Five Reasons Exterior Paint Fails Early in Wellington

When a repaint fails after three or four years instead of lasting, it is almost never the paint itself. It is nearly always one of five things, and each leaves a distinctive signature. Knowing which one you are looking at tells you whether you need a painter, a builder or a plumber.

1. Moisture coming from behind

What it looks like: blistering or peeling in a defined area rather than across the whole wall, often below a window, beside a downpipe, at the bottom of a wall, or in a vertical line. The paint comes away in sheets, and the timber underneath is dark or damp.

This is the most important one to identify, because it is not a painting fault. Water is getting into the structure and pushing the coating off from behind. Repainting without finding the source guarantees the same failure in the same place.

Common sources in Wellington: blocked or leaking spouting, failed sealant around joinery, wind-driven rain finding a gap in the cladding, and splashback where the ground level is too close to the bottom boards.

2. Preparation that was not done

What it looks like: peeling that reveals an older colour underneath, flaking along a clean line where new paint met old, or a finish that has come away in a broad area with sound timber behind it.

This is paint that never bonded. It happens when a coat goes over a dirty, chalky, glossy or damp surface, when loose material was not scraped back, or when bare and filled areas were never primed. Everything looks fine for a season or two, then it lets go.

It is the most common cause of premature failure and the reason preparation is the item most worth scrutinising in a quote. Our note on surface preparation covers what should be included.

3. Salt, on the exposed suburbs

What it looks like: general early breakdown, chalking and dulling across whole elevations, worse on the faces exposed to onshore wind, along with rust appearing at fixings and on metal fittings.

Salt deposits hold moisture against the surface and attack metal. Houses on the south coast, along the harbour and on exposed ridges deal with this constantly.

The fix is not an exotic product. It is washing. A freshwater wash once a year, twice on the most exposed properties, removes the salt load and makes a substantial difference to how long a coating lasts. It is the cheapest maintenance available and the most often skipped.

4. UV, and dark colours in particular

What it looks like: fading and chalking concentrated on the north and west elevations while the south wall still looks acceptable. On dark colours it can also show as more movement and cracking at joints.

Wellington gets strong UV, and it degrades pigment and binder. Dark colours make it worse twice over: the pigments are working harder, and the surface runs much hotter, which stresses the substrate and the joints beneath it.

If you have a dark house, expect the sunny elevations to need attention before the rest, and treat that as normal rather than as a fault. There is more in our note on choosing exterior colours for Wellington conditions.

5. The coating was applied in the wrong conditions

What it looks like: patchiness, streaking, poor colour uniformity, or a film that never hardened properly and marks easily. Sometimes visible lap marks where wet edges did not join.

Paint needs the surface within a temperature range and enough dry time before dew or rain. Applied to a cold shaded wall in late autumn, or late in the day with dew coming, or onto a surface that was still damp from the wash, it does not form a proper film. It looks acceptable at first and wears badly.

This is why a Wellington exterior job cannot be promised as a fixed run of consecutive days, and why a contractor who says so is telling you the truth rather than making excuses.

How to tell them apart

Localised and blistering, with damp timber, means moisture from behind: find the leak. Peeling to reveal an old colour means preparation. Even breakdown across whole exposed elevations means salt or UV. Patchy, streaky or soft film means application conditions.

The first one is the one worth acting on quickly, because it is getting worse while you look at it.

Getting a diagnosis

If your paint is failing sooner than it should, we will look at the pattern and tell you what is actually causing it, including when the answer is that you need a builder before you need a painter. Get in touch, or read more about exterior house painting.