Material
What Is Asphalt Shingles? Properties, Performance, and Uses in Roofing
Also called: bitumen, tar
Asphalt is a black, sticky, semi-solid form of petroleum used as a waterproofing and binding agent in roofing systems, typically applied as shingles or built-up roofing membranes.
In plain English
Asphalt is a black, semi-solid petroleum-based material used in roofing as a primary waterproofing agent and binder in products such as asphalt shingles, built-up roofing, and modified bitumen membranes, valued for its adhesive properties, durability, and resistance to water penetration in roofing applications.
How asphalt works
Asphalt is a petroleum-based, semi-solid material commonly used as a waterproofing and surface layer in roofing systems. In roofing applications, asphalt is typically found in built-up roofing (BUR) and asphalt shingle systems, where it serves as a binder and protective coating. Its structure consists of bitumen combined with mineral fillers and stabilizers, forming a flexible, durable membrane that can be applied in multiple plies or as a coating on fiberglass or organic mats.
Functionally, asphalt provides critical water resistance, preventing moisture intrusion through the roof deck. Its adhesive properties enable it to seal laps and penetrations, enhancing wind resistance and reducing the risk of uplift along ridges, eaves, and roof slopes. Asphalt’s viscoelastic nature allows it to accommodate minor structural movement and thermal expansion, contributing to the overall longevity and structural efficiency of the roofing assembly.
Asphalt is widely used on low-slope and flat roofs, where effective water drainage is essential to prevent ponding and leaks. It is also a key component in steep-slope asphalt shingle roofs, offering reliable performance in various climates, including areas with significant snow loads or wind exposure. Its versatility and proven track record make asphalt a fundamental material in modern roofing construction.
Why it matters for your roof
While cost-effective, asphalt materials are more prone to aging, UV damage, and shorter lifespan compared to metal systems. It also affects how homeowners, contractors, and specifiers evaluate roof durability, cost, risk, and long-term value.
Benefits
WEATHER RESISTANCE
Asphalt provides robust protection against rain, wind, and UV exposure, enhancing roof resilience in diverse climates.
IMPACT ABSORPTION
The flexible composition of asphalt helps absorb hail and debris impacts, reducing the risk of surface cracking or punctures.
INSTALLATION COMPATIBILITY
Asphalt roofing materials are compatible with a wide range of substrates and roof slopes, supporting versatile installation options.
COST-EFFECTIVE MAINTENANCE
Asphalt roofs allow for straightforward repairs and replacements, minimizing long-term maintenance costs for property owners.
Limitations
UV DEGRADATION
Asphalt roofing materials are susceptible to ultraviolet radiation, leading to surface cracking and accelerated material breakdown over time.
THERMAL MOVEMENT
Asphalt expands and contracts with temperature fluctuations, increasing the risk of surface fatigue, splitting, and premature aging.
CHEMICAL SENSITIVITY
Exposure to oils, solvents, or certain airborne pollutants can soften or degrade asphalt, compromising waterproofing performance.
WEIGHT LOAD
Asphalt-based roofing materials are relatively heavy, imposing structural load constraints on lightweight or inadequately supported roof assemblies.
Common problems
UV DEGRADATION CRACKING
Prolonged ultraviolet exposure causes asphalt roofing to dry out and crack, leading to premature surface failure and leaks.
THERMAL CYCLING FATIGUE
Repeated expansion and contraction from temperature fluctuations accelerates asphalt embrittlement, resulting in surface splits and compromised waterproofing.
CHEMICAL INCOMPATIBILITY DAMAGE
Contact with incompatible roofing materials or solvents can break down asphalt binders, causing softening, blistering, or membrane separation.
GRANULE LOSS EROSION
Wind-driven rain and hail dislodge protective granules from asphalt shingles, exposing the underlying material to accelerated weathering and water intrusion.
Where you'll see it
COLD CLIMATE DURABILITY
Asphalt roofing is commonly chosen in cold climates due to its flexibility and resistance to freeze-thaw cycling.
STEEP-SLOPE APPLICATIONS
Asphalt shingles are ideal for steep-slope residential roofs, providing effective water shedding and wind resistance.
COST-EFFECTIVE REPLACEMENT
Asphalt is frequently used for reroofing projects where budget constraints require a durable yet affordable material.
FIRE RATED OPTIONS
Asphalt roofing materials are selected in areas requiring Class A fire ratings for enhanced building code compliance.
Don't confuse it with
Not to be confused with similar roofing terms that sound related but perform a different role in the roof assembly.
- asphalt vs metal roofing
- asphalt vs tile roofing
- asphalt vs wood shingles
- asphalt vs slate roofing
Regional & climate notes
Most relevant in: Hot climates, Cold climates, Freeze-thaw climates, High-UV climates.
Frequently Asked Questions
What is asphalt in roofing materials?
Asphalt in roofing materials is a black, sticky, petroleum-based substance used as a waterproofing agent and binder in shingles and roll roofing, providing durability, weather resistance, and protection for residential and commercial roofs.
How does asphalt function as a roofing material?
Asphalt functions as a roofing material by providing a waterproof barrier, durability, and UV resistance. It is commonly used in shingles and built-up roofing systems to protect buildings from weather and extend roof lifespan.
Why is asphalt considered an important material in roofing systems?
Asphalt is important in roofing systems because it provides waterproofing, durability, and flexibility, making it ideal for shingles and built-up roofs. Its cost-effectiveness and proven performance contribute to its widespread use in residential and commercial applications.
How does the performance of asphalt roofing compare to other materials in extreme weather conditions?
Asphalt roofing offers good performance in moderate climates but may be less durable than metal or tile in extreme heat, cold, or hail. It can crack or lose granules faster under severe weather conditions.
How is the quality of asphalt roofing material measured or evaluated?
The quality of asphalt roofing material is measured by its thickness, weight per square, granule adhesion, fire resistance, wind rating, and compliance with industry standards such as ASTM D3462 for shingles.
What factors can affect the lifespan of an asphalt roof?
The lifespan of an asphalt roof depends on installation quality, ventilation, climate, roof slope, maintenance, and the grade of asphalt shingles used, with typical lifespans ranging from 15 to 30 years.
Related terms
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