You can take an active role in protecting your property from flood damage. The method you choose depends on your particular situation. Sandbagging alone is not an effective method for protecting a structure from flooding. You must caulk to keep water out. Expanding foam and duct tape are more effective than sandbags but can damage finishes. Latex, Tub & Tile, and Silicone caulking works fairly well to protect a structure from flooding. It requires between eight (8) to twenty four (24) hours of curing.  For best results please check manufacturers recommended curing times on the product label.  Duct tape and expanding polyurethane foam works as well as the caulks, but the surface needs to be very clean, dry, and smooth in order for the tape to stick onto the surface. As far as efficiency, durability, and affordability, duct tape and expanding foam is the best and effective method of protecting a structure from flooding.