Gypsum vs Gypcrete
Gypsum is a mineral. Gyp-Crete is a brand of floor underlayment made from it. The two are not competing products, and treating the question as a head-to-head is the most common mistake people make with the term. Gyp-Crete is a registered trademark of Maxxon Corporation, the product that started the poured gypsum underlayment category in 1972. Lowercase “gypcrete” has since become generic shorthand for any poured gypsum underlayment, the way people say “kleenex” or “dumpster.” In law, it still belongs to one company.
So “gypsum vs gypcrete” sets a raw material against a brand name. The question worth asking sits one level down: which poured gypsum underlayment, and on what specs.
Why the two get pitched against each other
Gyp-Crete launched in 1972 as the first poured gypsum underlayment on the market. It got common enough that the brand name turned into the word the trades use for the whole product type. Other manufacturers followed. USG introduced its Levelrock line in 2000. Hacker makes Firm-Fill, and a number of regional applicators run their own formulations. The generic habit held anyway. That is how a genericized trademark forms: one product defines a category so completely that its name absorbs the category. The catch for anyone writing a spec is that Gyp-Crete® is still a live, enforceable Maxxon trademark. On a drawing or a submittal, writing “Gyp-Crete” specifies Maxxon’s product specifically.
What gypsum underlayment actually is
A poured gypsum underlayment is gypsum cement and washed sand, mixed with water into a slurry, pumped through a hose and screeded flat. Some formulations carry a portion of Portland cement. It goes down thin, usually 3/4 inch, over a subfloor, most often on wood-framed multifamily floors. Two things justify the pour. First, performance in the floor-ceiling assembly: fire-resistance ratings from UL and ULC tested designs, plus sound control measured as IIC and STC. Second, a flat, hard surface ready to take the floor covering. The category went commercial in the early 1970s as an alternative to the cellular concrete being poured for the same job. Once it cures, the technical name for the material is “gypsum concrete.” So “gypcrete,” “gypsum concrete,” “gypsum underlayment,” and “cementitious underlayment” all point at the same thing. Gyp-Crete is one brand inside it. Levelrock and Firm-Fill are others.
The comparison that actually matters
If you are specifying or buying, the real decision is between products, on the numbers that change the assembly: compressive strength (psi), weight and dry density, fire-rating designs, sound ratings, and cure time before the floor covering goes down. Compressive strength moves the most. Published products run from around 2,000 psi on basic residential pours up to 8,000 psi on high-strength commercial formulations. The number you need comes from the floor covering and the structural design. The brand on the bag does not set it. Two products both called “gypcrete” in conversation can sit 4,000 psi apart. That gap is the comparison worth making.
Sources
Gyp-Crete launched in 1972 and started the poured gypsum underlayment category, per Maxxon Corporation. Gyp-Crete is a registered trademark of Maxxon Corporation. Levelrock is a registered trademark of USG Corporation. Firm-Fill is a product of Hacker Industries. Brand names are used here for identification only.