Modified bitumen roofing is a type of asphalt-based membrane often reinforced with fiberglass or polyester, designed for durability and flexibility. Seam failure occurs when the edges where two membrane sheets overlap start to separate, which can lead to leaks and water damage. This issue typically happens because of poor installation, aging, exposure to extreme weather, or trapped moisture beneath the seams. Diagnostics are straightforward – a visual inspection might reveal curling, cracking, or bubbles along the seams, and a careful check during or after rainfall can help spot leaks. If the roof is flat or low-sloped, walk carefully and look for soft or wet areas beneath the surface, which are signs of water entry due to seam problems. A safe DIY check involves gently inspecting the seams for any lifting or loose edges without using sharp tools or walking heavily on the roof to avoid causing further damage.
While minor seam failures can sometimes be temporarily repaired with roofing adhesive or patch kits made for modified bitumen, it’s usually best to call a professional roofer when you notice significant seam separation or recurring leaks. The roofer should offer a clear explanation of the issue along with a plan to reseal, reheat weld, or possibly replace affected sections. When speaking with a contractor, ask: "How will you ensure the seams are properly sealed to prevent future leaks?" and "Do you provide a warranty on seam repairs, and what does it cover?" These questions help ensure the repair involves the correct materials and techniques, keeping your roof code-compliant and protecting your home’s insurance coverage.