When the spec calls for a substrate that can handle forklift traffic, wet-area exposure, or a 48-hour return to service that gypsum cannot deliver, cementitious underlayment is the answer. ATR Floors installs self-leveling, high-strength cement-based underlayment systems — including Combimix CM 920/960 series polishable toppings and CM 960 Industrial Super Top — across the Twin Cities metro.
7,000+ psi
Industrial Super Top Strength
2–4 hrs
Walkable Rapid-Set
Combimix
CM 920 / 960 Certified
The problem
High and low areas prevent flooring from meeting flatness, appearance, or performance requirements.
How ATR solves it
ATR prepares the slab and installs a high-strength cementitious underlayment to create the specified plane.
The problem
Substrate variation, patch lines, and surface defects will remain visible through resilient flooring and other finishes.
How ATR solves it
ATR corrects the substrate before installation so the finished floor is supported by a smooth, uniform surface.
The problem
Adjacent rooms, additions, or finish materials meet at different heights and create difficult transitions.
How ATR solves it
ATR builds controlled transitions and adjusts elevations for the specified flooring thicknesses.
The problem
The concrete is outside the manufacturer’s flatness or surface requirements for tile, LVT, vinyl, or wood.
How ATR solves it
ATR coordinates preparation and underlayment around the actual flooring specification and installation tolerance.
Both gypsum and cementitious underlayment are pumpable, self-leveling substrate systems — but they serve different conditions. Cementitious wins when strength, moisture, or schedule push past gypsum's envelope.
Cementitious is cement-based and will not deteriorate in wet areas. Bathrooms, commercial kitchens, lobbies with exterior door exposure, pool decks, and mechanical rooms all call for cementitious over gypsum.
Standard systems deliver 3,000–5,000 psi; industrial-grade toppings like Combimix CM 960 Industrial Super Top exceed 7,000 psi. Gypsum tops out at 2,500–3,500 psi.
Rapid-set cementitious systems are walkable in 2 to 4 hours and ready to receive floor covering in 4 to 24 hours. Standard gypsum requires 14 to 28 days of cure before floor covering installation.
Combimix CM 920/960 toppings can be polished, stained, or sealed as the final floor surface — no floor covering required. Integral color and aggregate options for decorative applications.
Retail, warehouse, distribution, and manufacturing applications where rolling loads, pallet jacks, and chemical exposure exceed the capabilities of gypsum.
Bonds to existing concrete, plywood/OSB (with lath), metal deck, lightweight concrete, and even properly prepared tile or terrazzo in renovation projects.
ATR Floors installs the full Combimix commercial underlayment and topping line. Product selection depends on compressive strength, decorative requirements, and finished floor type.
Combimix CM 960 Industrial Super Top exceeds 7,000 psi — forklift, pallet jack, and chemical exposure rated.
Chemical removal of coatings and contaminants — no grinding, no silica dust before the pour.
Written warranty on pour quality, flatness, and adhesion. Material warranty separately from Combimix.
Walkable in hours, ready for floor covering in 4 to 24 hours on rapid-set systems.
Cementitious is cement-based: higher strength, moisture-tolerant, and faster curing. Gypsum is gypsum-based: lighter weight, integral to fire-rated UL assemblies, and the primary contributor to STC/IIC sound control in multifamily construction. The choice depends on code, moisture exposure, and structural loading. Many projects use both — gypsum in residential floors, cementitious in lobbies and wet areas.
Rapid-set systems are walkable in 2 to 4 hours and ready for floor covering in 4 to 24 hours. Standard-set systems require 24 to 72 hours. Polishable toppings (Combimix CM 920/960) typically cure for 7 to 14 days before grinding and polishing begins.
Yes. Combimix CM 920 and CM 960 series toppings are specifically formulated for diamond polishing. They can be ground, honed, and polished to the same gloss levels as site-cast concrete — from a matte hone to a high-gloss mirror finish. Integral color and aggregate options are available.
Standard self-leveling systems: 3,000 to 5,000 psi. High-performance toppings (Combimix CM 960): 5,000 to 7,000+ psi. For comparison, standard gypsum underlayment achieves 2,500 to 3,500 psi, and typical cast-in-place concrete achieves 3,000 to 4,000 psi.
Yes. Unlike gypsum, cementitious is cement-based and will not degrade when exposed to moisture. It is the standard substrate choice for commercial kitchens, bathrooms, locker rooms, pool decks, and any area where standing water or high humidity is expected.
Include sq ft, substrate type, intended floor covering, and project schedule. We respond within one business day.
