Insulating Below the Purlin - White Interior - Existing Roof for Post Frame Building and Pole Barn

Insulation Bottom of Purlin - White Interior - Existing Metal Roof Application

Installation Instructions

  • The InfraStop® insulation is installed with the "white side" towards the interior of the building.

  • Inspect the roof area for clutter in buildings where there is no ceiling.

  • Measure the distance between the trusses. Many times, the distance will be 4' or less. In some geographical areas, due to snow load, the distance will be as close as 2'"

  • Cut pieces of the InfraStop® Reflective Double Bubble insulation, 6" longer than the distance between the ridge pole and the bird's mouth."

  • Staple the product to the bottom of the purlins with 5/16" staples, 3" to 4" apart. Turn the edges down and staple to the side of the top cord of the trusses."

  • Staple the top of the insulation to the ridge pole and the bottom to the top plate at the wall.

  • Tape any butt seams with InfraStop® Foil Tape. Make sure the tape is applied so that a proper bond occurs.

Standard Size Rolls for Barns: Square Edge and Staple Tab

Custom Size Rolls for Barns: Square Edge

Thermal Insulation

Open Interior - R-6.4* 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 94% + reduction of the radiant energy that ordinarily would be transmitted to the interior of the building is blocked.

*Includes thermal resistance of 0.61 UP and 0.92 DOWN for interior air film.

Product Information

InfraStop® 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 InfraStop®. Our products are recognized for their thermal performance, easy installation, versatility, price and environmental friendliness.


  • 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

Testing and Certification

InfraStop® 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. For a copy of an actual test report, please e-mail us at

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