Painting & coatings: the finish your client actually judges the job by

Paint is the most visible element of the build, and it’s the element clients judge the entire job by. Get the spec, prep and application right and the job lasts 8–12 years exterior, 15+ interior. Get any one of those wrong and it’s 3–5 years to failure — so the finish is worth treating as a system, not an afterthought.

Paint families and where they’re used

Different jobs call for different coatings. The common families on an NZ site are:

• Acrylic (water-based) — the most common NZ exterior. Flexible, UV-stable, fast-dry, low-VOC. Examples: Resene Sonyx 101, Dulux Weathershield, Wattyl Solagard.
• Solvent-based (oil) gloss — historically used for joinery and doors. Harder finish, less flexible. Resene Lustacryl is a water-based alternative gaining ground.
• Epoxy — garage floors, kitchen splashbacks (tile & grout sealer). Two-pot, hard.
• Polyurethane — joinery clear coats, decking oils.
• Lime wash — heritage / character look. Breathable, but limited durability.

Substrate prep for exterior timber

Most paint failures start with prep, not the paint. Work through these before a brush touches the timber:

• Seal the end grain BEFORE installation — primer on every cut end. This is the most-skipped step, and end-grain absorbs water like a sponge.
• Check moisture content is below 18% — verify with a moisture meter. Wet timber traps water under the paint film, which leads to blistering.
• Sand smooth — 80–120 grit. Remove mill glaze (the factory glaze repels primer).
• Pressure wash if dirty or weathered, then allow 48 hours to dry.
• Prime within 6 weeks of pre-prime weathering, or sand back and reprime (BRANZ).
• Sand between coats — 220 grit for adhesion of topcoats.

A typical NZ exterior weatherboard spec

For NZ residential exterior weatherboards, a standard build-up runs in this order:

1. 1 coat pink/grey primer (end-grain seal, plus factory primer if pre-primed).
2. 2 coats acrylic semi-gloss or low-sheen topcoat.

That’s 3 coats minimum — factory-primer plus 2 site coats is common. A few application rules that go with it:

• Spreading rate is roughly 12–14 m²/L per coat for acrylic.
• Don’t paint in direct sun on a hot day — the film skins before it levels.
• Don’t paint below 10°C or above 35°C ambient.

Colour, LRV and heat

Colour choice isn’t just aesthetic — it drives how long the coating lasts and whether the warranty holds.

• Lighter is longer-lasting. Dark colours absorb heat, so they expand and contract more, and the paint cracks faster.
• LRV (Light Reflectance Value) — manufacturers recommend above 40% for exterior timber, and above 55% for fibre cement or steel.
• Dark colours on steel or fibre cement need heat-reflective pigments (Resene CoolColour technology, Dulux Climate Choice).
• Warranty terms are often void if the LRV falls below the threshold.

NZ paint brands and a lead-paint warning

Builder consensus on the main brands (anecdotal):

• Resene — NZ-made, widest colour range, free expert advice, strongest exterior products. The reference standard.
• Dulux — Australia/NZ, strong commercial range, good interior.
• Wattyl — reliable mid-tier; Solagard exterior well-regarded.
• British Paints — budget range, OK for sheds and non-critical work.
• Taubmans — Australian; mixed reviews in NZ.

Lead paint: pre-1990 paint may contain lead. Sanding releases lead dust, which is a serious health hazard, so test first before you disturb it.