Built-up roofing (BUR) is a traditional roof system made of alternating layers of asphalt and reinforcing materials like felt or fiberglass, topped with a protective layer of gravel or mineral granules. Common failure modes include blistering, cracking, and splitting, often caused by trapped moisture, thermal expansion, or UV damage. Blisters happen when moisture gets trapped between layers or trapped air expands with heat, causing bubbles that can break the surface. Cracks and splits usually appear due to temperature fluctuations causing the materials to expand and contract. Other issues like gravel loss expose the layers to direct sunlight, speeding up deterioration. Simple diagnostics include looking for visible bubbles, cracked seams, loose gravel, or dark streaks indicating water intrusion. You can safely inspect your BUR roof from the ground using binoculars or by gently walking on a dry day, avoiding areas that show signs of weakness or softness, which may indicate rot or delamination.
If you notice any signs of damage, such as blisters that don’t quickly flatten out, exposed layers, or leaks inside your home, it’s wise to call a professional roofer. A contractor can perform in-depth evaluations like moisture tests, infrared scans, or core sampling to determine the extent of damage and the best repair approach. When talking to your roofer, ask if the system is still under warranty and how repairs might affect it, since some warranties cover materials and workmanship for specific years. You might also want to know, “How will you prevent trapped moisture recurrence?” and “What maintenance steps can I take to extend the BUR’s life?” These questions ensure clarity on long-term care and help avoid recurring failures.