Typically, we recommended 2″ but some states now require 3″ or R-15. Some promote the use of thin sheets of foil/bubble or an insulating blanket. These products claim a high R-value but most of this comes from its reflective properties. You lose the reflective properties of the material once you pour concrete over it.
Place the radiant heat tubing at the industry-recommended depth down from the surface of the slab. Typically the maximum depth that tubing should be placed in a concrete floor slab is 2" down from the finished floor surface.
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Frequently Asked Questions
How deep should PEX be in concrete?
4-5"Since in non-reinforced slabs tubing is generally positioned at the bottom (secured with foamboard staples or PEX rails), their thickness should not exceed 4-5".
How thick is radiant floor heating?
The industry standard for radiant heat tubing is 5/8” Pex tubing (O.D. of approx ¾”), therefore a 1-1/2” thick Gypsum Concrete topping is most typical.
Where to put radiant heat tubing in a concrete floor?
Most contractors are conscientious and are glad to hear about good design. Radiant heat tubing in a concrete slab needs to be closer to the top of the slab than its bottom, normally in the top 2-inches of concrete.
How big of a radiant heat slab do I Need?
With 7/8” XL PEX you can expect a heat output of at least 50 BTU’s per foot in a slab on grade installation and 40 BTU’s per foot in a floor joist application. It is potable and ultraviolet resistant for protection against sun damage during installation.
How tall should concrete be above PEX tubing?
Concrete height above PEX adds additional R value, and while it’s minimal in most instances, more energy would be required to heat the topmost surface. Since in non-reinforced slabs tubing is generally positioned at the bottom (secured with foamboard staples or PEX rails), their thickness should not exceed 4-5".
How big of a pipe do I need for a slab of concrete?
For 1/2" or 5/8" PEX, 3-4ft long pieces of 1" PEX can be used for sleeving. Sleeve ends should be duct-taped to prevent concrete mixture from getting inside. If using a split pipe (cut open length-wise), tape the seam also. Have a couple PEX splicing/repair kits and a tool handy.