Cem-Rock Extreme x4 1/2” Wall Sheathing board was developed from the widespread need for a board with racking, pull-through, and pull-out strength. It is an ideal substrate for exterior walls, interior partitions, and tile backing for wet and humid areas.

Cem-Rock® Extreme x4 (1/2”) is a new age smooth faced multi-purpose magnesium oxide board which is highly durable noncombustible board for use in applications requiring a combination of moisture and thermal resistance as well as superior performance in fire. The board will not rot and can be used as an alternative to fiber cement board, where greater dimensional stability is required.

Product Options

Other Available Thicknesses:1/8”, 1/4”, 3/8”, 5/8”
Other Available Edges: Tapered, Beveled

Internal Partitions
Backer Board for the Wet Areas
External Substrate with EIFS
External Sheathing Board
SIP Panel Production


High Strength

Fire resistant

Water resistant

Sound Insolution

Moisture Resistance


Technical Specifications

Prodcut Name/ Category:

Cem-Rock Extreme X4 MgO Board

1/2" Load-bearing Wall Board


4’ x 8’


1/2” (12mm)



Per Sheet Weight:

79 lbs

Pallet Quantity:

38 Sheets

Fire Performance:

ASTM E84: Zero Flame, Zero Smoke

ASTM E136: Passed

Environment Certifications:

UL Green Guard

UL Green Guard Gold