SBS Membrane — Overview
SBS (Styrene-Butadiene-Styrene) modified bitumen membranes are premium waterproofing sheets produced by blending SBS elastomeric polymer with penetration-grade bitumen. The addition of SBS polymer transforms standard bitumen into a highly elastic, rubber-like material with outstanding cold-temperature flexibility and crack-bridging properties — making SBS membranes the preferred choice for cold climates, green roofs, and high-movement structures.
What is SBS Modification?
Styrene-Butadiene-Styrene (SBS) is a thermoplastic elastomer that, when blended with bitumen at concentrations of 12–15%, creates a material with dramatically improved elastic properties:
- Remains flexible at temperatures as low as -20°C
- High elongation at break (up to 150%)
- Excellent crack-bridging and movement accommodation
- Recovers original dimensions after stretching (elastic memory)
- Compatible with self-adhesive application systems
Technical Specifications
| Property | Value | Test Method |
|---|---|---|
| Softening point | 110–130°C | ASTM D36 |
| Cold flexibility | -20°C to -25°C | EN 1109 |
| Tensile strength (L/T) | ≥ 700/500 N/50mm | EN 12311-1 |
| Elongation at break | ≥ 100% | EN 12311-1 |
| Heat resistance | 110°C | EN 1110 |
| Water impermeability | Pass (200 kPa) | EN 1928 |
| Thickness | 3–5 mm | EN 1849-1 |
| Carrier | Polyester / Fiberglass / Composite | — |
Key Applications
Cold Climate Roofing SBS membranes are the standard choice for roofing in cold climates where thermal cycling and freeze-thaw movement would crack conventional bitumen membranes:
- Scandinavia, Canada, Russia, Central Asia
- High-altitude construction
- Cold storage facilities
Green and Vegetated Roofs SBS membranes — particularly root-resistant grades — are widely used as the primary waterproofing layer in green roof assemblies:
- Extensive green roofs (sedum, grass)
- Intensive green roofs (shrubs, trees)
- Biodiverse and brown roofs
Tunnel and Underground Waterproofing The elasticity and crack-bridging properties of SBS membranes make them ideal for tunnel lining waterproofing:
- Road and rail tunnels
- Metro and subway structures
- Underground car parks
Below-Grade and Foundation Waterproofing SBS membranes — including self-adhesive grades — provide reliable below-grade waterproofing for:
- Basement walls and floors
- Foundation slabs
- Elevator pits
Bridge Deck and Infrastructure SBS membranes provide elastic waterproofing for bridge structures subject to dynamic loading and thermal movement.
SBS vs APP — When to Choose SBS
| Criterion | Choose SBS | Choose APP |
|---|---|---|
| Climate | Cold / temperate | Hot / temperate |
| Flexibility required | High movement | Low to moderate |
| Installation | Torch or self-adhesive | Torch-applied |
| Below-grade | Excellent | Good |
| Green roof | Preferred | Acceptable |
| UV exposure | Covered/protected | Exposed |
Advantages
- ✅ Outstanding cold flexibility — remains flexible to -20°C
- ✅ High elongation — up to 150% elongation at break
- ✅ Elastic memory — returns to original shape after deformation
- ✅ Crack-bridging — accommodates structural movement and settlement
- ✅ Self-adhesive options — for flame-free installation zones
- ✅ Root-resistant grades — certified for green roof applications
- ✅ Long service life — 25–30 years with proper installation
- ✅ Versatile — suitable for roofing, below-grade, and civil applications
Quality Standards
- EN 13707 — Reinforced bitumen sheets for roof waterproofing
- ASTM D6163 — SBS modified bituminous sheet materials
- EN 1928 — Water impermeability
- EN 1109 — Flexibility at low temperature
- EN 1110 — Heat resistance
- FLL Guidelines — for green roof root resistance certification
