Glossary · Insulation & windows
Soffit vent and baffle
Also called: soffit vent · soffit vents · baffle · baffles · rafter vents · insulation baffles
Soffit vents let outside air into the attic at the eaves, and baffles keep insulation from blocking that airflow.
What it means
Most pitched attics are ventilated: air enters through vents in the soffit (the underside of the roof overhang) and leaves through roof or ridge vents. Baffles fixed between the rafters hold insulation back from the eaves so air can still flow, and insulation stops keep loose-fill from spilling into the soffits. NRCan advises against powered attic fans, which can pull house air into the attic.
Why it matters in an audit
Adding insulation without baffles can block ventilation and trap moisture in the attic, so audits check for them.
Typical numbers
Reference values with their sources. Your energy advisor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| NRCan attic ventilation guidance | About 50% of vent openings at the soffits; total unobstructed vent area about 1:300 of insulated ceiling area (pitched roofs with accessible attics) | natural-resources.canada.ca ↗ |