How long exterior paint lasts

How many years does exterior paint last?

BRANZ Bulletin 633 says repainting is typically needed every 7 to 10 years. Resene gives the same span for a quality three-coat acrylic system on timber weatherboards, but only 4 to 6 years for an oil-based or alkyd system. On window sills and other surfaces that face the weather head-on, both figures drop.

Those are averages for houses that are washed and looked after. Two houses of the same age and cladding, one on an exposed headland and one in a sheltered valley, can need repainting years apart.

What makes exterior paint fail sooner?

BRANZ lists the factors: cracking at board edges and ends where paint is thin, how much rain washes the walls, how much sun they get, how often they are cleaned, the colour, the quality of past preparation and the quality of the paint. Most of these vary wall by wall, which is why one side of a house often fails years before the others.

• Sun. North and west walls take the most UV, which breaks down the paint binder and leaves a chalky surface.
• Salt. Salt left on paint attracts moisture and speeds up breakdown, especially under eaves where rain never rinses it off.
• Colour. BRANZ notes that some darker colours make timber move more as it heats and cools, which stresses the paint film. Infrared-reflective pigments can reduce this.
• Thin edges. Paint is thinnest on the edges and ends of boards, and end grain soaks up water. Cracks start there.
• Past prep. Paint laid over dirt, chalk or loose old coats fails early, whatever the brand.

Coastal houses on the North Shore

Much of the North Shore sits close to the sea. The NZS 3604 building standard normally treats land within 500 m of the sea, including harbours, as Zone D, a high-risk sea-spray zone, and an MBIE determination shows it is settled site by site rather than suburb by suburb: a street on a ridge may be well clear, while a house on the waterfront is right in it.

For houses near the water, washing matters more than anything else. Rinsing salt off the walls that rain does not reach, under eaves and verandahs, keeps the paint in good order for longer. Exposed coastal houses often need a closer look every few years rather than waiting for the full interval.

Signs your house needs repainting

Run a finger over a sunny wall. If it comes away white, the paint is chalking, which BRANZ names as the first sign a repaint is due. The others are early peeling, flaking, blistering or fine cracks along board edges and ends. Catching the house at the chalky stage is far cheaper than waiting for bare timber.

• Chalky residue on your finger
• Hairline cracks along the bottom edge of weatherboards
• Paint lifting at board ends, sills and the bottom of window frames
• Blisters on the sunny walls
• Grey or bare timber showing through

If the paint is sound but dull, a wash may bring it back for another year or two. If cracks have reached bare timber, the house is past the cheap repaint stage and needs scraping, filling and priming at those spots.

How to make exterior paint last longer

Three things matter most: the prep before painting, two full finish coats, and a yearly wash afterwards. BRANZ recommends washing every year to remove dirt, salt, moss and mildew. Gentle washing with a soft brush and low-pressure water is enough. High-pressure water blasting is the wrong tool for weatherboards, because it forces water behind them.

• Wash once a year, and more often on salt-exposed walls.
• Touch up cracks and chips on sills and board ends as soon as they appear.
• Keep gardens and shrubs trimmed back from the walls so they can dry.
• Clear gutters so overflow does not soak the boards below.
• Choose lighter colours on the sunniest walls if you want the longest life.

Prep is where most of the life of a paint job comes from. How a house is prepared for painting covers each step.

Asked before a repaint

How many years does exterior house paint last in New Zealand?

BRANZ says repainting is typically needed every 7 to 10 years. Resene gives the same 7 to 10 years for a quality three-coat acrylic system on timber weatherboards, and 4 to 6 years for an oil-based system. Sills, sunny walls and salty coastal sites wear out sooner.

Does washing a house make the paint last longer?

Yes. BRANZ recommends washing exterior paintwork once a year to remove dirt, salt, moss and mildew, and Resene says salt-blown walls that rain does not reach need particular attention. Salt and mould left on paint break it down faster. A soft brush and low-pressure water are enough.

Is it worth repainting before the paint starts peeling?

Usually, yes. BRANZ advises repainting before the paint deteriorates, especially on timber. Once paint peels, water gets into the wood, and the next repaint needs far more scraping, filling and priming. Repainting at the chalky stage keeps the job to a wash, light sand and two coats.