Paint is peeling from one wall of a house while the others are sound. What should an inspector consider?

Paint fails from behind far more often than from in front. When a single elevation peels while identical paint on the other walls holds, the variable is not the coating — it is what is happening inside that wall. Moisture reaching the siding from behind breaks the paint's bond with the substrate and lifts it, and the sources are all worth checking: a plumbing leak within the wall, missing or failed flashing above, a bathroom or kitchen exhaust discharging into the cavity rather than outdoors, or vapour drive from a humid interior room with no air barrier. The clue is the distribution — a whole wall failing uniformly points to a wall-wide condition rather than a local leak. The inspector reports the pattern, notes what is on the other side of that wall, and recommends the moisture source be identified before the wall is repainted, since repainting over the source guarantees the failure repeats.

Paint that fails on one elevation while identical paint elsewhere holds points to moisture reaching the siding from behind, which breaks the coating's bond. The single-wall distribution is what identifies the cause as internal to that assembly.

Exterior coatings fail from behind when moisture in the wall assembly breaks the paint's bond with the substrate. Sources include plumbing leaks, flashing failures, exhaust ducts discharging into cavities and interior vapour drive. Repainting without addressing the source produces recurring failure.

One Wall Means Look Behind It. Same paint, same weather, different result — the difference is inside the assembly.

Report that the source should be found before repainting. A recommendation to repaint without that condition sets the client up to pay twice.

• •Attributing single-wall failure to the coating or to sun exposure
• •Recommending repainting before the moisture source is identified
• •Failing to consider what rooms sit behind the failing elevation