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Michael,

Continuous air barrier is defined in the IECC as: “A combination o=
f materials and assemblies that restrict or prevent the passage of air thro=
ugh the building thermal envelope.”

An air barrier is a material or assembly of materials that blocks the mo=
vement of air through a building’s envelope (walls, floors, ceilings, doors=
, windows, and foundation (for moisture),) drywall, acoustic tile, insulate=
d glass, vapor barrier, roofing felt, and other interior or exterior finish=
ing materials will also behave as an air barrier.

This helps improve energy efficiency, control moisture, and enhance indo=
or air quality.

Insulation, on the other hand, primarily deals with thermal resistance a=
nd preventing the transfer of heat (such as…R-13, R-19 or R-30 (wher=
e applicable).)

2018 IECC, Section C-402, suggests that the insulation should be install=
ed in a way that doesn’t compromise the effectiveness of the air barrier. T=
his would mean ensuring that there are no gaps or voids around the insulati=
on that could allow air to pass through.

We may say that the drop ceiling and or soffit must be airtight (such as=
using caulking to seal all joints) to qualify as an air barrier, whereas t=
he insulation must be installed directly against the surface of the air bar=
rier.

In general, the air barrier must be continuous, with any seams around wi=
ndows, doors, and other penetrations properly sealed and flashed. The goal =
is to deny the outside or inside air from entering insulated spaces (such a=
s attics, ceiling, soffits, and of course walls’ cavities.)

Any seams between sheets of material, or joints between one material and=
another, or holes around pipes, lighting fixtures or power outlet boxes mu=
st be sealed with a long-lasting air-sealing material for the air barrier t=
o be continuous.

Thanks!

On 2023-08-14 09:40, Michael Riehm wrote:

Allen: