Top Causes of Leaks in BUR Roofs—And How to Prevent Them

Built-up roofing (BUR) systems are among the oldest and most trusted commercial roofing types, prized for their durability and multi-layer protection. However, like all systems, they are not immune to problems—especially leaks. BUR roof leak causes can be complex and varied, often resulting from age, poor maintenance, or installation flaws. Fortunately, with proper knowledge and proactive steps, many of these issues can be prevented, saving property owners thousands in repairs and downtime. This blog explores the most common sources of leaks in BUR systems and offers expert guidance on how to prevent BUR roof leaks before they become serious problems.

Weathering and Aging of Roofing Materials

One of the most inevitable BUR roof leak causes is natural weathering over time. BUR systems are made up of alternating layers of bitumen (asphalt or coal tar) and reinforcing fabrics, finished with a gravel or reflective top layer. While these systems are designed for longevity—typically 20–30 years—exposure to harsh elements gradually breaks down even the most robust materials.

UV radiation, thermal expansion and contraction, freeze-thaw cycles, and constant exposure to wind and precipitation accelerate aging. The bitumen can dry out and crack, leading to brittleness and loss of waterproofing properties. Meanwhile, the gravel or surface coating may erode, leaving underlying layers vulnerable.

To prevent leaks caused by aging, a robust preventative maintenance program is essential. Regular inspections should identify early signs of cracking, blistering, or alligatoring—patterns of drying bitumen that resemble reptile skin. Applying reflective coatings can extend the roof’s life by reducing heat absorption and UV damage. Additionally, re-saturating the roof with asphalt or applying a new flood coat can restore flexibility and water resistance. The key is to intervene early, before visible deterioration becomes a source of water intrusion.

Poor Installation and Workmanship

Another leading factor in BUR roof leak causes is poor installation. BUR systems are complex to install, requiring precise sequencing and temperature control when applying hot bitumen. Mistakes during the installation process—such as improperly heated asphalt, inadequate membrane adhesion, or misaligned layers—can create weaknesses that eventually allow water to infiltrate.

These problems often remain hidden for months or years until the roof is tested by a heavy storm or temperature swing. Seams may begin to separate, flashing may pull away from walls, or air pockets may evolve into blisters and ruptures. In worst-case scenarios, moisture becomes trapped during installation, only to expand and force its way out through cracks, creating pathways for more water to enter.

Prevention in this area starts with hiring qualified, certified roofing contractors with experience in BUR systems. Adhering to manufacturer specifications and industry standards is crucial. Quality control during installation—including checking temperatures, layering consistency, and lap integrity—can prevent future headaches. Insist on a warranty that covers both materials and workmanship, and follow up with post-installation inspections to catch issues before they develop into leaks.

Flashing Failures and Penetration Points

Flashing components are critical in protecting vulnerable areas of a roof—like transitions, edges, vents, and pipes—but they are also among the most common BUR roof leak causes. When metal or membrane flashing separates from the main roofing system due to movement, weather exposure, or improper fastening, it opens a direct channel for water to enter.

Roof penetrations such as HVAC units, skylights, plumbing vents, and electrical conduits complicate matters further. These areas often have complex flashing details, which, if not sealed properly, can become leak hot spots. Over time, even minor movement from building settling or thermal expansion can create cracks at these junctions.

To prevent leaks at flashing and penetration points, it’s vital to inspect these areas frequently—especially after extreme weather events or seasonal transitions. Flashing should be securely fastened and adequately sealed with compatible materials. Modern flashing solutions, such as reinforced liquid membranes or custom-fabricated metal components, offer improved longevity and flexibility. Keeping penetration details clean and free from debris ensures the seals remain effective and drainage is not obstructed.

Ponding Water and Poor Drainage

Flat roofs are notorious for water accumulation, and BUR systems are no exception. While these roofs are technically “low-slope,” inadequate pitch or clogged drains can lead to ponding—standing water that remains on the surface for more than 48 hours. This issue is one of the more preventable BUR roof leak causes but often overlooked.

Ponding water accelerates material degradation, especially when the protective gravel or cap sheet has worn thin. Over time, water finds its way through micro-cracks or poorly adhered areas. Worse, standing water can exert pressure on the roof membrane, pushing moisture into small voids and seams. Algae growth, debris accumulation, and freeze-thaw expansion exacerbate the risk of leaks and structural damage.

The best strategy to prevent BUR roof leaks related to ponding is to ensure effective drainage from the start. This includes properly sloped insulation layers, functioning internal or perimeter drains, and regularly maintained scuppers and downspouts. Adding tapered insulation during reroofing projects or retrofit drains in problem areas can significantly improve water runoff. Property managers should incorporate drainage checks into routine maintenance to keep water moving and reduce stress on the roofing system.

Roof Traffic and Physical Damage

Commercial buildings often require rooftop access for maintenance, inspections, or equipment servicing, which introduces another common BUR roof leak cause: physical damage. Repeated foot traffic, dropped tools, or careless movement of HVAC units can fracture the protective layers of a BUR system, especially if the top gravel or cap sheet has been displaced.

Even minor tears in the membrane or crushed insulation can compromise the roof’s waterproofing. Over time, exposed areas deteriorate more quickly under the sun and rain. In winter, water entering damaged spots can freeze and expand, worsening the breach. Left unaddressed, a small tear can become a full-blown leak affecting interior spaces.

To prevent damage-related BUR roof leaks, access control and protection strategies must be implemented. Walk pads or designated walkways help distribute weight and minimize wear in high-traffic areas. Staff and service providers should be trained to avoid stepping on vulnerable spots and report any damage they observe. Additionally, post-maintenance inspections are invaluable in identifying accidental punctures or dislodged gravel before they evolve into leak sites.

A Proactive Approach to BUR Roof Longevity

Understanding the key BUR roof leak causes is the first step in establishing an effective preventative maintenance strategy. While time and nature inevitably take their toll, many leaks are avoidable with routine inspections, quality installation, and attentive upkeep. Whether you’re managing a single facility or a portfolio of properties, knowing how to prevent BUR roof leaks can drastically reduce repair costs, downtime, and occupant disruptions.

A proactive mindset—rooted in regular assessments, prompt repairs, and long-term planning—ensures your BUR system continues to perform at its best. When paired with professional guidance and reliable contractors, this approach protects not just the roof, but the integrity of the entire building envelope for years to come.

Need a Roofing Company in Springfield, MA?

Since 1987, R & H Roofing has remained one of the most trusted names in the roofing industry. We specialize in commercial and industrial roofing and offer a wide variety of roofing systems including EPDM systems, TPO Systems, Metal Roofing Systems, BUR Tar & Gravel Systems, Asphalt Shingles, and PVC Systems. We also work with some of the leading manufacturers including Firestone, Carlisle, Duro-last, and Garland. Contact us today to learn more about what we can do for you!

Categorised in: BUR Roofing

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