Asphalt and tar roofing materials remain common choices for durability, cost efficiency, and broad applicability across modern and historic structures. This guide explains the differences between asphalt-based products and tar-based roofing, their composition, performance under various conditions, typical lifespans, maintenance practices, and selection tips. Homeowners and contractors will gain practical insights into installation considerations, cost comparisons, environmental aspects, and long-term value when choosing between asphalt shingles, built-up roofs, and tar-based membranes.
What Are Asphalt And Tar Roofing Materials
Asphalt roofing materials primarily include asphalt shingles and built-up roofing systems that use asphalt as a waterproof binder. Tar roofing refers to historical and modern systems that rely on coal tar or pitch as the primary waterproofing layer, often used in built-up roofs and certain flat-roof membranes. Asphalt products are widely used for sloped roofs, while tar-based systems are more common in flat or low-slope applications. Both rely on hydrocarbon binders, but asphalt is typically more flexible and resilient to temperature fluctuations, whereas tar can offer robust waterproofing in certain environments.
Composition And How They Work
Asphalt shingles blend granular mineral surfacing with a fiberglass or organic mat and asphalt adhesive layers. The granules protect against UV exposure and fire, while the asphalt provides waterproofing and durability. Built-up roofs (BUR) use alternating layers of asphalt or coal tar and reinforcing fabrics, topped with a protective cap sheet. Tar-based systems often feature coal tar pitch and asphalt blends, delivering high moisture resistance; however, they can be heavier and less flexible at low temperatures. Environmental exposure, ventilation, and substrate condition influence performance for both systems.
Applications And Lifespan
Asphalt shingles are a versatile choice for residential roofing, offering color options, ease of installation, and reasonable lifespans typically ranging from 15 to 30 years depending on quality and climate. Architectural or laminated shingles provide greater durability and dimensional appeal. Built-up roofs and modified bitumen systems serve commercial and industrial buildings with low-slope or flat profiles, often lasting 20 to 40 years with proper maintenance. Tar-based membranes historically served flat roofs well but have declined in prevalence due to environmental concerns and advances in asphalt technologies.
Durability And Weather Resistance
Asphalt shingles perform well in a wide range of climates, especially with mineral granules that shield from UV damage. They resist wind uplift when properly installed and benefit from modern underlayment and ventilation. BUR systems, including tar and asphalt blends, offer excellent waterproofing on flat roofs but can be sensitive to temperature-induced cracking or delamination if not correctly installed or maintained. Tar-based products may fare better in severe thermal cycling when properly specified, yet modern asphalt alternatives often provide similar or superior performance with lower volatility and easier repairs.
Maintenance And Repairs
Regular inspection for missing shingles, flashing integrity, and sealant wear is essential for asphalt roofs. Clean debris from gutters and ensure attic ventilation to prevent moisture buildup. For tar-based or BUR roofs, inspect the membrane seams, gravel ballast (if present), and any blisters or puckering in the surface. Repairs typically involve resealing seams, replacing damaged sections, or applying compatible coatings. Timely maintenance reduces moisture intrusion, extends life, and helps preserve warranty coverage for both asphalt and tar systems.
Cost And Availability
Initial costs for asphalt shingles are generally lower per square foot than BUR systems. Asphalt products offer a favorable price-to-performance ratio and broad availability through residential and commercial suppliers. Tar-based systems tend to be more expensive upfront due to material heaviness and specialized installation requirements, though they can offer strong waterproofing in certain flat-roof scenarios. Long-term costs include maintenance, energy efficiency, and potential replacement needs, all of which should be weighed when comparing total cost of ownership.
Environmental Considerations
Asphalt roofing materials are largely recyclable, with many shingles reclaimable for use in asphalt pavement after abandoned service life. Tar-based systems may pose greater environmental concerns due to the presence of coal tar pitch and associated volatile compounds in some formulations. When selecting materials, consider the environmental impact of production, installation, and disposal, as well as local recycling options and energy efficiency benefits from reflective or cool-roof asphalt products.
Installation Considerations
Proper substrate preparation, ventilation, and adherence to manufacturer guidelines are critical for both asphalt and tar-based roofs. Asphalt shingles require appropriate nailing patterns, starter courses, and edge/valley detailing to resist wind uplift. BUR and modified bitumen systems demand careful surface preparation, ply installation, and compatible cap sheets or torched-on applications. Contractors should assess roof slope, climate, and local code requirements to determine the best-suited material and installation method for the project.
Choosing Between Asphalt And Tar Roofing Materials
- Climate and Slope: Asphalt shingles excel on sloped roofs with varied weather; tar-based BUR suits flat or low-slope applications.
- Budget And Lifespan: For lower upfront costs with a moderate lifespan, asphalt shingles are compelling; for long-term waterproofing on flat roofs, BUR tar-based systems may be advantageous.
- Maintenance: Asphalt typically requires regular inspection and venting adjustments; tar-based systems demand attention to seams and surface integrity.
- Environmental Impact: Consider recyclability, heat reflectance, and local disposal options when evaluating environmental footprints.
- Warranty And Codes: Review manufacturer warranties, code compliance, and regional climate considerations with a qualified roofer.
Frequently Asked Questions
What is the main difference between asphalt and tar roofing materials? Asphalt roofing uses asphalt-based binders in shingles or membranes for sloped roofs, while tar roofing relies on coal tar or pitch for waterproofing often in flat roofing systems. Is asphalt safer for the environment than tar? In many contexts, asphalt shingles are more recyclable and have wider recycling pathways, though both materials can be produced with low-VOC binders in modern formulations. How long do asphalt shingles last? Typical lifespans range from 15 to 30 years, influenced by climate, ventilation, and installation quality.