Delamination is the outer fiberglass skin separating from the substrate behind it. The cause is almost always water intrusion at a seam, window, or roof edge — and by the time it’s visible it has been happening for a while.
How to check: look down the wall in raking light for bubbles, ripples or soft-looking waves. Press gently with your palm — a delaminated section feels spongy and may flex where sound wall doesn’t. Tapping produces a duller sound over affected areas.
Why waiting costs money: the wet area keeps growing, the substrate keeps degrading, and the repair scope is set by how far the water traveled. A patch over a spongy wall is cosmetic and will fail.
A proper repair cuts back to sound material, dries and rebuilds the substrate, lays up and fairs the fiberglass flat, then refinishes and blends. It also fixes the leak that caused it — otherwise you’ll do this again.
If you’re seeing bubbles now, get it looked at before the next rainy stretch rather than after.