Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Radiant under 3/4 ply & cement board/tile

MW29
MW29 Member Posts: 3
I want to install 1/2" pex to bottom side of 3/4 sub floor plywood . Put cement board on top of plywood & than tile. I intend to use aluminum plate on pex & than insulate under sub floor with 3 or 4 inches of spray foam insulation . Will the heat be able to make it through

3/4 ply wood,1/2" cement board & approximately 1/4" tile to warm home. Doing this on my 1st floor after lifting house( took 1&1/2 feet of ocean through 1st floor from Sandy storm

Comments

  • MW29
    MW29 Member Posts: 3
    Radiant under 3/4 ply & cement board/tile

    Spray foam insulation will be sprayed directly on to aluminum covered radiant tubeing
  • Rich_49
    Rich_49 Member Posts: 2,610
    Underfloor plates

    will work but there are other products methods that are in the same price range that will be more efficient .  Have you had a proper hat loss performed or done one yourself ? This is a must .  What type of equipment do you have or wish to use ?
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • MW29
    MW29 Member Posts: 3
    MW

    Didn't do a heat loss , I have a baxi wall hung unit

    It now services cast iron baseboard in part of the house

    And radiant heat in one room( lowering temp with mixing valve for radiant)& Argo 4 zone controller-

    Was just gonna fill every bay with 2 loops

    About 8" apart & aprox 3" away from joists

    Keeping each loop aprox 300' at around 6 loops

    Area is 18' wide x 33' long part of it has kitchen

    Cabs & appliances was gonna shorten up a lil

    Under that stuff
  • Zman
    Zman Member Posts: 6,985
    Spray foam

    I am always concerned about spray foam and pex. The heat from the curing foam can damage the tubing as can the chemical interaction.

    I like to seperate the foam with a barrier of foil insulation.

    I know SWEI has had success with spray in product directly on the tubes. Perhaps he will weigh in.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SWEI
    SWEI Member Posts: 7,356
    Not foam

    Wet-spray cellulose (or dry blown, after stapling perforated Tyvek to the bottom of the joists) does work quite well.  It's also possible to remove for repairs, unlike foam.



    Chemical compatibility is one issue, the other is that small amounts of liquid foam tend to creep between the plates and the subfloor.  When those expand, your heat transfer goes bye-bye.
  • Rich_49
    Rich_49 Member Posts: 2,610
    edited April 2014
    SPF and pex

    Plates must be sealed at edges , I use inexpensive adhesive tape for this when SPF is to be used .  The first and second layers applied should only be 1 inch lifts , the tubing can handle that easily . 
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833