Multi-Ply Systems
Modified Bitumen Roofing
Multi-ply systems engineered for industrial strength. Superior impact resistance, foot traffic durability, and reliable performance for demanding commercial environments.
What Is Modified Bitumen?
The Multi-Ply Advantage
Modified bitumen roofing is an evolution of traditional built-up roofing (BUR), enhanced with polymer modifiers: either APP (Atactic Polypropylene) or SBS (Styrene Butadiene Styrene): to improve flexibility, elongation, and temperature performance.
Unlike single-ply systems, modified bitumen is a multi-layer assembly: a base sheet mechanically fastened or adhered to the substrate, followed by one or more cap sheets for surface protection. This redundant construction provides inherent resistance to punctures, foot traffic, and mechanical damage: qualities that single-ply systems cannot match.
For industrial facilities, manufacturing plants, rooftop mechanical equipment areas, and buildings with high foot traffic demands, modified bitumen remains one of the most appropriate solutions available.
System Overview
APP vs. SBS: Two Modifier Types
APP: Atactic Polypropylene
Application: Torch-applied or hot-mopped
- Superior UV and heat resistance
- Higher softening point: ideal for hot Southeast climates
- Smooth or granulated surface options
- Torch application fuses layers for watertight bond
- Common in re-roofing over existing BUR systems
SBS: Styrene Butadiene Styrene
Application: Cold-applied adhesive or self-adhered
- Rubber-like flexibility: accommodates building movement
- Better performance in temperature extremes
- Cold-applied: no open flame required on site
- Self-adhered versions simplify installation
- Preferred for occupied buildings during re-roofing
Technical Specifications
| Property | APP | SBS |
|---|---|---|
| Tensile Strength | 200+ lbf/in | 175+ lbf/in |
| Elongation at Break | 25–40% | 50–150% |
| Softening Point | 230°F+ | 190°F+ |
| Low-Temp Flexibility | -4°F | -22°F |
| Fire Rating | Class A (with suitable cap) | Class A (with suitable cap) |
| UV Resistance | Excellent | Good (requires coating) |
| Puncture Resistance | High | High |
| Foot Traffic Tolerance | Excellent | Good |
| Warranty Range | 10–15 years | 15–20 years |
Is Modified Bitumen Right for Your Building?
We'll evaluate your roof, foot traffic requirements, and budget to recommend the optimal system.
7am – 7pm | Mon–Sun | 24/7 Emergency Response Available