Gypcrete Flooring: Pros, Cons, and Buying Guide

If you live in an apartment, condo, or townhouse built after 1980 and your floors feel surprisingly quiet between units, you’re probably standing on gypcrete. Gypcrete flooring is a gypsum-based poured underlayment, not a finish floor, and it sits between the subfloor and your hardwood, tile, or LVP. The original product was developed by Maxxon in 1972 and remains the dominant brand spec’d into multifamily construction across North America. After working on retrofit projects in three different metro areas, I can tell you exactly when gypcrete makes sense, where it falls short, and what it costs to install over an existing slab.

What Gypcrete Actually Is

Gypcrete is a proprietary blend of calcium sulfate (gypsum), Portland cement, sand, and water. Mixed at the truck and pumped through a hose to the upper floor, it self-levels into a smooth pour roughly 3/4 inch to 1-1/2 inches thick. It cures in 90 minutes to walkable hardness, fully sets in 24 hours, and can have finished flooring installed within 5 to 7 days depending on humidity.

It’s lightweight (about 13 pounds per square foot at 1.5 inches) compared to traditional concrete (18 pounds at the same thickness), which matters for wood-framed multifamily structures with weight limits per joist.

The Two Main Reasons People Pour Gypcrete

1. Sound Attenuation Between Floors

Multifamily building codes require minimum STC (Sound Transmission Class) and IIC (Impact Insulation Class) ratings between dwellings — typically STC 50 / IIC 50 or higher. Gypcrete poured over an acoustic mat (Maxxon Acousti-Mat 3 is the most common) easily hits IIC 60-65, meaning your downstairs neighbor doesn’t hear your dropped phone.

2. Radiant Floor Heat Encapsulation

Gypcrete is the standard pour over PEX radiant heat tubing in residential builds. The high gypsum content transfers heat efficiently to the surface, and the self-leveling pour completely encapsulates the tubing without air gaps that would cause hot/cold spots.

Pros of Gypcrete Flooring

• Excellent fire rating. Gypsum is naturally fire-resistant; 1.5 inches of gypcrete adds 1-hour fire rating to a wood floor assembly.
• Strong soundproofing. Cuts impact and airborne noise dramatically when paired with an acoustic mat.
• Self-leveling. Hides minor subfloor irregularities up to 3/8 inch in a single pour.
• Lightweight. 30% lighter than concrete at the same thickness.
• Fast cure. Walkable in 90 minutes, ready for finish flooring within a week.
• Best substrate for radiant heat. Encapsulates PEX tubing for even thermal transfer.

Cons and Limitations

Gypcrete has real drawbacks that homeowners often discover too late.

• Not waterproof. Gypcrete absorbs water and can soften, crumble, or grow mold if a leak goes unaddressed. Bathrooms and laundry rooms still need a separate waterproof membrane.
• Cannot be a finish floor. Gypcrete is always covered. Carpet, hardwood, LVP, or tile must go over it.
• Lower compressive strength than concrete. 2,000-3,000 PSI vs 4,000+ for standard concrete. Heavy point loads can dent it.
• Difficult to repair. Patches don’t bond perfectly to existing pours; transitions can telegraph through tile.
• Specialty installer required. Pumping, mixing, and finishing gypcrete is licensed work — Maxxon trains and certifies installers.
• Adds weight. Even at 13 lbs/sq ft, the existing structure must be engineered for it on a remodel.

Gypcrete Flooring Cost

Materials and installation typically run $1.50 to $4.00 per square foot depending on thickness, region, and access. The installed price for a standard 1-inch pour over a flat plywood subfloor in a multifamily building is around $2.25 per square foot. Adding an acoustic mat underlayment (Acousti-Mat 3) brings the total to $3.50 to $4.50 per square foot.

For a 1,200 sq ft condo unit, expect $3,000 to $5,400 installed for the underlayment alone — before the finish flooring goes down on top.

Common Brand Names and Products

Several gypsum underlayment brands dominate the US market. Most contractors use them interchangeably, but specs differ.

• Maxxon Gyp-Crete: the original; available in 2000, 3200, and 4000 PSI versions
• Maxxon Level-Right: high-flow self-leveling product for thinner pours
• USG Levelrock: direct competitor, similar performance
• Hacker Industries Firm-Fill: popular on the West Coast
• CGC ProRoc: Canadian market equivalent

Installing Finish Flooring Over Gypcrete

Each finish floor type has specific requirements when installing over gypcrete.

Hardwood

Use floating engineered hardwood with a moisture barrier underlayment. Nail-down solid hardwood is generally not approved over gypcrete because nails won’t bite into the gypsum the way they do plywood. Some manufacturers permit glue-down with specific adhesives.

Tile

Apply a primer coat (Maxxon Floor Primer or equivalent) before thinset. Use modified thinset rated for gypsum substrates. An uncoupling membrane like Schluter Ditra is cheap insurance against cracks.

LVP, Laminate, Carpet

All install normally with floating or glue-down methods. Confirm the moisture content of the gypcrete is below 75% RH before installation — Maxxon recommends a calcium chloride or in-situ probe test.

Common Failures and How to Avoid Them

Most gypcrete problems trace back to one of three causes:

1. Insufficient cure time. Installing finish flooring while gypcrete is still releasing moisture causes hardwood cupping and tile cracking. Always test moisture before laying finish flooring.
2. Water exposure during construction. Plumbing leaks before the floor is sealed can saturate the pour. Severely wet gypcrete must be removed and replaced.
3. Heavy point loads. Refrigerator wheels, piano legs, or jack stands can dent uncured or thin pours. Use distribution pads under heavy items.

Removal and Renovation

If you ever need to remove gypcrete during a remodel, expect noise and dust. It chips up with a rotary demo hammer and a chisel bit. Most disposal facilities accept it as construction debris. Plan on $1.50 to $3.00 per square foot for removal, depending on access and thickness.

Is Gypcrete Right for Your Project?

For new multifamily construction, condo conversions, or any retrofit where soundproofing or radiant heat is a priority, gypcrete flooring is the proven solution. For a single-family home on a slab with no acoustic concerns, traditional self-leveler or simply a flatter subfloor is usually a better and cheaper choice. Hire a Maxxon-certified installer, plan the cure schedule into your construction timeline, and gypcrete will quietly do its job under your finish floors for the life of the building.