ThermalSheet Insulating Underlayment (2’ x 3’) - 6 Sq. Ft. - 1 Sheet

Part Number: TS-SH6MM-24x36
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Common Support Questions (8)

Publications and Manuals (4)

Specifications (13)

Related Items (1)

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Common Support Questions

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.

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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.

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Any type of underlayment/padding may be used as long as it has a density of 6-8 pounds per cubic foot. Certain underlayment, such as ¼” (6mm) thick cork, or 6mm ThermalSheet are recommended for Environ™ Flex Rolls. It is also acceptable to place a vapor barrier, such as a plastic sheet, under the underlayment. Underlayment papers are not compatible with Environ™ Flex Rolls. Underlayment is necessary to prevent Environ™ Flex Rolls from damage from the weight of the floor, furniture, and people. Unavoidable wooden floor movements will not harm Environ™ Flex Rolls. Wooden floors expand and contract with temperature and moisture change. The wooden floor “moves” on top of Environ™ Flex Rolls. This movement will not damage Environ™ Flex Rolls when the installation is done correctly and the underside of the final floor covering is installed evenly. Some underlayment materials also have a noise reducing and insulating effect. When installing over concrete, a ¼” underlayment is mandatory. Any underlayment available in ¼” size is acceptable in most cases. ThermalSheet, cork, or ¼” to 3/8” of expanded polystyrene (EPS) with a density of 2 pounds per cubic foot or more, are recommended for installation under Environ™ Flex Rolls. When installing over a concrete slab, choose the underlayment with the highest R-Value.

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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.

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

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

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Yes, all pressure-sensitive adhesives are fine.

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Yes, ThermalSheet should be bonded to the subfloor with any high quality modified thin-set, or with a bond coat adhesive. Further installation information can be found in the installation manual. 

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Publications and Manuals


Insulation Specification

Acoustic testing on 6" slab, no ceiling IIC 52 wood construction. FIIC 59 - 7.5″ concrete slab. ΔIIC 20 - 6″ concrete slab
Compressive Strength 41 psi at 25% strain, 54 psi at 50% strain, and 110 psi at 75% strain
Material Expanded Polypropylene (EPP)
Thermal Insulation 1.5 R-Value


Country of Origin (COO) United States of America

Product Dimensions

Coverage 6 ft²
Depth 0.2362″
Length 36″
Width 24″


SKU TS-SH6MM-24x36
UPC (GTIN-12) 881308077037

Warranty / Certifications

TCNA Robinson test Residential
Warranty 5 years

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