Modified Bitumen Roof Repair: 5 Steps to Fix Common Issues

Modified bitumen roof repair is a critical task for business owners and property managers who want to protect their investment and extend the life of their commercial roofing system. Whether you’re dealing with standing water, cracks in the membrane, or visible bubbling and blistering, understanding the repair process is key.

Here’s what this article covers:

• The top warning signs that your modified bitumen roof needs attention
• Step-by-step guidance on repairs you can plan or expect
• Why working with a reliable roofing team matters

⚠️ Common Signs Your Modified Bitumen Roof Needs Repair

Recognizing problems early can prevent major damage and extend the roof’s lifespan. Here are the most common indicators your roof might need professional attention:

Ponding Water

Flat and low-slope roofs are notorious for poor drainage. If water sits on your modified bitumen roof for more than 48 hours after rainfall, it’s a red flag.

• Contributes to membrane degradation
• Can lead to leaks and internal damage
• Indicates potential slope issues

Surface Cracks or Splits

Thermal expansion and contraction can cause the membrane to crack or split over time. These vulnerabilities can be hard to spot but allow moisture to seep in, leading to more serious issues.

Blistering or Bubbling

Air or moisture trapped beneath the membrane often causes blisters or bubbles. These are early warnings of membrane separation and need to be addressed before they rupture and expose the underlayment.

💧 Causes of Damage to Modified Bitumen Roofing Systems

Understanding the root causes helps with prevention and proper planning for repairs.

• Weather Exposure: UV rays, hail, high winds, and freeze-thaw cycles gradually break down the roofing material, particularly at seams and flashing points.
• Poor Installation: Improperly installed layers or lack of proper adhesion can cause premature failure, especially at edges and transitions.
• Foot Traffic: Frequent foot traffic from HVAC maintenance or inspections can wear down protective surfaces and create indentations or punctures.
• Age: Even the best-maintained roofs degrade over time. Modified bitumen typically lasts 15–20 years with good maintenance. Past that point, small repairs might no longer be enough.

✅ 5 Steps to Fix Common Modified Bitumen Roof Issues

Fixing a modified bitumen roof doesn’t always mean replacing the entire system. The following five steps outline how to approach repairs methodically and safely.

1. Inspect and Assess the Damage

A comprehensive inspection helps identify all problem areas, not just the visible ones.

1. Walk the entire roof looking for blisters, ponding, cracks, and lifted seams.
2. Check flashing around penetrations like vents, HVAC units, and skylights.
3. Use infrared thermography if needed to detect moisture below the surface.

2. Clean the Repair Area

Before any repair work begins, the roof surface must be free from dirt, debris, and loose granules.

1. Sweep or blow off dirt and debris.
2. Use a mild detergent if the membrane is stained or greasy.
3. Let the area fully dry to ensure proper adhesion of repair materials.

3. Remove Damaged Sections

Cut away any damaged membrane, taking care not to disturb the layers below more than necessary.

1. Use a utility knife to cut an even shape around the blistered or cracked area.
2. Remove the section carefully, exposing the substrate.
3. Check for moisture damage or rot in the substrate and insulation.

4. Apply New Bitumen and Membrane Patch

This step restores waterproofing and integrity to the affected section.

1. Heat the area using a torch (for torch-down systems) or apply cold adhesive (for self-adhered systems).
2. Press a pre-cut patch of modified bitumen over the damaged area.
3. Roll the patch with a weighted roller to eliminate air pockets and ensure solid adhesion.

5. Seal Edges and Inspect

Finish by sealing all seams and edges, and inspecting the repair for proper bonding.

1. Use roofing cement or flashing compound to seal the edges.
2. Reinforce with polyester fabric if needed.
3. Allow 24–48 hours of cure time and conduct a follow-up check.

🛠️ Preventive Maintenance Tips

Staying proactive with regular care can save you from expensive repairs or early replacements.

Schedule Regular Inspections

Plan bi-annual inspections—spring and fall are ideal times—to catch issues before they escalate.

• Look after heavy storms or major snow events
• Check penetrations, edges, and drains

Maintain Drainage Systems

Clogged drains are a major contributor to ponding water.

• Clear out leaves, dirt, and debris at least twice a year
• Consider adding strainers or guards to prevent clogs

Install Walk Pads

If technicians frequently access the roof, walk pads help minimize wear on the surface.

• Position them around HVAC units and along common access routes
• Look for heat-weldable options compatible with bitumen membranes

⭐️ When Repairs Aren’t Enough

In some cases, spot repairs aren’t enough to restore performance or prevent future leaks.

Signs You May Need a Replacement

• More than 25% of the roof surface is damaged
• Leaks persist even after repairs
• Roof is over 20 years old with a history of problems

Alternatives to Full Replacement

Some systems allow for a cap sheet overlay, which adds a new layer without a full tear-off. This can buy you time and improve performance for 5–10 years.

🤝 Trust Roofing: Your Partner for Reliable Repairs

At Trust Roofing, we understand how crucial your commercial property is to your bottom line. Our team has decades of experience working with modified bitumen systems across all industries. Whether you manage a retail strip center, industrial facility, or school building, our roofers bring precision, safety, and professionalism to every job.

We don’t just fix problems—we identify root causes and provide long-term solutions that protect your property and reduce future costs. Our technicians are trained in both torch-down and cold-applied systems, and we follow strict protocols to ensure safe and code-compliant repairs.

Ready to get your roof back in shape? Contact Trust Roofing today to restore your peace of mind. Let’s fix your roof the right way.