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.
- United States International Residential Code (IRC) Coming soon
- New Zealand New Zealand Building Code Coming soon
- United Kingdom Building Regulations (Approved Documents) Coming soon
- Canada National Building Code of Canada (NBC) 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.