How to Paint Wood Siding (Complete Prep and Painting Guide)

Painting wood siding is roughly eighty percent preparation and twenty percent painting. The short version: wash the siding and treat any mildew, scrape and sand off every bit of failing coating, feather the edges of the sound paint so the transitions disappear, repair rot and reset popped nails, spot prime every square inch of bare wood, caulk only the joints that are meant to be sealed, then apply two coats of an exterior coating rated for wood in suitable weather. Skip any one of those and the job fails early, usually within a couple of seasons rather than a decade.

This guide is about real wood siding: bevel and clapboard, shiplap, tongue and groove, board and batten, shingles and rough sawn cedar. If your walls are plastic or metal, the method is genuinely different and you want how to paint vinyl siding or how to paint aluminum siding instead. Both of those are mostly a cleaning and adhesion problem. Wood is a moisture and movement problem, which is a harder one.

Why wood is the highest-prep siding there is

Wood does three things no other siding does, and all three work against your paint film.

It moves. Wood swells when it takes on moisture and shrinks when it dries, and it does that seasonally, forever. The paint film has to stretch and relax with it. Films that have gone brittle with age cannot, so they crack, and once cracked they let water in behind the film, which lifts the paint off in sheets.

It splits and checks. End grain, knots and exposed edges open up small cracks as boards age. Those cracks are direct water paths into the board.

It holds moisture. Vinyl and metal shed water. Wood absorbs it, from rain on the face, from splashback at the bottom course, from a leaking gutter above, and sometimes from vapour pushing out from inside the wall. Paint applied over wood that is still carrying moisture will blister or peel no matter how good the product is.

The practical consequence is that old coatings on wood fail by cracking, peeling and blistering rather than by simply chalking away. Chalked siding can often be washed and recoated. Peeling siding has to be taken back to a sound edge, and that is the work most people underestimate.

Assess the siding before you buy anything

Walk the whole house slowly, one elevation at a time, with a stiff putty knife. Push at the paint in a dozen places per wall. You are sorting every surface into one of three categories, and the mix tells you how big the job actually is.

Sound paint

The film is tight, the putty knife will not lift it, and the colour is intact or only mildly faded. Sound paint needs washing, a light scuff sand for adhesion, and nothing else. On a well-maintained south-facing wall you might find the paint sound but heavily chalked, meaning it leaves powder on your hand. Chalk has to be washed off completely or the new coat is bonding to loose powder.

Failing paint

The film lifts, flakes, curls at the edges, or shows a network of fine cracks. Failing paint comes off. All of it, out to where the remaining film will not lift under a scraper. There is no product that reliably bonds failing paint back down, and the coatings that claim to bridge cracks will still move with whatever is underneath them.

Bare weathered timber

Wood that has been exposed for months or years is not the same wood underneath. Ultraviolet light degrades the surface fibres, leaving a soft, grey, loosely bonded layer. Paint will stick to those fibres perfectly well, and then those fibres will let go of the board. This is the single most common invisible cause of early peeling on wood siding. Grey weathered wood must be sanded back to sound, lighter-coloured fibre before you prime. If you can rub the surface with your thumb and get grey on it, keep sanding.

Also check moisture. Siding that is damp will not hold paint. Give the house a few consecutive dry days after any wash or rain before you prime, and be extra patient on north elevations and shaded walls, which dry far more slowly than the sunny sides.

Pre-1978 homes and lead paint

Scraping exterior siding is the classic lead exposure scenario. Old exterior paint on US homes built before 1978 may contain lead, and scraping or sanding it generates dust and chips that land in the soil around the house, exactly where children play and vegetables grow. This is not a theoretical risk and it is not optional to think about.

If the house dates from before 1978, test before you disturb any coating. Read how to test for lead paint for how testing works and what the results mean. If lead is present, the safe route is a certified renovator working under lead-safe rules, with ground sheeting, containment, wet methods, no open flame or high-speed power sanding, and proper cleanup of chips and dust. Dry-scraping a whole elevation of leaded siding on a windy day is one of the worst things a homeowner can do to their own yard.

Ladder safety, because this is all ladder work

Siding above the first course of a single storey means you are working from a ladder for days, often with a scraper in one hand while leaning. Set the ladder at roughly a four to one angle, on firm level ground, with the top extending well past your working point where it rests against something solid. Never lean sideways past the ladder rails to reach the last board. Move the ladder. It is the single most broken rule in exterior painting and the most common way people get hurt.

For anything above two storeys, or for long uninterrupted runs of siding, staging or a scaffold is faster and much safer than repositioning a ladder forty times. Our guide to choosing a ladder for painting covers sizing, duty ratings, stabilisers and standoff brackets that stop the ladder crushing your fresh work.

Wash the siding and deal with mildew

Start with a wash. You are removing dirt, chalk, pollen, cobwebs and spider dirt, and any mildew. Mildew shows as grey or black speckling, usually heaviest on shaded elevations, under eaves and behind shrubs. The test is simple: dab it with a household bleach solution on a cloth. Dirt stays dark, mildew lightens within a minute or so.

Mildew has to be killed, not just covered. Painting over live mildew simply feeds it through the new film. Use a cleaning solution appropriate for exterior mildew per its label, work from the bottom up so the cleaner does not run over dry surfaces and streak, keep the growth wet for the dwell time the label specifies, then rinse thoroughly from the top down.

If you use a pressure washer, keep the pressure low, use a wide fan tip, hold the wand well back, and always spray at a downward angle. Wood is soft. High pressure at close range carves the soft spring wood out from between the grain lines, leaves a fuzzy surface that then needs sanding, and drives water up behind the boards where it will sit for weeks. A garden hose, a pump sprayer and a soft brush will usually do a better job on wood than a pressure washer in inexperienced hands.

Scrape, sand and feather

Scraping is the part everyone rushes. Work each board with a sharp scraper, pulling along the grain, until you have removed every piece of film that will lift. Sharpen the scraper blade often. A dull scraper skates over loose edges and leaves them for the new paint to peel off later.

Feathering is what separates a professional-looking result from a patchy one. Wherever paint has come off, you are left with a step between the bare wood and the remaining film. Sand that step down with medium grit until you cannot feel the edge with your fingertips, then finish with a finer grit. If you can feel the ridge, you will see it through two coats of paint, and the sharp edge is also where the next round of peeling starts.

While you are sanding, take the grey off any bare weathered wood as described above, and scuff-sand the sound painted areas so the new coat has a mechanical key. Glossy old coatings especially need dulling. Vacuum or brush the dust off the siding, or wipe it down, before priming. Dust is a bond breaker.

Repairs: rot, splits, popped nails and holes

Do all repairs after scraping and before priming, because scraping is what exposes the damage.

Probe suspect areas with an awl or screwdriver. If the tool sinks in easily, the wood is rotten. Small localised rot in an otherwise sound board can be cut out and filled with an exterior-grade epoxy wood filler used to its label instructions. Anything larger, anything structural, and anything at a board end where water is clearly getting behind, means replacing the board. Cutting out and replacing a length of clapboard is a straightforward job and it is always cheaper than repainting a wall twice.

Popped nails are common on older siding as boards move. Drive them back below the surface with a nail set, or if the nail no longer holds, pull it and fasten nearby with a corrosion-resistant nail. Rusty nail heads must be spot primed with a stain-blocking primer or the rust will bleed a brown halo through your finish coat within a year.

Fill nail holes and small dents with an exterior filler, then sand flush. Do not use interior filler outdoors. It absorbs water and fails.

Caulk the joints that should be sealed, and only those

Caulking wood siding is where good intentions cause real damage. Seal the wrong joints and you trap water inside the wall with no way out.

Seal: the vertical joints where siding meets corner boards, door and window casings, and any trim; gaps around window and door frames; and joints between siding and other materials. Do not seal: the bottom edge of each clapboard where it laps over the course below, the weep or drainage gaps at the bottom of the wall, or the underside of window sills. Those are drainage paths by design. Water that gets behind siding needs to run out, and a homeowner who caulks every lap line has just built a bathtub inside their wall.

Use an exterior-grade paintable caulk rated for the joint movement you are dealing with, tool it in properly, and let it cure to the label before painting over it. Full technique is in how to caulk before painting.

Prime every bare spot, knot and bleeder

Every square inch of bare wood gets primer. Not most of it. All of it. Bare wood is porous and will suck the binder out of a finish coat, leaving a weak, patchy film exactly where you already removed the old one.

Three situations need particular attention. Knots in any species will bleed resin through a finish coat, so they need a stain-blocking primer rather than a general-purpose one. Tannin-rich species, cedar and redwood most notably, will bleed brown tannin stains through light-coloured paint whenever they get wet, so those species want a primer specifically labelled for tannin blocking, usually applied over the whole surface rather than as spots. Rusty fasteners need blocking as above.

If the siding is bare across most of a wall, prime the whole wall rather than spotting it. Uniform sealing gives you uniform sheen and colour in the topcoat. Our guide to whether you need primer before painting walks through which primer type suits which situation, and the primer label is always the authority on recoat timing.

Choose the coating and pick your weather

For wood siding you want an exterior coating with enough flexibility to move with the substrate and enough film build to resist water. Modern exterior acrylic latex products dominate here for good reason, and product data sheets will tell you the spread rate, film thickness and recoat window for the specific product. Compare the options in best paint for wood siding before you buy, and read the can before you open it.

Weather matters more on wood than on almost any other exterior job. Avoid painting in direct hot sun, which flashes the film off before it can flow out. Avoid painting late in the day in cooler seasons, when dew can settle on an uncured film. Avoid painting when rain is forecast within the manufacturer's stated window, and avoid painting outside the temperature range on the label, including the overnight low. Very high humidity slows drying dramatically. The detail is in best weather conditions for exterior painting.

Application: brush, roller or spray

Brushing gives the best penetration into wood and the best working of paint into the lap edges, and on a small house it is perfectly practical. A quality brush loaded properly, worked along the length of the board, is the traditional method for a reason.

Rolling the flat of the board and brushing the edges is faster on wide, smooth siding. The roller lays paint on, the brush works it in and cleans up the laps.

Spraying is the fastest way to move material and the easiest way to produce a job that peels. Sprayed paint sits on the surface. On rough sawn cedar and on any textured or weathered wood, spraying without back-brushing leaves the paint bridging over the texture instead of wetting into it. If you spray, you back-brush or back-roll every pass while it is still wet, which usually means two people, one spraying and one following. Masking is also substantial on a house: windows, roof, plants, driveway, neighbouring property. See how to use a paint sprayer for setup, tip selection and overspray control.

Two finish coats is the normal specification over primer for wood siding, and it is what most manufacturers assume when they publish a film life expectation. One coat over primer on a colour change, on rough sawn wood, or on a wall with heavy sun exposure will look thin and will not last as long.

Beating lap marks on long runs

Lap marks happen when you brush fresh paint into an area that has already started to set. On a long run of siding, the temptation is to paint the top board all the way along, then the next one down. That maximises the number of wet edges you have to keep alive and guarantees visible overlap streaks.

Work board by board across a manageable width instead. Paint the full width of three or four courses at a time, from one natural break to the next, so you always end at a corner board, a downpipe, a window casing or a butt joint. Keep a wet edge within that section, and never stop mid-board in the middle of a wall. Follow the shade around the house if you can, so you are not fighting a sun-heated surface.

Trim, soffit and the rest of the exterior

Siding is usually the largest surface but rarely the only one. Corner boards, window and door casings, and any decorative woodwork are a separate colour and a separate step, covered in how to paint exterior trim. The undersides of the eaves and the fascia boards behind the gutters are their own awkward overhead job, handled in how to paint soffit and fascia.

Order of operations that saves the most time: prep everything first, then prime everything, then paint the siding, then cut in the trim colour last so any siding overspill gets covered by the trim rather than the other way round.

What this job is worth

The scale of a wood siding repaint is driven almost entirely by prep condition, not by square footage. A house with sound paint that needs washing and two coats is a fraction of the labour of the same house with fifty percent peeling and rot at every board end. If you are pricing the work or checking a contractor quote, the cost to paint wood siding breaks down how surface condition, house height, access, number of coats and colour change each move the number.

Frequently asked questions

Do I have to remove all the old paint from wood siding?

No. You remove all the paint that is not firmly bonded. Sound, tight paint is a perfectly good base and stripping it back to bare wood everywhere creates far more work, far more dust and, on pre-1978 homes, far more lead risk. Full stripping is only worth it when the accumulated film has become so thick and brittle that it is cracking everywhere, or when you are moving to a semi-transparent stain and need bare timber.

How long should I wait after washing before I paint?

Long enough for the wood to be genuinely dry all the way through, not just dry to the touch. In warm, dry, breezy conditions that can be a day or two. In cool or humid weather, on shaded elevations, or after a pressure wash that drove water behind the boards, it can be considerably longer. If in doubt, wait. Painting damp wood is the fastest route to blistering.

Can I paint cedar siding a light colour?

Yes, but you have to block the tannins first. Cedar and redwood contain water-soluble extractives that migrate to the surface and leave brown or rust-coloured stains through light paint whenever the wood gets wet. Use a primer specifically labelled for tannin or extractive bleed blocking, over the full surface rather than as spot treatment, and follow its stated coverage rather than stretching it thin.

Should I paint or stain wood siding?

If the siding is already painted, painting is the practical answer, because getting back to bare wood for a semi-transparent stain is a very large job. Paint gives a thicker, more protective film and the widest colour range, but it fails visibly by peeling. Solid-colour and semi-transparent stains soak in more and tend to weather away rather than peel, which makes recoating simpler, at the cost of shorter intervals and less colour hiding.

What is the grey layer on bare wood siding and does it matter?

It is the wood surface degraded by ultraviolet light. The lignin binding the surface fibres breaks down, leaving a soft layer that is only loosely attached to the sound wood beneath. Primer will bond to it beautifully and then the whole assembly will lift off, because that grey layer is the weak link. Sand it off until you reach lighter, firm fibre. This is a genuine cause of early failure, not a cosmetic preference.

Why did my last paint job peel in sheets after two years?

Almost always moisture or bond failure, and often both. The usual suspects are painting over damp wood, painting over grey weathered fibre, painting over chalk that was never washed off, skipping primer on bare areas, caulking the lap lines shut so water could not drain, or a leaking gutter feeding water behind one wall. Diagnose which one applies before you repaint, because the same job done the same way will fail the same way.