Insulation Comparisons

Compare HotRockPanels with other insulations currently used for in-floor heating applications


HotRockPanels provide an all-in-one solution for insulating hydronic floor heating applications. Our original panels are rated R10, lock together quickly with u-shaped edges, grip the PEX tubing in place without the need for additional fasteners or mesh, have a thermoformed moisture barrier, and possess compressive strength of 30 PSI.

Not only do they boast the listed qualities but, they also reduce the installation times of the insulation and PEX by up to 66%; saving customers time and money. Custom runs are available to address higher R value or PSI requirements up to R15 and 60PSI.

Our insulation is made of EPS and is proven to hold nearly all of its insulation properties over the lifetime of the concrete slab compared to the following insulations which lose up to half of their insulation value in as little as 2 years!

XPS/SM Board

The pink/blue boards are taped together which does not provide an adequate seal between the panels. The PEX tubing is then tied to wire mesh over the insulation. Although this is the most common method in the past, it is not ideal for keeping the PEX tubing in place during the concrete pour. This also adds excessive labour costs with the added steps required to fasten the tubing while also leaving the tubing open to possible damage or rupture before the floor is poured.

This form of insulation is prone to breaking/cracking when walked on reducing its effectiveness. Another important reason to avoid the use of the XPS boards is its inability to hold it’s R-value over time. The gas used in the production of the xps insulation off-gases over time allowing moisture to work its way in to the insulation. This results in continually increasing heating bills as the thermal break below your concrete slab deteriorates annually allowing moisture to replace the gas that escapes from the insulation. This XPS vs EPS Long Term study illustrates just how drastic the two insulation types perform over time while the video visually illustrates the same outcome.

Garage Door Cut-outs

Old doors and garage door cut-outs also circulate as an option for in-floor insulation which is advertised as a low cost alternative. They are, however, not designed for in-floor heating and are the least expensive option for a reason.

This insulation is a type of polyurethane spray foam and the panels cannot be sufficiently sealed together which allows for moisture to easily enter the polyurethane and begin to turn the insulation in to a wet sponge. This results in the loss of R-value and draws heat away from your concrete slab resulting in your heating costs to continually increase.

Polyurethane Foam

Although an effective form of insulation for walls and roofs, this option is not well suited for below-grade insulation.

Polyurethane has similar downfalls to the XPS board and struggles further as water and moisture are trapped in the foam which greatly reduces it’s R-value (EPS vs Polyurethane).

It is also difficult to determine the PSI of the foam as it is manually sprayed resulting in varying thicknesses throughout the concrete slab. Not only is this an ineffective insulator, but it is also the most expensive option when looking to insulate your in floor heating project.

Polytarp Insulation

This method consists of a thin poly-film, sometimes in conjunction with a 3/8″ layer of EPS foam which together provide very minimal insulation resulting in a weak thermal break below your heated concrete slab. The tarp and foam act as a great moisture barrier however, they do not offer the structural stability to hold and protect the PEX tubing and can also trap moisture in the insulation due to the location of the tarp.

The tarp provides minimal insulation (usually less than R-2) to satisfy the highly important R-value required so that your money spent on heating does not simply pass into the ground below the tarp. This results in your heater consistently running as heat escapes below your heated concrete slab. Remember, “Hot Air Rises, but Heat Goes to the Cold”.