PEX-A in unconditioned crawl space

[Russell Harris]

Hello,
I'm about to start work on the re-piping for a 1952 ranch built on pier and beam in Central Texas. I'll be using PEX-A pipe and expansion fittings/manifolds. The question regards insulation of the PEX piping. In the code for City of Austin, it mentions that supply 'piping' in an unconditioned crawl space must have insulation of R value 4.
My crawl space is ventilated but unconditioned. Just frame house over dirt, pier and beam. I do not have any floor insulation. I'm assuming that since they only say 'pipe' that means the PEX will need to be insulated?
Second question, it's very tight in the space (working on my back) and assuming that I will need to use insulated pex, I was thinking of using the plastic DWV hangers to support the PEX on it's runs. I was unsure if there is a better way to hang the insulated PEX?
Thanks,
RH

 

[Reach4]

I think most people would use add-on foam pipe insulation, rather than buy insulated pex. You need to support the pex every 23 inches.
I have not done it, but I am thinking they might use 13.5 inch piece of foam fitting between the joists on 16 inch centers. I understand that is not continuous. Maybe you could use 16 inch pieces with notches pre-cut to clear the joists while keeping most of the pipe insulated below the joists. I am thinking slicing off the upper 1/3 of 1.5 inches of one end of each piece would be good. An electric knife is nice for cutting foam. They sell "Foam Self Seal Pipe Insulation", which looks interesting. I am not a pro. Others may have better info for you.

Screw-type Talons driven with a battery powered drill lets you not have to try to accurately swing a hammer in awkward situation. Screw into the center to minimize weakening the joist.