Modified Bitumen Roofing Seam Re-Welding: What Property Owners Need to Know
Modified Bitumen Roofing Seam Re-Welding: What Property Owners Need to Know
Modified bitumen roofs are tough—but their seams can still fail over time. Whether you manage a commercial property in Denver or own a home in Atlanta, understanding when and how to re-weld seams is critical to preventing costly leaks and water damage.
Here’s what you need to know.
What Is Seam Re-Welding?
Modified bitumen roofs are made of asphalt-based sheets that are heat-welded or cold-adhered. Over time, exposure to sun, wind, hail, and foot traffic can cause seams to:
Dry out
Lift
Crack
Split
Seam re-welding is the process of reheating or fusing those laps back together using hot-air or torch application. It restores the watertight seal—without a full roof replacement.
Signs You May Need Seam Re-Welding
Look for these common symptoms:
Bubbling or blistering near seams
Visible separation between laps
Water stains inside the building
Granule loss at the seams
Loose flashing at membrane joints
Annual inspections—especially before and after winter—can catch these issues early.
Why Seam Re-Welding Matters
Ignoring compromised seams can lead to:
Water infiltration
Mold and rot in insulation
Premature membrane failure
Structural deck damage
In Colorado and Georgia, seasonal temperature shifts and hail events can accelerate seam deterioration.
Best Practices for Seam Re-Welding
Whether it’s torch-applied SBS or self-adhered APP modified bitumen, follow these industry-supported steps:
Clean the Area: Remove dirt, debris, and loose granules.
Dry the Surface: Moisture in seams can cause steam and delamination.
Heat Evenly: Use a controlled flame or hot air welder to soften the bitumen.
Apply Pressure: Roll the seam with a weighted roller to ensure adhesion.
Check for Voids: Probe the seam after cooling to confirm full bonding.
Per ARMA guidelines, always match the patching material to the original membrane type.
FAQs
How often do modified bitumen seams need to be re-welded?
With proper installation and maintenance, seams can last 15–20 years. Re-welding may be needed after severe storms, poor initial installation, or aging past 10–12 years.
Can you re-weld seams in cold weather?
Yes, but the surface must be dry and above 40°F for best adhesion. In colder temps, seams may need primer or extended heating times.
Is seam re-welding a DIY job?
Not recommended. Improper heating or pressure can cause more damage. Hire a qualified roofing contractor familiar with bitumen systems.
Local Help from Roof Nuts
If you're in Denver, Colorado Springs, Atlanta, or Savannah, our certified crews at Roof Nuts can evaluate your modified bitumen roof and re-weld seams quickly and correctly.
📞 Colorado: 303-276-2403
📞 Georgia: 404-476-6851
🌐 RoofNutsCO.com | RoofNutsGA.com
Don't wait for water stains to show up inside—inspect your seams annually and act early. Seam re-welding is fast, cost-effective, and can extend the life of your roof by years.
