Better to run PEX through floor joist or suspend?

[larsonist]

I’m running my own Uponor and the longer runs in my house will unfortunately be going perpendicular to the floor joists for most of the run length. It’s a one story with crawl space and fully insulated between joists, and PEX homerun system.

Suspending them from the bottom of the joists (Similar to gas and power conduit seen in photo) and then adding pipe insulation seems to be the easiest option, but I’m wondering if pulling back the insulation and boring holes is the better move long term?

The longest runs are the main water supply (about 40 ft to the manifold and then 3 exterior faucets lines with the longest being 40 ft). Most dedicated lines from the manifold will be in the 20 ft range. As for groupings of dedicated lines running in the same general directions, I’m looking at roughly (10) 1/2 in. lines running towards 2 bathrooms and 4 lines towards the kitchen.

 

[Bannerman]

I’m wondering if pulling back the insulation and boring holes is the better move long term?

Is the crawlspace likely to experience freezing temperatures?

Assuming the pipes within the crawlspace are unlikely to freeze, since it appears you would be forced to lie on your back for either installation method, what do you consider would be gained in drilling holes through each joist and then threading the tubing through each of those holes vs simply fastening pre-insulated tubing to the bottom of the joists with clips designed for that purpose?

 

[Sponsor]

 

[Jadnashua]

Pulling pex through multiple holes in a floor joist is a major pain, and you have the possibility of scoring the tubing as you do it. It's also tougher to prevent kinking it in the process. It's hard to get all of the holes perfectly aligned, and you don't really want to make them huge as it does affect the joist strength. Not much when placed properly according to the recommendations, though.

But, depending on how cold the crawl space gets, just pipe insulation may not be enough to keep it from freezing.

 

[larsonist]

Thanks for the quick replies. I didn’t really have any “pros” in mind for boring through the joists, so I mainly was looking to see if I was missing something.

I live in western Washington state, so our insulation climate zone is 4. We have about 20-25 nights per year where it dips below freezing, but generally we never have severe temps (stays above 20 degrees F).

Looks like I’ll continue with the plan of mounting them to the bottom of the joists and insulating the tubing.

 

[Terry]

In Western Washington I have not seen pipes freeze in a crawl space. By code they get insulated, not that it really helps for freezing there. It would help with heat loss on the hot lines.
I would not drill floor joists in a crawl for that. Suspending them or attaching to the bottom of the joists is what we normally do.

 

[Jadnashua]

One good aspect of pex is that it isn't damaged if it does end up getting frozen, but that does NOT apply to any fittings used. It still would be annoying if a line was blocked for that reason.

 

[larsonist]

In Western Washington I have not seen pipes freeze in a crawl space. By code they get insulated, not that it really helps for freezing there. It would help with heat loss on the hot lines.
I would not drill floor joists in a crawl for that. Suspending them or attaching to the bottom of the joists is what we normally do.

Thanks Terry and everyone else. I bought the tube talons so I’ll attach those to the bottom of the joists.

 

[Terry]

Since code requires insulation in the crawlspace, I insulate first and then hang the PEX with straps.