Preparing and Repainting Cedar Siding

Start with joints, seams, and where the cedar meets the soffits. Check that pieces fit properly and required seals are intact. This applies to new and previously painted cedar; on painted cedar, also inspect for coating failure.

Loose, hanging, or displaced siding needs installation repair before coating work. Tight, straight siding with a gap at a joint that requires sealing may need only caulking. Preserve intentional drainage and ventilation openings; do not treat every opening as a caulk joint. Correct water-entry problems before covering their symptoms.

Inspect for mold or mildew, soft spots, splits, and other damage. Record whether the material is plank siding or shakes, whether it is smooth or rough-sawn, and whether the intended finish is paint or penetrating stain. The same coating approach is not automatically suitable for every profile or finish.

Determine whether failure is isolated or widespread. Record its relationship to windows, doors, penetrations, elevations, and earlier repairs. Extent guides investigation but does not establish the cause.

Identify what is separating from what. Several coats releasing together and exposing cedar suggest failure deep in the system. One old coat releasing from another indicates an intercoat failure. A new topcoat peeling from sound older paint calls for investigation of recent preparation, contamination, compatibility, and application conditions.

Ask about the age of the siding and coatings, repaint history, and whether failure appeared gradually or suddenly. Sudden failure warrants questions about leaks, wind-driven rain, roof damage, and other changes. Age alone is not a diagnosis.

Check joints, windows, doors, flashing, penetrations, roofs, and gutters for plausible water-entry paths. Compare those observations with the failure pattern.

Only after investigating other likely causes should widespread, gradual release at the original coating-to-wood bond be attributed to age-related failure. Newer coats can remain bonded to each other while the oldest layer carries them off the cedar. Keep an unresolved cause open rather than guessing.

Use a hardener intended for the repair and exposure, following its instructions.

If the cedar is soft all the way through, I recommend replacement even when the spot is small. Discuss replacement versus a limited repair with the client. A cosmetic filler repair is not equivalent to replacing a damaged board and does not correct an underlying moisture or attachment problem.

When a client chooses a suitable localized filler repair, I cut out the soft wood and wipe the area clean. Use a two-part exterior wood-repair filler with its specified hardener; Bondo Wood Filler is one example I have used. Follow the product's preparation, dryness, mixing, and cure requirements.

Apply only enough filler to bring the repair level with the plank. As it begins to harden, while still malleable, use a graining tool to imitate the surrounding cedar texture. Once cured, remove unwanted high spots with limited sanding or trimming, taking care not to sand away the grain pattern.

Spot-prime a filler repair for a painted finish. Do not spot-prime beneath a penetrating stain. Filler can take color differently from cedar, so a textured patch may remain visible under stain. Explain this before work; appearance is another reason to recommend replacement.

Choose cleaning for the intended finish. For cedar that will be painted, my Florida practice includes pre-rinsing the wood, wetting surrounding areas, applying a chlorine-based treatment, and rinsing thoroughly. I treat isolated areas by hand and larger areas with a gentle wash. Avoid pressure that damages the cedar or drives water behind siding.

For bare cedar siding receiving penetrating stain, use a cedar-compatible cleaner suited to the chosen finish. The Western Red Cedar Lumber Association identifies commercial mildew treatments and oxygen-bleach cleaning as options. Do not mix vinegar and hydrogen peroxide. I avoid my chlorine method on this siding because discoloration may show through stain. I have used chlorine washing on fences, treating the entire area evenly; that experience is not a universal fence-cleaning specification. Test the selected labeled cleaner in an inconspicuous area and evaluate its effect before full treatment.

Remove all loose, lifting, bubbling, and poorly adhered paint. I generally favor scraping as a practical approach; complete chemical stripping can exceed a client's budget. Prepare transitions to sound coating without unnecessarily erasing cedar texture. Assess older coatings for lead and use the applicable lead-safe preparation practices before disturbing them.

Explain the limits of partial removal: extensive scraping is not complete stripping, and retained old layers may later fail. Primer cannot make loose paint sound. Cleaning and preparation must leave the surface free of residue and debris before coating.

Weather, exposure, and site conditions determine drying time. I sometimes find a few hours of full sun sufficient, but time alone is not proof of readiness. I use a moisture meter when drying is uncertain or conditions are wet. Confirm the wood meets the selected coating's moisture requirement; allow longer when it does not.

For penetrating stain, do not apply a paint primer. Follow the stain system's preparation and application instructions. Detailed stain selection and application are outside this repaint procedure.

For paint, choose an exterior wood primer with tannin-blocking capability and compatibility with the finish coat. On previously painted cedar with sound surrounding paint, spot-prime exposed wood and the entire prepared repair, including exposed sound older coating and transitions where another layer has peeled away. Do not automatically prime the whole house.

I do not recommend elastomeric coatings for cedar and prefer an exterior acrylic system suitable for the wood and its moisture behavior. Avoid the blanket claim that every elastomeric is non-breathable: some are vapor-permeable masonry coatings, but that does not make them suitable for cedar.

Choose the spray tip for the product's viscosity and permitted tip range, the siding width, and the required pattern. I typically start with a 515 tip for the acrylics discussed, then check the actual product's requirements and test the application. Detailed setup, tip selection, spray technique, and cleanup will be covered in the separate airless spraying article.

Start in a test area and check the application with a wet-film thickness gauge. Use the manufacturer's specified film-thickness range rather than judging only by hiding or by how much paint can be applied without runs. The gauge checks local wet-film thickness; it does not replace the required coat count or drying interval. Take representative readings and account for the limitations of a rough surface.

Back-roll or back-brush the wet coating to work it into pores and texture as appropriate to the surface and product. The choice is situational for both shakes and plank siding; I usually find back-rolling more efficient.

Smoother surfaces call for shorter nap and rougher surfaces longer nap. See the shared roller-nap tables, under “Cedar and stucco: back-rolling paint,” for my current cedar cover and nap selections. Match the cover to the actual wood texture and the coating. Use a brush where the profile or access makes it more practical; do not apply these paint selections automatically to penetrating stain.

Keep application even and maintain the wet edge. Observe the selected coating's surface-temperature, weather, drying, and recoat limits. Inspect at each stage so problems are corrected before more coating conceals them.

After drying, inspect for uneven coverage, missed spots (holidays), flashing, and tannin bleed-through. Assess the complete area and transitions, not only the center of the siding boards.

If tannin bleed returns, address it with the compatible stain-blocking primer system before restoring the finish. Do not keep covering a recurring stain with finish paint alone. Confirm a uniform result after the repair dries.

Use the glossary for the current definitions and aliases of holiday, flashing, and mist coat (spray correction). The holiday entry also includes its sourced nautical history.

In this article, paint flashing concerns the appearance of the coating. Construction flashing at windows, roofs, and building joints is a separate water-management detail. The inspection and correction step above explains how I use the spray-correction method on cedar.