Insulating Below the Purlin - New Roof for Post Frame Building and Pole Barn

Insulation Below Purlin - New Metal Roof Application

Installation Instructions

  • After the trusses are set, run two purlins to make sure the trusses stay true.

  • Attach the InfraStop® double bubble product to the purlins with at least 5/16” staples. Temporarily nail a 2” x 4” block over the end of the product at the starting edge to prevent it from pulling away.

  • Roll out the product across the top of the trusses, pull tight and staple.

  • Tape the seams with InfraStop® Foil Tape (goal is an air-tight, snug seam seal).

  • Install purlins over the insulation. Nail or screw to the trusses through the product.

  • Install the metal roof to the purlins.

Standard Size Rolls for Barns: Square Edge and Staple Tab

Custom Size Rolls for Barns: Square Edge

Thermal Insulation

Metal Interior - R-11 Heat Flow Down (and a Radiant Barrier) | R-5.1 Heat Flow Up

Open Interior - R-9.0* Heat Flow Down (and a Radiant Barrier) | R-4.4* 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 1.32 UP and 4.55 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

  • White One Side Post Frame Pole Barn Insulation Category
  • Post Frame Pole Barn Insulation Main Page

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