ThermalSheet Insulating Underlayment (2’ x 3’) - 6 Sq. Ft. - 1 Sheet
- Single 2' x 3' sheet of synthetic cork insulating underlayment that functions as a thermal break
- Heat and cold resistant, and will not rot, support mold and mildew, or absorb moisture
- ThermalSheet has a 1.5 R-value, and it offers crack isolation of up to 1/4”
- This lightweight insulating underlayment will increase the energy efficiency of your floor heating system
- Can be used under a wide range of floor coverings like tile, stone, LVT, and laminate and can be used over any acceptable subfloor
Notices
Quebec Repairability Notice
Avis important pour les consommateurs du Québec:
WarmlyYours n’offre pas de services de réparation pour ce produit. Les seules pièces de rechange disponibles sont les kits de raccordement (splice kits) ; l’élément chauffant lui-même n’est pas offert comme pièce de rechange. Si votre système de chauffage par le sol intérieur tombe en panne pendant la période de garantie, nous remplacerons l’unité complète conformément à notre politique de garantie. Notre équipe d’assistance technique est disponible 24h/24 et 7j/7 par téléphone pour toute aide à l’installation ou au dépannage. Pour plus de détails, consultez notre politique de retour. Cet avis est fourni conformément à la Loi sur la protection du consommateur du Québec, article 39 (telle qu’amendée en 2025).
Important Notice for Québec Consumers:
WarmlyYours does not provide repair services for this product. The only replacement parts available are splice kits; the heating element itself is not available as a replacement part. If your indoor floor heating system fails within the warranty period, we will replace the entire unit according to our warranty policy. Our technical support team is available 24/7 by phone for installation and troubleshooting assistance. For full details, see our Return Policy. This notice is provided in accordance with Québec’s Consumer Protection Act, section 39 (as amended in 2025).
ThermalSheet Insulating Underlayment Description
ThermalSheet is a synthetic cork underlayment that is installed on top of a subfloor and below a heating element. It is recommended when installing an electric floor heating system over a concrete slab to prevent heat loss. By creating a thermal break, the heat is prevented from sinking into the concrete, and more heat radiates into the floor covering and room. In addition to preventing unnecessary heat loss, ThermalSheet provides sound dampening benefits and double the crack isolation benefits when compared to cork.
ThermalSheet is lightweight—up to 25 times lighter than traditional 1/4" backer board. This product is a 6 mm (less than 1/4 in.) thick, synthetic cork underlayment that can be installed with modified thinset and is specifically designed for setting tile and stone. It is an excellent insulation choice under our TempZone™ or Environ™ electric radiant floor-heating products. It’s a very resilient underlayment with compressive strength of 41 psi at 25% strain, 54 psi at 50% strain, and 110 psi at 75% strain. ThermalSheet has been rated for residential use according to the Robinson Test.
This item is a 2' x 3' (6 sq. ft.) single sheet.
Specifications
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 |
Product Dimensions
| Coverage | 6 ft² |
| Depth | 0.2362″ |
| Length | 36″ |
| Weight | 0.4 lbs |
| Width | 24″ |
Identifiers
| SKU | TS-SH6MM-24x36 |
| UPC (GTIN-12) | 881308077037 |
Warranty / Certifications
| TCNA Robinson test | Residential |
| Warranty | 5 years |
Documents
Installation
- ThermalSheet Insulating Underlayment Installation Instructions (English)
- ThermalSheet Insulating Underlayment Installation Instructions (Spanish)
Technical Information
Sell Sheets
Frequently Asked Questions
Showing all 5 questions
Typically, an uncoupling membrane like Prodeso will be best for this application because it can be paired with accessories to effectively waterproof the subfloor.
However, if you have a cement subfloor, then ThermalSheet synthetic cork is a good choice because of its high 1.5 R-value and moisture resistance.
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.
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.