Modified Bitumen Roofing in San Antonio
Modified bitumen is asphalt improved with rubber- or plastic-like polymers, made into reinforced sheets and laid in layers. Tell us about your building and the roof's history, if you know it.
Call (210) 778-8060Commercial roof types
- What a modified bitumen roof is
- Why layers help
- Repairing a modified bitumen roof
What a modified bitumen roof is
It grew out of traditional built-up (tar and gravel) roofing, with factory-made sheets in place of layers mopped together on the roof.
- Sheets are reinforced with polyester or fiberglass
- A base sheet goes down first, then a cap sheet, often with a mineral granule surface
- SBS-modified sheets are rubber-like and flexible; APP-modified sheets are more plastic-like
- Sheets are torched, set in hot asphalt, glued with cold adhesive or self-adhered, depending on the product
Why layers help
With more than one ply, a damaged top layer still has another beneath it to keep water out. Layered sheets also stand up well to punctures and foot traffic. A white granule cap sheet can make the roof cooler.
Repairing a modified bitumen roof
Common problems are open laps between sheets, blisters, cracked or worn cap sheets and flashing that has pulled away. Repairs are made with compatible sheets and materials, and a sound but weathered roof can sometimes be coated.
Commercial roof repair
What to identify before planning work
The existing system
Modified bitumen may be SBS or APP, with different layers and application methods. The present roof determines the repair options.
Where water enters
Note whether stains follow a seam, wall, drain or rooftop unit; those details often matter more than the open field.
How the building is used
Access, odors and occupied areas affect which installation method may be suitable.
Common questions
Is modified bitumen the same as a tar and gravel roof?
No. It comes from the same family, but uses factory-made reinforced sheets rather than layers built up on the roof.
What's the difference between SBS and APP?
Both are polymers added to the asphalt. SBS makes the sheet more rubber-like; APP makes it more plastic-like. The product decides how it's installed.
Tell us about your building
Send the form with the property address and what you need. We'll call to talk it through.