What to Know About Tar and Gravel Flat Roofs
Flat roofs have been a popular choice for both commercial and residential buildings due to their modern aesthetic and efficient use of space. One of the most enduring types of flat roofing systems is the tar and gravel roof. This type of roofing has been used for decades and continues to be a reliable option for many property owners. If you’re considering a tar and gravels flat roof for your property, here’s what you need to know.
What is a Tar and Gravel Roof?
A tar and gravel roof, also known as a built-up roof (BUR), is composed of multiple layers that provide durability and weather resistance. The basic structure includes:
- Base Layer: This is often made of a high-quality felt or fiberglass matting.
- Bitumen Layers: Alternating layers of hot tar (bitumen) and roofing felt or fiberglass are applied. Typically, three to five layers are used.
- Gravel or Aggregate: A final layer of gravel or other small aggregate is spread over the bitumen. This layer protects the underlying materials from UV rays, weather, and physical damage.
Advantages of Tar and Gravel Roofs
- Durability: The multiple layers in a tar and gravel roof make it highly durable and able to withstand harsh weather conditions. Properly installed and maintained, these roofs can last 20-30 years or more.
- Weather Resistance: The combination of bitumen and gravel provides excellent resistance against water, wind, and UV radiation. The gravel acts as a protective barrier, preventing the bitumen from cracking under the sun’s rays.
- Fire Resistance: Gravel is non-combustible, adding a layer of fire resistance to your roof.
- Cost-Effective: Compared to other roofing systems, tar and gravel roofs are relatively affordable. The materials are readily available and the installation process is straightforward for experienced contractors.
- Low Maintenance: With regular inspections and minor repairs, tar and gravel roofs require minimal maintenance.
Disadvantages of Tar and Gravel Roofs
- Weight: The multiple layers and gravel topping make this roofing system quite heavy. Ensuring your building’s structure can support the weight is crucial.
- Ponding Water: Flat roofs can sometimes suffer from ponding water if they do not have adequate drainage. Prolonged exposure to standing water can shorten the roof’s lifespan.
- Installation Complexity: Installing a tar and gravel roof requires skilled professionals to ensure each layer is correctly applied. Poor installation can lead to leaks and other issues.
- Aesthetic Limitations: While effective, tar and gravel roofs may not offer the same aesthetic appeal as some modern roofing options.
Installation Process
The installation of a tar and gravel roof is a meticulous process that should be handled by professionals. Here’s a brief overview of the steps involved:
- Preparation: The roof deck is cleaned and prepped to ensure a smooth surface for the base layer.
- Base Layer Application: A base layer of felt or fiberglass matting is laid down.
- Bitumen Application: Hot tar is applied over the base layer, followed by another layer of felt or fiberglass. This process is repeated to build up the required number of layers.
- Gravel Layer: Once the bitumen layers are in place, a layer of gravel is spread across the surface. The gravel is embedded in the hot bitumen to secure it.
- Final Inspection: The roof is inspected to ensure all layers are properly applied and there are no weak spots or potential leaks.
Maintenance Tips
To extend the life of your tar and gravel roof, regular maintenance is essential. Here are some tips:
- Regular Inspections: Inspect your roof at least twice a year, particularly after severe weather. Look for signs of damage, such as cracks in the bitumen or displaced gravel.
- Clear Debris: Remove leaves, branches, and other debris that can trap moisture and cause damage.
- Check for Ponding Water: Ensure your roof has adequate drainage and address any areas where water pools.
- Prompt Repairs: Address any issues, such as cracks or leaks, as soon as they are discovered to prevent further damage.
Cost Considerations
The cost of installing a tar and gravel roof varies depending on several factors, including the size of the roof, the number of layers, and local labor rates. On average, homeowners can expect to pay between $3.50 and $7.50 per square foot. While the initial cost may be higher than some other roofing options, the longevity and low maintenance requirements can make it a cost-effective choice in the long run.
Final Thoughts
Tar and gravel roofs are a time-tested option for flat roofing systems, offering durability, weather resistance, and cost-effectiveness. While there are some potential drawbacks, such as weight and the need for professional installation, the benefits often outweigh these concerns. If you’re considering a tar and gravel roof, consult with a professional roofing contractor to ensure it’s the right choice for your property. With proper installation and maintenance, a tar and gravel roof can provide reliable protection for many years.