Exterior House Painting: Prep, Weather Windows and Paint That Lasts

Exterior paint lasts 10 years or more when the prep is done properly: wash the surface, scrape all loose paint to a firm edge, spot-prime bare wood, caulk gaps up to 1/4 in (6 mm), and apply two full coats — because paint failure is almost always a prep failure, not a paint failure. Paint only when the surface and air are between 50°F and 85°F (10°C and 29°C) and no rain is forecast for 24 hours. Estimate paint with the Exterior Paint Calculator, budget the job in the exterior painting cost guide, and read pro painting tips before you buy a single gallon.

Prep: the 80 percent of the job that decides the result

Prep is roughly 80 percent of a lasting exterior paint job, and skipping it is why a $3,000 paint job peels in two years. Start by washing the whole house: a garden hose and a stiff brush with a house-wash solution handles most siding, while a pressure washer at 1,500 to 2,000 PSI with a wide fan tip works faster — but never blast closer than 12 in, because high pressure drives water behind siding and shreds wood grain. Let the surface dry fully, at least 24 to 48 hours for wood siding, before scraping or priming.

Scrape every loose, peeling, or alligatored patch down to a firm edge with a carbide scraper, then feather the edges with 80-grit sandpaper so the new paint does not show a ridge. Any bare wood gets spot-primed with a quality exterior primer — latex primer for most siding, oil-based primer for tannin-bleeding woods like cedar and redwood. Replace rotted boards and soft trim now, not after painting; paint over rot just hides it for one season. Finally, caulk every gap up to 1/4 in wide around windows, doors, and trim joints with a paintable polyurethane or siliconized acrylic caulk, and use backer rod for wider gaps — caulk is not a filler for cracks wider than 1/4 in.

Weather windows: temperature, humidity, and dew

Paint only when the air and the surface are between 50°F and 85°F, and the surface temperature is at least 5°F above the dew point — painting onto a surface near the dew point traps moisture under the film and causes blistering. Check the forecast for the whole drying window: no rain for at least 24 hours after the final coat, and ideally 48 hours for the first coat on bare wood. Late spring and early fall give the best windows in most of the US, because summer heat above 90°F makes latex paint dry too fast to level properly, leaving lap marks and a weak film.

Follow the sun around the house, not the clock. Paint the east side in the late morning after dew has burned off, the south side in the afternoon, the west side in the late afternoon, and the north side at midday when it is warmest — never paint a surface in direct, blazing sun, because the top skin dries before the paint underneath, trapping solvents that later blister. Stop painting at least 2 hours before sunset so the fresh coat skins over before evening dew settles. Humidity above 70 percent slows drying dramatically; if the air feels heavy and the paint stays tacky after 4 hours, stop and wait for a drier day.

Choosing paint and applying two full coats

Buy 100 percent acrylic latex paint for almost all exterior siding — it flexes with temperature swings, resists fading, and cleans up with water. Expect $50 to $80 per gallon for quality exterior acrylic, and avoid paint below $35 per gallon for a house exterior: cheap paint covers less per gallon, needs a third coat, and fades within 3 to 4 years, making it the most expensive option over a decade. For trim, choose a satin or semi-gloss finish that sheds water and wipes clean; for siding, satin or low-luster hides imperfections better than gloss and still resists dirt.

Apply two full coats, not one heavy coat. A single thick coat looks covered but dries with a weak, uneven film that cracks at joints within a few seasons. Cut in edges with a 3 in angled brush, roll large flat areas with a 3/4 in nap roller for rough siding or 3/8 in for smooth siding, and spray only if you back-roll — spraying alone leaves a thin, uneven film and heavy overspray on windows and landscaping. A gallon covers roughly 350 to 400 sq ft per coat on smooth siding and 250 to 300 sq ft on rough or textured surfaces; two coats on a 2,000 sq ft house typically need 12 to 16 gallons of body color plus 3 to 5 gallons of trim paint.

Siding-specific prep that beginners miss

Different siding needs different prep, and treating them all the same causes failures. Wood siding must be checked for rot with a screwdriver probe at board ends, corners, and anywhere water splashes — soft wood gets replaced, not painted. Cedar and redwood need an oil-based or stain-blocking primer, because their tannins bleed brown through latex primer within weeks. Fiber cement (Hardie) takes paint beautifully but needs any factory finish scuffed and all cut edges primed, since unprimed cut edges wick water. Aluminum siding needs a thorough wash and a bonding primer if the old paint is chalking heavily — test chalking by rubbing a dark cloth on the surface; if it comes away white, the surface needs extra prep.

Stucco needs crack repair before paint: hairline cracks under 1/16 in take an elastomeric patch, wider cracks need a proper stucco patch and curing time, and painting over a moving crack just reproduces it in the new paint. Masonry and brick need a masonry primer and, ideally, a breathable coating — never trap moisture behind a non-breathable paint on a brick wall that gets wet, or the paint will peel in sheets. Vinyl siding can be painted, but only with a color the same lightness or lighter than the original, because dark paint absorbs heat and warps vinyl panels on a sunny wall.

Cost, timing, and keeping the job looking new

A professional exterior paint job on a 2,000 sq ft two-story house typically runs $4,000 to $9,000 depending on condition, height, and region, while a careful DIY job runs $1,000 to $2,500 in materials. Budget a full week of work for a DIY whole-house job — two days of prep and washing, a day of priming and caulking, and two days of painting — and do not compress it: the most common DIY mistake is painting on day one before the house is actually ready. Rent scaffolding or a boom lift for high work rather than stretching from a ladder; a fall from a second-story eave is the most serious risk in this project.

Maintain the finish with a yearly walk-around: look for peeling at board ends and trim joints, cracked caulk around windows, and mildew on shaded north walls. Touch up small failures immediately — a 6 in peel repaired in spring stays a 6 in repair, while the same peel ignored for two winters becomes a 6 ft scrape-and-prime job. Wash the house annually with a garden hose to remove dirt and mildew spores, and repaint trim every 5 to 7 years even if the siding still looks good, because trim fails first and protects the joints that matter most.

Ladders, safety, and working at height

Exterior painting puts you on a ladder for most of the job, and ladder falls are the most serious risk in the project — thousands of homeowners end up in emergency rooms every year from ladder falls, many from heights under 10 ft. Use an extension ladder rated for your weight plus tools and paint (a Type IA ladder rated at 300 lb is the right choice for most adults), set it at a 4-to-1 angle (1 ft out from the wall for every 4 ft of height), and extend it 3 ft above the eave or roofline so you have something to hold when stepping off. Never stand on the top two rungs, never lean sideways to reach a spot — move the ladder instead, even when it feels slow — and never paint from a ladder in wind above 15 mph or on wet or uneven ground.

For second-story work, consider renting scaffolding ($150 to $300 per week for a basic setup) or a boom lift ($250 to $400 per day) rather than stretching from a ladder: scaffolding gives a stable platform, room for paint and tools, and a guardrail, which transforms both safety and finish quality, because you can cut in carefully instead of rushing from an awkward perch. Keep three points of contact on a ladder at all times, wear shoes with good grip, and never carry a full 5-gallon bucket up a ladder — haul paint up in a 1-gallon can with a handle, or use a rope and bucket. If any part of the job feels unsafe from a ladder, that is the part to hire out: a professional crew with proper equipment paints high work faster and safer than a homeowner on an extension ladder.