Buildings, rooms and structures
Checklists and rough rules for the working model (step 2) and the feasibility check (step 4). Every value is rough and codes differ by country. Always flag that local building rules apply, and recommend a structural engineer for anything that carries people or a building.
Load path
Section titled “Load path”- Trace every load continuously down to the ground: roof → rafters → walls or beams → columns → foundations → soil. A gap anywhere in the chain means it fails.
- Loads to consider: its own weight, people and contents, snow, wind (including uplift), and point loads such as a bath or a bookcase.
- Rough residential floor load: about 1.5–2 kN/m² of people and contents, on top of the floor’s own weight.
- Openings in load-bearing walls need a beam (lintel) and something solid under each end.
- Anything that sways needs bracing: diagonals, shear panels or rigid joints.
Rough member sizes (for sanity checks only)
Section titled “Rough member sizes (for sanity checks only)”| Member | Rule of thumb | Example |
|---|---|---|
| Timber floor joist (at ~400 mm spacing) | depth ≈ span / 20–24 | 4 m span → about 175–200 mm deep |
| Steel beam | depth ≈ span / 20 | 6 m span → about 300 mm deep |
| Concrete slab | thickness ≈ span / 30 | 5 m span → about 170 mm |
| Shelf (wood, 18 mm) | span up to about 70–80 cm for books | longer spans sag |
Circulation and clearances
Section titled “Circulation and clearances”- Doors: clear width at least about 80 cm, and about 85–90 cm for wheelchairs.
- Corridors: at least about 90 cm, and about 120 cm for wheelchairs.
- Stairs: rise about 15–19 cm and going about 25–30 cm (2 × rise + going ≈ 60–63 cm). Headroom at least about 2.0 m. Handrail at about 90 cm.
- Ceiling height: about 2.4 m is typical for living spaces.
- Space to use things: about 1 m in front of kitchen counters and wardrobes, and room to open every door and drawer.
Daylight and ventilation
Section titled “Daylight and ventilation”- Glazing of about 10–20% of the floor area for daylight.
- Every room needs fresh air. Kitchens and bathrooms need extraction.
Services
Section titled “Services”- Water supply, and drainage that falls continuously (about 1:40 for small waste pipes), with traps and venting.
- Electrical: circuits and their capacity, and the zones where water is present.
- Heating, cooling and ventilation routes, and space for the plant.
Moisture, insulation and condensation
Section titled “Moisture, insulation and condensation”- Keep rain out, let vapour escape, and put the vapour barrier on the warm side of the insulation.
- Cold bridges (steel, concrete through the insulation) cause condensation and mould.
- Wood rots if it stays wet. Keep it off the ground and ventilated.
- Escape routes from every room, with limited travel distance and no route that passes through a room at higher risk.
- Smoke alarms, and fire separation between homes and garages.
Accessibility
Section titled “Accessibility”- Step-free entry, door and corridor widths, turning space (about 1.5 m circle), and switch heights.
Codes and permits
Section titled “Codes and permits”Rules and permits vary by country and region: planning permission, building regulations, and heritage or zoning rules. Always name this as an open item and point the user to their local rules or authority.