In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Open-Cell Foam Directly on Sheet-Plate Radiant Underfloor Systems- Pros/Cons?
My insulation contractor says that the only way he will use open cell spray foam to insulate my underfloor radiant install is if I use bubble-foil stapled-up between the joists and about 1" or more away from the radiant, making an air space between the radiant and the foil. Then he'll spray foam on the foil between the joist bays.
I would much rather skip the foil install and just apply spray foam to the radiant directly. I can't understand WHY? I would want to create an airspace in the joist bay between the radiant and the insulation, if I'm willing to commit to 3+ or more inches of foam making sure the floor to be heated is colder than below the radiant (ie, heat goes up, right? especially with insulation making sure so...)
My Main Question: Will I regret applying foam directly to my radiant without leaving an airspace in the joist bay between the radiant and the insulation by using the bubble foil sheets???
Background - I installed an underfloor radiant system using staple-up sheet plates which cover the PEX piping. The plates are spaced about a 1/4" apart and are 14.5" wide, meaning they cover the entire exposed underside of the sub-floor. Essentially, we used plates everywhere we could, except for the bends in the PEX at the ends of each bay loop. So, almost the entire house floor is covered with sheet plates.
The plates were ideally for 5/8" pipe but I used 1/2" PEX. I did my best to install the plates with as much contact with the PEX as possible. But, it was inevitable that contact between the plates and the PEX was good but not great. There are slight spaces between the PEX and the plate channels at the ends of each plate. So...
I'm a little worried expanding foam might get in those cracks and isolate the PEX from the plates and floor...but am considering using 2 foams. One would hopefully be a low-expanding type and could be applied to the spaces between plates only. Then, another higher expanding foam would be applied to finish the install.
Is this nuts, or OK practice? Thanks in advance for any thoughts...