Homeowners often ask:
“How many inches of insulation should I have?”
That sounds simple.
But thickness alone is not the correct measurement.
Different insulation materials provide different amounts of thermal resistance.
The better number to understand is:
R-value.
Natural Resources Canada defines R-value as a measure of a material’s resistance to heat flow. Higher R-values indicate greater resistance.
Why Can’t You Just Measure Inches?
Different insulation products have different R-values per inch.
Natural Resources Canada publishes thermal-resistance ranges for materials including:
- Fibreglass
- Mineral fibre
- Foam products
- Other insulation types
That means 12 inches of one product may not equal 12 inches of another.
How Much Does an Ontario Attic Need?
There is not one number for every home.
Requirements and practical retrofit targets depend on:
- Climate zone
- Existing insulation
- House construction
- Local building requirements
- Available attic space
- Retrofit goals
Natural Resources Canada’s climate-zone guidance shows roof and ceiling insulation recommendations increasing in colder regions, with guideline values ranging from approximately R-45 upward depending on climate zone.
A contractor should evaluate your actual home rather than simply advertising:
“Everyone needs R-60.”
Why Does Existing Insulation Matter?
Suppose your attic already has insulation.
Before adding more, determine:
- What type is present?
- How much?
- Is it dry?
- Is it evenly distributed?
- Has it settled?
- Are soffit vents blocked?
- Are there air leaks?
Adding new insulation over a moisture problem is not an upgrade.
It hides the evidence.
Air Sealing Matters Too
Insulation slows heat transfer through materials.
Air sealing controls unwanted movement of indoor air into the attic.
Natural Resources Canada stresses that attic insulation and air sealing should be considered together.
Common leakage locations may include:
- Attic hatches
- Wiring penetrations
- Plumbing openings
- Ceiling fixtures
Don’t Block Soffit Ventilation
More insulation is not better if it interferes with the attic’s intended ventilation path.
The eaves should be assessed to ensure insulation is not blocking required airflow.
Why Blown-In Insulation?
Blown-in insulation can provide broad coverage across existing attic spaces, including irregular areas where batt insulation may be harder to fit consistently.
Envirotech currently provides blown-in attic insulation in Burlington, Hamilton, and Niagara.
Questions to Ask Before an Attic Top-Up
- What is my current R-value?
- What insulation is already installed?
- Is there evidence of moisture?
- Are air leaks being addressed?
- Are soffit vents clear?
- What target R-value is being recommended?
- Why is that number appropriate for this house?
Don’t Buy Insulation by the Inch. Understand the Thermal Performance.
Not sure how much insulation your attic actually has? Request an attic insulation assessment from Envirotech Exteriors.