Oriented strand board

Absorbs water strongly at exposed edges and may remain swollen after drying.

What changes first

Look for raised edges, flaking strands and persistent thickness change. The pattern and location usually matter more than color alone.

Moisture and movement behavior

Record whether the material changes after rain, water use, heating cycles or seasonal humidity. A material can display the damage while the source is somewhere else.

Before repair

Determine whether the material is the source, a pathway or only the final surface. Correct the controlling condition before replacing finishes.