Exterior paint peels and blisters for three main reasons: water moving through the wall and pushing the paint off (moisture blisters and peeling to bare wood), fresh paint heated by direct sun before it dries (temperature blisters), and new paint put over chalky, dirty or poorly primed surfaces (intercoat peeling). Each has a tell-tale pattern. The fix depends on the cause; for moisture problems, repainting without stopping the water does not last. This page draws on the Purdue Extension and USDA Forest Products Laboratory bulletin NCR-133.
On this page: Read the pattern · Causes · Homeowner tests · Fixes · Basis · When to call
Read the pattern
| What you see | Likely cause |
|---|---|
| Peeling to bare wood near roof lines, gutters, windows or kickouts | Outside water getting into the wall |
| Blisters or peeling over bathrooms, kitchens or laundry rooms | Water vapor from inside the house |
| Bubbles only in the last coat, within two days of painting, on a sunny wall | Temperature blistering |
| New paint lifting in sheets off older paint | Intercoat peeling (chalk or dirt not cleaned) |
| Fine cracks across the grain through thick old paint | Too many coats built up |
The causes in detail
- Moisture blisters. Water from rain, ice dams or leaks outside, or vapor from cooking, bathing and dryers inside, moves through the wall and lifts the paint. These blisters usually go through all coats to the wood and are worst in spring and summer.
- Temperature blisters. Paint applied to a surface that the sun then heats can skin over before solvent escapes. NCR-133 says this mostly happens with oil-based paint, and dark colors and thick coats are more prone. NCR-133 advises painting each side of the house after the sun has left it.
- Intercoat peeling. New paint does not bond to chalky or dirty old paint, or to an oil primer left more than about two weeks before the topcoat.
- Weathered wood. USDA research shows bare wood left outdoors even one or two weeks before painting holds paint poorly, and peeling can follow within a few years.
- Paint build-up. Many coats become thick and rigid and crack across the grain; the cure is stripping to bare wood.
Homeowner tests
- Map the failure. Walk the house and note where paint fails. Clusters near water sources outside or wet rooms inside point to moisture.
- Check the depth. Lift a loose flake. Bare wood on the back side points to moisture or weathered wood; old paint underneath points to intercoat peeling.
- Bandage test. On a cleaned, painted test spot dried two days, press an adhesive bandage on and snap it off. Paint on the tape means poor adhesion.
- Time it. Bubbles that appear within hours or a day or two of painting on a sunny wall are temperature blisters.
Homes built before 1978 may have lead paint. Do not dry-scrape or sand old paint until it has been tested; the EPA requires paid contractors who disturb paint in pre-1978 homes to be lead-safe certified.
The correct fix, and the wrong ones
| Fix | When it fits |
|---|---|
| Stop the water first: flashing, gutters, kickouts, window leaks, bath and dryer vents | Moisture blisters or peeling to bare wood. |
| Scrape loose paint, feather edges, clean, treat bare wood, prime and topcoat | After the source is fixed, or for localized failure. |
| Let temperature blisters dry, scrape, sand and spot paint in shade | Top-coat blisters only. |
| Scrub off chalk and dirt, use a bonding or oil-based primer if the bandage test fails, then topcoat | Intercoat peeling. |
| Strip to bare wood and refinish | Cross-grain cracking or widespread failure. |
Wrong fixes: repainting over moisture blisters, a thicker coat to “seal” the wall, painting over chalk, or painting the south and west walls in full afternoon sun.
Research basis
- Purdue Extension and USDA FPL, NCR-133 Paint Failure Problems and Their Cure. Covers moisture and temperature blistering, intercoat peeling, the adhesive bandage test and cross-grain cracking, and says the moisture source must be removed before repainting.
- USDA FPL, Weathering of Wood (R. Sam Williams). Bare wood starts degrading within one to two weeks outdoors; paint over weathered wood bonds poorly.
- EPA Renovation, Repair and Painting program. Paid work that disturbs paint in pre-1978 homes requires certified renovators and lead-safe practices.
Chalk on your hand is covered in chalking and fading paint; dark spots in shade are covered in mildew on paint and siding. If paint peels in a vertical stripe below a roof line, read water behind siding.
When to call
Call when paint peels to bare wood in the same places after repainting, or when blisters show up near roof lines and windows. Integrity paints exteriors and also fixes the roofing, gutter and flashing problems that cause paint to fail. See our Colorado Springs painting page and the exterior problems guide.
Book a paint and exterior check
Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews. Colorado Springs area: call (719) 488-2800 or book a free inspection. Denver metro: call (303) 209-0152 or book a free Denver inspection. Austin: call (512) 610-5897 or book a free Austin inspection. We reply the same business day.
Sources: Cassens and Feist, NCR-133 Paint Failure Problems and Their Cure (Purdue Extension and USDA FPL); R. Sam Williams, Weathering of Wood (USDA FPL, 2005); U.S. EPA, Lead Renovation, Repair and Painting Program.
