Ask The Expert: What Makes Under Slab Insulation Unique?

Posted by Ecofoil on

Austin Dopp Blog Writer Austin Dopp Ecofoil BUF™At EcoFoil, we get many calls. Out of curiosity, we ask customers what they plan to use our product for. To our surprise, we hear many customers say they are wanting to use our standard bubble insulations underneath a concrete slab in conjunction with radiant heat. We appreciate these calls as they give us an opportunity to educate customers on what products should be used and why. When insulating under a concrete slab, the clear cut #1 answer is EcoFoil Under Slab Insulation.You may be thinking, “What is the difference between EcoFoil Bubble Insulation and EcoFoil Under Slab Insulation?” It's important to realize there's more than just one difference to keep in mind. First, aluminum and concrete don’t play well together; there is an adverse chemical reaction when the aluminum in the foil meets the lime in the concrete. Second, in fresh concrete, bubbles can form on the surface as the concrete cures. This is important because the concrete will cause the foil to corrode which will greatly reduce its effectiveness.


Unlike traditional bubble insulation, where the foil is exposed, our patented under slab insulation is encapsulated. This was done for two main reasons; the integrity of the foil and the airspace it creates for effectiveness. If the foil surface comes into direct contact with certain acidic soils, it can corrode the reflective properties of the insulation as well. For this reason, traditional bubble insulation is not an appropriate insulation for an underground application. It is also important to maintain an airspace on one side of the insulation for it to be reflective.Image depicting under slab insulation. Foil encapsulated between bubbles.

Won't the bubbles in the insulation pop?

The answer to this question is “No, they will not.” EcoFoil Under Slab Insulation is specifically designed to handle the abuse during construction and withstand the weight of the slab. With a rated compression strength of 140 psi and a bursting strength of 180 psi it is virtually indestructible.EcoFoil Under Concrete with Pex Tubing on top


  • In addition to reflecting radiant heat back to your radiant floor you will receive an R-Value of 3.8, as well as a 100% vapor and radon barrier all in one product.
  • EcoFoil Under Slab Insulation is the only product on the market with the reflective foil between two layers of bubbles. This isolates the foil from the concrete and from the humid conditions below the slab, which increases the effectiveness and lengthens the life of the foil.
  • There is no up or down to the product making installation virtually foolproof.
  To purchase our under slab insulation, please visit or call (888) 349-3645 for more information. If you prefer, you can also send us an e-mail at