A facility owner starts asking about epoxy film thickness after a walk-through reveals wheel ruts, chipped edges near a dock door, or a maintenance log full of patch jobs. The question "how thick should this floor be" sounds simple, but manufacturer data sheets describe thickness very differently depending on whether the product is a thin-film roller coat, a self-leveling slurry, or a troweled mortar. This guide walks through what thickness means in each category, what the manufacturer sheets actually say about mil ranges for specific products, and how to turn those numbers into a written scope rather than a guess. It also looks at the common question of 30-mil versus 50-mil systems, and how to frame the choice around your traffic, impact exposure, and substrate prep rather than price alone. For a broader system-by-system comparison, see the commercial flooring cost guide covering every system.
Thickness in epoxy flooring is reported in a few different units depending on the product type: mils (thousandths of an inch), millimeters, or fractions of an inch for mortars. It also matters whether a sheet is reporting wet film thickness (how thick the material is right after application) or dry/cured film thickness (how thick it ends up once cured). These are not always the same number, and a written scope should specify which one is being quoted.
The table below pulls only the product-specific figures available from manufacturer data sheets, each kept with its source so you can compare like with like.
| System type | Thickness range | Source |
|---|---|---|
| Thin-film roller coat (Sikafloor-264) | 12 to 15 mils wet film | Per Sika Sikafloor-264 product data sheet |
| Thin-film coat (Tnemec N222 primer) | 6.0 to 12.0 mils dry film | Per Tnemec Series N222 data sheet |
| Thin-film coat (Tnemec N222 intermediate/topcoat) | 8.0 to 16.0 mils dry film | Per Tnemec Series N222 data sheet |
| Self-leveling slurry (Sikafloor-264 with filler) | 60 to 120 mils | Per Sika Sikafloor-264 product data sheet |
| Self-leveling system (Sika MultiDur SL) | 62 to 125 mils (1.6 to 3.2 mm) | Per Sika Sikafloor MultiDur SL system data sheet |
| Self-leveling (Stonhard Stonlux SL) | 2 mm (80 mil) or 3 mm (120 mil) | Per Stonhard Stonlux SL product data |
| Self-leveling broadcast (Sika MultiDur SLB) | 125 to 156 mils (3.2 to 4.0 mm) | Per Sika Sikafloor MultiDur SLB system data sheet |
| Epoxy mortar (Stonhard Stonclad GS) | 1/8 to 1/4 inch (3 to 6 mm) | Per Stonhard Stonclad GS product data |
| Epoxy mortar (Tnemec N222) | 3/16 to 1/4 inch (min 1/8, max 1 inch) | Per Tnemec Series N222 data sheet |
Because these ranges come from different manufacturers and different product families, don't average them or assume a competing product falls in the same range. Ask the contractor which specific product line they are quoting and request that data sheet directly, and compare options through the cost calculator once you know the product class.
Sika describes Sikafloor-264 as a roller coat at 12 to 15 mils wet film; Tnemec N222 lists per-coat dry film ranges. Sika's Sikafloor-264 epoxy is specified as a wear coat at 12 to 15 mils wet film thickness. Tnemec's Series N222 lists a recommended dry film thickness of 6.0 to 12.0 mils for a primer coat and 8.0 to 16.0 mils for an intermediate coat or topcoat. A separate Tnemec line, Series 282 Tneme-Glaze (a polyamine novolac epoxy), lists a recommended dry film thickness of 6.0 to 12.0 mils per coat on horizontal surfaces.
These are film-build numbers for individual coats, not whole systems — a thin-film floor is built from a primer plus one or more topcoats, each with its own mil range on the data sheet. Because wet film and dry film thickness are not the same measurement, confirm which one a quote references before comparing bids.
Questions to ask your contractor:
What to put in the written scope:
Some manufacturers publish self-leveling systems in mils or mm and mortars in inches; ranges are product-specific and can overlap. Sika describes its MultiDur SL self-leveling epoxy slurry system as installed at 62 to 125 mils (1.6 to 3.2 mm), while its MultiDur SLB version, which adds an aggregate broadcast to improve slip resistance, is installed at 125 to 156 mils (3.2 to 4.0 mm). Stonhard offers its Stonlux SL self-leveling epoxy in 2 mm and 3 mm thicknesses, listed on its coverage table as 80 mil and 120 mil respectively; the same sheet describes Stonlux SL as oriented toward clean-room and laboratory settings. Sika's Sikafloor-264 epoxy, the same product used as a thin-film wear coat, can also be used as a self-leveling slurry when mixed with filler and spread to a desired thickness of 60 to 120 mils — a different application of the same resin, not a separate product.
These self-leveling ranges are specific to each manufacturer's formulation and should not be treated as an industry-wide standard for "self-leveling epoxy." Decorative broadcast systems sit in a related but distinct category: Sika's DecoDur Quartz FX decorative epoxy and colored quartz broadcast system is installed at 1/8 inch (3.1 mm), a figure specific to that system rather than to broadcast systems generally.
Questions to ask your contractor:
What to put in the written scope:
Troweled epoxy mortars are built from resin mixed with graded aggregate and are measured in fractions of an inch rather than mils. Stonhard describes Stonclad GS as a troweled epoxy mortar system applied at 1/8 inch to 1/4 inch (3 to 6 mm) depending on application requirements, and lists it at 10,000 psi compressive strength after 7 days and 1,750 psi tensile strength per its product data. A related Stonhard product, Stonclad HD, is described as a 1/4-inch epoxy mortar at 11,000 psi compressive strength after 7 days and 2,000 psi tensile strength. Tnemec's Series N222 epoxy, used as a mortar, is applied at 3/16 to 1/4 inch, with a stated minimum of 1/8 inch and maximum of 1 inch, using a rock-to-resin ratio set by the data sheet.
Some systems combine mortar with reinforcement for specific exposures. Stonhard says a fiberglass surface veil should be installed in Stonclad HT epoxy mortar areas exposed to instantaneous temperature changes greater than 100 degrees F (38 degrees C) — a system recommendation tied to that product, not a general rating of thermal shock resistance.
Because compressive and tensile strength values are measured under specific lab test methods, don't compare a mortar's psi figures directly against a self-leveling binder's psi figures tested under a different method; ask the contractor which test standard produced each number.
Questions to ask your contractor:
What to put in the written scope:
If a quote says "30-mil" or "50-mil," ask which product, how many coats, and whether the number is wet film, dry film, or total build. Rather than treating these numbers as fixed tiers, use them as a prompt to ask which specific product and coat structure produces that figure. Ask which product and coats produce the quoted figure, wet or dry, with per-coat ranges from the data sheet.
Because manufacturers publish their own ranges and test their own products, a 30-mil system from one manufacturer is not necessarily built the same way as a 30-mil system from another. Ask for the product name, the per-coat mil figures from its data sheet, and whether the quoted number is wet or dry film before comparing two bids side by side.
Questions to ask your contractor:
What to put in the written scope:
Facility type and traffic pattern are useful starting points for a conversation with your contractor, even though the right thickness ultimately comes from the product data sheet rather than a general rule. Warehouses and distribution facilities dealing with continuous forklift traffic, pallet jacks, and loading dock impact are one example of a facility type where abrasion and impact resistance are a stated priority; you can review product and contractor options on the Colorado warehouse floor coatings hub and the Colorado hub for warehouses and distribution centers. Facilities such as commercial kitchens, manufacturing plants, or healthcare settings often weigh chemical resistance and cleanability; confirm requirements for your facility, and start with the Colorado commercial epoxy flooring hub.
Surface preparation is part of this decision, not a separate one. Several manufacturer sheets tie a specific concrete surface profile, described on the ICRI 310.2R scale (CSP 1 through CSP 10, used to specify and verify surface preparation for coatings and overlays), to their product. Tnemec specifies ICRI CSP 3-4 for its Series 208 Epoxoprime MVT (CSP 3 is the target for best performance), noting that over-aggressive blasting can create pinholes and prevent reaching the necessary film thickness, while its Series 215 Surfacing Epoxy requires a minimum CSP 5. Sherwin-Williams requires the surface be shot blasted to a CSP 3-5 for its Resuprime MVB, specifying that grinding or acid etching is not permitted for that product. Sika specifies CSP 3 to 4 for Sikafloor-264. These examples show that the required profile is set per product, not as one universal number, so get the CSP requirement from the actual data sheet for the product being quoted.
Budget is another input, and it should be pulled from current, project-specific numbers rather than general mil-to-dollar assumptions. The cost calculator estimates installed cost by service and Colorado city, and the commercial epoxy flooring cost guide and warehouse floor coatings cost guide break down cost drivers in more detail.
Questions to ask your contractor:
What to put in the written scope:
Not necessarily; thickness is product-specific, so ask which product and thickness range the contractor proposes and what the data sheet says about the intended use. The right thickness for a warehouse depends on the product chosen and the facility's actual traffic pattern, which is why the data sheet and a written scope matter more than a single mil number. Ask your contractor which product and thickness range they are proposing and why.
Wet film thickness describes how thick the material measures immediately after application, while dry or cured film thickness describes the thickness once the coating has fully cured. Manufacturer data sheets specify which measurement applies to a given mil figure, and the two numbers are not interchangeable. Always confirm in writing which measurement a quoted thickness refers to.
These figures are not defined in the manufacturer data sheets reviewed; ask for the product name and per-coat data-sheet ranges. Ask for the specific product name and its data sheet so you can compare the actual mil ranges per coat rather than relying on the shorthand number alone.
Mortar systems are built from resin and graded aggregate, and some mortar data sheets list a range (for example Stonhard Stonclad GS 1/8 to 1/4 inch "depending on application requirements"; Tnemec N222 min 1/8, max 1 inch); the sheet sets the thickness for the product. The specific thickness used on a project depends on the product chosen and the conditions it needs to address, as set by that product's data sheet.
Several manufacturers specify a required concrete surface profile, described on the ICRI 310.2R CSP scale, for a given product. Tnemec notes for Series 208 Epoxoprime MVT that over-aggressive blasting can create pinholes and prevent reaching the intended film thickness; required CSP is set per product on its data sheet. The required CSP number differs by product, so it should be confirmed on the specific data sheet for the system being installed.
Not directly in all cases, because different products are sometimes tested under different test methods, which can produce numbers that are not apples-to-apples even when both are reported in psi. Ask your contractor which test method produced each published strength figure before comparing two systems.
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