Radiant under 3/4 ply & cement board/tile

MW29

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

MW29

Radiant under 3/4 ply & cement board/tile

Spray foam insulation will be sprayed directly on to aluminum covered radiant tubeing

Rich_49

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 ?

MW29

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

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

SWEI

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

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 .