Updated July 13, 2026 · HomeFixx Editorial Team

Symptoms: What You're Seeing

• Alligatoring pattern: Paint surface shows a tight, cracked pattern that looks like reptile skin, usually on old oil-based coats. You'll see hairline cracks running both directions forming small rectangular or diamond-shaped cells, and pressing a fingernail into it often flakes off multiple layers at once. This pattern almost always means the paint has simply reached the end of its service life — typically 15-20 years of sun and temperature cycling — and the fix is a full strip rather than a patch, since spot-priming over alligatored paint just creates a visible seam where old and new paint meet.
• Bubbling or blistering: Raised bumps appear on the painted surface, ranging from pinhead size to over an inch across. Some pop when pressed, releasing trapped moisture or a faint musty smell; others stay firm, indicating the bubble formed during application and trapped solvent underneath instead. Size matters here — blisters under a quarter-inch that appear only on sun-exposed afternoons are often just heat blistering from painting in direct sun, while larger, randomly distributed blisters that persist in shade point to a moisture source working from inside the wall.
• Peeling at laps and seams: Paint lifts in curling strips, most often where siding boards overlap, at butt joints, or along the bottom edge of clapboard. You can slide a putty knife under the edge with almost no resistance, and bare wood or old primer is visible underneath. These joints fail first because they're where water naturally collects and where caulk dries out and cracks fastest, so check laps and butt joints even on walls that otherwise look fine — this is where a $10 tube of caulk now prevents a $400 board replacement in two years.
• Cracking and flaking near trim: Paint around window sills, door casings, and fascia boards splits into small chips that fall off when brushed with a hand, often leaving a chalky white residue on your fingers from degraded pigment binder. Trim fails faster than flat siding because it has more end-grain exposed — end grain absorbs water at roughly 10 times the rate of face grain — so sills and casing edges deserve a closer inspection even when the surrounding wall paint looks intact.
• Peeling concentrated on one exposure: One side of the house — usually south or west facing — shows heavy peeling while the other three sides look fine. This directional pattern points to sun exposure or a localized moisture source rather than a paint quality problem. If the affected side also faces prevailing wind-driven rain or sits near a downspout discharge point, that's a strong clue the cause is water volume rather than UV, and fixing drainage will do more good than any amount of repainting.

What's Actually Causing This

• Moisture intrusion from behind the siding: This is the number one cause we find on service calls — roughly 70% of peeling jobs trace back to water getting behind the paint film from a leaking gutter, missing flashing, or condensation from an unvented bathroom fan. The moisture pushes outward through the wood, breaking the paint's bond from the inside regardless of how good the paint job was. In older homes, we also frequently find that a previous owner ran a bath fan duct into the attic instead of through a roof or wall vent, dumping humid air into the space above the wall cavity every time someone showers — this alone can cause peeling on an entire gable end within 2-3 years.
• Painting over a dirty or damp surface: Paint applied over pollen, dust, mildew, or morning dew never fully bonds to the wood. This shows up 6 months to 2 years later as sheeting peel, where large flat sections come off in one piece because the paint bonded to the contaminant layer instead of the substrate. Painters working on a tight schedule sometimes start before morning dew has fully evaporated, especially in spring and fall when humidity stays high past 10 AM — a rushed 7 AM start on a shaded wall is a common, invisible cause of failures that don't show up until the following year.
• Too many coats or incompatible paint layers: Houses painted every 5-7 years for 30+ years can carry 8-10 coats of paint, and old oil-based layers underneath new latex paint don't flex together. The layers separate from each other rather than from the wood, which is why you'll see multiple colors peel off in one flake. Each added coat also adds stiffness and thickness, so a wall that once flexed slightly with seasonal wood movement becomes brittle enough to crack along old nail lines and board seams even without any moisture problem at all.
• Poor surface prep before painting: Skipping a scrape-sand-prime cycle and painting directly over chalky, weathered old paint accounts for a large share of callbacks contractors see within 2 years of a repaint. Cheap contractors who skip $200-400 worth of prep labor per job to win a bid save the homeowner nothing — the paint fails faster than the old coat did. A simple way to catch this before hiring: run a dark cloth across any existing painted surface: heavy white chalk residue means the old paint needs a dedicated cleaner or pressure wash before anything new goes over it, and any bid that doesn't mention this step is underpricing the prep work.

Step-by-Step Diagnosis

Work through these steps before calling a contractor. Each step tells you what to look for and what it means.