If I understand the 2012 International Energy Conservation Code (IECC) correctly, it appears that hot water supply lines are to be insulated with at least R-3 insulation under almost all applications. To bring my house up to those new standards, I have been adding 5/8" thick polyethylene foam pipe insulation rated at R-4.2 (Frost King) to my 1/2" and 3/4" PEX domestic hot water tubing. (It only comes in 3/8" and 5/8" thick at my hardware store, and 3/8" does not meet the R spec.) In the old days with copper pipes this was quick and easy. As I sit here picking the slinters out of my hands from trying to wrap the insulation around the PEX lines that are fastened to the floor joists in the crawl space every few feet, I wonder if there will be changes to the way PEX is fastened in the future to make adding the insulation easier? Thanks for any input.

Hopefully in the future, they will attach the insulation and then staple to the floor. :-)

Do you mean put the insulation on the tubing first, and then attach the tubing with insulation to the wood? This would imply a larger diameter fastener, I assume. I wonder if the PEX will be supplied with insulation already attached?

I wonder if the PEX will be supplied with insulation already attached?

It sounds like your project was unpleasant because it was a retrofit. I just installed a bunch of PEX in new construction and went through two boxes of the foam pipe insulation. It went pretty well, but stripping the backer off the self-adhesive edges was a little tedious towards the end. I'd do it again that way, though. Really long runs might be another story. I think I did 400'-500' all told, with about 50'-60' runs. Let's say it took two hours extra. That's about $.30/foot for the labor.

Uponor offers Aquapex, which is a pre-insulated R4.3 PEX-a for less than $2.00/foot for the 1/2" size.

ICFHybrid-

Thanks for the comment and the information on the Aquapex.

So did you install the foam pipe insulation on the PEX prior to installing the tubing? If so, did you use fasteners that were large enough to go around the PEX plus pipe insulation?

Slightly different situation in that just about all the lines were under slab instead of in framing. I laid the lines and set all the elbows and risers around the reinforcing steel and then slipped the insulation on. I used just enough fastening to secure it the first time around, then went back and finished up with zip ties and duct tape after the insulation was on.

Seems like it would be hard to pull the pre-insulated tubing through structure and that penetrations would have to be bigger to accommodate in the first place.

I guess I should not complain about my retrofit job that just involved a few splinters. Now if I had to dig under a slab to get to the PEX lines to insulate them, then I would really be complaining.

How about insulating the cold pipes? I read somewhere (maybe here?) that it keeps them from sweating and causing problems in the walls. Thoughts?

I tried to put my water pipes where they wouldn't be exposed to extremes of heat or cold so things like freezing and condensation would be less of an issue. I suppose if you had a cold water line that had to pass through an unconditioned space in a hot, humid climate, you'd want to insulate that to reduce the likelihood of condensation. I think PEX is probably better in this respect than copper to begin with.

I agree with ICFHybrid's comments. I checked my cold water pipes in the conditioned crawl space, and there was no condensation on the PEX tubing. This was not surprising since I live in a very dry, cool climate (Colorado mountain valley). The condensation is more of an issue east of the Mississippi and along the Gulf Coast. But insulation would certainly help if condensation is occurring on cold water pipes. The 2012 IECC requirements that I referred to in the original post only pertain to the hot water pipes.