You've paid for more attic insulation, so a deeper blanket looks like good news. The awkward bit is right out at the eaves, where that same insulation can block the air route you're trying to preserve.

In a vented attic, the insulation and the incoming air need room to do different jobs. Piling one into the other's route is not an upgrade.

What a baffle actually does

A baffle maintains a passage near the eaves between the insulation and the underside of the roof. Natural Resources Canada's attic guidance describes preserving ventilation openings and keeping insulation from spreading over vented soffits.

The important word is passage. We've opened up an eave where the new baffle looked fine from the hatch, but old insulation was still packed across its lower end. The installer had added a channel without clearing its entrance. Before the top-up, we had the intake checked and the obstruction resolved. Ask for a photo of that junction, not just a row of tidy channels farther up the roof.

Separate the roof-side and room-side work

Ventilation concerns the intended outdoor air route through a vented attic. Air sealing concerns leaks from the house into that attic. NRCan's air-leakage guide addresses those ceiling penetrations and connections.

A new baffle does not seal a leaky hatch or a plumbing penetration. More insulation does not establish that the air barrier beneath it is continuous. We separate that preparation from the blowing work in the scope: what gets sealed, what stays clear, and what gets photographed. Otherwise the quickest part of the job can bury the unfinished part.

Ask for evidence before the top-up

  • Photos showing representative eave conditions and the actual intake route.
  • Identification of blocked, missing, or damaged channels where relevant.
  • The proposed baffle and insulation detail at the roof edge.
  • Air-sealing work needed before the new insulation hides access.
  • Confirmation that exhaust ducts terminate outdoors rather than in the attic.

Request photographs from the installer instead of entering a cramped attic yourself. Ceiling finishes are not a safe walking surface, and access can expose wiring or other hazards.

Do not redesign the attic from one photograph

Some roofs use an unvented assembly or have construction details that need a different approach. Establish the intended roof design before adding vents or cutting openings.

Before the installer packs up, ask to see the eave photos and the completed preparation list. You should be able to point to the clear air route and understand what was sealed below the insulation. From the hatch, a finished top-up can look much the same whether those details were handled or buried.