The Exterior Surface Prep Checklist That Determines Whether Your Paint Job Lasts

Paint fails from the bottom up. The color, the brand, the number of coats, none of it matters if the surface underneath isn’t properly prepared. A thorough exterior surface prep checklist before painting is what separates a job that holds for years from one that starts peeling before the next winter arrives.

Why Prep Is Where Paint Jobs Are Won or Lost

Most homeowners focus on paint selection. That matters, but it’s downstream of prep. Paint needs a clean, stable, sound surface to bond to. Give it that, and it performs. Skip steps, and it doesn’t matter how good the product is.

In the Pacific Northwest, this is especially true. The moisture, the mildew, the freeze-thaw cycles, all of it exposes shortcuts faster than a dry-climate paint job ever would. We’ve seen it across Centralia, Chehalis, and every corner of Lewis County. The homes that need repainting far ahead of schedule almost always have one thing in common: someone cut corners on prep.

Step 1: Inspect Every Surface Before You Touch a Brush

Walk the entire exterior and look hard at what you’re working with. You’re looking for:

• Peeling, flaking, or bubbling paint
• Cracked or missing caulk around windows, doors, trim, and joints
• Wood rot, soft, spongy, or visibly deteriorated sections
• Mold or mildew growth (often shows as dark streaking or green haze)
• Rust stains from metal hardware or fasteners
• Gaps where dissimilar materials meet (wood to masonry, trim to siding)

Don’t just look at eye level. Check the soffits, fascia, and areas near the foundation. Problems hide in corners. Find them now, not after you’ve primed.

If you find soft or rotted wood, that needs to be addressed before anything else happens. Paint over rot and you’re just sealing in the damage. It will continue to spread, and it will push your new paint off the surface within a season or two.

Step 2: Pressure Wash, But Do It Right

A clean surface is non-negotiable. Dirt, chalk from old paint, algae, mildew spores, if any of that stays on the surface, it sits between the new paint and the substrate and breaks the bond.

Pressure washing works well when it’s done correctly. A few rules:

• Use the right pressure for the surface. Soft wood siding can’t take the same force as concrete. Too much pressure raises wood grain and creates an uneven surface that shows through paint.
• Wash from top to bottom. Water finds gravity. Don’t push debris up into seams you just cleaned.
• Use a mildewcide solution if there’s any biological growth. Water alone doesn’t kill mildew, it just moves it around. Mildew that isn’t treated will grow back under your new paint and lift it off the surface.
• Let it dry completely. This is where patience matters. In the Pacific Northwest, “dry” needs to mean genuinely dry, not just surface dry. Depending on conditions, that can mean 24 to 72 hours or more before you’re ready to proceed.

Step 3: Scrape and Sand Everything That Needs It

After the surface is clean and dry, every area with peeling or loose paint needs to be scraped back to a stable edge. If old paint is bonded tightly, it can stay. If it’s lifting at all, it has to go.

A paint scraper handles most of this. A heat gun helps with stubborn areas, especially on older siding. Wire brushing is useful for heavily weathered wood and any areas with significant surface rust on metal components.

After scraping, sand the edges where old paint meets bare wood. This is called feathering, and it matters. If you paint over a hard edge, you’ll see that step in the finished surface. Feathering those transitions gives you a smooth final coat.

Pay particular attention to south-facing walls. In Lewis County, south-facing surfaces take the most direct sun exposure year-round. That UV load breaks down paint faster than anything else, and those surfaces typically need more scraping attention than north or east-facing walls.

Step 4: Repair Before You Prime

Any damaged wood, cracks in siding, holes from hardware or fasteners, all of it gets addressed at this stage. Not after priming. Not after painting. Now.

Options for wood repair:

• Two-part epoxy filler for areas of localized rot or significant damage. Epoxy filler doesn’t absorb moisture, doesn’t shrink, and takes paint well.
• Wood filler or spackle for small nail holes and minor surface voids. Use an exterior-grade product.
• Board replacement for sections where the damage is too extensive to fill. There’s a point where repair becomes more expensive than replacement, and experienced painters know where that line is.

Fill all fastener holes. Sand repairs smooth once cured. Inspect your work before moving on.

Step 5: Caulk the Gaps

Caulk is your moisture barrier. Every gap where two surfaces meet, window frames to siding, door trim to wall, corner boards, any joint where wood pieces come together, needs to be sealed before you paint.

Use a paintable exterior caulk rated for the application. Acrylic latex caulk with silicone works well for most exterior joints. Pure silicone caulk doesn’t take paint and should stay off exterior siding joints.

Tool the caulk smooth with a wet finger or a caulk tool. Rough caulk lines show through paint, especially in low-angle light. Take the extra minute to make it clean.

Let caulk cure per the manufacturer’s specs before painting over it. Painting over uncured caulk can cause wrinkling and adhesion issues.

Step 6: Prime, Don’t Skip This

Primer does two things paint can’t do on its own. It seals the surface and it creates a bonding layer that paint adheres to better than raw wood or repaired areas.

Bare wood should always be primed. Any repaired areas should be spot-primed at minimum. If you’ve done significant scraping and have a lot of bare wood exposure, a full prime coat before the finish coat is the right call.

Stain-blocking primer matters on surfaces with tannin bleed (cedar and redwood are common for this) or with any discoloration you don’t want telegraphing through your topcoat. If you’re painting over a darker color with a lighter finish color, a tinted primer will reduce the number of topcoats you need to get full coverage.

We use Sherwin-Williams products on the jobs we do, and their primer options are well-matched to the Pacific Northwest climate conditions we deal with across Centralia and the surrounding area. Product selection matters here, the chemistry of primer and topcoat should be compatible.

Step 7: Protect What Isn’t Being Painted

Masking and protection go on before the first drop of paint moves. This means:

• Cover windows, light fixtures, outlets, and anything else that isn’t getting painted
• Protect landscaping and plants near the foundation, paint and primer aren’t good for them
• Tape trim lines cleanly if you’re painting body and trim separately
• Lay drop cloths or plastic sheeting on decks, patios, and walkways below work areas

Masking takes time. Cleaning overspray or drips off glass and metal takes longer. Do the masking.

The Pacific Northwest Factor

Everything above applies everywhere. But in Western Washington, a few things get amplified.

Mildew is a bigger issue here than almost anywhere else in the country. The combination of moisture, mild temperatures, and low light creates ideal conditions for biological growth. Any mildew that isn’t fully treated and removed before painting will regrow under the new film and push it off the surface. Treat it, don’t just paint over it.

Moisture content in wood is a real concern outside the summer window. We watch forecasts carefully and check surface conditions before committing to a start. If the wood is holding moisture from recent rain, it’s not ready. This isn’t being overly cautious, it’s following the manufacturer’s specs for the product and making sure the investment holds.

Homes across Lewis County that have gone too long between paint cycles are more common than they should be. Deferred maintenance compounds quickly in this climate. By the time a homeowner calls us, there’s often more prep work involved than they anticipated. That’s not a problem, we handle it, but it’s worth understanding that a home that hasn’t been painted in 15 years needs more prep time than one on a normal cycle.

What Happens When You Skip Steps

Paint that wasn’t applied over a properly prepared surface doesn’t age gracefully. It peels. It bubbles. It cracks along the edges where old paint met new without feathering. Mildew grows back under the film. Wood that was rotted before painting continues to deteriorate and pushes the paint off from below.

The worst part is that the failure often shows up within a year or two. By then, the job needs to be stripped and done correctly from scratch. You’ve paid twice. The first time for a job that didn’t hold, and the second time for the work that should have been done originally.

That’s the real cost of cutting corners on prep. Not the immediate price of doing it right the first time, but the compounded cost of doing it wrong and having to start over.

If you’re planning an exterior paint project and want it done with the kind of prep that makes it last, reach out to Gullard Painting. We’re licensed, bonded, and insured, and we work across Centralia, Chehalis, and the surrounding Lewis County communities. We work from a running list, so the earlier you get in touch, the better. Call us at 360-790-2726 or visit gullardpainting.com to get on the list.