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/.
Click here to Find a Contractor in your area.

Radiant over existing floor - old house

I am installing PEX over the existing floors throughout my old (1902) farmhouse. I would like some advice on how to prepare the floor before I put down the 2x2 sleepers. I guess I am asking the question because the floors are not completely level. Some is the old hardwood. Other areas are new t-g 3/4 OSB . Can I just put down the sleepers and let the gypcrete self-level. I suppose that I will need to put down a layer of plastic first because there are several spots where the gypcrete would just flow into the basement.

Any advice would be appreciated.



  • Gordy
    Gordy Member Posts: 9,546

     It depends how out of level the floors are. In other words you would not want 3" of gypcrete at one end of the room, and 3/4" at the other to obtain level.

     Can the floor joists support the added weight of the gypcrete? As specially if it is drastically thicker in spots could have adverse effects to the floor framing.

     A little out of level is okay, and gypcrete is a good way to level it up, but if there are drastic areas they should be corrected through enhanced framing before you pour gypcrete.

  • Trapper_Dave
    Trapper_Dave Member Posts: 10
    That helps


    Thanks for your help. No I don't think that the floors are that crazy. If they are within reason it sounds like I can just throw down the 2x2's and get PEXing.

    Yes the joists are all doubled up to support the weight.

    Would you recommend double-bubble for my plastic sheeting? It would give a bit of r-value.


  • Gordy
    Gordy Member Posts: 9,546
    Double bubble

     No, just use visquine, and insulating under floor will be a must. Putting down bubble foil would not only be unstable for the gypcrete its pretty much worthless in my opinion for any reasonable r value. Plenty of white papers out debunking bubble foil claims. Save the dollars for real insulation.

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
    You do know about climate panels right?


    They save having to pour the gypcrete.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
This discussion has been closed.