Before you start
- Primer plus two top-coats of paint: about 10 to 20 years on wood, the Wood Handbook says.
- Paint on the north side lasts about twice as long as on the south side.
- A two-coat system gives about half the service life of three coats.
Key takeaways
- Paint over a good primer with two top-coats lasts longest.
- Different sides of the house wear at different speeds; you need not repaint them all at once.
- Washing sound paint is better than repainting it too often.
Homeowners in Everett often ask how many years a new paint job will buy them. The most useful answer comes from the U.S. Forest Products Laboratory’s Wood Handbook, which compiles decades of outdoor tests on wood finishes. The ranges below are for vertical surfaces such as siding, and they depend on preparation, climate and exposure, the amount and quality of finish and the wood itself.
Service life by type of finish
| Finish | How it is applied | Typical service life on siding |
|---|---|---|
| Paint | Primer plus two top-coats | 10 to 20 years |
| Solid-color stain | Primer plus two top-coats | 6 to 15 years |
| Semitransparent stain | One coat, second only if the wood absorbs it | 4 to 8 years on saw-textured or weathered wood |
| Tinted clear finish | One or two coats | 2 to 3 years |
| Water-repellent preservative | One or two coats | 1 to 3 years |
The handbook adds an important caution: a two-coat paint system, primer and one top-coat, cuts the service life to about half of these values. On saw-textured wood, a three-coat system about 0.10 to 0.13 millimeters thick, or 4 to 5 mils, may last 20 years.
Why the south side fails first
Sunlight erodes paint. The Wood Handbook notes that paint on the north side of a house in the northern hemisphere lasts about twice as long as paint on the south side. That means you do not have to repaint every side on the same schedule. Many homeowners refresh the south and west walls first and the rest a few years later.
Tip: When top-coats wear thin enough to show the primer, add one or two new top-coats. If the old paint is still sound, washing it is usually all the prep it needs.
What shortens paint life
- Painting wood that is too wet; above 20% moisture content the risk of blistering and peeling increases.
- Leaving bare wood to weather before priming. In the handbook’s western redcedar tests, boards left out for 16 weeks before painting peeled within 3 years.
- Thin coats; too little film wears through quickly.
- Unsealed end grain and open joints that let water behind the paint.
- Painting over mildew or dirt, which hurts adhesion.
What makes paint last longer
Good preparation, a quality primer and two top-coats are the core. Saw-textured wood holds more finish than smooth-planed wood, and the handbook notes that finishes adhere better and last longer on saw-textured surfaces. Acrylic latex top-coats hold their gloss longer than oil-alkyds, which tend to lose gloss within a year or two and can become brittle with age.
Do not repaint too often
It sounds odd, but repainting too soon is a common mistake. The Wood Handbook warns that frequent repainting can build an excessively thick film, and thick oil-based paint is likely to crack across the grain. If paint is sound but discolored by mildew, wash it; it does not need repainting. Protected areas such as porches and soffits often need repainting only every other cycle.
Planning ahead
Keep a simple record of when each side was painted, what product was used and how many coats went on. When you get bids, ask how many coats are included and whether the primer is part of the price. See What Exterior House Painting Costs in Everett, and What Drives the Price and How to Hire a House Painter in Everett: Registration, Bonds, Bids and Red Flags.
Signs it is time to repaint
- Top-coats worn thin enough to show the primer.
- Peeling or flaking, especially near the ground, under windows and at board ends.
- Heavy chalk that rubs off on your hand.
- Bare wood showing through on the south and west walls.
Mildew alone is not a reason to repaint. Wash it off and look again; the Wood Handbook stresses that discolored but sound paint only needs washing. Fading is different: the handbook notes that many dark colors fade to an unacceptable look long before the paint fails, and its service-life figures do not account for fading.
Stains follow the same logic. Solid-color stain over a primer typically lasts 6 to 15 years on siding, and semitransparent stain 4 to 8 years on saw-textured or weathered wood, according to the Wood Handbook’s table. Penetrating finishes rarely peel, so renewing them is mostly cleaning and brushing on a fresh coat when the color fades.
Climate matters too. Everett’s long wet season keeps siding damp for months, and mildew grows readily on shaded walls. Annual washing and quick touch-ups where water gets in are the cheapest way to reach the long end of the ranges above. Our Exterior Paint Prep Checklist for Everett Homes: From Washing to the Last Coat covers what to check.
How long will your paint or stain last? Try the paint life check.