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Community and Q&A

frost protect well water line for structure on piers / no conditioned crawlspace?

neutral_grey | Posted in Mechanicals on

I’m building a small conditioned structure (iecc 5b or 6b) that houses well pressure tanks & bathroom while we build our house over the next few years.  I’d like to avoid pouring a foundation, and my engineer has approved a simple structure on just a handful of pre-cast “deck footings”

The only issue is the “intake” from the well – how do I (to code) get this line from frost depth (~24″; i’ll be running my well line at 4-5ft) to the heated space? 

Ideally there would be a sort of “heated plenum” product, so I could avoid “skirting” and insulating the entire structure.  I see and similar – but can I run that through free-air (above grade), and do I just run that to 5ft down then add a fitting to the black poly well line?  I’d be worried about getting that past inspection …

If i need to frame an enclosure, can this be done without a concrete pour?  It seems mobile homes in cold climates would have to solve this – but the only method I see them using is skirting and insulating the entire structure.  As detailed in another thread, the entire structure must go after we build (per input there, i’ve made some small design changes and think I can sell it for re-use , rather than scrapping it) – so any concrete, or substantial structure below it will just be thrown away, in addition to a lot more work.

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  1. Expert Member
    BILL WICHERS | | #2

    I agree with a heat tape, but I would recommend you use a very specific type: ONLY use the SELF REGULATING type. These type heat cables are much more expensive, but also far more reliable as they have no thermostat -- they self-adjust their temperature based on how cold it is. I have always used the Raychem cables like this one:

    These are much, much heavier duty than cheap cables made for gutters that you find in your local hardware store.


  2. neutral_grey | | #3

    @nynick & @bill - thanks, yes I've seen these (same idea as in the insulated underground cable i used). I do like the idea of self-regulating cables.

    is any of this to CODE though? This seems like something I might be comfortable doing myself, but i need to pull a permit here as it's the "initial" addition of site water & bathroom

    1. Expert Member
      BILL WICHERS | | #4

      You'll need to check with your local building department on that code issue. They might require an underground shutoff valve (you can get these as an assembly with the valve down at frost depth but the handle up above ground, they're commonly used with water wells that have buried pressure tanks). Some physical protection for the pipe coming up out of the ground to get to the structure may be required too.


  3. Expert Member
    Akos | | #5

    Instead of building on block and crawlspace and having to deal with freezing water pipes, I would build right on the ground.

    I've used this for outdoor sheds without any foundation. In your case, you don't want the structure to heave so you need some skirt insulation, same as a shallow frost protected foundation.

    Level the ground and build a 6x6 PT frame as a foundation. Fill between the PT with gravel and cover with either plywood or some patio pavers. Set your walls over the PT frame.

    Instead of digging to put the skirt insulation bellow ground, I would leave at the surface and cover with patio pavers.

    This way there is no floor structure to build and no frozen pipes to deal with.

  4. Expert Member


    This project used what I think is a simple and elegant solution:

    Make sure the centre pipe is large enough to allow heat from above to circulate around the well pipe and you should be good.

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