Why Hot Rubberized Roofing Systems Are Ideal for Waterproofing in Toronto

Toronto’s climate presents unique challenges for commercial and industrial building owners. With frigid winters, hot summers, and the constant freeze-thaw cycles that characterize the region, finding the right waterproofing solution is critical for protecting your investment. As precipitation patterns become more unpredictable and extreme weather events more common, the integrity of your building’s waterproofing system has never been more important.

Hot rubberized asphalt (HRA) roofing systems have emerged as one of the most effective waterproofing solutions for Toronto’s demanding conditions. These systems combine the durability of asphalt with the flexibility of rubber to create a seamless, fully-bonded membrane that offers superior protection against water infiltration.

At Nusite Group, with over 30 years of experience providing waterproofing solutions throughout the GTA, we’ve seen firsthand how hot rubberized asphalt systems outperform traditional waterproofing methods in our local climate. This article will explain what hot rubberized roofing systems are, why they’re particularly well-suited for Toronto’s climate, and the key benefits they offer commercial and industrial property owners in the GTA.

What Are Hot Rubberized Asphalt Roofing Systems?

Hot rubberized asphalt (HRA) is a 100% solids blend of selected asphalts, synthetic rubber polymers, and mineral stabilizers. Unlike traditional asphalt materials, hot rubberized asphalt is engineered specifically to provide enhanced flexibility, durability, and waterproofing performance.

The Composition and Installation Process

Hot rubberized asphalt typically consists of:

High-quality asphalt base
SBS (Styrene-Butadiene-Styrene) or SEBS (Styrene-Ethylene-Butylene-Styrene) polymers
Mineral stabilizers and fillers
Reinforcement fabrics or membranes

The installation process involves:

Surface Preparation: The substrate is thoroughly cleaned and primed to ensure proper adhesion.
Heating: The rubberized asphalt is heated in specialized melters to temperatures between 350-400°F (175-205°C).
Application: The hot material is applied to the prepared surface in controlled thicknesses, typically forming a monolithic layer.
Reinforcement: Polyester or fiberglass reinforcement fabric is embedded into the first layer while still hot.
Second Layer: A second layer of hot rubberized asphalt is applied over the reinforcement.
Protection Layer: A protection board or course is installed to shield the membrane from damage during subsequent construction activities or throughout its service life.

The result is a seamless, fully-adhered waterproofing system that forms a monolithic barrier against water infiltration.

Common Applications in Commercial and Industrial Settings

Hot rubberized asphalt systems are highly versatile and can be used in various applications, including:

Plaza decks and outdoor amenity spaces
Protected membrane roofing assemblies (PMRA)
Split-slab construction
Parking decks and garages
Green roofs and rooftop gardens
Below-grade waterproofing
Foundation walls
Tunnels and bridges

This versatility makes hot rubberized asphalt an excellent choice for Toronto’s diverse commercial and industrial building stock.

Why Hot Rubberized Asphalt Excels in Toronto’s Climate

Toronto’s climate presents several challenges for building waterproofing systems. Hot rubberized asphalt is particularly well-suited to address these challenges due to its unique properties.

Extreme Temperature Fluctuations

Toronto experiences temperatures ranging from below -20°C in winter to above 30°C in summer—a range of more than 50 degrees throughout the year. These extreme fluctuations cause repeated expansion and contraction of building materials, which can lead to cracks and failures in conventional waterproofing systems.

Hot rubberized asphalt is specifically designed to maintain flexibility even at very low temperatures, allowing it to accommodate the thermal movement of the substrate without cracking or losing adhesion. The SBS or SEBS polymers in the formulation enable the material to stretch and return to its original state repeatedly, making it ideal for Toronto’s variable climate.

Freeze-Thaw Cycle Resistance

One of Toronto’s most challenging climate features is its frequent freeze-thaw cycles. During winter months, temperatures often fluctuate above and below freezing, causing water to repeatedly freeze and thaw. This cycle creates immense pressure on building materials as water expands when it freezes.

Hot rubberized asphalt systems excel in these conditions because:

They remain flexible even at freezing temperatures
They maintain a strong bond to the substrate despite repeated expansion and contraction
The seamless application eliminates joints where water could penetrate
Their elasticity allows them to bridge minor cracks that may develop in the substrate

These properties make hot rubberized asphalt exceptionally resistant to the damage caused by Toronto’s freeze-thaw cycles, extending the life of the waterproofing system and protecting the building structure.

Heavy Precipitation and Snowmelt Management

Toronto receives significant precipitation throughout the year, with heavy snowfall in winter months followed by spring thaws that create large volumes of water. This precipitation pattern demands waterproofing systems that can withstand prolonged exposure to moisture and occasional ponding water.

Hot rubberized asphalt is ideally suited for these conditions because:

It forms a completely seamless membrane, eliminating potential entry points for water
It can withstand continuous immersion in water without degrading
The monolithic application ensures complete coverage, even in complex architectural details
It maintains adhesion to the substrate even in wet conditions
It can be sloped to facilitate drainage and prevent ponding

These characteristics make hot rubberized asphalt highly effective at managing Toronto’s precipitation patterns and protecting buildings from water damage.

Key Benefits of Hot Rubberized Asphalt Roofing Systems

Hot rubberized asphalt offers numerous advantages over traditional waterproofing systems, making it an excellent roofing option for commercial and industrial property owners in the GTA.

Superior Waterproofing Performance

The primary function of any waterproofing system is to prevent water infiltration, and hot rubberized asphalt excels in this regard:

Seamless Application: Unlike sheet membranes with seams that can fail, hot rubberized asphalt creates a continuous, monolithic membrane without joints or overlaps.
Full Adhesion: The system bonds completely to the substrate, preventing lateral water migration even if the membrane is breached at one point.
Self-Healing Properties: The material retains some flow capability at elevated temperatures, allowing it to self-heal minor damage over time.
Thickness Control: Applied at a minimum of 215 mils (5.5 mm) thickness, hot rubberized asphalt provides a substantial barrier against water penetration.

These features combine to create one of the most reliable waterproofing systems available for Toronto’s challenging climate.

Extended Lifespan and Durability

Hot rubberized asphalt systems are known for their exceptional durability and longevity:

Service Life: Properly installed and maintained systems can last 25-40+ years, significantly longer than many alternative waterproofing solutions.
Chemical Resistance: The material resists deterioration from exposure to common chemicals, including those found in urban environments.
UV Stability: When used in protected membrane assemblies, the material is shielded from UV exposure, further extending its service life.
Impact and Puncture Resistance: The thickness and elasticity of the membrane provide good resistance to physical damage.

For Toronto building owners, this durability translates to reduced maintenance costs and fewer disruptive replacements over the building’s lifetime.

Versatility and Adaptability

Hot rubberized asphalt systems can be adapted to meet various design requirements and building conditions:

Complex Geometries: The liquid-applied nature allows it to conform to irregular shapes and difficult details.
Compatibility: Works well with a variety of substrates, including concrete, metal, wood, and existing waterproofing systems.
Integration with Other Building Systems: Can be designed to incorporate drainage systems, expansion joints, and penetrations.
Green Roof Integration: Ideal base for green roof systems, which are becoming increasingly popular in Toronto due to the city’s Green Roof Bylaw.

This versatility makes hot rubberized asphalt suitable for both new construction and renovation projects across the GTA.

Environmental Considerations

While sustainability is increasingly important in construction, hot rubberized asphalt offers several environmental benefits:

Longevity: The extended service life reduces the frequency of replacement and associated waste.
Energy Efficiency: When used in protected membrane roof assemblies, the system contributes to improved building thermal performance.
Green Roof Support: Provides an excellent waterproofing layer for green roof systems, which offer numerous environmental benefits.
Urban Heat Island Mitigation: When combined with reflective protection courses or green roof systems, helps reduce urban heat island effects.

These environmental attributes align well with Toronto’s sustainability goals and green building initiatives.

Toronto Building Code and Regulatory Considerations

When implementing hot rubberized asphalt systems in Toronto, it’s important to understand the relevant building codes and regulations.

Ontario Building Code Requirements

The Ontario Building Code (OBC) recognizes hot rubberized asphalt as an approved waterproofing material when installed according to applicable standards. According to the OBC:

Hot applied rubberized asphalt roofing must be installed in accordance with CAN/CGSB-37.51-M, “Application for Hot Applied Rubberized Asphalt for Roofing and Waterproofing.”
The material must meet the requirements of CAN/CGSB-37.50-M89 for one-part, hot-applied rubberized asphalt.
Systems must be designed to provide adequate drainage, with minimum slopes as specified in the code.
Protected membrane assemblies must include appropriate insulation and ballast components.

Compliance with these requirements ensures that your hot rubberized asphalt system will meet all local building code requirements.

Toronto’s Green Roof Bylaw

Toronto was the first city in North America to adopt a bylaw requiring green roofs on new development. The Green Roof Bylaw applies to:

New commercial, institutional, and residential development with a minimum gross floor area of 2,000 m²
New additions to existing buildings that exceed 2,000 m² of new gross floor area

Hot rubberized asphalt systems are particularly well-suited for green roof applications because:

They provide a reliable waterproofing layer beneath the growing medium
Their monolithic nature eliminates potential leak points
They resist root penetration when combined with appropriate protection layers
They can withstand the constant moisture exposure associated with green roofs

For buildings subject to the Green Roof Bylaw, hot rubberized asphalt offers an excellent foundation for compliant green roof systems.

Sewer Bylaw Considerations

In 2016, Toronto amended its Sewer Bylaws (Municipal Code Chapter 681) to address groundwater discharge issues. These amendments encourage “bathtub” style waterproofing to prevent groundwater infiltration into below-grade structures.

Hot rubberized asphalt is ideal for this approach because:

It creates a continuous waterproofing envelope
It can be applied to both horizontal and vertical surfaces
It fully bonds to the substrate, preventing lateral water migration
It provides reliable long-term performance in below-grade applications

Complying with these requirements can help avoid costly discharge fees and potential regulatory issues.

Maintenance and Longevity Considerations

While hot rubberized asphalt systems are known for their durability, proper maintenance is essential to maximize their service life.

Recommended Maintenance Practices

To ensure optimal performance of your hot rubberized asphalt system:

Regular Inspections: Schedule professional inspections at least annually, with additional inspections after extreme weather events.
Drainage Maintenance: Keep drains and scuppers clear of debris to prevent ponding water.
Protection Layer Maintenance: Repair or replace damaged protection courses or paver systems promptly.
Penetration Inspections: Regularly check the condition of flashings and seals around roof penetrations.
Green Roof Maintenance: For green roof systems, follow appropriate maintenance protocols for the vegetative components.

Following these maintenance practices will help extend the life of your hot rubberized asphalt system and protect your investment.

Signs of Potential Issues

Be alert for these indicators that your hot rubberized asphalt system may need attention:

Water staining or leaks on interior surfaces
Ponding water that doesn’t dissipate within 48 hours
Damage to protection layers or exposed membrane
Displaced or damaged flashings around penetrations or terminations
Vegetation growth in unwanted areas (for conventional roof assemblies)

Addressing these issues promptly can prevent more serious problems and extend the system’s service life.

Long-Term Performance Expectations

With proper installation and maintenance, building owners can expect:

25-40+ years of reliable waterproofing performance
Minimal maintenance requirements compared to alternative systems
Excellent resistance to Toronto’s climate challenges
Long-term protection for the building structure and contents

This long-term performance makes hot rubberized asphalt an excellent value despite the potentially higher initial installation cost compared to some alternatives.

FAQ: Common Questions About Hot Rubberized Asphalt Systems

How long do hot rubberized asphalt roofing systems typically last in Toronto?

Hot rubberized asphalt systems typically last 25-40+ years when properly installed and maintained. This longevity is particularly impressive in Toronto’s challenging climate, where freeze-thaw cycles, extreme temperature fluctuations, and significant precipitation can quickly deteriorate lesser waterproofing systems. The actual lifespan depends on factors such as installation quality, exposure conditions, and maintenance practices.

How does the cost of hot rubberized asphalt compare to other waterproofing systems?

Hot rubberized asphalt systems generally have a higher initial cost than some alternative waterproofing methods, such as conventional modified bitumen or single-ply membranes. However, when considering the total lifecycle cost, hot rubberized asphalt often proves more economical due to its extended service life, reduced maintenance requirements, and superior performance. For Toronto buildings, this means fewer replacements and repairs over the structure’s lifetime, resulting in significant long-term savings.

Can hot rubberized asphalt be installed in winter conditions in Toronto?

While installation during extreme cold is not ideal, hot rubberized asphalt can be installed in cooler temperatures than many alternative systems. The heated application process helps overcome some cold weather challenges. However, proper substrate preparation becomes more critical in cold conditions, and temporary heating or enclosures may be necessary to ensure optimal installation quality. Whenever possible, scheduling installation during Toronto’s milder seasons (late spring, summer, or early fall) is recommended.

What makes hot rubberized asphalt particularly suitable for Toronto’s freeze-thaw cycles?

Hot rubberized asphalt’s exceptional flexibility at low temperatures makes it ideal for Toronto’s freeze-thaw conditions. The rubber polymers (SBS or SEBS) in the formulation enable the material to stretch and contract as temperatures fluctuate without cracking or losing adhesion. Additionally, the seamless application eliminates the joints and seams found in other systems, which are typically the first points of failure during freeze-thaw cycles. This combination of flexibility and seamless application results in superior resistance to the stresses caused by Toronto’s frequent temperature fluctuations above and below freezing.

Investing in Long-Term Waterproofing Protection

For commercial and industrial property owners in Toronto, waterproofing isn’t just about preventing leaks—it’s about protecting your entire investment. Water infiltration can lead to structural damage, mold growth, decreased energy efficiency, and disruption to business operations. In the GTA’s challenging climate, choosing the right waterproofing system is a decision with long-term implications.

Hot rubberized asphalt roofing systems represent one of the most reliable, durable, and cost-effective waterproofing solutions available for Toronto’s commercial and industrial buildings. Their unique combination of seamless application, flexibility, and longevity makes them exceptionally well-suited to withstand the region’s freeze-thaw cycles, temperature extremes, and precipitation patterns.

At Nusite Group, our 30+ years of experience in the GTA has shown us that hot rubberized asphalt consistently outperforms other waterproofing options in local conditions. Our team of specialists is dedicated to providing top-quality hot rubberized asphalt applications that protect your property for decades to come.

If you’re considering waterproofing options for your commercial or industrial property in Toronto, we invite you to contact us for a consultation. Our experts will evaluate your specific needs and help you determine if a hot rubberized asphalt system is the right solution for your building. With proper installation and maintenance, you can enjoy decades of worry-free waterproofing protection, regardless of what Toronto’s climate throws your way.