Before any remodeling project begins, you should have the area professionally inspected for:

mold and fungus,

dampness,

radon gas,

pests (including termites), and

structural problems that will need to be corrected before the project begins.

If you are using a licensed contractor s/he should be able to give you a list of inspectors. If you are doing the project yourself, your local building codes and inspections office will be able to make recommendations.