Building Codes
Building Codes Around the World
The building rules that govern your job, country by country — plus the on-site maths that's the same wherever you build.
Pick your country
Building rules are set country by country — and often state by state. Start with where you build.
National Construction Code (NCC) — which edition applies where you build, plus the rules you can actually calculate.
International Residential Code (IRC) — which edition applies where you build, plus the rules you can actually calculate.
New Zealand Building Code — one national code, no regional variations, plus the rules you can actually calculate.
Building Regulations (Approved Documents) — which edition applies where you build, plus the rules you can actually calculate.
National Building Code of Canada (NBC) — which edition applies where you build, plus the rules you can actually calculate.
Building Regulations (Technical Guidance Documents) — one national code, no regional variations, plus the rules you can actually calculate.
Code de la construction et de l'habitation (+ arrêtés / NF DTU) — one national code, no regional variations, plus the rules you can actually calculate.
Landesbauordnungen + DIN 18065 — which edition applies where you build, plus the rules you can actually calculate.
Código Técnico de la Edificación (CTE) — one national code, no regional variations, plus the rules you can actually calculate.
SNI + Peraturan Menteri PUPR (Bangunan Gedung) — one national code, no regional variations, plus the rules you can actually calculate.
- Japan Building Standard Law (建築基準法) + Enforcement Order Coming soon
- India National Building Code of India (NBC 2016) Coming soon
- Norway Byggteknisk forskrift (TEK17) Coming soon
- Sweden Boverkets byggregler (BBR) — replaced 1 Jul 2025 Coming soon
Universal calculators
The maths that's the same wherever you build — concrete volumes, bag counts and post holes don't change with the code book.
- Concrete Calculations: The Complete On-Site Guide How much concrete do I need? Work out slab volume, bags per cubic metre, mix ratios and post holes by hand — the on-site concrete numbers at a glance, in metric.
- How to Calculate Concrete Volume for a Slab Work out how much concrete you need for a slab: length × width × depth in metres gives cubic metres. A worked example, plus how much to add for wastage.
- How Many Bags of Concrete Per m³? (20kg, 25kg, 40kg) Work out how many bags of concrete you need per cubic metre — the simple weight-over-density method, a yield table for 20kg, 25kg and 40kg bags, and a worked slab example with wastage.
- Concrete for Post Holes: Volume Per Hole & Bags Needed Work out the concrete for a fence post hole the honest way — cylinder volume minus the post — then convert litres to bags. Worked example: a 300 mm × 600 mm hole with a 90 mm post.
- Concrete Mix Ratios Explained: 1:2:3, 1:2:4 & Water-Cement Ratio What a concrete mix ratio like 1:2:4 actually means, how to turn it into cement bags and litres of water per cubic metre, and why the water-cement ratio decides your strength.
- Roof Pitch to Angle: Convert Rise/Run to Degrees & Grade The formula, quick, plus a conversion table for common roof pitches — rise over run to degrees, and to percentage grade.
- Rafter Length Calculation: Run, Rise & Overhang Work out common rafter length with Pythagoras — run and rise to the exact length, plus how the eave overhang and birdsmouth seat cut change what you order and cut.
- Stair Rise & Run Setout: Riser, Going & the Comfort Formula How to mark out a stringer by hand — riser height, going, tread count, and the 2R+G comfort check (Blondel's rule) — with a worked example from a real floor-to-floor rise.
- How to Convert a Fall or Gradient: Ratio, Percentage & Degrees Convert a fall or gradient between ratio (1:X), percentage and degrees — the formulas, a drainage-fall worked example, and a ramp-gradient worked example.
- Stud & Joist Spacing Takeoff: How Many at 400, 450 & 600 mm Centres Work out how many studs or joists a wall or floor run needs at any on-centre spacing — the run-length-over-spacing formula, plus the corner and opening extras that get missed.
- Gravel & Base Volume: Compacted Depth vs Loose-Fill Order Quantity Work out how much gravel or road base to order for a compacted sub-base — area × depth for the compacted volume, then a compaction (bulking) factor to get the loose-fill quantity to order.