Water pipes in the home are generally made of either copper or a type of plastic called CPVC. The best way of insulating water pipes is with hollow foam tubes that come in 2.4 metre (8 foot) sections and various diameters to fit snugly around the pipe. Every tube has a slit down one side for the water pipe to enter the centre of the tube. To insulate PVC drain pipes, fibreglass wall insulation is installed around the pipe to prevent it from freezing.
Cut the section of wall/ceiling/floor insulation to length, using scissors. Pull apart the insulation along one of its sides so that half its thickness lies on each side. Only pull apart the insulation to the point where the PVC drain pipe will be positioned.
Push the length of insulation into the wall cavity -- paper retarder facing out and towards you -- with the PVC pipe in the centre of the two pulled-apart sections. Staple the paper lips running down each side of the retarder to the sides of the studs or joists every 20 cm (8 inches) to hold the insulation in place. Repeat this process with all sections of PVC drain pipe.
Pull apart the slit running down the side of the foam insulation tube and push the CPVC water supply pipe into the hollow centre of the tube. Do this along the entire length of the tube. Then pull off the plastic strips from each side of the slit. Press together the slit along the length of the tube -- this will help the glue inside seal the slit together.
Install another foam tube on the next section of CPVC pipe, following the same process. Pull the ends of each foam tube section together and wrap insulation tape around the joint. Repeat this entire process until the entire run of CPVC water pipe has been insulated.
To install foam insulation tubes around angled couplings, make a mitre cut completely through the tube at the point where it will be wrapped around the coupling. The mitre cut will be the same angle as the coupling -- 30, 45, 90 degrees. Then wrap both parts of the tube around the pipe, pushing them together around the angled coupling. Wrap insulation tape around the joint.
Wall/ceiling/floor insulation rolls come in different values to convey the quality and thickness of the insulation. Make sure you have the correct insulation before starting the job.