Choosing the right roofing sealant is crucial for maintaining a durable and weather-resistant roof. Roofing cement and tar are two common materials used in roofing repairs and maintenance, each offering distinct benefits and drawbacks. This article explores the differences, applications, and performance of roofing cement versus tar to help property owners and contractors make informed decisions for their roofing projects.
| Aspect | Roofing Cement | Tar |
|---|---|---|
| Base Material | Asphalt-based with added fillers and solvents | Derived from refined petroleum, pure asphalt pitch |
| Consistency | Thick, putty-like | Viscous, sticky liquid |
| Best Use | Sealing small cracks, patching leaks, flashing | Large surface areas, waterproofing membranes |
| Application | Brush, trowel, or putty knife | Hot applied or cold applied |
| Durability | Moderate; prone to cracking under severe conditions | High; excellent water resistance and longevity |
| Safety Concerns | Fewer fumes; safer for DIY projects | Strong fumes; requires professional handling |
What Is Roofing Cement?
Roofing cement is a bitumen-based sealant composed of asphalt, mineral fillers, and solvents designed to form a thick, sticky paste. It is typically used to patch minor roof leaks, seal around flashings, vents, and chimneys, or repair cracks in roofing membranes. The thick consistency makes roofing cement easy to apply with tools such as a trowel or putty knife, allowing it to fill gaps and bond effectively.
Roofing cement is usually cold-applied and does not require heating, which makes it convenient for quick repairs. It adheres well to a variety of roofing materials including asphalt shingles, metal, and concrete. Despite its ease of use, roofing cement may degrade under prolonged exposure to extreme weather conditions and fluctuating temperatures.
What Is Tar?
Tar is a sticky, viscous material obtained from the distillation of petroleum or coal. It has been used as a traditional roofing waterproofing agent for decades. Tar is well-known for its excellent adhesive properties and water resistance. It is primarily used on flat or low-slope roofs for coating large surface areas or creating waterproof membranes.
Tar can be applied hot or cold, but hot-applied tar provides a stronger bond and longer-lasting protection. However, hot tar application involves higher safety risks due to fumes and burns. Tar’s durability and elasticity make it highly resistant to water infiltration and damage from weather, but it can become brittle over time and requires professional handling during installation and repair.
Key Differences Between Roofing Cement and Tar
| Feature | Roofing Cement | Tar |
|---|---|---|
| Material Composition | Asphalt with fillers and solvents | Refined petroleum or coal derivative |
| Application Method | Cold-applied, hand spread | Hot or cold-applied; hot is preferred |
| Surface Suitability | Small repairs on various roofing types | Large flat roofs, membranes |
| Durability | Moderate; best for patching | High; long-lasting waterproofing |
| Ease of Use | Easy; suitable for DIY | Requires professional skill and safety measures |
| Environmental Resistance | May crack under extreme conditions | Highly resistant to weather extremes |
Applications and Suitability
When to Use Roofing Cement
- Repairing minor leaks: Ideal for sealing cracks and small punctures.
- Flashing and seam sealing: Provides a quick, effective seal around roof joints and penetrations.
- Emergency patching: Easy to apply during unexpected roof damage.
- DIY projects: Less hazardous and simpler to handle without protective equipment.
When to Use Tar
- Large surface waterproofing: Best suited for flat roofs requiring full coverage.
- Structural roof protection: Provides a strong, flexible membrane to shield against moisture.
- Long-term roofing systems: Preferred for commercial or industrial buildings.
- Professional installations: Requires expertise for hot-applied methods.
Performance and Longevity
Roofing cement generally offers a moderate lifespan, often lasting 3 to 10 years depending on roof conditions and exposure. It is prone to drying out and cracking in extreme heat or cold, which limits its effectiveness over time.
Tar provides superior durability and water resistance. Hot-applied tar can last over 20 years with proper maintenance. Its elasticity allows it to withstand expansion and contraction caused by temperature changes, reducing the risk of cracks.
Safety and Environmental Considerations
Roofing cement poses fewer health hazards as it emits minimal fumes and can be applied without heating. This makes it a safer choice for homeowners and small repair jobs.
Tar emits strong fumes, especially during hot application, requiring proper ventilation and protective gear. Environmental concerns over tar’s petrochemical origins and potential pollutants have led to alternative roofing solutions gaining popularity. Responsible disposal and careful handling are essential when working with tar.
Cost Comparison
| Material | Cost per Gallon | Labor Requirements | Maintenance Frequency |
|---|---|---|---|
| Roofing Cement | $15 – $30 | Minimal; DIY friendly | Higher; needs regular touch-ups |
| Tar | $30 – $60 | Specialized labor needed | Lower; longer intervals between repairs |
Tips for Proper Application
- Roofing Cement: Ensure the surface is clean and dry before application for optimal adhesion.
- Tar: Only trained professionals should apply hot tar to minimize risk.
- Use protective gear, especially when handling tar to guard against fumes and burns.
- Apply in favorable weather conditions to enhance curing and bonding.