Radiant Floor – Over an Existing Floor


Note: Installation instructions and illustrated drawings are recommendations only, while proper local construction methods are the responsibility of the installer.

Reflectix® has an insulating upgrade available for a radiant floor system installed over an existing floor; our specially designed Concrete Slab Insulation. The unique characteristics of this product contribute to energy savings along with a more even floor surface temperature. The bonus characteristic to this product is how easy it is to handle and install.

Recommended Products

Concrete Slab Insulation

Concrete Slab Insulation, White/Reflective/Bubble/Bubble – Roll

  • DBWEF48050 (48” x 50’)
  • DBWEF48100 (48” x 100’)
  • DBWEF48125 (48” x 125’)


  • R-1.1
  • Promotes even heat distribution
  • Increases system efficiency
  • Reduces annual energy costs of the system
  • Installs quickly and easily
  • Non-toxic / non-carcinogenic
  • Vapor retarder

Installation Instructions

Installation Instruction pdf: PRO Rad Fl Over Existing Floor Revised 022024

Note: Installation instructions and illustrated drawings are recommendations only, while proper local construction methods are the responsibility of the installer.

  • Unroll the Reflectix® Concrete Slab Insulation over the existing floor prior to pouring the concrete (white poly side facing up). Cut product flush with the walls.
  • Butt the seams of the product and seal with 3” wide poly tape. Note: Utilize a flat edge taping tool to assure good adhesion on all tape.
  • Install Radiant Floor System per manufacturer’s specifications.


Review These Important Safety Guidelines Prior to Installation:

  • ALWAYS check local building codes before installing Reflectix®.
  • ALWAYS check the area you are insulating and make any needed repairs. Any worn wiring should be replaced before you begin installing Reflectix®.
  • ALWAYS make sure work areas are well ventilated and well lighted.
  • ALWAYS use eye protection when operating a staple gun.
  • ALWAYS use caution and common sense when using a staple gun. Be aware of electrical wiring locations. Stapling into a wire can cause severe shock or death. NEVER staple into electrical wiring.
  • ALWAYS be careful when working with large pieces of Reflectix® on windy days.
  • When installing Reflectix® on bright sunny days, it is best to wear sun glasses.
  • Do not work in areas such as attics when temperatures are too hot.
  • Please Note: The intention of these Installation Instructions and 3-D renderings are for the sole purpose of illustrating the correct location and relative position of the Reflectix® products in specific building assemblies. The correct construction methods and techniques are the responsibility of the installer or contractor. The methods outlined are recommendations on location of the Reflectix® products as a guideline. There are no claims on the part of Reflectix, Inc. that these building assemblies are finite standards or meet building code requirements (as they can vary by region).

Testing and Certification

Reflectix® products are thoroughly tested at either nationally approved, independent laboratories or leading universities. Tests are performed to current American Society of Testing and Materials (ASTM) standards when a standard exists. To obtain a copy of our Product Testing Specifications, please refer to the “Additional Resources” tab. The documents are also available by e-mail at or call (800) 879-3645.


Pictured: 1. Concrete Slab Insulation, 2. Product Close-up