THE SHORT ANSWER
Insulation slows heat flow; air sealing controls unintended airflow.
An attic can have substantial insulation and still allow air movement through gaps around the hatch, ceiling penetrations, wall-top transitions and service openings. Accessible leakage paths may be sealed before additional insulation makes them harder to reach.
Air sealing should be planned around the actual components and safe working conditions. It is not a promise to eliminate every draft in the home.
WHEN TO LOOK CLOSER
When air sealing may be discussed
- Before an attic insulation top-up
- After old insulation is removed
- Around an accessible attic hatch or curb
- At suitable ceiling and service penetrations
- Where visible leakage paths connect to the living space
- When warm indoor air may be reaching cold attic surfaces
WHAT MAY BE CHECKED
What affects the sealing scope
- Accessibility beneath existing insulation
- Type and size of the gap or penetration
- Electrical, exhaust, chimney or heat-producing components
- Required clearances and approved materials
- Continuity of the existing air barrier
- Other draft sources outside the attic
- Whether diagnostic testing is actually included
OPTIONS AND CONSIDERATIONS
Common areas considered during attic work
Attic hatch
The lid, frame and surrounding curb can be reviewed for insulation, gaskets and suitable seals.
Ceiling penetrations
Accessible service openings may create leakage paths that need an appropriate treatment.
Transitions and edges
Wall-top and assembly transitions may be visible when the attic floor is accessible.
A DEFINED PROCESS
How the work is planned
Identify accessible leakage paths
Review the hatch, penetrations and visible attic-floor transitions included in the scope.
Confirm safe materials and clearances
Select an appropriate treatment for the component and surrounding conditions.
Complete the agreed sealing
Address accessible approved areas before the attic floor is covered.
Proceed with insulation
Install the confirmed top-up or new coverage without undoing the completed sealing work.
IMPORTANT TO KNOW
Air sealing does not replace ventilation
The home’s air barrier and the attic’s intended ventilation perform different functions. Sealing uncontrolled leakage should not mean blocking intended attic airflow.
Natural Resources Canada recommends sealing attic air leaks and treating the attic hatch similarly to an exterior door. The exact scope must still be connected to the property.
CLEAR ANSWERS
Questions about this attic service
Does insulation already stop attic air leaks?
Not necessarily. Insulation resists heat flow but may allow air movement through or around it.
Can air sealing be completed without removing insulation?
Some accessible areas may be reached, while others can remain hidden. Removal may be discussed where the scope justifies it.
Will air sealing stop every draft?
No guarantee should be made. Drafts can also come from windows, doors, walls, ducts and other building areas.
Is the attic hatch important?
Yes. The hatch is a large interruption in the ceiling assembly and should be considered for insulation, gaskets and perimeter sealing where appropriate.
Do you include blower-door testing?
Whole-home blower-door testing is not included in a standard attic assessment unless it is separately stated in the written scope. An attic assessment is not a formal whole-home energy audit.
RELATED SERVICES
Build the right attic scope
Attic conditions often overlap. These pages explain the related work that may be discussed after the attic is assessed.
Attic Insulation Top-Ups
Explore the related service, what it addresses and when it may be considered.
Attic Ventilation
Explore the related service, what it addresses and when it may be considered.
Drafts & Attic Air Leaks
Explore the related service, what it addresses and when it may be considered.