Perforated Radiant Barrier (vs. Non-Perforated Solid Vapor Barrier)
When installing a radiant barrier over the attic
floor, over existing insulation in place or not, you MUST use a perforated
radiant barrier. This is because moisture-laden air generated in
your home from breathing, washing clothes, bathing, running the dishwasher,
etc travels upwards and must be able to pass through the radiant barrier to
escape your attic. If a solid radiant barrier were used in this location,
it would trap the moisture in the air and condensate resulting in water droplets
that would drip onto your insulation/attic floor and rafters causing damage.
Ultima radiant barrier
comes in both a perforated (breathable) and solid (vapor barrier) version. Our RadiantGUARD®
bubble insulation products are
only available in a solid (vapor barrier) version.
Breathable vs. Solid vapor barrier (VB)
As a general rule of thumb, a breathable perforated
radiant barrier should be used when the product is installed in an area
that has air movement such as in an attic or as a house wrap on the
A solid vapor barrier product (radiant barrier or
reflective bubble insulation) is typically used in the northern climate
zones on the interior wall side. Another use for solid vapor
barriers is when installed in stucco structures or in high hydrostatic
pressure areas along the southern US coast.
For most all steel / metal buildings, a reflective
bubble insulation vapor barrier is recommended to help control
condensation which is a typical issue with these structures.
If you are unsure about what version to use, we
highly recommend you contact your local building code department for
For more information regarding
vapor barriers, please visit the following