Think about the source and the exit.
In winter, indoor air leaking into a cold roof space can deliver heat and moisture to the underside of the roof. Insulation reduces heat flow, but typical fibrous insulation does not form a continuous air barrier. Ventilation deals with the roof space; air sealing addresses air travelling from the home into it.1
These are connected tasks, but they should appear as distinct items in a proposal. Ask the assessor to explain the evidence for each one. A recommendation that says only “add ventilation” leaves important questions unanswered if the ceiling is leaky.
Describe the pattern before naming a repair.
Record whether a stain or frost patch appears after cold weather, during a thaw or after rain. Note the room below and any recent change, such as a bathroom renovation or new insulation. Ask whether the observed pattern supports a roof leak, indoor-air leakage, a duct problem or more than one cause.
For example, recurring frost near a bathroom deserves an assessment of the ceiling penetrations and exhaust route as well as the attic vents. This is a question to investigate, not a diagnosis made from the room name.
Ask what the air-sealing scope includes.
Have the contractor identify the accessible attic hatch, service penetrations, wall-top connections and other relevant ceiling details. The scope should explain the chosen materials, safe installation around services, access limitations and how continuity will be checked. Air sealing around heat-producing equipment and electrical components needs appropriate details; generic foam is not a universal solution.
Keep the work coordinated. If insulation will conceal the air barrier, ask for the relevant inspection and photographs before coverage. If an area cannot be reached, ask whether the quote includes another access method or leaves that area unresolved.
Keep ventilation and exhaust ducts distinct.
A bathroom or kitchen fan is part of the home's exhaust system. Its duct route and outdoor termination are separate from attic ventilation. Ask the assessor to trace the route, check connections and identify any visible condensation or damage. Do not assume that a nearby roof vent proves that the fan duct reaches outdoors.
Use a scope with clear responsibilities.
| Item | Request in writing |
|---|---|
| Assessment | What was inspected, evidence supporting the concern and inaccessible areas. |
| Air barrier | Locations to be sealed, relevant installation details and verification method. |
| Insulation | Proposed coverage, how eave paths are maintained and any excluded areas. |
| Ventilation | Intake, exhaust, connected paths, product free area and design basis. |
| Follow-up | Completion records and what happens if the original symptom returns. |
Use the proposal worksheet to compare this scope across quotes. A lower price can reflect a different amount of work; line up the responsibilities before comparing totals.
Primary references
1. Natural Resources Canada: Roofs and attics — air and moisture control, insulation and ventilation.
Building Science Corporation: Understanding Attic Ventilation — heat and moisture behaviour in roof assemblies.