How to Insulate Water Pipes
Begin by removing any dirt or grease from the pipes with a rag and mild cleanser. Allow the pipes to dry thoroughly before installing the insulation.
Choose the insulation, Foil, Fiberglass, or tubular-sleeve insulation which is the easiest to install and comes in a variety of sizes. Simply cut the sleeve to length and wrap it around the pipe. If more than one sleeve is needed to cover a longer pipe, be sure to duct tape the seam where the pipes meet
When working with fiberglass insulation, wrap the fiberglass in plastic to keep the pipes from dripping condensation. Foil or Fiberglass insulation can be wrapped around the pipe with a 1/2″ overlap. Secure each end of the insulation with duct tape. Be sure to cover the entire pipe when wrapping around corners and bends and wrap with duct tape.
When insulating around corners or T-joints, cut slits or make miter angles where necessary, and secure these areas with duct tape.