Concrete

Transports moisture and salts through pores and cracks while remaining structurally different from its surface finish.

What changes first

Look for efflorescence, damp bands, cracks and rust staining. 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.