Many rain flies and tent floors use a Polyurethane coating to keep you dry. After time, this coating can break down and you'll start to get wet.
Re-coat worn areas on your tent floor and retreat your rain fly with Tent Sure™.
Thoroughly clean the surface to remove any remaining Polyurethane coating. Isopropyl alcohol and some soapy water (use a specialized cleaner or a mild detergent that has no additives) will do the trick.
Apply Tent Sure to the inside of the surface using a foam paintbrush.
For best results apply Tent Sure in a thin film, using even, sweeping motions to avoid puddles. A single thin coat works best.