Like any area where water is used, before you start remodeling you should inspect for any indication of leaks or of water damage from previous leaks or overflows.

Check pipes, ventilation, heat/air vents.

Always check for mold and mildew, as well as pests.

If you are planning to bring in larger and heavier appliances, cabinetry or furniture, you should check on the structure to ensure that there is adequate support for your design.