Gypsum Concrete Floors Offer Lower-Carbon Alternative for Mass Timber Buildings

So, mass timber construction, which uses materials like CLT and DLT, is becoming popular because it has lower embodied carbon and quicker build times. But there’s a catch: the sound insulation isn’t great. Exposed timber floors often don’t hit the necessary STC and IIC ratings, leading people to add concrete toppings, which ironically increase weight and carbon emissions, negating the environmental perks of timber. According to the National Ready Mixed Concrete Association, making lightweight concrete generates about 1,230 pounds of CO₂ for every metric ton. Companies like USG are addressing this with products like Levelrock® Brand SAM-N™ underlayment and the SAM-N25™ acoustic mat, which can achieve impressive sound ratings when paired correctly. Plus, using gypsum concrete can cut embodied carbon by 75% compared to traditional lightweight concrete. At Baker’s Place in Madison, Wisconsin, they installed a 2-inch gypsum concrete layer over an acoustic mat in just two days per floor. USG claims that switching to their Levelrock® systems in a large building can save nearly 50 metric tons of CO₂e emissions, emphasizing how important these additional layers are for the future of mass timber.