If you spend any time looking down from the top of a tall building in Denton or Dallas, you will likely see acres of gray, pebbled surfaces. These are tar and gravel roofs—more formally known in the industry as Built-Up Roofing (BUR). While modern single-ply membranes like TPO and PVC have captured a significant share of the market, tar and gravel remains a workhorse for low-slope and flat commercial structures.
At DKG Roofing, we have seen materials come and go in this industry. Property managers often ask if these systems are "old fashioned." The truth is that while the technology is decades old, the multi-layered redundant protection provided by BUR is still incredibly effective at combatting the intense North Texas sun and storm damage.
Understanding Built-Up Roofing (BUR)
A tar and gravel roof is not just a single layer of material. It is a "built-up" system created by alternating layers of bitumen (asphalt or coal tar) and reinforcing fabrics (ply sheets or felts). The process concludes with a top layer of flood-coat asphalt and a surfacing of gravel or crushed stone.
The gravel serves several critical purposes in the DFW climate. First, it protects the underlying bitumen layers from ultraviolet (UV) degradation. Without it, the sun would bake the oils out of the asphalt, causing it to crack and become brittle within a few years. Second, the gravel provides a degree of fire resistance and makes the surface safe for light foot traffic during routine maintenance.
Why Tar and Gravel Still Makes Sense in North Texas
The primary reason many building owners in Denton County stick with tar and gravel is its legendary durability. Unlike a single-ply membrane, which can be punctured by a dropped tool or a sharp piece of wind-blown debris, a four-ply BUR system has multiple backup layers. If the top layer is compromised, the layers beneath it still provide a water-tight seal.
In North Texas, we also deal with extreme temperature swings. A tar and gravel roof has a high thermal mass, which can help stabilize the temperature of the roof assembly. When installed correctly by an experienced roofing contractor, these roofs can withstand the expansion and contraction cycles common in our region.
- Excellent resistance to foot traffic and mechanical impact.
- High-performance waterproofing due to multiple redundant layers.
- Superior protection against UV rays and heat.
- Lower cost per square foot compared to some high-end synthetic systems.
The Challenges of GRAVEL Systems
While durable, tar and gravel roofs are heavy. A typical BUR system can weigh between 400 and 600 pounds per square (100 square feet). This means the building's structural integrity must be verified before an installation or a heavy roof-repair-service project. If a building was not originally designed for this load, a lighter synthetic membrane may be the only option.
Leak detection is another hurdle. Because the gravel covers the entire surface, a technician cannot simply look for a tear in a membrane. We often have to "broom back" large sections of gravel to find the source of a leak, which increases labor time. Furthermore, the installation process involves heating asphalt in a kettle, which creates heavy smoke and odors. For retail centers or medical offices in Denton, this often requires scheduling work during off-hours to avoid bothering occupants.
- Increased weight requires a stronger structural deck.
- Finding and repairing leaks is more difficult due to the gravel surfacing.
- Installation produces strong odors and fumes that can be disruptive to tenants.
- The heavy specialized equipment required for installation.
Maintenance and the Modern Alternative
If you currently have a tar and gravel roof, regular roof-inspections are vital. The most common issue we see in the DFW area is "scouring," where wind or heavy rain pushes the gravel away from the corners and edges, leaving the bare asphalt exposed to the sun. Timely maintenance involves redistributing the gravel or adding a fresh flood coat to protect those vulnerable areas.
For those looking to move away from asphalt-based systems, TPO (Thermoplastic Polyolefin) is the leading alternative. It is reflective, lighter, and easier to repair. However, for a building owner who wants a roof they can "set and forget" for 25 years, the proven track record of a multi-ply tar and gravel system is still hard to beat. As a veteran-owned business, we believe in giving you the straight facts on which material fits your budget and your building’s structural capacity.