Hi. I am in zone 4a and building monolithic slab for my house.

I will be running pex under the slab. I have been looking for the appropriate insulation for my 3/4″ pex water lines. To protect the cold line and to insulate the hot. I will have a hot water loop running around the house and back to the hot water heater.

So far, all I can find are 6ft foam sections and that does not sound very efficient. seems like there should be a 50 or 100ft section of the foam. 

I already have the pex a buddy gifted me from his house build leftover, so purchasing already insulated pex is not a good option. 

Thanks very much for your advice.

-Mike