Install Radiant Barrier under Rafters on preexisting construction

Directions to install Radiant Barrier rFOIL Series 4800 NT under rafters in a warm climate on a preexisting building

NT (No Tear) Radiant Barrier by rFOIL is quick, safe and easy to install.


Warm Climate Application

  1. Check the attic area and make any needed repairs before installing rFOIL NT Radiant Barrier.
  2. For easier installation, measure your attic dimensions and pre-cut the insulation as needed. Pre-cutting the material before entering the attic is safer, more comfortable, and will save time.
  3. Having a second helper is recommended, with one person unrolling the insulation, and the other person stapling.
  4. rFOIL should run perpendicular to the rafters, with a 2” overlap at the seams. Taping the seams is not required. Staple the material directly to the rafters at regular intervals (3-6”).
  5. Install the first row of radiant barrier along the bottom of the rafters, about 18” from the eaves. Be sure to avoid blocking any intended ventilation, if present.
  6. The adjacent row of insulation should start 46” above (diagonally) the previous row. This allows for a 2” overlap of the 48” radiant barrier material. The upper row should overlap the lower row on the ATTIC side.
  7. Wherever attic vents are present, leave a gap of at least 1”. rFOIL Radiant Barrier can be easily cut to work around any penetrations.
  8. At the roof peak, leave a 2-3” gap on both sides.
  9. At the gables, staple rFOIL Radiant Barrier directly to the studs, leaving at least a 1” gap around all vents.

Rfoil Radiant Barrier NT 4800P Series
Ruler, Staple Gun and Utility Knife.


  • Check local building codes for compliance before installation. This installation sheet is intended solely to illustrate the proper location and placement of rFOIL Reflective Insulation products in specific constructions applications.They are not intended to illustrate proper construction methods (which is ultimately the responsibility of the builder or contractor). The installation instructions are only recommendations relating to the location and placement of rFOIL Reflective Insulation products and rFOIL makes no claims that these construction systems are universally accurate
  • All warranties are void if rFOIL Reflective Insulation products are used in exterior applications, or in non-enclosed systems or buildings.
  • Exercise caution when using rFOIL Reflective Insulation products near and around electrical wiring and devices. Click here to see full instruction sheet.