Insulation is the most invisible upgrade in a home — and one of the most consequential. Done correctly, it reduces heating and cooling costs for decades, improves comfort, and qualifies for significant government rebates. Done incorrectly, it can trap moisture in wall cavities causing mold and rot, create ice damming on the roof, block soffit ventilation, or install the wrong product in the wrong application — all of which are invisible until the damage is done.
It’s also a trade where the quality range is enormous. A contractor who installs attic insulation to the correct depth, maintains proper clearances, seals air leaks before adding insulation, and preserves soffit ventilation delivers a result that lasts for decades. One who simply blows material in without addressing air sealing, blocks vents, or installs spray foam at inadequate thickness delivers a result that may actually create new problems.
The questions in this guide apply whether you’re hiring for attic insulation top-up, basement insulation, wall insulation, spray foam for air sealing, or a full home re-insulation project.
“The most important thing I tell homeowners is that insulation and air sealing are different things — and both matter. You can have the right R-value of insulation in the attic and still lose enormous amounts of heat through air leaks at penetrations, around pot lights, at the attic hatch. Air sealing first, then insulation on top, is the correct sequence. A contractor who adds insulation without addressing air leaks is doing half the job.”
— Amarildo from Absolute Spray Foam Insulation, spray foam insulation specialist with over 20 years of experience providing residential and commercial insulation solutions across Toronto and the GTA with a focus on energy efficiency, code-compliant installation, and long-term performance
Table of Contents
Before You Call Anyone
What type of insulation work do you need?
Attic insulation (top-up or new): The highest-return insulation upgrade in most local homes. Attics are frequently under-insulated relative to current recommendations. Adding insulation here is typically straightforward and cost-effective.
Basement insulation: Insulating basement walls (from inside or outside) and/or the basement ceiling (the floor above). Different strategies depending on whether the basement is conditioned, semi-conditioned, or unconditioned.
Wall insulation: Typically done during renovation when walls are open, or by injection of dense-pack cellulose or foam into closed walls. Harder to retrofit than attic insulation.
Air sealing: Sealing gaps, penetrations, and bypasses that allow conditioned air to escape and unconditioned air to enter. Often combined with insulation work and sometimes the more important of the two.
Spray foam: A two-component liquid that expands and cures to create a rigid, airtight insulation layer. Used for air sealing, rim joists, cathedral ceilings, and specialty applications.
Crawlspace insulation: A distinct application with specific moisture management requirements.
Have you had a home energy audit?
A professional home energy audit — performed by a certified energy advisor using blower door testing and thermal imaging — identifies exactly where the home is losing energy, what the most cost-effective improvements are, and which improvements qualify for government rebates. An energy audit before insulation work gives you an objective basis for what to do and in what order.
In many regions, a national energy-efficiency rebate program and your gas utility’s efficiency rebate program program both require a pre-upgrade energy audit to qualify for rebates. Ask whether the contractor works with certified energy advisors and whether audit costs are rebatable.
For more: Questions to Ask About Home Energy Audits and Rebates
Questions to Ask Before Hiring
Is your company a registered business with insurance and workers’ compensation coverage?
Insulation work in attics and crawlspaces involves confined space entry, working at heights on rafters, and in some cases handling spray foam chemicals with specific safety requirements. Liability insurance is essential. Workers’ compensation coverage covers workers if injured.
Ask for a certificate of insurance and a workers’ compensation coverage Clearance Certificate and verify both.
Are you certified for the type of insulation you’re installing?
Different insulation products and applications have specific certification requirements:
Spray polyurethane foam (SPF): Spray foam applicators should hold certification from the Canadian Urethane Foam Contractors Association (CUFCA) or have training from the foam manufacturer. Spray foam involves chemical hazards and requires proper PPE and ventilation. Uncertified applicators are a safety risk to themselves and can create health hazards for occupants.
General insulation: The Insulation Association of your country (IAC) and regional associations provide training and certification programs. Ask whether the company holds any industry certifications.
Energy advisor partnership: For rebate-eligible work, ask whether the contractor coordinates with a certified energy advisor for pre and post-upgrade audits.
What a good answer looks like: Specific certifications named, with verification information provided.
Do you perform air sealing alongside insulation installation?
This is one of the most important questions to ask any insulation contractor. Air sealing and insulation work together — insulation slows heat transfer through conduction; air sealing prevents heat loss through convection (air movement). A home with excellent insulation but poor air sealing still loses significant energy through gaps and penetrations.
Ask specifically: do you include air sealing as part of your insulation scope, and what air sealing work is included in this quote?
What a good answer looks like: A described air sealing scope — specific locations to be sealed (attic hatch, around penetrations, at pot lights, at the top plates) — not just a general statement that “we seal as we go.”
For more: Questions to Ask an Insulation Contractor About Air Sealing
Questions About Attic Insulation
What R-value are you targeting, and is that appropriate for your region?
R-value measures thermal resistance — higher R-value means better insulation performance. Natural Resources your country recommends:
Attic insulation in many regions: R-50 to R-60 for climate zones covering most regions. Many older homes have R-12 to R-20 in the attic — significantly below current recommendations.
Ask specifically what R-value will be achieved after the work is complete, and confirm it meets or exceeds current recommendations for your climate zone.
What a good answer looks like: A specific target R-value stated, with the existing R-value also assessed so you know the net improvement.
Will soffit ventilation be maintained?
Attic insulation must not block the soffit vents (the ventilation openings under the eaves). Blocked soffits reduce attic ventilation, which can cause moisture buildup, ice damming, and premature roof deterioration. Baffles (also called rafter vents or vented channels) should be installed at each rafter bay between the attic floor and the soffit to maintain a clear ventilation channel.
Ask specifically whether baffles will be installed to protect soffit ventilation.
What a good answer looks like: Baffles installed at each rafter bay as standard, confirmed in writing.
Will the attic hatch be insulated and air-sealed?
The attic hatch is one of the most significant thermal bypasses in an attic — a thin, uninsulated door opening directly between conditioned and unconditioned space. Ask whether the hatch will be insulated (with a rigid insulation cover or insulated box built around it) and air-sealed.
For more: Questions to Ask an Insulation Contractor About Attic Insulation
Questions About Spray Foam
What type of spray foam is being used — open-cell or closed-cell?
Open-cell spray foam: Lower density, softer, more vapor-permeable. Lower R-value per inch (approximately R-3.7/inch). More affordable. Appropriate for interior air sealing applications where vapor permeability is desired. Not appropriate for below-grade or exterior applications.
Closed-cell spray foam: Higher density, rigid, vapor-impermeable. Higher R-value per inch (approximately R-6–7/inch). Also functions as a vapor barrier and air barrier. Appropriate for rim joists, cathedral ceilings, below-grade applications. More expensive. Required where both insulation and vapor control are needed.
Ask which type is being proposed and why it’s appropriate for the specific application.
What thickness will be installed?
Spray foam must be installed at adequate thickness to achieve the target R-value. For closed-cell foam targeting R-20, approximately 3 inches is required. Ask what target R-value and what thickness is being installed.
For more: Questions to Ask an Insulation Contractor About Spray Foam
Red Flags to Watch For
No mention of air sealing. A contractor who proposes adding insulation without discussing air sealing is doing incomplete work. Air sealing is not optional — it’s typically more impactful than additional insulation in many homes.
No mention of soffit ventilation protection for attic work. Blocked soffits cause real damage. A contractor who doesn’t mention baffles for attic insulation is not thinking about the system.
Unable to specify the R-value being achieved. A professional insulation contractor knows exactly what R-value they’re installing and what R-value the finished assembly will achieve.
Spray foam applied by uncertified applicators. Spray foam involves chemical hazards. Uncertified applicators are a quality and safety risk.
Quote provided without any assessment of current conditions. A proper insulation quote requires knowing the existing insulation level, the air sealing condition, and the specific configuration of the attic or space being insulated. A price quoted without visiting the site is guesswork.
For a full guide: Red Flags When Hiring an Insulation Contractor
Before They Start: A Quick Checklist
- Business registration and insurance verified
- Workers’ compensation coverage clearance verified
- Spray foam certifications confirmed (if applicable)
- Air sealing scope agreed and in writing
- Target R-value confirmed in writing
- Soffit ventilation protection (baffles) confirmed for attic work
- Attic hatch insulation and sealing confirmed
- Energy audit coordination confirmed (for rebate-eligible work)
- Payment schedule agreed
Related Questions
- Questions to Ask an Insulation Contractor About Attic Insulation
- Questions to Ask an Insulation Contractor About Air Sealing
- Questions to Ask an Insulation Contractor About Spray Foam
- Questions to Ask About Home Energy Audits and Rebates
- What R-Value Do I Need for My Home?
- How Much Does Insulation Cost ?
- Red Flags When Hiring an Insulation Contractor
- What to Do If an Insulation Contractor Does Bad Work
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