Gypcrete is a gypsum-based concrete underlayment that improves the fire rating, soundproofing, and structural stability of buildings. Only trained, licensed gypcrete applicators should install this material to confirm the quality and durability of the product. Here is more information about how underlayment professionals like Hacker Industries install gypcrete in residential and commercial spaces:

Site Preparation

When preparing for an underlayment installation service, the applicator inspects the site to confirm it is structurally sound and can withstand the weight of new flooring. After inspection, they will sweep the surface to remove any dirt and debris that could mix with the concrete and cause bubbles or uneven spreading. These materials include oil, grease, wax, and other potential contaminants.

The substrate floor should be completely dry, and the room temperature should be maintained at 50 degrees Fahrenheit or above with low humidity to prevent excess moisture buildup. Keeping the room and floor surface dry before and after installation deters mold and mildew growth. After cleaning and drying the floor, applicators coat the installation site with a gypcrete primer. This primer helps the concrete mixture adhere to the subfloor covering. The primer must be mixed with water and can be applied using a sprayer or paint roller. Hacker Industries carries a floor primer that is compatible with all Hacker underlayment products.


Once the primer is applied, the concrete can be mixed and poured. Gypcrete comes in a powder form that combines gypsum minerals and cement. This combination must be mixed with water and sand to become pourable. The sand and water should be carefully mixed in to prevent too thin or thick of a slurry.

Applicators can create an underlayment that is three-quarters of an inch to three inches thick. The thickness of the underlayment depends on the property owner’s preferences for weight and sound dampening. Gypsum-concrete underlayment is a self-leveling product, which means it doesn’t require further treatment once it’s poured. This product should not be installed outdoors or in other areas prone to high moisture levels.


Freshly poured gypsum-concrete underlayment requires proper ventilation to dry fully. If the outdoor weather isn’t humid, opening the windows during installation and until the underlayment is completely dry can keep the air circulating to help the product set up. In cold weather or humid areas, applicators may place additional fans or heaters in the space to speed up the drying process. The concrete should be fully dry within 8-14 days, with thicker pours taking longer to dry. If property owners or contractors must walk across the underlayment before it’s dry, applicators may recommend placing temporary planking in high-traffic areas to protect the gypcrete while it cures.

Floor coverings can be installed once the underlayment is dry and has been tested for moisture content. Moisture tests are completed using pin moisture meters. Hacker Industries recommends using the Delmhorst BD-2100, Delmhorst G-79, or Tramex CRH meters. Flooring professionals place the pins of the meter into the cement to receive a moisture percentage reading. We do not recommend using the calcium chloride testing method, which involves placing a dish of calcium chloride on the concrete’s surface and assessing how it’s affected by the concrete’s moisture vapor emission. This method is not entirely reliable as it only tests the surface level of the underlayment.

Types of Compatible Subflooring

Wood is used as a subflooring material in residential and commercial buildings, and it works well with Hacker Industries’ FIRM-FILL® 2010+ gypcrete product. The gypsum concrete forms a solid, smooth layer that prevents nail movement or squeaking boards. Wood subfloors are stiffened by the gypsum concrete, reducing the amount of deflection on the floor’s surface.

Gypcrete underlayment can help repair cracked or damaged concrete subflooring. New construction and renovation projects for spaces like hotels, sports facilities, and schools are simplified with gypcrete. Hacker Industries’ FIRM-FILL® 4010 underlayment is designed for thin pours and capping in transitional or damaged areas, creating a crack-resistant surface.

Gypsum concrete is an ideal underlayment material for subfloor radiant heat systems. Gypcrete fills the gaps between the systems’ electrical cables and hot water tubing without creating air bubbles. This underlayment also provides even heat distribution across the cured surface. Hacker Industries carries a gypcrete product made specifically for radiant heat systems called GYP-SPAN® Radiant. Adding this energy-efficient and cost-effective underlayment product over a radiant heat system creates a smooth, durable surface that is ready for the installation of finished flooring materials.

Use Gypcrete in Your Next Project

Hacker Industries supplies a range of gypcrete products to help contractors and property owners create more comfortable and safe indoor spaces. Our team can recommend the most suitable gypsum-concrete product based on your project goals and needs. We can also help you find a licensed and trained applicator in your area, providing you with an underlayment installation that follows strict quality control guidelines. Contact us today to learn more about the benefits of using soundproof underlayments in residential and commercial buildings.