Advice needed for pex install

[Turk73]

Hi All,

Been registered a number of weeks and usually just looking for tips and ideas.
I now need some advice. I had walls poured for my new garage yesterday and slab will be installed late next. I'm running 4 loops of 1/2" O2 barrier pex in a 22'x40' slab. Nibco gave me a design layout and sized the length. Pex will be stapled to 2" Dow 250 on top of vapor barrier. My concrete guy is telling me that I should install insulation under the slab sheets on the inside walls of the foundation. I believe that the heat loss will be through the outside wall. The foundation walls are 8" poured with inset lip that 5" slab will rest upon (no thermal break, and he says expansion joint not needed). Outside foundation above grade will be zero in front, ranging to almost 48" in back (hence the reason for footings and poured walls). BTW the garage is detached. I'm intending to insulate 3 sides with same 2" xps to a depth of 4 feet. Should I insulate under front apron? I'm considering doing the front wall on the inside to between 2 and 4 feet. I'd like to do the outside wall before I start construction as my concrete contractor will be backfilling after slab install. They moved a lot of fill 'cause they needed the room to set the forms. I worry about trashing the outside wall insulation during the construction process. Finally, regarding the pex exiting the concrete. Should I put a scrap 2x6 across anchor bolt span and just temporarily attach the 8 pex lines (they will be marked as to in/out) or do I install right angles?
Thanks, Turk

 

[Bricen18]

My concrete guy is telling me that I should install insulation under the slab sheets on the inside walls of the foundation

I have insulated foundations in the inside before. We would insulate from the top of the footer to where the bottom of the poured floor would be. i believe this to be common in my area.

As for exiting the pex watch how to save money with pex on youtube he uses a plastic peice to put the pex into to make a 90. I would leave the pex extra long and tie it off up and out of the way. I would leave a gap between the wall and pex

 

[MonteMike79]

I would get the manifold and run the pex from that, then you have the exact length you need and no fighting later. You can pressurize it too and make sure there are no leaks before and during pouring. I ran mine up through conduit elbows and just zip tied them together. Here's a picture hope it helps.

 

[anthony666]

i used to pressurize all my installs before the concrete guys poured, and i guess that's good practice if you're actually there while the pour is happening .. but after one too many disasters where the concrete guys burst my pex and ripped it right out of the floor i find it's way easier for me to fix stuff after the floor is a few weeks old .. that's when i put 50 or 60 pounds in her and watch the gauge, if it goes down my ears will get me close and then i pour a little water and watch for bubbles .. i can chip out 6 or 8" around the leak and get it cut out and coupled

 

[Jackfre]

I used to add oil of wintergreen or peppermint to the pressurize tubing. That way you would know if there was a leak. Of course, that said, it was always good to let the meatheads doing the pour that you did have a 12 ga loaded with rock salt at the ready.