Attic baffles are rigid channels, usually foam or cardboard, installed at the eave between the rafters to hold a clear air path from the soffit vents into the open attic. Without baffles, loose insulation can slump down and block the soffit intake entirely, choking off the airflow a ridge vent depends on. Baffles are inexpensive and simple to install, but they are also one of the most commonly skipped steps when attic insulation is added or upgraded.
Insulation and ventilation share the same space at the edge of the attic, right where the roof meets the outside wall, and without something to keep them apart, insulation tends to win.
Attic baffles are rigid, channel-shaped pieces, commonly foam or heavy cardboard, installed between the rafters right above the soffit. They hold a clear, unobstructed gap so air can travel from the soffit vent below up into the open attic above the insulation.
Without a baffle in place, loose-fill or batt insulation naturally settles or gets pushed down into that same space, and once it packs against the roof deck at the eave, it seals off the soffit vent from the inside just as effectively as if the vent were never cut.
That is a quiet failure, because the soffit vents still look open from outside the house while the airflow behind them is completely blocked. A ridge vent with no working intake air has nothing to draw on, and the whole ventilation system stalls.
Baffles are inexpensive and take only minutes to install per rafter bay, which makes them an easy thing to skip when insulation is blown in or added later without anyone specifically checking the eaves first.
For a homeowner, missing or crushed attic baffles are a common, invisible reason a roof with correctly built ridge and soffit vents still runs hot in summer.
Ask about them any time attic insulation work is done. Baffles are genuinely rarely visible without actually looking inside the attic itself first.
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