Why MgO Board Wall Sheathing Outperforms Traditional Wall Sheathing: Real-World Tests

MgO board can withstand temperatures up to 800°C (1472°F) without igniting. These boards perform better than traditional wall sheathing materials in fire safety tests. Our tests show that magnesium oxide boards protect exceptionally well against fire, water, and impact damage. This makes them a great choice for residential and commercial construction projects. Most conventional sheathing boards can warp or deteriorate when exposed to moisture. MgO boards stay structurally sound in both humid and dry environments. These sheathing boards weigh 20 to 30 percent less than other cement-based options. The lighter weight makes installation easier and cuts down on labor costs.

MgO boards shine in durability and safety, but there's more to them. Manufacturing these magnesium oxide boards uses 25 to 50 percent less energy than traditional materials like Portland cement. This appeals to builders who care about environmental impact. Buildings with magnesium oxide sheathing board often qualify for lower insurance premiums because of their fire-resistant properties. They also help cut down energy costs for heating and cooling. Test results show that MgO boards consistently beat traditional wall sheathing materials in many performance categories.

Understanding Magnesium Oxide (MgO) Wall Sheathing Boards

MgO sheathing boards are a game-changer in modern construction that's giving traditional materials like plywood, oriented strand board, and gypsum products a run for their money. These boards are becoming more popular thanks to their great performance and eco-friendly features. My hands-on construction experience backs up what the research shows - these boards pack some impressive benefits that deserve a closer look.

Composition of magnesium oxide board

MgO boards combine several elements that create their unique properties. The boards' core is magnesium oxide—a natural mineral compound that forms when magnesium and oxygen combine under specific pressure and heat conditions. This process creates a stone-like material after heating that gives the board its strength and durability.

The manufacturing starts with magnesium oxide powder mixed with a binding agent, for the sulfate-based new formulation of magnesium sulfate (MgSO₄). These binders kick off important hydration reactions that build the boards' structural strength. The manufacturers also add several key materials:

• Wood dust: Adds flexibility and stops cracking

• Perlite: Makes the board lighter and better at insulating

• Fiberglass mesh: Makes it stronger and more impact-resistant

• Non-woven fabric: Helps resist moisture and adds flexibility

  
  

China and Europe supply most raw magnesium carbonate, which goes through calcination to become magnesium oxide powder. Manufacturers grind this powder and mix it with water, binding agents, and other components to create the slurry that turns into the final sheathing board.

These boards are great for eco-conscious builders because they need 25-50% less energy to make than Portland cement or calcium hydroxide. The boards are also free of harmful substances like asbestos, formaldehyde, ammonia, silica, and benzene.

How sulfate-based MgO differs from chloride-based variants

The construction industry now uses two main types of MgO boards: ones made with magnesium chloride (MgCl₂) and others with magnesium sulfate (MgSO₄). These binding agents create boards that work quite differently in terms of performance and durability.

Magnesium chloride-based boards, or MOC (magnesium oxychloride), are the original and most common MgO board type. These boards come from Sorel cement and form when light-burned MgO mixes with concentrated magnesium chloride brine. They're popular but face a big challenge - they tend to soak up moisture from their surroundings.

Magnesium chloride naturally pulls in and holds water molecules from the air around it. This can lead to what builders call "sweating" or "weeping" boards, where moisture leaks out slowly. This moisture not only makes the board weaker over time but can also rust nearby metal fasteners and framing.

Magnesium sulfate-based boards (MOS) came along as an alternative in 1891. These boards use magnesium sulfate instead of magnesium chloride as the binding agent.

This chemical switch brings some real advantages:

The sulfate-based boards handle moisture much better. They soak up way less water in humid conditions and keep their shape even in 90% relative humidity. Since 2010, after Denmark lost over €100 million due to moisture-damaged chloride-based boards, builders have started choosing sulfate-based options more often.

Among the sulfate MGO board, the most innovative and creative formulation is the Jinpeng group’s MagMatrix brand BMSC 517 new sulfate MGO BOARD formulation and technology.

The sulfate-based BMSC 517 news sulfate MGO boards do not corrode the metal they touch. This means metal framing systems last longer - a big plus for building longevity.

The trade-off is that MOS boards aren't quite as strong as their MOC cousins. Some manufacturers have worked around this by coming up with better formulas and production methods to make them more consistent.

A new player has entered the game - boards using basic magnesium sulfate cementitious 517(BMSC 517).

Builders are starting to embrace magnesium oxide sheathing boards as they see how well these versatile panels work in different situations. From keeping heat in to keeping moisture out, these panels offer some compelling advantages over traditional sheathing materials, especially when installed correctly.

Fire Resistance Performance in Real-World Tests

Fire resistance is one of the most compelling advantages that MgO boards bring to construction applications. Lab testing shows these boards perform better than traditional sheathing materials. This makes magnesium oxide boards a popular choice in projects where fire safety matters most.

ASTM E136 and E84 fire rating results

The ASTM E136 test is the gold standard to assess if building materials are non-combustible. This tough evaluation puts material samples in a vertical tube furnace heated to 750°C (1382°F) for at least 30 minutes. Materials pass this test only when four specimens complete the evaluation. Three of these must meet two key criteria: surface and interior temperatures can't rise more than 30°C above the stabilized furnace temperature, and specimens must not flame after 30 seconds.

The ASTM E136 guidelines show that building materials with at least 3% combustible material are more likely to fail non-combustibility testing. This is a big deal as it means that MgO boards' Total Organic Carbon (TOC) content varies a lot between manufacturers:

Independent research confirms that several prominent MgO structural panels in the US market fail ASTM E136 testing despite what manufacturers claim. These samples recorded maximum temperatures much higher than the 780°C (1436°F) failure threshold.

Some MgO board manufacturers show different results. MagMatrix's MgO panels were tested in 2018 by Intertek and proved non-combustible according to ASTM E136. MagMatrix Structural panels also meet ASTM E136 standards.

The ASTM E84 test, also called the Steiner Tunnel Test, is another significant fire safety evaluation. Quality magnesium oxide boards excel in this test that measures flame spread and smoke development across a material's surface over 10 minutes:

• Flame Spread Index: 0 (lowest possible rating)

• Smoke Developed Index: 0 (lowest possible rating)

  
  

These results are much better than traditional building materials. MgO boards earn a Class A (Class 1) fire rating - the highest possible classification. Materials with this rating show minimal flame spread (FSI of 0-25) and limited smoke production (SDI of 0-450).

Building codes sometimes ask for an extended ASTM E84 test with 20 extra minutes. The flame front can't move 10.5ft or more beyond the burner's centerline during this extended test. High-quality MgO boards show no flame movement at all during this extended testing period.

Quality magnesium oxide boards also resist heat remarkably well. Many products can handle temperatures above 750°C (1,382°F) for over 30 minutes without changing color. These boards show no flame spread even at 1,200°C (2,192°F).

Non-combustibility in multi-family housing tests

Multi-family construction needs stricter fire safety requirements. Complete wall assemblies must be tested instead of individual parts. The ASTM E119 (also known as ANSI-UL 263) is the key standard here.

ASTM E119 puts complete wall assemblies through standardized fires that exceed 1600°F. This tough test looks at three key factors:

1. Structural integrity: The ability to support design loads

2. Fire containment: Prevention of flames passing through the wall

3. Thermal insulation: Limiting temperature rise on the unexposed side

   
   

Well-made magnesium oxide boards get impressive 1-hour and 2-hour fire ratings in wall assemblies without extra materials. Some manufacturers have achieved UL two-hour fire-rated floor/ceiling assemblies (like Design #UL G575). These ratings meet building code requirements for many uses, including exterior load-bearing walls in Construction Types III and VA, which need 2-hour and 1-hour fire resistance ratings.

MgO boards' unique moisture content makes them great at fighting fires.

These boards release up to 30 pounds of water as vapor during a fire, which helps cool and contain flames. When exposed to high heat, these panels char and absorb thermal energy instead of making toxic fumes or smoke. This delays fire and smoke spread.

NFPA 285 compliance matters most for exterior walls in multi-family construction. This standard looks at how fire spreads in exterior wall assemblies with combustible parts. Many MgO board manufacturers have approvals for over 20 different NFPA 285 wall assemblies. Architects can keep code compliance while creating different exterior wall systems.

Multi-family housing developers now look for magnesium oxide sheathing boards because they work so well against fire. Tests show MgO boards resist fire for up to 4 hours, making buildings safer for people inside. This works great in Wildland Urban Interface (WUI) zones, where MgO sheathing boards follow Section 707A of the California Building Code.

Moisture Resistance and Mold Prevention Capabilities

Quality MgO boards excel at moisture protection, especially in construction where water damage can compromise structural integrity. These innovative building materials manage water better than traditional sheathings and provide excellent fire resistance.

Water absorption rate in humid environments

MgO boards react differently to moisture-rich environments. Their chemical makeup plays a big role in how they handle water. Research shows clear differences between the two main types of MgO boards.

Tests show that magnesium sulfate-based (MOS) boards absorb 37% less moisture than magnesium chloride-based (MOC) products at 95% relative humidity. Magnesium chloride naturally draws in moisture from the air because it's hygroscopic. Magnesium sulfate doesn't share this trait, which makes it work better in humid conditions.

High-quality MgO boards absorb just 0.34% moisture compared to gypsum board's 3%. Quality MgO sheathing takes in 4-11% moisture when relative humidity hits 75%, while standard plywood soaks up much more and starts breaking down.

Chloride-based boards' hygroscopic nature creates problems. MOC boards can develop a "crying" or "weeping" effect in high humidity - water droplets with chloride ions form on the surface. Denmark first reported this issue, where poor-quality MOC boards caused over €100 million in damage.

Tests revealed that about two-thirds of MOC boards showed this issue within 57 days of high humidity exposure. The moisture these boards collect speeds up corrosion in nearby metal fixtures and fasteners.

Sulfate-based MgO boards stay dry under similar test conditions. This difference matters a lot for buildings in areas where humidity levels change often.

Performance in coastal and flood-prone areas

Quality MgO sheathing boards work great in coastal regions and flood-prone areas. These boards don't rot, warp, or swell when wet, thanks to their stone-like properties.

MgO boards stand out because they keep their shape when wet. Wood-based products expand, contract, and break down with moisture, but magnesium oxide boards stay stable. This stability helps in areas with frequent rain or humidity changes.

MgO boards resist water damage well, but they're not waterproof. Long exposure to water can cause hydrothermal expansion. Manufacturers suggest using water-resistant barriers with these boards for the best long-term results.

These boards handle wetting-drying cycles amazingly well. After 25 cycles, quality MgO panels barely changed in strength. OSB lost 40% strength, plywood dropped 9%, and gypsum fell 36-52%. These numbers show why MgO boards last longer in wet environments.

MgO boards also fight mold effectively in humid areas. Mold can't grow on these boards. Their inorganic makeup offers no food for mildew or fungi, unlike paper-faced gypsum. The high alkalinity actively stops microbial growth.

Lab tests back this up. MgO sheathing scored a perfect 0/0/0 on the ASTM G21 fungal resistance test, showing complete mold resistance in all moisture conditions.

MgO boards' water and mold resistance makes them perfect for:

• Bathrooms and kitchens with high moisture

• Damp basements

• Coastal homes fighting salt spray and humidity

• Flood-prone areas

• Hurricane zones

  
  

Quality MgO boards help create healthier indoor spaces with better air quality. They prevent mold and mildew growth while maintaining structural strength - a unique advantage over traditional sheathing materials.

Impact Resistance and Structural Durability

MgO boards stand out from regular sheathing options because of their structural integrity, especially in tough construction projects. Tests and real-life use show that these boards perform better than alternatives when faced with physical stress and environmental challenges.

Drop test results on MgO vs OSB

Drop tests show big differences between MgO boards and regular oriented strand board (OSB). MgO sheathing boards barely get damaged in standard impact tests. OSB, on the other hand, often cracks, splinters, or gets permanently deformed.

MgO boards really shine when it comes to handling impacts in wet conditions. These boards keep their strength even after getting wet, which makes them much more reliable in unpredictable weather. OSB and plywood don't do as well - they either become brittle or too soft when moisture levels change.

This toughness goes beyond lab tests. A building expert put it this way: "Even painted, these MgO panels are tough and durable. You can run a cart or a hammer into them and they won't be damaged". This real-life toughness means lower maintenance costs over time, especially in busy areas like:

• Breezeways and hallways that get bumped a lot

• Stairwells that just need tough walls

• Commercial spaces where heavy equipment moves around

  
  

MgO boards are tough because they're made differently. Unlike wood products that use glued wood fibers, high-quality magnesium oxide creates something more like stone, with even density throughout. This prevents the splitting and peeling you often see with OSB after it gets hit repeatedly.

Tests show these boards also hold fasteners really well. A single #10-13 pancake head screw in half-inch MgO sheathing can hold more than 155 pounds - that's almost five times stronger than the usual 32-pound requirement. You can attach cladding directly to the sheathing without extra support.

Shear strength tests back this up too. Half-inch MgO structural sheathing handles maximum shear stress above 280 psf, matching or beating traditional OSB and plywood. Architects and engineers can use MgO boards instead of regular sheathing in load-bearing spots without worry.

Wind load resistance in hurricane zones

MgO boards really prove their worth in places with extreme weather. Quality boards can handle wind speeds over 200 mph without failing. This makes them perfect for hurricane zones where building strength directly affects safety.

These boards handle wind so well for a couple of reasons. They're naturally rigid, so they don't flex and wear out like other materials during strong winds. They also hold fasteners better, preventing the nails from popping out during pressure changes.

Quality MgO panels can stay exposed for up to six months during construction while keeping their warranty. This helps a lot in coastal areas where weather often delays construction.

MgO sheathing works even better when used in Structural Insulated Panel (SIP) systems. Tests show that MgO-faced SIPs stay strong under simulated hurricane conditions. Unlike OSB-faced SIPs that often fall apart in humid coastal air, well-made MgO panels keep their strength.

These boards also keep their shape no matter the weather. Traditional materials often swell, warp, or come apart in harsh weather, but MgO boards stay the same size and keep their strength. They'll perform just as well years later in tough conditions.

Architects and builders working in hurricane-prone areas get more durable buildings that need less maintenance and last longer. MgO boards beat regular sheathing materials technically, especially in areas that face lots of severe weather.

Thermal and Acoustic Insulation Properties

MgO boards offer more than just durability and safety. These boards deliver remarkable thermal and acoustic advantages that boost building comfort and energy efficiency. Their insulation qualities make them valuable for residential and commercial construction projects where temperature control and sound management matter most.

Thermal conductivity comparison with plywood

MgO boards outperform traditional wall sheathing materials in thermal performance. Their thermal conductivity value is just 0.038 W/mK, which means they conduct heat at a much lower rate than conventional materials. This measurement is way below drywall (0.160 W/mK) and cement board (0.130 W/mK). MgO boards are four times better at limiting heat transfer.

Some MgO products have a thermal conductivity coefficient of 0.216 W/m·K, which still shows excellent insulation properties. The specific formulation and density of the board usually cause this variation. Even with higher conductivity measurements, MgO sheathing boards resist heat flow better than most building materials.

The thermal benefits really shine when MgO boards include insulation components. To cite an instance, MgO panels with pressure-fused polyurethane foam reach an R-value of 6.5 per inch. This beats both polystyrene and conventional spray-applied polyurethanes. Such integration creates a detailed thermal barrier that improves the building's envelope performance.

MgO sheathing boards' superior thermal properties lead to practical benefits:

• Lower heating and cooling costs by minimizing thermal bridging

• More consistent indoor temperatures across seasons

• Less energy use in winter and summer

• Better comfort by eliminating cold or hot spots on walls

Buildings with MgO board systems show more consistent indoor temperature distribution compared to those built with plywood or OSB sheathing.

Sound transmission class (STC) ratings

MgO boards excel at acoustic performance, which is vital for multi-family housing, commercial spaces, and anywhere sound control matters. Lab tests show that floor assemblies with STEADFAST™ sheathing panels achieve an STC rating of 53 and an impact insulation class (IIC) of 72 when tested to ASTM E90 and ASTM E492 standards.

Wall assemblies with MgO boards consistently achieve STC ratings between 53-54 on UL-rated assemblies. These numbers exceed typical building code requirements for sound isolation between adjacent living spaces. MgO's natural density helps block airborne noise transmission effectively.

Sound-proofing benefits become clear in specific uses. A 6mm MgO board provides 29dB noise resistance. A partition system using double-sided 9mm magnesium oxide board with 75mm keel and 50mm rock wool achieves noise resistance above 42dB.

MgO boards work well with other sound-dampening materials. Their rigid structure makes them perfect for acoustic treatments, creating high-performing systems for:

1. Theater and studio spaces that need precise sound control

2. Hotel rooms requiring guest privacy

3. Office environments where focus needs minimal distraction

4. Educational facilities that benefit from quieter learning spaces

   
   

MgO boards offer excellent thermal and acoustic properties in one sheathing material, giving them an edge over traditional options that might excel in just one area. Builders can meet multiple performance requirements with a single product, which streamlines materials selection and installation.

Installation Process and On-Site Handling

MgO boards work best when you install them correctly. My experience shows that knowing how to cut, fasten, and handle these materials will give you the best results and make your construction projects last longer.

Cutting and fastening techniques for MgO boards

You need the right tools and methods to cut MgO boards cleanly and precisely. A circular saw with a carbide-tipped blade works best for straight cuts. These blades create cleaner edges and last longer when cutting through dense magnesium oxide material. The score and snap method with a utility knife works well for thinner boards under 8mm.

Here's what you need to do when cutting:

• Work in a well-ventilated area, outdoors if possible

• Put on safety equipment - dust mask, gloves, and safety goggles

• Support the board's ends to stop it from cracking

MgO boards don't need OSHA-approved respirators during cutting, but you should still wear a standard dust mask.

Your fastening needs to meet these requirements:

• Pick corrosion-resistant fasteners (hot-dipped galvanized or better)

• Wood framing needs 0.113-inch ring-shank nails that go at least 1.5 inches into the frame

• Choose wood-rated (W) or steel-rated (S) countersunk screws; wood screws must go 1 inch into framing

• Keep fasteners 8 inches apart maximum along edges and field

• Start fastening from one side and work across instead of securing corners first

  
  

Your fasteners should sit flush or slightly below the MgO board surface. Place them 3/8-inch to 3/4-inch from edges and at least 2 inches from corners.

Weight and handling comparison with gypsum board

MgO boards weigh more than regular gypsum products, which changes how you work with them on site. This extra weight brings both good and bad points. The density makes MgO boards stronger and more durable, but they're harder to move around and position.

MgO boards need simple tools like drills, screws, and saws for installation, unlike gypsum boards that need special finishing tools such as tape and joint compound. You can use MgO boards right after installation, while gypsum products need up to seven days to set properly.

Regular construction crews can install MgO boards without special training. The material's weight should shape your installation plans and team size. New installers will find that thinner MgO sheets bend more easily than Portland cement boards while staying stronger than gypsum products.

Cost Analysis

MgO boards' economic value shows a complex relationship between costs and benefits that goes beyond the purchase price. These boards cost USD 1.50 to USD 3.00 per square foot, which is higher than gypsum (USD 0.30-0.70) or OSB (USD 0.50-1.00). Budget-conscious builders might hesitate due to this price difference, especially in cost-sensitive markets.

The long-term savings make up for the purchase costs. MgO boards' exceptional durability eliminates the need for frequent replacements that other materials require. This longer lifespan saves money throughout a building's lifetime, making them a smart choice for future-focused builders.

The boards' installation benefits help offset their higher price. They weigh 20-30% less than other cement-based options, which reduces labor costs. Contractors can install these boards using a 'tile' approach and paint them the same day. This speeds up project completion by a lot.

These boards offer more cost advantages:

• No corner beads needed (40% savings compared to gypsum installation)

• No backing materials required for shelving, cabinets, or grab bars

• Simple disposal without special waste removal[371]

• Less bracing needed due to superior stiffness

  
  

Builders can use thinner MgO boards—12mm for walls and 6mm for ceilings—which cuts material costs. The boards' fire-resistant properties may also reduce insurance premiums.

MgO sheathing boards deliver positive ROI from a complete financial perspective. Their resistance to moisture, fire, mold, termites, and impacts prevents costly damages and repairs. Builders and homeowners now recognize that despite higher upfront costs, MgO boards' lifetime advantages make them economically smart for modern construction projects.

Brand Old website: www.magmatrixboards.com

Group New Website: www.jinpenggroups.cn