A compact footprint stacked twice
A narrow suburban lot rewards building up rather than out. This plan puts the living rooms downstairs and three bedrooms above, on a footprint small enough that one slab and one perimeter footing carry both floors. Every exterior wall appears twice in the drawing, once per storey, and the estimator counts each storey's studs and sheathing on its own level so you can see what goes up in each lift.
The storeys are 2.6 m (8 ft 6 in) floor to floor, which leaves room for a floor structure between them; the floor joists themselves are not a row here, because the site has no calculator that counts joists from a span and a spacing yet.
What advanced framing changes
Two-by-six studs at 24 inch centres are the core of what builders call optimum value engineering. The deeper cavity holds 5 1/2 in (140 mm) of mineral wool instead of 3 1/2, and wider spacing means fewer studs bridging the insulation. The wall drawn here is thicker than a 2×4 wall by the difference in stud depth, and the plan shows it.
The saving is not automatic. Studs at 24 in have to land under the joists or trusses above, sheathing and siding must both be rated for that spacing, and window openings want their headers designed rather than guessed. Compare the stud row with the swap below to see what the wider spacing actually saves on this house.
The weather side
Plywood sheathing is chosen for its nail holding and its tolerance of a wet week before the wrap goes on. Fibre-cement lap siding goes over it; its row carries the higher cutting waste that brittle planks produce. A polyethylene membrane sits on the warm side of the mineral wool, the arrangement many cold-climate codes describe, with the openings deducted from its inside face area.
Checks before the order
An 8 in 12 roof over a two-storey house is a long way up: arrange scaffolding or a lift with your own supplier, because no row here measures access. And read the outside door count: two doors on the ground floor, each with its flashing, casing, sealant and paint rows, are counted from their own size, 920 × 2100 mm (36 × 84 in).