[protechplumbing]

PE for cold pipes. Will last about 6 years in UV.

Synthetic rubber(armaflex, armacell) for really hot pipes. It will get brittle and looses R-value with time. Will last about 10 years in UV.

Great stuff foam for either if you don't mind working on it for days. It does have the best R-value though and it heat and flame resistant. Very messy and doesn't look good at all.

Fiber glass is time consuming. has the poorest R-value, and it gets worse if pipes form condensation or are exposed to the elements. It is by far the most heat, flame and U.V. resistant. It needs to be coated with aluminum tape and then duct mastic to make it weather proof. If you don't mind raping every thing 3-4 inches thick then taping and coating, it will handle the most extremes and last the longest.

Their is also cork tape and foamed glass. I wouldn't recommend either.