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Under subfloor install ?

sgtmikey Member Posts: 14
When installing pex under the subfloor with Joist Trak panels, does it make more sense to have the pex loop within the joist bay at the exterior wall? The plans I have show the pex going from one bay to the next via a hole in the joist near the exterior wall. The loop is in the middle of the joist bay, half way into the house. Does it matter?



  • AirborneTrav
    AirborneTrav Member Posts: 29
    Interior holes

    When at all possible, we drill our holes on the interior side of the bays. It just makes sense to have better floor coverage with the loops toward the exterior (coldest) walls of the house. Probably doesn't make a huge difference, but people love to try to find cold spots with their feet and I feel like this alleviates those somewhat.
  • Weezbo
    Weezbo Member Posts: 6,232
    edited November 2013
    First ,

    i am not a huge proponent of staple up plates ,

    however ,

    the perimiter is important to cover. where i live it gets plenty cold and the building envelope and construction details are of massive consideration.


    as heating installers we make the very best decisions that are available and run this by the general early on so there is no sudden OMG you are gong to change What? going on...


    and Oh No! you were supposed to see to it that the floor was insulated with R- xxx ! now we have a Problem Huston ! because that is NOT going to Fly !


    The reasons for the plates extending to the exterior is because when the pipe is installed one straight run of holes is drilled out , the pipe run from the farthest point , then the pipe anchored , then the pipe is fed thru the closest bay that it was anchored slowly preferably in a heated environment , ....

    let me say something about types of construction materials a 2x 14" has become very uncommon to find for decades , 2 x 12 is not all that easy to come by at certain lengths .

    the BCI TJI and what every engineered name floor joist are called these days has basically become the norm , they have a wide top and bottom cord with a skinny osb / plywood piece that makes up a preponderance of the dimension ..the cords say are 2 " thick and the holes we drill are best not drilled thru them , or even within say 3/8 ths of them maybe even 3/4 " so that means the pipe is not going thru holes right immediately beneath the sub floor.

    enough of that for now..

    so when we pull the pipe thru the holes and into the "Bay we take the loop out to the perimeter and flip the pipe usually always in the same direction so that there is uniformity and ease of installation , .

    me and the mouse in my pocket have this stuff Down . lol

    any way now we have some plates ok well the pipe has a preformed groove in it that holds these pipes . the end out near the perimeter , can be put into these plates "Higher ,(Directly beneath the sub floor ) than at the interior where they already enter the bay 3 " or so down just to avoid any structural damage requiring someone in another trade countless hours of "Fixing" that.


    where the pipe enters the bays one is twisted above the other this means they converge at an angle the plates are straight , they are made of metal . so to get as much heat to the outside we can run the pipe and plates straight until we get to where they make a loop the they curve in a semi circle that allows for minor temp differences expansion of the tubing within the tubing or pipe.

    we often use two tallon clamps at about 45 degrees , rather than one in the middle of the loop to afix the tubing in that area to the floor.

    this proves to satisfy most of the floor area , the detail on the outside where the pipe is in a bay that is built to support the walls usually the gable end , needs consideration as well , ...there, squash blocks and all manner of minor technicalities exist .

    the outside corners are real important because if the "Hawk" gets in the house you wont get it out . so more effort is taken along that area ...

    i hope that helps prior to you embarking on a DIY or worse yet a micro engineered job telling someone who does this for a living that you want it done YOUR way , because

    your not going to be being very helpful having them do something , twice when you discover you have undermined your own best interests . i know i feel sick with the thought of someone going out of their way to make my job miserable, thru lack of consideration ...

    if you want i am thinking of getting a general contractors license and hiring myself out as a sabotuer then , i can ensure every aspect of the job takes at Least twice as long, Costs twice as much and you wont have to pay me much because i may end up enjoying the living hell other workers have to go thru trying to think of how to get the job done. Right . : )) ok so maybe i digressed a bit ... : )

    Weezbo .

    when the radiant heat is something homeowner wants to put sweat equity into then i make sure the perimeter has plates and do a couple complete bays with them so they get the drift on the whys and wherefores of what they are doing usually the two outside plates are fastened and pipe installed and "Pinned and on to the next bay ...

    the control of the water temps is a big deal also , floor coverings etc change the complexion of the job as do neglected aspects .

    forgive me for vventing lol...
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