Cold/hot tar roof system/repair

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When it comes to roofing, understanding the nuances of different systems can greatly influence longevity, efficiency, and suitability. Among these systems, the cold/hot tar approach has been a longstanding preference, particularly for flat roofs. This article offers a deep dive into cold/hot tar roofing and its repair methodologies.

1. Understanding Cold/Hot Tar Roof Systems

Cold/Hot tar roofing is based on bituminous coal tar products. It involves the application of alternating layers of bitumen (tar) and reinforcing fabrics to create a finished membrane. While “hot tar” refers to bitumen that is heated for application, “cold tar” products can be applied at ambient temperatures without the need for heating.

2. Salient Features of Cold/Hot Tar Roofs

  • Durability: Cold/hot tar roofs are known for their longevity, with many systems lasting upwards of 20-30 years with proper maintenance.
  • Waterproofing: The inherent properties of bitumen provide excellent water resistance, making it a choice material for areas with heavy rainfall.
  • UV Resistance: Coal tar roofing materials are typically resistant to UV degradation, prolonging the life of the roof.

3. Benefits of Cold/Hot Tar Roof Systems

  • Adaptability: Suitable for a variety of building types, especially those with flat or low-slope roofs.
  • Cost-Effective: The durability and low maintenance requirements often result in long-term savings.
  • Protective: Offers protection against elements, including water, UV rays, and even certain chemicals.

4. Repair and Maintenance

  • Regular Inspections: Periodic checks for blistering, cracking, or erosion are essential to maintain the integrity of the roof.
  • Sealant Application: Over time, minor cracks or gaps can emerge, which can be sealed using appropriate bitumen-based sealants.
  • Professional Repairs: For more extensive damage or wear, professional roofing contractors should be engaged. They may employ hot or cold tar patching techniques to mend the roof.
  • Safety Precautions: Especially with hot tar repairs, safety is paramount. Professionals utilize specialized equipment and adhere to safety protocols.

5. Cost Implications

The initial costs associated with cold/hot tar roofing systems can vary based on factors such as location, labor rates, and material quality. However, the system’s longevity and reduced maintenance costs can render it a cost-effective solution over its lifespan.

6. Potential Limitations

  • Odor: The application of hot tar can produce a strong odor which some might find unpleasant.
  • Weight: Multiple layers of bitumen and reinforcing fabrics can add significant weight to the roof structure.
  • Temperature Sensitivity: While cold tar applications are less affected, hot tar applications might be sensitive to ambient temperature, which can influence the outcome.


The cold/hot tar roof system has carved a niche in the roofing landscape, largely due to its resilience and adaptability. For structures with flat roofs or for those seeking a long-term roofing solution with minimal disruptions, this system can be an ideal choice. As with any construction decision, consulting with industry professionals can guide decision-making, ensuring the roofing system aligns with specific needs and conditions.