Roofing Cement vs Tar: Which Is Best for Your Roof

Choosing between roofing cement and tar affects roof longevity, leak repair quality, and maintenance costs. This article compares composition, performance, application, safety, and cost to help homeowners and contractors make informed decisions when addressing roofing projects. Key differences center on flexibility, adhesion, and suitability for modern roofing materials.

Criteria	Roofing Cement	Tar
Primary Use	Patch and flashings, roofing repairs	Built-up roofing, seam sealing
Composition	Asphalt binder with fillers and solvents	Coal-tar pitch or asphalt-based blend
Flexibility	Moderate to high (with modern formulations)	Low to moderate; can become brittle
UV Resistance	Often improved with additives	Poor; degrades without surfacing
Application	Caulking gun, trowel	Hot-applied or liquid in cans
VOC/Safety	Lower VOC options available	Higher fumes; carcinogenic concerns with coal-tar

For localized repairs, flashing, and shingle work, roofing cement—especially polymer-modified, low-VOC formulations—is generally the better choice due to ease of use and safer profile. Roofing cement is ideal for spot repairs and maintenance tasks.

For large built-up roofing projects that require multi-layer waterproofing, traditional tar-based BUR systems historically performed well but now face competition from modern membranes and coatings. If tar is used, ensure proper surfacing and compliance with regulations. Project scope, roof type, and regulatory context determine suitability.

Practical Tips For Safe And Effective Use

• Surface Prep: Clean, dry, and dust-free surfaces ensure best adhesion for both products.
• Temperature: Apply roofing cement within manufacturer-recommended temperature ranges; hot tar requires skilled crews and safe equipment.
• Compatibility: Use products compatible with existing roofing materials to prevent bonding failures.
• Protection: Protect tar from UV with surfacing or cap sheets; consider reflective coatings for asphalt cements to improve UV resistance.
• Safety Gear: Use respirators, gloves, and eye protection when applying solvent-based or tar products.

Sources And Further Reading

Information in this article draws from roofing industry technical guides, manufacturer product data sheets, and environmental health sources. For specific product recommendations and local code compliance, consult roofing professionals and material manufacturers. Review product technical data sheets before purchase and application.