Radiant Barrier Attic Rafters

A control study was published in 2013 showing the radiant barrier effectiveness of paint foil backed sheathing and foil that was stapled onto the rafters.

Radiant barrier attic rafters.

Attics heat up when the sun s radiant energy heats the shingles and the heat is transferred to the interior attic space through the roofing materials via conduction. A radiant barrier under the rafters will keep more heat in the roofing and hence somewhat reduce the lifespan of the shingles and it will limit drying to the interior should there be a roof leak that saturates the sheathing unless the rafters are vented from bottom to top. Radiant barrier installation attic radiant barrier installation most of the heat entering a home comes through the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces including the air ducts and the attic floor.

When a good radiant barrier is employed under the attic rafters directly before the sheathing decking new construction or along the bottom of the rafters preexisting construction a majority of the heat is reflected back through the roof and never enters the attic at all. Radiant barrier applied either under the roof rafters or under the roof sheathing is probably the most common application of a radiant barrier but many homeowners shy away from it because they don t fully understand what radiant barrier is or how it works. A radiant barrier combo installs radiant barrier on the attic rafters attic floor over your existing insulation and or attic floor plywood decking exterior facing vertical walls and interior facing vertical walls. A radiant barrier works best when it is perpendicular to the radiant energy striking it.

Radiant barrier paint performed the worse providing a heat decrease in the conditioned space of around 19. Radiant barriers are utilized to reduce summer heat gain in attics. For really high roofs you should consider doing a flat top installation for radiant barrier for tall attics. A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.

So you would order 2 500 sq ft of atticfoil to cover an area this size. A radiant barrier applied horizontally over the attic floor insulation is the more popular application for existing homes in cool climates. The results were very telling. Attic area of 55 x 35 1925 sq ft x 1 3 for a medium pitch roof about 8 9ft high at peak 2 503 sq ft.