ThermalSheet Insulating Underlayment Support

When installing electric floor heating over a concrete slab, an insulating underlayment like ThermalSheet is highly recommended to ensure efficient operation, faster heating times and warmer floor temperatures.

When WarmlyYours electric floor heating systems are being installed on a concrete slab, we strongly recommend adding a layer of insulation over the slab prior to installing the system. While our electric floor heating provides up to 25% more heating power per square foot than many of our competitors, the slab will always act as a "heat sink." Some of the heat that would otherwise be transferred to the flooring surface will remain in the slab, causing the floor’s surface temperature to be considerably lower. This is true with any electric radiant floor heating system.

When installed on top of a concrete slab without insulation, it is generally accepted that electric floor heating will take the chill away from the floor and provide a small amount of warmth. Adding insulation on top of the slab and beneath any electric radiant floor heating system will allow a greater percentage of the heat generated to transfer to the flooring surface. This results in greater efficiency and therefore faster warm up times, higher expected surface temperatures and lower energy usage. The floor will have the capacity to warm to a comfortable temperature, and in some cases can be employed as the primary heat source for that room.

The recommended types of insulation are natural cork, insulated tile backer boards and insulated underlayment, such as ThermalSheet™ synthetic cork.

WarmlyYours has recently begun including floor sensors with our heating elements to help ensure customers will have everything they need for optimal operation of their radiant heating systems.

The sensor included with your floor heating element can be installed with the heating system (the sensor is equally spaced between runs of the heating wire--see your install manual for more info). Installing this sensor with your floor heating control will enable energy efficient operation of the floor warming system based on the floor temperature instead of the ambient room temperature.

We generally recommend that you install a second, unconnected backup floor sensor alongside the primary one. In the very unlikely event that your first floor sensor is damaged, this install method will save you from having to pry up flooring to replace a floor sensor. You simply disconnect the damaged sensor from the thermostat and connect the backup sensor.

In addition to the floor sensor that was included with your heating element, our nSpiration Series thermostats also come with a floor sensor. If you purchase both a heating element and an nSpiration Series thermostat from WarmlyYours, you'll have a primary and a backup floor sensor for your system.

No, for the installation of an Environ heating system with a floating floor like laminate, it is not necessary to adhere the ThermalSheet underlayment to the subfloor. The underlayment should instead be allowed to float freely on the subfloor. Make sure to stagger adjacent sheets of underlayment and tape them together to prevent any overlaps, ensuring a flat and even layer beneath your flooring. This method helps accommodate the natural expansion and contraction of the floating floor.

Yes, the sensor wires may be trimmed.  Most local code requirements call for 6“-7“ of extra wire from the gang box.

Yes, unlike natural cork, ThermalSheet will not expand from self leveling cement (SLC).

A digital meter with a 0-200 Ohms scale ( Ω ) to measure the heating wire's resistance, and a 20K scale to measure the sensor's resistance.

ThermalSheet Insulating Underlayment is a synthetic cork, a lightweight thermal barrier made of hemi-crystalline thermoplastic.

WarmlyYours recommends ThermalSheet underlayment when installing a floor heating system over a concrete slab to prevent heat loss and protect against moisture. It will not rot, support mold and mildew, or absorb moisture.

- ThermalSheet synthetic cork underlayment (6mm) has a 1.5 R-value, crack isolation up to 1/4“, reduces sound by up to 22 dB, and is Robinson tested (TCNA) and rated for residential loads.

- Cork (6mm) has a .72 R-value, crack isolation up to 1/32“, reduces sound by up to 23 dB, and is Robinson tested (TCNA) and rated for residential loads.

No. Put a skim coat of SLC (Self-Leveling Cement), or even plywood over it first. Then, the vinyl flooring product can be installed.

Yes, all pressure-sensitive adhesives are fine.