How Long Does Exterior Paint Last in Portland?

On wood siding, a primer and two topcoats of good exterior paint typically last about 6 to 15 years, according to estimates from the USDA Forest Products Laboratory, and 15 to 20 years on saw-textured cedar. Leave off one topcoat and the expected life drops by about half. In Portland the sunny south and west walls usually wear out years before the shaded sides, so the whole house rarely needs repainting at once.

Those figures come from the Forest Products Laboratory's Wood Handbook (2021), which compiles many researchers' observations for an average location in the lower 48 states and notes that climate and exposure change the result. Below: the numbers for each siding type, how Portland weather shifts them, and how to tell when your own paint is due.

How long does paint last on each type of siding?

The Handbook rates finishes by species, grain and surface texture. Its estimates for wood siding found around the Portland metro, from fir lap siding and cedar shingles to T1-11 and hardboard:

Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282, 2021), Table 16–2. Walls at an average U.S. location; paint figures assume a primer and two topcoats, and one topcoat roughly halves them.

Three patterns run through the table. Texture helps: rough, saw-textured boards take on more finish and hold it longer than smooth-planed ones. Grain matters: vertical-grain boards, with growth rings meeting the face at a steep angle, shrink and swell less than flat-grain boards and hold paint better. Species matters: Douglas-fir and the southern pines have wide, dense bands of latewood that make good paint performance harder to get, while western redcedar, redwood and white pine paint well.

One caveat: the Handbook's fir figures are for flat-grain boards. It gives no separate number for vertical-grain fir.

What about fiber cement, hardboard and engineered wood?

The Handbook covers wood only. For fiber cement, James Hardie backs its factory-finished ColorPlus boards with a 15-year limited finish warranty against peeling, cracking and chipping. That is a warranty, not a lifespan, and Hardie describes it as prorated. The edition of the warranty we were able to read (form HS12121, April 2021) pays up to $1.00 per square foot for paint and labor on the damaged area in the first year and 6.67 percent less each year after, and it excludes the gradual fading and chalking it calls normal weathering, unless the color shifts by more than four Delta E units (a measure of visible color change) in the first three years. Mold and mildew are excluded. Terms can change between editions, so read the version that came with your siding.

Primed boards are different. Hardie says pre-primed siding should get an acrylic topcoat, and its finish warranty excludes other makers' paints, so a board painted on site runs on the schedule and warranty of that paint. Hardie also warns that a pressure washer can damage its siding and suggests a garden hose and a soft brush once or twice a year.

Hardboard lap siding gets an 8-to-12-year paint estimate, primed or not. For engineered wood, the Handbook says a well-applied factory coating will typically outlast one applied on site, and sealing all four edges of every board maximizes its life. Soft boards of any kind need replacing first, because decayed wood does not hold paint. Stucco is outside the Handbook's scope; our exterior house painting page covers recoating it.

Why Portland's climate is hard on paint

Portland splits the two things that wear paint out across the calendar. NOAA's 1991–2020 normals for Portland International Airport show measurable rain on about 157 days a year, including 18 or 19 days in each of November, December and January, and the Handbook puts covered outdoor wood in the Pacific Northwest at about 16 percent moisture, against 12 to 14 percent across most of the country. Then July and August turn dry, with fewer than four rainy days each, and the sun goes to work.

Water is the main cause of peeling and the source of moisture blisters, and repeated wetting and drying opens checks and splits in the wood that then crack the paint film. Sunlight works on the paint surface slowly, showing up as chalk and faded color, but it attacks bare wood quickly. In one Forest Products Laboratory test on vertical-grain western redcedar, boards left unpainted in the sun for 16 weeks before priming peeled within three years, while boards painted right away were still in good condition after 20.

The Portland takeaway: prime bare wood quickly during a repaint, since even a week of sun before priming measurably shortens paint life, and keep liquid water out of the siding with working gutters, sound caulk at trim joints, and a gap where siding meets a roof or flashing below: the Handbook recommends about 2 inches above a roof and 3/8 to 1/2 inch above flashing.

Which side of the house needs paint first?

The Handbook says paint on a shaded side often lasts twice as long as on a fully exposed, sunny side, so the sides of a house need not be painted on the same schedule. Areas under porches, soffits and deep overhangs can usually be repainted every other cycle, after washing off the dirt they collect.

• South and west walls take the most sun, so they chalk and fade first. If two topcoats everywhere is not practical, the Handbook suggests two on the fully exposed south and west sides and one elsewhere.
• North walls and walls under trees see less sun damage but more mildew, which grows where moisture lingers out of the sun and air does not move, such as behind tall shrubs.
• Eaves, soffits and porch ceilings stay out of the rain, but dew forms on them because they cool quickly, and that dew feeds mildew too.
• Dark colors run hotter in the sun, which means more fading, blistering and checking in the wood underneath; the Handbook notes many fade to an unacceptable look long before the paint fails. Our guide to choosing exterior house colors covers light reflectance value and the dark-color limits on vinyl siding.

Signs it's time to repaint your house

The Handbook's test is simple: repaint when the topcoats have worn thin enough to expose the primer, or the finish no longer protects the wood. In rough order of urgency:

1. Peeling down to bare wood. Don't wait on this one. Sunlight starts breaking down exposed wood within hours, and once the primer has let go, the repaint means scraping, sanding and priming, not just washing and recoating. Find the water source too; our guide to why exterior paint peels, blisters, or chalks covers the usual causes.
2. Primer showing through. On a sunny wall, look for patches where the topcoat has worn through to the primer. That is the Handbook's cue to recoat while the job is still simple: wash, then one or two new topcoats.
3. Heavy chalk. Rub a dark cloth across a sunny wall. A little powder is normal weathering; a thick layer means the surface is eroding. The industry test, ASTM D4214, grades chalk picked up on a cloth, a fingertip or adhesive tape against photographic reference standards; a rough home version is clear packing tape pressed onto the wall, peeled off and stuck to dark paper. Either way, Sherwin-Williams tells painters to wash chalk off completely before the next coat.
4. Cracking. Fine cracks along the grain, common on smooth flat-grain boards, can often be sanded and given one or two more topcoats if caught early. Cracks across the grain usually mean thick layers of old oil paint, which the Handbook says to strip to bare wood; on an older house that paint may contain lead.
5. Failed caulk. Cracked or pulled-away caulk at trim joints, window and door casings and siding butt joints lets rain in behind the paint, and the Handbook warns that failed sealant often traps water. Replace it during the repaint, but leave the horizontal seam where one lap board overlaps the next uncaulked; that gap lets water drain and the siding dry.
6. Soft or rotting wood. Push a small screwdriver into window sills, the bottoms of trim boards and the lowest course of siding. If it sinks in, that wood has to be replaced before anything is painted.
7. Fading. On a sound surface, faded color is cosmetic, not a sign the paint has failed.

Not on the list: mildew on otherwise sound paint. The Handbook calls it an appearance problem that needs washing, not repainting. To tell mildew from dirt, put a drop or two of household bleach on the spot; mildew usually bleaches out within seconds, dirt does not.

How often should you repaint your house exterior?

By condition rather than by calendar, and one side at a time. By the Handbook's estimates, a three-coat job on most smooth wood siding comes due 6 to 15 years after it went on, and the sunny walls get there first. A walk around the house each spring or fall, starting on the south and west sides, tells you more than the age of the last paint job.

Two of the Handbook's points argue against repainting too early:

• Too much paint is its own problem. Every repaint adds film, and the Handbook warns that too many coats of latex can eventually make the primer lose its grip on the wood. Cross-grain cracking, similarly, shows up mostly on houses carrying thick layers of old oil paint.
• A recoat is a lighter job than a repair repaint. Over paint that has only worn thin, prep is mostly washing off dirt, chalk and mildew, and one topcoat may be enough if the old surface is in good shape. Once paint has peeled from the wood, the job adds scraping, sanding and priming bare wood.

Before recoating, a careful painter paints a small test patch, lets it dry overnight, then presses an adhesive bandage onto it and snaps it off. Paint on the bandage means more cleaning or priming is needed; old and new paint coming off together means the old paint has to go. The Handbook says peeling between coats usually appears within a year when old paint was not cleaned first.

Catching paint at the worn-thin stage keeps the prep, and the quote, smaller. For Portland-area price ranges by house size, see what an exterior repaint costs in our cost guide. On a house built before 1978, the scraping and sanding also has to follow lead-safe rules, which our guide to painting a pre-1978 home explains.

Does a lifetime paint warranty mean it lasts a lifetime?

No. A paint warranty is a promise about the product, not a forecast of how long the job will last. Two examples:

• Benjamin Moore Aura Exterior's limited lifetime warranty says the paint will not blister or peel from properly prepared and primed surfaces, or wear through to the coat underneath. It lasts while the original buyer lives in the home, is not transferable, and pays in replacement paint with the original receipt. Labor is excluded.
• A Sherwin-Williams 15-year limited warranty, published for some of its exterior paints, covers peeling and blistering with replacement paint or a refund. It excludes labor and does not apply to failures caused by poor surface preparation, structural defects, a failing previous coat or improper application.

In both cases the remedy is paint, not a crew to scrape and repaint a failed wall, so ask what the painter's own workmanship warranty covers and for how long. Our guide on how to choose a painter lists that question with the others.

What makes a repaint last longer?

The Handbook names the usual causes of early failure: water, wood that weathered before it was painted, poor surface preparation, and too thin a film. A repaint aimed at the long end of the ranges above deals with all four.

• A real primer and two topcoats. On smooth wood the Handbook recommends a primer plus two topcoats for a total dry film of 4 to 5 mils, and it says “paint and primer in one” products are not ideal as either.
• Stain-blocking primer on cedar and redwood, whose water-soluble extractives otherwise bleed through as reddish-brown stains.
• Sealed end grain. Water can enter the cut end of a board 10 to 100 times faster than its face, which is why the Handbook ranks sealing end grain among the most valuable improvements in standard construction.
• The right weather. The Handbook advises latex paint only at 50°F or above, expected to hold for 24 hours, and not late in the day before a heavy dew. See the best time to paint a house exterior in Portland for when local weather allows it.
• Lead-safe prep on older houses. On a pre-1978 house, assume old layers contain lead. The Handbook's rule is not to sand lead-based paint without special precautions.

Decks and fences run on a shorter clock

Horizontal boards and ground-contact posts take far more weather than siding, and the Handbook notes film-forming finishes on decks often last no longer than penetrating stains, which are easier to renew. Restain intervals by stain type are on our deck and fence staining page.

Found peeling on the sunny side or primer showing through? Get an estimate before bare wood starts to weather. The project request form takes about a minute.

Common questions

Paint problems this guide explains