Magnesium Oxide Roof Sheathing Board
Magnesium Oxide Roof Sheathing Board is a new generation of chlorine-free, eco-friendly magnesium structural sheathing dedicated to roof systems. It has undergone all-round performance optimization and structural customization for the core roof requirements such as outdoor weather resistance, structural load-bearing, water and seepage proofing, and fire and corrosion protection, completely solving the industry pain points of traditional roof sheathing (wood-based boards, gypsum boards, cement boards, magnesium oxychloride boards) such as easy rot, flammability, moisture absorption and deformation, metal corrosion, and short service life.
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Product Introduction
Magnesium Oxide Roof Sheathing Board
Magnesium Oxide Roof Sheathing Board (abbreviated as MgO Roof Sheathing) is a chlorine-free, eco-friendly magnesium structural sheathing specially developed for building roof systems. It features the magnesium oxysulfate (MgO-MgSO₄-H₂O) ternary cementitious system as its core, combined with high-toughness reinforcing materials, weather-resistant fillers and special modifiers, and is manufactured through high-pressure pressing and constant-temperature curing. Optimized for core roof performance requirements such as wind load resistance, weathering resistance, water and moisture proofing, and structural load-bearing, this board completely solves the pain points of traditional roof sheathing (wood-based board, gypsum board, ordinary cement board) such as rot, flammability, moisture absorption and deformation, and metal corrosion. It is a dedicated structural substrate for various roof systems including light steel roofs, sloped roofs and flat roofs, widely applied in roof engineering of industrial, civil and prefabricated buildings, and compatible with mainstream international roof waterproofing and decorative finish layers.
Based on conventional magnesium boards, MgO Roof Sheathing has undergone ingredient upgrades and structural customization for roof scenarios such as outdoor service, slope load bearing, rain scouring, and high-low temperature cycles, ensuring the board meets the special mechanical and environmental requirements of roofs. The core ingredients and their functions are shown in the table below, and the structural design prioritizes flexural, anti-seepage and anti-slip properties.
| Ingredient Category | Core Materials | Exclusive Functions for Roofs |
|---|---|---|
| Cementitious System | High-purity active MgO, industrial-grade high-quality MgSO₄ | Forms stable magnesium oxysulfate crystalline phases, chlorine-free and non-efflorescent, provides basic strength and water resistance, and causes no corrosion to metal keels |
| Reinforcing Materials | Double-layer high-toughness glass fiber mesh, basalt fiber strips | Improves the board's flexural strength and impact resistance, preventing cracking and fracture caused by roof loads and strong winds |
| Fillers | Wood fiber, vitrified microspheres, lightweight perlite | Reduces board density (lowering roof structural load), enhances weather resistance and thermal insulation, and avoids board embrittlement under extreme temperatures |
| Modifier System | Weather-resistant polymers, UV stabilizers, water repellents | Optimizes hydration reaction, improves the board's outdoor anti-aging, UV resistance and rain scouring resistance performance, and reduces water absorption rate |
- Basic Structure: Double-layer high-toughness glass fiber mesh + magnesium oxysulfate composite core + weather-resistant modified coating, comprehensively improving stability for outdoor use;
- Edge Design: Mainly shiplap edge, with tongue-and-groove (T&G) edge optional for some specifications. The overlapping joint forms a sealed lap to prevent rainwater from seeping into the roof base through seams;
- Surface Design: Optional matte anti-slip surface to prevent workers from slipping during roof construction, and simultaneously improve the interfacial adhesion with roof waterproof membranes/bonding layers;
- Thickened Core: For long-span roofs, a reinforced core design is available to enhance the board's span load-bearing capacity.
All performance indicators of MgO Roof Sheathing are formulated around roof application scenarios, focusing on meeting four core requirements: structural load-bearing, weathering resistance, water and fire proofing, and dimensional stability. All indicators comply with international/domestic building roof material standards such as ASTM, EN and GB, with typical parameters shown in the table below:
| Performance Indicator | Typical Value | Applicable International Standards | Adaptation Explanation for Roof Scenarios |
|---|---|---|---|
| Fire Rating | Class A1 Non-Combustible | EN 13501-1, ASTM E119 | Non-flammable at 1200℃ with no toxic smoke release, eliminating roof fire hazards from the substrate level |
| Density | 800-1050 kg/m³ | ASTM C1185 | Over 40% lighter than ordinary cement roof boards, greatly reducing roof structural load and avoiding main building settlement |
| Flexural Strength | ≥15 MPa (transverse/longitudinal) | GB/T 7019, ASTM C966 | Far higher than wall sheathing, withstanding roof slope loads, snow loads and strong wind impacts |
| Water Absorption | ≤8% | JIS A5441 | Low water absorption, preventing board deformation and strength loss due to moisture absorption after rain immersion |
| Weather Resistance | No cracking or chalking after 50 cycles of high-low temperature test (-40℃~80℃) | ASTM D2244 | Suitable for roof use in extreme temperature areas such as high-altitude, coastal and northern regions |
| Wind Load Resistance | ≥2.0 kPa | ASTM E1399 | Withstands negative pressure impact of strong winds on the roof and prevents board falling off |
| Formaldehyde Emission | Not Detected (ND) | EU E0 Standard | Zero formaldehyde, asbestos-free, VOC-free, green and eco-friendly, suitable for roof spaces connected to the interior |
| Dimensional Stability | Dry shrinkage and moisture expansion rate ≤0.1% | ASTM D1037 | Almost no deformation when outdoor temperature and humidity change drastically, avoiding seam cracking and waterproof membrane damage |
| Impact Strength | ≥3.0 kJ/m² | ASTM C1415 | Withstands impacts from roof construction and hail, preventing board damage |
| Chloride Ion Content | ＜0.01% | Magnesium Building Board Standard | Chlorine-free, completely avoiding corrosion to light steel roof keels and metal accessories |
MgO roof sheathing has clear core advantages: better outdoor performance, stronger structural safety, and easier construction. It beats traditional wood boards, gypsum board, regular cement board, and standard magnesium oxide boards in durability, weather resistance, and compatibility - making it the top choice for modern roofing.
Chlorine-Free & Weatherproof
- No white efflorescence, no moisture absorption, no corrosion to steel frames. Perfect for light steel roofs and works great in coastal, high-humidity, and high-salt environments.
- With UV and weather stabilizers, it stays flexible at -40°C and doesn't warp at 80°C, suitable for cold northern, hot southern, and high-altitude areas.
- Low water absorption, won't swell or deform even in heavy rain, ideal for gutters and roof corners.
Lightweight & Strong
- Lighter than regular cement board and similar to solid wood, reducing roof load and lowering the risk of structural settlement.
- High bending and wind resistance, stands up to snow, hail, and strong winds - stable even on large industrial roofs.
- Very stable dimensions, won't warp or crack, preventing roof membrane damage and leaks.
A1 Non-Combustible Fire Protection
- Roofs are fire-prone from lightning, wiring issues, or external flames. MgO sheathing is non-flammable even at 1200℃, with no toxic smoke.
- Forms a fireproof base layer, far safer than wood and gypsum, meeting strict fire codes for factories and commercial buildings.
Easy to Install & Compatible
- Can be cut, nailed, and drilled with regular tools, flexible for custom roof shapes.
- Works directly with asphalt shingles, metal roofing, tiles, and waterproof membranes - no extra treatment needed.
- Simple to install without heavy machinery, cutting high-altitude construction time and cost.
Long-Lasting & Low Maintenance
- Insect-proof, mold-resistant, and anti-aging. The chlorine-free formula protects metal parts.
- Service life over 50 years, with almost no upkeep. Much longer than wood (5–10 years) and standard cement board (15–20 years).
Eco-Friendly & Green Building Certified
- No formaldehyde, asbestos, VOCs, or chloride. Safe to produce and recyclable.
- Meets LEED and green building standards for modern eco-friendly construction.
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| Comparison Item | MgO Roof Sheathing | Solid Wood Substrate | Ordinary Gypsum Roof Board | Ordinary Cement Roof Board | Traditional Magnesium Oxychloride Roof Board |
|---|---|---|---|---|---|
| Fire Rating | Class A1 Non-Combustible | Class B3 Flammable | Class B Combustible | Class A1 Non-Combustible | Class A1 Non-Combustible |
| Water & Moisture Resistance | Excellent (Water Absorption ≤8%) | Poor (Easily rotted & deformed) | Extremely Poor (Softens in water) | Good (Easily cracked) | Poor (Efflorescent & moisture-absorbent) |
| Anti-Metal Corrosion | Excellent (Chlorine-free) | No Impact | No Impact | Good | Extremely Poor (Corrodes keels) |
| Weather Resistance | Excellent (Stable at -40℃~80℃) | Poor (Easily aged & cracked) | Poor (Easily chalked at high temperature) | Medium (Embrittles at low temperature) | Medium (Easily efflorescent & chalked) |
| Density (kg/m³) | 800-1050 | 400-600 | 700-800 | 1600-1800 | 900-1100 |
| Flexural Strength | ≥15MPa | ≥10MPa | ≤5MPa | ≥20MPa | ≥12MPa |
| Service Life | More than 50 years | 5-10 years | 3-5 years | 15-20 years | 8-12 years |
| Eco-Friendliness | Zero formaldehyde, recyclable | Requires anti-corrosion treatment (contains formaldehyde) | Contains VOCs | No harmful substances | Contains chlorine, easily efflorescent |
MgO Roof Sheathing is a universal roof-specific substrate that can be adapted to roof systems of all building types, especially suitable for roof engineering with high requirements for fire protection, weather resistance, anti-corrosion and structural stability. Its core application scenarios are as follows:
- Light Steel Roof Systems: Long-span light steel roofs of industrial factories, warehouses and logistics centers. The chlorine-free feature avoids corrosion to light steel keels, and the lightweight and high-strength performance adapts to the load requirements of long spans;
- Sloped Roof Engineering: Sloped roofs of residential buildings, villas and commercial buildings. The shiplap edge design prevents water seepage, and asphalt shingles, ceramic tiles, colored stone metal tiles and other finishes can be directly laid;
- Flat Roof Engineering: Flat roofs, roof gardens and terrace roofs. Low water absorption is suitable for roof waterproofing, and it can be combined with insulation layers to form a composite roof, with load-bearing capacity meeting the light load requirements of roof gardens;
- Prefabricated Building Roofs: Roofs of container houses, prefabricated houses and modular buildings. Lightweight and high-strength performance adapts to prefabricated assembly processes, and weather resistance meets the outdoor use requirements of temporary/permanent buildings;
- Roof Renovation Engineering: Replacing old wood-based and gypsum roof boards, it can be directly laid on the original base (when strength meets the standard), quickly improving the fire protection, water resistance and durability of the roof, and reducing renovation costs;
- Special Environment Roofs: Roofs in coastal high-salt spray areas, high-altitude high-low temperature areas, rainy humid areas and northern snowy areas, solving the problems of corrosion, deformation and cracking of traditional boards in a targeted manner;
- High-Standard Fire Protection Roofs: Roofs of densely populated/important buildings such as hospitals, schools, shopping malls and data centers. Class A1 fire protection meets the high-standard fire protection requirements of fire fighting.
About The Factory：
Company Advantage：
We are a company dedicated to magnesia cement products. Our main products are Magnesium Oxide Boards (MGO Board) for construction and laminated MgO boards with for furniture and renovation. Our mission is to provide the world's construction markets with environmentally friendly, high-performance and sustainable green materials.
We work with China Magnesium Materials Association (CMMA) and Magnesium Oxide Association (MOCA) in North America to raise awareness and promote the use of magnesium oxide cement products. We focus on the quality control and consistency of the MGO products. We have been actively involved in developing American Society for Testing and Materials (ASTM) standards related with MGO products.
Packing and Shipping:
FAQ
Q: Why must MgO Roof Sheathing use screws with rubber waterproof washers?
A: The roof is a key outdoor waterproof area. Ordinary screws will leave nail holes after fixing, and rainwater can easily seep into the roof base through the nail holes and cause water leakage. When tightened, the rubber waterproof washer on the screw will closely fit the board surface and seal the nail hole, eliminating nail hole water leakage from the source, which is a core waterproof requirement for roof installation.
Q: Can asphalt shingles/ceramic tiles be directly laid on sloped roofs with MgO Roof Sheathing?
A: Yes. The surface of MgO Roof Sheathing has excellent interfacial adhesion, and asphalt shingles, ceramic tiles and other finishes can be directly laid with roof-specific adhesives without additional treatment. The overlapping design of shiplap edges can also improve the overall anti-seepage performance of the roof, forming a double waterproof barrier with the finish layer.
Q: Will MgO Roof Sheathing corrode light steel keels when used in coastal high-salt spray areas?
A: No. The board adopts a chlorine-free magnesium oxysulfate system with a chloride ion content of ＜0.01%, completely avoiding metal corrosion caused by chloride ion migration. Combined with hot-dip galvanized light steel keels, it can be used for a long time in coastal high-salt spray areas without problems such as keel corrosion and board efflorescence.
Q: How does MgO Roof Sheathing compare with solid wood substrates in terms of service life and maintenance costs?
A: MgO Roof Sheathing has a service life of more than 50 years, is naturally insect-proof, mold-proof and anti-aging, and requires almost no post-maintenance. In contrast, solid wood substrates have a service life of only 5-10 years, need regular anti-corrosion and waterproof treatment, and have high maintenance costs. They are also prone to roof water leakage due to corrosion and deformation. Overall, MgO Roof Sheathing has a much higher long-term cost performance than solid wood substrates.
Q: Can MgO Roof Sheathing be directly laid on old wood-based/gypsum boards during roof renovation?
A: If the structural strength of the old base meets the standard and there is no loosening/rot/deformation, MgO Roof Sheathing can be directly laid on the original base without demolition, greatly reducing the cost of renovation construction. If the old base is already rotted or loose, it must be demolished first before laying MgO Roof Sheathing to ensure the stability of the roof structure.
Q: Is the load-bearing capacity of MgO Roof Sheathing sufficient for use in roof gardens?
A: Conventional 15mm/18mm thick MgO Roof Sheathing, combined with densely laid keels, can meet the load-bearing requirements of light-load roof gardens (planting soil thickness ≤30cm, small green plants). For heavy-load roof gardens (planting soil thickness ＞50cm, large shrubs/rockeries), keel reinforcement must be added under the MgO Roof Sheathing, or customized thickened/reinforced boards can be used.
Q: Can MgO Roof Sheathing withstand snow loads when used in northern snowy areas?
A: Yes. With a flexural strength of ≥15MPa and combined with densely laid keels with spacing ≤300mm, the board can withstand conventional snow loads (≤0.5kPa) in northern regions. For blizzard areas, 18mm/20mm thickened boards can be selected, and the keel spacing can be densified at the same time to further improve the snow load-bearing capacity of the roof.
Q: Will roof water leakage occur if the sealant at board splices cracks?
A: If the sealant cracks due to aging, weather-resistant silicone sealant can be replaced in a timely manner, and butyl waterproof tape can be pasted again. The overlapping design of the shiplap edges of MgO Roof Sheathing itself has a certain anti-seepage performance. Even if the sealant cracks slightly, it can prevent rainwater from directly seeping into the base, reserving a buffer time for post-maintenance.
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