Huber Engineered Woods EXACOR MgO Wall Sheathing 1/2" 4' x 9'

EXACOR MgO panels solve the speed problem that traditional wet-lay fire assemblies create. 30% faster installation than wet-lay systems — that matters when Montana’s construction season runs late April through early October. The panels deliver 1-hour and 2-hour fire-resistance ratings in tested assemblies for Type III and V multifamily construction while cutting out the drying time that gypsum-based systems demand.

This kit shines in multifamily projects, light commercial builds, and anywhere fire ratings drive the spec sheet. Non-combustible throughout the panel core (ASTM E136) means genuine fire protection, not just surface treatment.

Fire-Rated Assembly Performance

The fire numbers tell the whole story. Tested per ASTM E119 & ANSI/UL 263 with both 1-hour and 2-hour ratings achieved in complete assemblies. ICC-ES Evaluation Report ESR-4635 backs the structural claims — not just manufacturer promises.

The panels are also appreciated for their ease of installation, as they can be handled similarly to traditional OSB or plywood, and their dimensional stability and durability. Crews who know wood sheathing can install EXACOR without retraining. Standard wood-cutting tools with carbide-tipped blades or circular saws with masonry blades handle the cutting.

Specification	Value
Panel Size	4 ft x 9 ft (1219 mm x 2750 mm)
Thickness	1/2 in. (12 mm nominal)
Weight	2.7 lb/ft² (approx. 97.2 lbs per 4x9 panel)
Compressive Strength	Approx. 1,300 psi
Flexural Strength	High flexural strength, exceeds 5/8” gypsum board by approx. 10%
Fire Classification	Class A surface-burning classification

The High-density structural Magnesium Oxide (MgO) cement with glass-fiber mesh reinforcement construction creates a panel that handles jobsite abuse better than gypsum while maintaining fire performance. Case studies highlight improved scheduling due to the elimination of ‘wet’ trades and superior jobsite durability against rain and foot traffic.

Installation Speed and Structural Requirements

Fastening follows standard sheathing patterns. Typically 6 in. on-center at edges and 12 in. on-center in the field gets the job done. Stagger joints by at least 12 in. in vertical applications for proper load distribution.

The panels demand respect for expansion. Maintain 1/8 in. to 1/4 in. expansion gap at panel perimeters and joints. Skip this and panels can buckle — same as any rigid sheathing in Montana’s temperature swings.

Corrosion-resistant nails or screws (e.g., self-drilling MgO screws or common nails) are required. Regular drywall screws won’t cut it. The material compatibility extends beyond fasteners — Compatible with polyurethane and silicone sealants as specified in the EXACOR Installation Manual.

For finishing, the panels take whatever contractors throw at them. Accepts stucco, EIFS, siding, paint, and interior gypsum finishes. Can be used in conjunction with Zip System tapes and liquid flashings for air/water sealing — integrating with modern weather barrier systems.

Bottom Line for Montana Contractors

EXACOR earns its place on Type III and V multifamily jobs where fire ratings matter. The 30% faster installation times compared to gypsum-based systems translate to real schedule gains in Montana’s compressed building season. At 97 pounds per panel, it’s heavier than OSB but lighter than multiple layers of 5/8” Type X gypsum.

10-Year Commercial Limited Warranty; Covers material defects, dimensional stability, and moisture resistance; Requires project registration and a pre-construction meeting with Huber technical staff to qualify for full benefits. That pre-construction meeting requirement signals this isn’t grab-and-go material — it’s engineered product that demands proper installation.

The trade-off is clear. Higher material cost than standard sheathing, offset by labor savings and simplified assemblies. The panels can help reduce the number of layers needed for 2-hour fire-rated exterior walls, potentially lowering material and labor costs. For contractors chasing fire ratings in multifamily work, EXACOR delivers genuine performance backed by third-party testing.

Frequently Asked Questions

What tools do I need to cut EXACOR MgO panels?

Standard wood-cutting tools with carbide-tipped blades or circular saws with masonry blades handle the material. No specialty equipment required — if your crew can cut OSB, they can cut EXACOR.

Can EXACOR panels get wet during construction?

Case studies highlight improved scheduling due to the elimination of ‘wet’ trades and superior jobsite durability against rain and foot traffic. The panels handle jobsite moisture better than gypsum-based alternatives.

What’s the actual weight difference between EXACOR and other sheathing?

2.7 lb/ft² (approx. 97.2 lbs per 4x9 panel) makes it heavier than OSB but manageable for two-person crews. Still lighter than stacking multiple layers of 5/8” Type X gypsum.

Do I need special fasteners for EXACOR panels?

Yes. Corrosion-resistant nails or screws (e.g., self-drilling MgO screws or common nails) are required. Standard drywall screws won’t provide adequate holding power.

What fire ratings can I achieve with EXACOR?

1-hour and 2-hour fire-resistance ratings in tested assemblies per ASTM E119 and ANSI/UL 263 testing. Specific assembly details determine exact ratings.