A sound mat, also known as an acoustic underlayment, is a material designed to reduce sound transmission and impact noise between floors. It’s an effective way to increase privacy in multi-family housing or other buildings with shared floors and ceilings. Hacker Industries supplies both customers and licensed applicators with some of the highest-quality sound mats and gypcrete solutions in North America. The installation process varies depending on the product and project.

Sound Mats and Gypcrete

Sound mats are made from netting, foam, fabric, and other materials that reduce sound transmission. They range from 3 mm to 19 mm thick and are rolled out as a base layer for the flooring. Sound mats work well over hardwood, plywood, concrete, corrugated steel deck, and other common substrates.

Gypcrete, or gypsum concrete underlayment (GCU), is made from a mixture of gypsum, sand, and water. Gypsum is a mineral that is naturally fire-resistant and uniquely effective at regulating humidity. Applicators pour GCU on the subfloor to create an even, smooth, sound-reducing underlayment. It can fill any cracks or gaps in the subflooring that would otherwise cause noise or weaken the building’s structural integrity.

The Installation Process

The installation process varies depending on the materials that work best for the project. Here’s the general process that we train our applicators to follow:


Before installing sound mats or GCU, we check that the subflooring is clean, dry, and level. If necessary, we remove any existing flooring or wall coverings.

Measurement and Cutting

We then measure the dimensions of the area where the underlayment will be installed. This allows us to cut the mat and measure the GCU solution accordingly.

Underlayment Installation

With the base floor completely prepped, we’re ready for installation. We roll out the sound mats, starting at the wall, to keep each roll even and straight. Rollers and other pressure-applying tools allow us to keep the sound mat snugly fitted without air pockets.

If we’re using GCU, we pour the solution onto the base floor and use flat-edged tools to even it out, filling all cracks and gaps. Once the entire underlayment is in place, it’s ready for a sealant. 

Sealant Application

Applying a sealant keeps the underlayment in good condition so that it can continue to provide sound resistance and resilience for years to come. Hacker TopCoat® SP (Surface Prep) is our choice sealant. It’s a water-based, vinyl acrylic co-polymer sealant that secures the sound mat or GCU. When used with Hacker underlayment products, it provides ideal surface bonding conditions for the next and final layer of floor covering. 

We also sometimes use Hacker Reinforcement in conjunction with Firm-Fill GCU® and Firm-Fill® SCM Sound Control Mats. This is an affordable way to provide crack suppression and reduce underlayment pour depth when necessary. Once the gypsum concrete underlayment is installed, the flooring material can be installed on top of it.

Hacker Industries: Promoting Privacy

At Hacker Industries, we design products that will create optimal living conditions for multi-family housing. Soundproofing underlayments allow residents to enjoy their privacy along with the benefits of affordable shared living spaces. Contact a member of our team if you have any questions about our products or installation processes.