The grooves aren’t just cosmetic — they create vertical channels that suck water upward by capillary action. Once the bottom edge touches damp ground or a splash zone, moisture wicks into the untreated plywood core. Result: swelling, delamination, and a perfect mold buffet.
Factory-primed T-111 often fails within 3–5 years. Peeling starts at groove edges, then spreads. Why? The grooves hold moisture longer, and the thin face veneer expands/contracts at a different rate than the backing. Once water gets under the coating, the sun bakes it into vapor that blows the paint off. t-111 siding problems
Because T-111 is structural (often used without sheathing), rot can spread into wall studs, insulation, and framing before you see a single brown spot on the exterior. A seemingly solid panel may be held in place only by paint film. The grooves aren’t just cosmetic — they create