MgO Sulfate board is an excellent choice for a roof substrate, particularly in high-performance or fire-rated roofing systems. Because it is chloride-free, it avoids the structural risks associated with traditional MgO boards when they come into contact with metal roof components.
Role as a Roofing Substrate
In a roofing assembly, the MgO Sulfate board acts as the rigid deck or recovery board. It provides a flat, stable surface for the final waterproofing layer.
- System Compatibility: It is compatible with most common roofing membranes, including TPO, EPDM, PVC, and modified bitumen.
- Fire Barrier: Because it is A1 non-combustible, it is often used as a “fire shield” over wood or metal joints to meet strict building codes.
- Impact Resistance: It provides a hard surface that protects the roof insulation from “puncture damage” caused by hail or foot traffic during maintenance.
- Why it Beats Other Substrates
| Feature | MgO Sulfate Board | Gypsum Roof Board | Fiber Cement |
| Fire Rating | Highest (A1) | Good | Good |
| Water Damage | High resistance | Can soften/mold | Very high resistance |
| Weight | Lightweight | Heavy | Very Heavy |
| Corrosion | Zero | Low | Zero |
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MAR
2026
MAR
2026
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