How do you know when your house exterior needs repainting?

Sherwin-Williams describes chalking as a fine, white powder on the surface of the paint film caused by weathering, which can look like the color fading. Some chalking is normal and can be a desirable way for a paint film to wear, but excessive erosion of the film may produce heavy chalking.

It lists likely causes of heavy chalk: oil paints, which tend to chalk more than latex; a low-grade, highly pigmented paint; an interior paint used outdoors; an unsealed porous surface; over-thinned paint; and paint spread too thin. Its fix is to wash or power wash the chalk off, wash again if some remains, scrub where needed, rinse with clear water and let the surface dry thoroughly. For the best resistance to chalking it recommends higher-quality acrylic coatings.

How to check: run a dry hand or a dark cloth over the paint in a sunny spot and a sheltered spot. Our guide on why exterior paint peels after a Wisconsin winter describes the cloth test and the bandage test for the bond of a repainted patch, both from the USDA Forest Products Laboratory. Chalk matters because Sherwin-Williams says that if chalkiness is not removed from aluminum siding, new paint will not adhere properly.

Sherwin-Williams describes caulk failure as the loss of the caulk’s first adhesion and flexibility, so that painted caulk cracks or pulls away from the surfaces it was applied to. Its causes: lower-quality caulk, the wrong type for the job, a surface that was not prepared or primed, and a bead that was too thin.

This is worth checking early because the same company lists worn-out or missing caulking at joints, corners and openings as a way for moisture to reach the wood behind exterior paint, and moisture is what makes a substrate swell and the paint loosen, crack and fall off. Its fix is to remove loose or cracked caulking and repair it with a quality product. For caulk that will be painted, it says a top-quality all-acrylic or siliconized acrylic caulk suits places where prolonged contact with water is not expected, and that pure silicone caulk should not be painted.

Sherwin-Williams describes fading as premature or excessive lightening of the color on sunny exposures. It says this is easy to see because hidden areas such as eaves do not usually fade, and that heavy chalking can make a color look lighter. Slight fading is acceptable, it says, provided it is gradual and uniform.

Its advice when the surface is otherwise in good condition: clean as needed and repaint with a fade-resistant paint, following the label’s surface-preparation directions. In other words, fading alone is a cosmetic call, not proof the paint has failed.

This guide does not give a rule of thumb, because the sources do not give one. What they do give is a way to reason about it. Washing alone may be enough for dirt and mildew. Sound paint with only fading may need only a clean and a fresh coat. Failures confined to one spot, such as a single run of cracked caulk or a patch of flaking, can be repaired, but the cause has to be found first: Sherwin-Williams’ fix for moisture peeling starts with the caulk, gutters, vents, roof and ground clearance, and not with a new coat.

Touch-ups carry their own catch. Sherwin-Williams lists the reasons a repaired spot shows: a different tool from the original, a different batch of paint, a repair with a different texture, and a much different temperature on the day. It suggests using the same tool, keeping some of the original batch, and feathering the repair into the surrounding surface.

Signs across many walls or elements, wide cracking and flaking, or chalk that returns after washing point toward repainting the whole surface. Whoever you ask, ask for the diagnosis in writing and the preparation that comes with it. Our exterior painting page describes how we prepare and paint siding and trim.

Sherwin-Williams puts a lead notice on every one of the problem pages cited here, and the repair steps for chalking, cracking and flaking involve scraping, sanding or power washing. For a home built before 1978, the Wisconsin Department of Health Services requires certified lead-safe work when more than 20 square feet of exterior painted surface is disturbed, and it publishes a list of certified companies. Our peeling guide goes through the rule in full.