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NZ Building Code guide
🪵 Materials — the plain-English guide
Timber, plywood, claddings, roofing, concrete grades, steel, fixings, sealants — encyclopedia entries for what you order. Free, plain-English NZ Building Code reference for builders — 14 topics.
NZ Timber SizesStandard NZ timber sizes per MiTek NZ + NZS 3604. Builders order by nominal call size ("4x2" or "100x50"), but timber… H-class TreatmentsNZ timber treatment hazard classes (NZS 3640) — chemical preservative treatment by exposure scenario. ⚠️ Two systems,… Structural Grades (SG)Structural grades classify the strength + stiffness of timber. Different from H-class (which is preservative… Timber Defects GlossaryCommon timber defects (BCITO Unit 24360). Knowing the names helps you reject below-grade timber at the merchant.… Cladding TypesPicking a cladding is a balance of four things: look, budget, durability and weathertightness risk . The risk part is… Roofing TypesRoofing systems for NZ residential. Pitch + profile + underlay + flashing must work as a system. NZ Metal Roof and… Plywood, LVL & GlulamEngineered timber is sawn wood broken down and re-glued — as veneers (plywood, LVL), laminations (glulam) or chips… Concrete Grades & MixesConcrete grades by MPa (megapascals — N/mm²). Higher MPa = stronger + denser. Mix design via cement type,… Steel Sections & ReoSteel earns its place in a house where timber runs out of puff — long clear spans , big point loads (a beam carrying… Fixings & FastenersThe fastener is the cheapest part of any connection and the one most likely to fail it. Two questions decide every… Sealants & AdhesivesFirst, know which job you're doing: a sealant stays flexible and is built to move with a joint (expansion, wind… Standard Panel SizesSheet products come in fixed sizes, and the smart move is to set out the framing and the job to those sizes — stud… Insulation InstallInsulation only delivers its rated R-value if installed correctly — fitted snugly, no gaps, no compression, vapour… Painting & CoatingsPaint is the most visible element of the build — and it's the element clients judge the entire job by. Get the spec +… Plain-English guide, not advice. This page helps you understand and navigate the rules — it is general information, not design, engineering or consent advice, and it does not reproduce the copyrighted tables of NZS 3604 or any Standard. Always check the current Standard or Acceptable Solution and your BCA, and use a suitably qualified LBP, engineer or QS where it matters.
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