Do You Have to Remove Everything First?
Not always.
Building Science guidance allows blown insulation to be added over existing attic-floor insulation when the attic is otherwise suitable and the work is properly prepared.
But:
Don’t bury a problem.
Inspect the Existing Material
Before adding insulation, check for:
- Moisture
- Mould
- Animal contamination
- Roof leaks
- Compressed areas
- Blocked ventilation
Natural Resources Canada advises correcting moisture and condensation issues before adding insulation.
Air-Seal First
Adding insulation does not automatically stop air leakage.
Building Science guidance recommends sealing attic-floor penetrations before installing the new insulation layer.
Keep Ventilation Clear
Baffles and soffit ventilation should remain open.
Do not bury intake vents with loose fill.
When Might Removal Be Necessary?
Existing material may need removal when it is:
- Wet
- Contaminated
- Damaged
- Interfering with another required repair
Keep Good Insulation. Correct Bad Conditions Before Covering Them.
Envirotech Exteriors can inspect the attic first and determine whether the existing insulation can remain as part of a properly prepared top-up.