What Is an Air Barrier and Why It Matters

An air barrier is a critical component of every commercial building envelope. Its purpose is to control air leakage — the unintended movement of air through walls, roofs, and floors that accounts for up to 40% of a commercial building's total energy loss. Without a properly installed air barrier system, conditioned air escapes the building while unconditioned outdoor air infiltrates, driving up HVAC costs, creating occupant discomfort, and introducing moisture that can cause structural damage, mould growth, and premature deterioration of building materials.

The National Building Code of Canada (NBCC 2020) now mandates air barrier systems for all commercial construction. Buildings must achieve a maximum air leakage rate of 0.2 L/(s-m2) at a pressure differential of 75 Pa. This requirement reflects growing recognition that air sealing is one of the most cost-effective strategies for reducing building energy consumption and meeting increasingly stringent energy codes across Ontario and Canada.

Heatlok ABS by Huntsman Building Solutions

Unique Fireproofing is a certified installer of Heatlok ABS (Air Barrier System), a premium spray-applied closed-cell polyurethane foam manufactured by Huntsman Building Solutions (formerly Demilec). Heatlok ABS is specifically engineered for commercial air barrier applications and is one of the most widely specified spray foam air barrier products in Canada. It meets CAN/ULC-S705.1 and S705.2 standards, carries a Canadian Construction Materials Centre (CCMC) evaluation, and is listed in major building code compliance guides across the country.

What makes Heatlok ABS exceptional is that it combines three functions in a single application: air barrier, thermal insulation, and vapour retarder. At just 1 inch of thickness, Heatlok ABS achieves an air leakage rate of less than 0.02 L/(s-m2) — ten times better than the NBCC requirement. At 2 inches, it also functions as a Class II vapour retarder with a permeance below 60 ng/(Pa-s-m2), eliminating the need for a separate polyethylene vapour barrier in most wall assemblies.

Spray Foam as a Combined Air Barrier, Insulation, and Vapour Retarder

Traditional building envelope construction requires separate products for air sealing, insulation, and vapour control — each installed by different trades at different stages of construction. This multi-layer approach creates opportunities for gaps, tears, and poor workmanship at every interface. Spray foam air barriers like Heatlok ABS eliminate this problem by delivering all three functions in a single monolithic application. The foam expands on contact to fill every crack, gap, and penetration, creating a seamless barrier that is far more reliable than assembled systems of membranes, tapes, and sealants.

For architects and engineers designing commercial buildings in Toronto, this means simplified wall assemblies, reduced construction schedules, and higher confidence in as-built performance. For building owners, it means lower energy bills from day one and reduced risk of moisture-related warranty claims.

Continuous Air Barrier vs. Component Air Barrier

The NBCC recognizes two approaches to air barrier design: continuous and component. A continuous air barrier is a single uninterrupted system that extends across the entire building envelope. A component air barrier relies on individual air-tight materials in each assembly, connected at transitions with sealants and tapes. While both approaches can meet code, continuous air barriers are far more reliable because they eliminate the hundreds of joints and transitions where component systems typically fail.

Spray foam is the ideal continuous air barrier material because it self-adheres to virtually any substrate — concrete, steel, wood, masonry, and gypsum — and bridges gaps up to 4 inches without supplementary sealing. This makes it particularly effective at the most vulnerable points in any building envelope: the wall-to-roof junction, the wall-to-foundation junction, window and door rough openings, and mechanical penetrations.

Testing and Commissioning

Unique Fireproofing recommends whole-building air leakage testing (blower door testing) on every commercial air barrier project. This testing, performed in accordance with ASTM E779 or CGSB 149.15, pressurizes the building to 75 Pa and measures the total air leakage rate. It provides definitive proof that the air barrier system meets NBCC requirements and gives building owners a benchmark for ongoing performance monitoring. Our Heatlok ABS installations consistently achieve tested air leakage rates below 0.1 L/(s-m2) — more than twice as tight as the code maximum.

Benefits for Commercial Buildings

A high-performance air barrier system delivers measurable benefits throughout the life of a commercial building. By reducing uncontrolled air leakage, buildings require smaller HVAC equipment — saving capital costs at construction and operating costs every year thereafter. Energy modelling studies show that commercial buildings with spray foam air barriers consume 25-40% less energy for heating and cooling compared to buildings with conventional air sealing. This translates to reduced HVAC sizing, lower utility bills, improved indoor air quality, and enhanced occupant comfort with fewer drafts and temperature variations.

Our Installation Process

Our certified installers follow a rigorous process for every commercial air barrier project. We begin with a site assessment to evaluate substrate conditions, identify critical transitions, and develop a detailed application plan. Surface preparation includes cleaning, priming where required, and masking of areas not receiving foam. The Heatlok ABS is then spray-applied in controlled lifts to achieve the specified thickness, typically 1-2 inches for air barrier applications and up to 4 inches where additional thermal performance is required. After curing, we inspect every square foot for coverage continuity and correct any deficiencies before the wall assembly is closed in.

Whether you are building a new commercial facility, renovating an existing building envelope, or upgrading an underperforming air barrier system, Unique Fireproofing has the expertise and certifications to deliver a code-compliant, high-performance result. Contact us today for a free on-site estimate.