Product: Reflective Both Sides

Post Frame Building – Roof – Retrofit – Bottom of Truss

Bottom of the Trusses
Open Interior
R-10* Heat Flow Down (and a Radiant Barrier) | R-3.7* Heat Flow Up

Please Note: In addition to the stated R-value, this application also provides a Radiant Barrier. As a result, a 96% reduction of the radiant energy that ordinarily would be transmitted to the interior of the building is blocked.

* Includes thermal resistance of 1.32 UP and 4.55 DOWN for interior air film.

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

Reflectix® Insulation products are a group of technologically advanced materials. They are ideal for new construction or retrofit applications in commercial, industrial, metal and post/frame buildings, along with many other DIY applications. When you think of insulation, you should think of Reflectix®. Our products are recognized for their thermal performance, easy installation, versatility and price.

Recommended Products

Double Reflective Insulation

Staple Tab, Reflective/Bubble/Bubble/Reflective – Roll

  • ST24100 (24” x 100’)
  • ST48100 (48” x 100’)


  • Easy to handle and install
  • Convenient roll sizes
  • Class A / Class 1 Fire Rating
  • Inhibits dew point condensation
  • Vapor retarder (0.02 perms)
  • Does not compress, collapse or disintegrate
  • Non-toxic / non-carcinogenic

Installation Instructions

Installation Instruction pdf: PFB2 Roof Retro – Btm of Truss Revised 012021

  • Pre-installation inspection – Check the roof area for clutter, water sprinklers, conduit and lights. Sprinkler systems are especially important. All water pipes must be below the Reflectix® Reflective/Bubble/Bubble/Reflective Foil, Staple Tab product to prevent the possibility of freezing in the winter.
  • Nail 1”x 2” furring strips on the bottom of and perpendicular to the trusses on 22” centers. (Note: When truss spacing is 24” it is recommended to install the Reflectix® 24” or 48” product directly to the bottom cord of the truss.)
  • Butt the furring strips together and tape. Staple tape for reinforcement.
  • Attach the product using 5/16” staples at approximately 4” intervals.
  • Staple the edges of the Reflectix® to the furring strips with the 3/4” tabs (so that they will overlap at the seam).
  • Tape the seams with a Reflectix® Foil Tape (goal is an air-tight, snug seam seal).
  • Tape any butt seams with Reflectix® Foil Tape, insure taped seam has a good full continuous bond.
  • Staple product down the middle of the sheet into the furring strip above.

* Includes thermal resistance of 1.32 UP and 4.55 DOWN for interior air film.

Calculation Disclaimer: All values are calculated based on the “ASHRAE Handbook of Fundamentals” heat flow up and down.


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. Double Reflective Insulation, 2. Double Reflective Insulation with Staple Tab