Manufacturers quote long warranties and the numbers rarely survive contact with a real house. What determines how long a paint job lasts is, in order: preparation, exposure, substrate, and finally the paint itself.
Typical service life
| Substrate | Years |
|---|---|
| Wood siding | 5–8 |
| Fiber cement | 10–15 |
| Stucco | 8–12 |
| Brick or masonry | 10–20 |
| Aluminium or vinyl | 8–12 |
| Trim and fascia | 4–7 |
Trim always fails first. It is more exposed, it has more end grain, and it takes the water running off everything above it.
Exposure explains most of the variation within one house
South and west elevations get direct sun for the longest and hottest part of the day. Ultraviolet degrades the binder, the film loses flexibility, and it chalks and cracks. Those walls routinely need repainting at half the interval of the north side.
Anywhere sheltered by an overhang lasts longer still. If a house needs painting and the north wall looks fine, that is not an argument for skipping it — it is the clearest possible demonstration that sun, not age, is what is doing the damage.
Preparation is the whole game
A premium paint over poor prep fails faster than a mid-grade paint over good prep. The order of importance:
Removing failing paint. New coating bonds to what is under it. Paint over loose paint fails when the loose layer lets go, and it takes the new coat with it.
Cleaning. Chalk, dirt, mildew and pollen all prevent adhesion. Washing and, where there is mildew, treating it — mildew grows back through a new coat if it was not killed first.
Sanding to feather edges so repaired areas do not telegraph.
Priming bare substrate. Every exposed area, without exception. Bare wood absorbs the binder out of the topcoat and leaves an under-bound film.
Caulking after priming, and only where a joint should be sealed.
Prep is most of the labour on an exterior job, and labour is most of the cost. When a bid comes in far below the others, this is where the difference is.
Two coats, and why one is not a saving
A single topcoat over primer gives a thinner, less uniform film, and film thickness is directly related to how long the coating resists UV and moisture.
The paint costs a fraction of the job. Skipping the second coat saves a small percentage of the total and can cut the service life substantially — which means paying for the whole labour cost again years earlier.
Signs it is time
Chalking — a powdery residue on a hand run down the wall. Normal in moderation, and a sign the binder is degrading when heavy.
Fading, particularly on deep colours and on sunny elevations.
Hairline cracking across the film, which means it has lost flexibility and can no longer follow the substrate's movement.
Peeling or blistering, which usually means moisture behind the film rather than paint failure. Repainting without finding the moisture source repeats the failure.
Bare wood showing, which is the point where it stops being a paint job and starts being a carpentry job.
The economic argument for going early
Repainting sound but tired paint is a wash and two coats. Repainting after the film has failed adds scraping, sanding, priming, and often wood repair — several times the labour.
The cheapest exterior paint job is the one done a year before it was obviously needed.
Colour changes the answer
Deep colours fade faster and run hotter. A dark wall in full sun reaches temperatures well above a light one, and the extra heat accelerates every degradation mechanism in the film at once.
The pigments matter too. Organic pigments used for bright reds, oranges and some blues are far less UV-stable than the inorganic oxides used for earth tones and whites. This is why a red front door needs attention years before the beige siding around it, and why the same brand's colour warranty often carves out deep and bright shades.
Where a dark colour is wanted on a sunny elevation, the answer is a premium 100% acrylic in that colour rather than a mid-grade one — the binder quality matters more here than anywhere else on the house.
What to do between repaints
Two habits add years to an exterior job and cost almost nothing.
Wash the house annually, particularly the shaded and north-facing walls where mildew establishes. Removing the growth before it works into the film keeps it from getting a hold that a future coat has to be applied over.
Deal with the water first. Blocked gutters, a downspout discharging against the wall, or shrubs holding moisture against siding will destroy paint locally regardless of how well it was applied. Almost every isolated patch of premature failure on a house has a water source directly above or beside it.