm (rear).
• Build as a trapezoid: studs 2100 / ~1950 / 1800 and trim/angle the top to match the slope.

Side wall trapezoid + roof slope line.

1. Raise back wall first, brace plumb.
2. Raise side walls, snug into corners, brace as needed.
3. Raise front wall last, align door opening square.
4. Screw bottom plates to floor at ~600mm intervals.
5. Screw corners together (2–3 long screws per corner from inside).

Pent roof slopes from high front wall to low back wall (approx 300mm drop across the span).

1. Cut ~6 rafters at ~1900mm (adjust for overhang preferences).
2. Place end rafters flush to outside edges, then space intermediates evenly (~400–600mm centres).
3. Fix with screws + metal ties/angles (recommended for beginners).
4. Check rafters are in-plane (no twist) before final tightening.

Rafter spacing and alignment across shed width.

1. Cut OSB3 roof sheets to suit overhangs; keep joins landing on rafters.
2. Fix with 40–50mm screws/nails every ~150mm along rafter lines.
3. Apply mineral felt starting at the low end; overlap strips ~100mm.
4. Nail felt with clouts at ~100–150mm spacing along edges/overlaps.
5. Fold felt over front/back edges where possible and nail down.

felt strip direction + overlap detail.

1. Make a rectangular door frame: 2 stiles + 3 ledges (top/mid/bottom).
2. Square it (match diagonals) before adding braces.
3. Fit two diagonal braces inside the frame.
4. Important: braces should rise towards the hinge side to resist sagging.
5. Fix T&G boards vertically to the outside face; trim edges flush.
6. Test fit in the opening; aim for ~5mm gaps on sides/top and ~10mm at bottom.

Correct brace direction (up towards hinge side).

1. Fix tee hinges to the door (strap across ledges for solid fixing).
2. Shim door in place to hold correct gaps, then mark hinge plate holes on frame.
3. Pre-drill and screw/bolt hinges to frame.
4. Fit latch/hasp at comfortable height; add a simple door stop if desired.

• Fix shiplap horizontally from bottom up. Keep groove facing down for weather shedding.
• Nail to each stud with galvanised nails (2 per stud for wider boards where needed).
• Cut side-wall top boards to the roof slope line.
• Add corner trims to protect joins and tidy the finish.
• Seal cut ends and apply a suitable exterior treatment/paint for long life.

Image placeholder: shiplap orientation (tongue up / groove down).