How to Paint a House Exterior the Right Way

Knowing how to paint a house exterior is mostly about prep, not painting. Pros spend 70% of project time on washing, scraping, sanding, caulking, and priming, then bang out two finish coats in two days. Skip the prep steps and your $1,200 in Sherwin-Williams Emerald paint will peel inside 18 months. Done right with quality primer, two-coat coverage at 250 to 350 square feet per gallon, and proper temperature timing, a paint job lasts 12 to 15 years on wood siding and 15 to 20 on fiber cement.

Choose the Right Window in the Calendar

Paint chemistry needs temperatures between 50 and 90 degrees F for at least 24 hours after application, and surfaces must stay above the dew point during cure. Most regions hit this window from April through October, with overnight lows above 50. Avoid painting in direct afternoon sun on south and west walls, which can flash the solvent off too quickly and trap moisture. Cloudy days in the 65 to 75 range are ideal. Check the forecast for 48 hours of no rain after each coat.

Wash, Scrape, and Sand Like You Mean It

Start with a pressure wash at 1500 to 2500 psi, holding the tip 12 to 18 inches from siding. Use a deck wash like Krud Kutter House Wash or Jomax Mildew Killer mixed in the pressure washer’s downstream injector. Let the house dry fully, which means 48 hours minimum for wood siding, 24 hours for fiber cement. Then walk every wall with a 2-inch Hyde scraper and remove every loose flake. Sand scraped edges flush with 80-grit on a Festool ETS 125 or Makita BO5041 random orbital sander.

Caulk every gap over 1/16 inch with a paintable polyurethane like Sherwin-Williams Power House SherMax or Sika Sikaflex 1A. Skip standard latex caulk; it cracks within three years in temperature swings. For cracks larger than 1/4 inch, use a backer rod first to give the caulk something to bridge.

Prime Bare and Stained Spots

Any bare wood, knotholes, water stains, or chalky old paint needs primer before topcoat. Use Zinsser Cover Stain (oil-based) or Sherwin-Williams Multi-Purpose Oil Primer on knots and tannin-bleeding cedar and redwood. For general bare wood and chalky surfaces, KILZ Adhesion Bonding Primer or Benjamin Moore Fresh Start work well at $35 to $50 per gallon. Roll or brush on at 350 sq ft per gallon and let cure 4 to 24 hours per the can directions before topcoating.

Pick Paint Built for Outside

Premium 100% acrylic exterior paints flex with siding movement and resist UV better than cheaper vinyl-acrylic blends. Sherwin-Williams Emerald Exterior at $90 per gallon, Benjamin Moore Aura at $85, and Behr Marquee at $55 are the heavy hitters. All three carry lifetime warranties when applied over proper prep and primer. Get the satin finish for most siding; gloss highlights every imperfection, and flat collects dirt.

• Sherwin-Williams Emerald Exterior: $90 gal, lifetime warranty
• Benjamin Moore Aura Exterior: $85 gal, 20-year
• Behr Marquee: $55 gal, lifetime warranty
• PPG Manor Hall Timeless: $60 gal, 25-year

Spray, Back-Brush, and Back-Roll

An airless sprayer like the Graco Magnum X7 ($450) or the contractor-grade Graco GX-21 ($1,200) lays paint twice as fast as rolling. Use a 515 or 517 tip for siding, set the pressure to 2000 to 2400 psi, and keep the gun 10 to 12 inches off the wall moving at a steady walking pace. Critical step: have a second person back-brush or back-roll the sprayed paint immediately to work it into the wood grain and lap marks. Spray-only finishes look fine on day one but fail prematurely because the paint sits on top instead of bonding into pores.

Apply two finish coats at 300 to 400 square feet per gallon each, with the recoat window from the can (typically 4 hours). Maintain a wet edge by working in panel sections, completing one wall before stopping. Hot afternoons reduce open time to 15 minutes; cool mornings extend it to 45.

Trim, Doors, and Tight Details

Cut in window frames, door casings, and corner boards with a Purdy Clearcut Glide 2.5-inch sash brush. Spray trim only if you have time to mask siding behind it with 1.5-inch FrogTape Pro Multi-Surface. For doors, remove hardware, sand to 220-grit, and use a 4-inch foam mini-roller with a brush for cut-ins. Two thin coats beat one thick coat every time; expect 6 to 8 hours of cure between coats in 70-degree weather.

Safety, Ladders, and Codes

Stick to OSHA-rated Type 1A or 1AA ladders like Werner D6228-2 or Little Giant Velocity. Set the base one foot out for every four feet of height, tie off the top to a fascia anchor, and never reach more than an arm’s length sideways. For two-story work above 20 feet, rent a 24 foot extension or scaffold from Home Depot at $80 to $120 per day. Houses built before 1978 may have lead paint; EPA RRP rules require certified renovators and containment if you disturb more than 6 square feet of painted surface per room exterior.

Cleanup and Waste Handling

Clean rollers and brushes with warm soapy water for latex products; never pour rinse water down a storm drain. Wrap unused trim brushes in plastic wrap or aluminum foil and refrigerate to extend usable life between coats by 24 to 48 hours. Allow leftover paint to fully cure in the can, then dispose at your local hazardous waste collection. Recycle empty plastic and metal cans curbside after drying. Saving a quart of each color in a labeled jar for touch-ups years later costs nothing and saves color-matching trips to the store.

Real Cost Math for a 2,000 Square Foot House

For DIY, expect $700 to $1,400 in materials (paint, primer, caulk, masking, rollers) plus $200 to $400 in tool rentals. A pro crew charges $2 to $5 per square foot of siding, putting a typical two-story job between $4,000 and $10,000. The middle of the range, around $6,500, gets you proper power washing, scraping, prep caulking, oil-bonding primer on bare spots, and two coats of premium acrylic finish that will hold up for at least 12 years.