

EXACOR™ Underlayment
EXACOR™ underlayment panels are specifically engineered to meet the fire-rating[1], sound-rating[1] and dimensional stability requirements of most multifamily and light commercial jobsites. Made of magnesium oxide and an integrated mesh core, EXACOR underlayment panels are fire resistant[2]. In addition, EXACOR underlayment panels can offer a base for floor coverings that can eliminate the need for gypsum underlayment and the jobsite delays that may come with it.

01 Products

Underlayment Panel, 1/2" × 4' × 8'
Panel Count | 38 |
Fire Resistant | E84 |

Underlayment Panel, 1/2" × 4' × 9'
Panel Count | 33 |
Fire Resistant | E84 |

Underlayment Panel, 1/2" × 4' × 10'
Panel Count | 32 |
Fire Resistant | E84 |
Performance Category | Panel Size | Edge Profile | Fire-Resistant Assemblies | Code Evaluation Report | Approx. Weight Per Panel | Panels Per Unit |
---|---|---|---|---|---|---|
Nominal 1/2" Thickness (12 mm) | Nominal 4' × 8' (1220 mm × 2440 mm) | Straight (Square) Edge | UL L528 | ESR-4750 | 86.4 lbs. | 38 |
Nominal 1/2" Thickness (12 mm) | Nominal 4' × 9' (1220 mm × 2743 mm) | Straight (Square) Edge | UL L528 | ESR-4750 | 97.2 lbs. | 33 |
Nominal 1/2" Thickness (12 mm) | Nominal 4' × 10' (1220 mm × 3048 mm) | Straight (Square) Edge | UL L528 | ESR-4750 | 108.0 lbs. | 32 |

02 Why It Works
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A Simple Solution for Sound Control
When used as part of a STC/IIC-tested floor/ceiling assembly, EXACOR underlayment panels installed over plywood or OSB subfloors can also help provide the fire and sound ratings you need for your build.
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Installation Speed & Ease
Unlike gypsum underlayment assemblies that require cure time that can slow or halt construction progress, EXACOR underlayment panels installed over plywood or OSB subfloors allow construction to continue without delay.
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High Quality
Manufactured in a quality-controlled environment to maintain product consistency you can depend on.
03 How to Install
Installing is fast and simple and doesn’t require additional training.
When used as underlayment, EXACOR MgO panels install in less time, with less steps, and within your crews’ current skill set. No extra tools or skill is needed. If they’ve been installing gypsum underlayment, they’re going to love EXACOR MgO panels.




Explore more products.
05 News & Articles
Behind the Build Blog
How to Streamline Fire Resistance and Acoustics in Multifamily Buildings
Learn how EXACOR™ magnesium oxide panels can offer fire resistance and sound-rated alternatives to traditional floor assemblies using gypsum underlayment in multifamily buildings.
Read MoreEXACOR™ MgO Panels vs. Gypsum Underlayment in Multifamily Buildings
Explore the differences between EXACOR™ MgO panels and gypsum underlayment for multifamily buildings.
Read MoreOA Showcase Home Creates Resilient Design with ZIP System® R-Sheathing
Project giving new life to 1920s-era Minneapolis home
Read MoreQ&A on Continuous Insulation with Green Builder Carl Seville
Carl Seville of SK Collaborative shares his thoughts on the building envelope and the role ZIP System® R-sheathing plays for managing air and thermal bridging.
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