A Reno garage floor does not fail because the resin was cheap. It fails because the surface the resin was asked to hold was never opened up. Concrete Surface Profile, or CSP, is the measurable roughness of that surface, and the specification for a heavy-duty broadcast system is CSP 3 to 4 as defined by ICRI. The question this article answers is practical: how does the profile of a Northern Nevada slab decide whether an epoxy floor anchors into the concrete, or simply sits on top of it until a hot tire or a freeze-thaw cycle lifts the film?
What CSP 3 to 4 Actually Measures
CSP is a texture scale, not a visual impression. ICRI profile numbers run from near-glass-smooth to deeply scarified, and CSP 3 to 4 is the coarse, uniformly open band required for a full-thickness garage floor. A power-troweled slab lands at CSP 1 or 2 — dense, closed and glossy — so resin sits on top of it rather than keying into it.
Too rough fails differently. Past CSP 4 the primer cannot fill the valleys, air stays trapped under the film, and pinholes and blisters follow. CSP 3 to 4 is the band where a 20–35 mil build wets out completely and still locks into the concrete.
Profiling the Field: Laitance Comes Off First
Every poured slab carries laitance, the thin cement-rich layer that rises as concrete cures. It looks like concrete and behaves like chalk, and anything bonded to it is bonded to powder. It is the most common cause of a floor that peels away in one large sheet.
A walk-behind shot blaster handles the field. Steel shot fractures away the laitance and the top fraction of the slab, and the machine recovers spent media and dust in the same pass. Shot blasting beats acid etching because it repeats: the same machine on the same setting produces the same surface, and that surface can be tested before any resin is mixed.
Edges, Corners and the Garage Door Apron
A shot blaster cannot reach the last six to twelve inches against a stem wall, around a post base or inside a floor drain recess. That is where floors fail first, and in Northern Nevada the reason is local. Summer surface heat and winter ice-melt chemicals both concentrate at the perimeter, and the apron collects snow, grit and brine all winter.
Edge work uses a planetary grinder on the open runs and hand grinders in the corners, worked to the same CSP 3 to 4 target. If the perimeter of a finished floor feels smoother than the middle, or the edge coating lifts before the field does, that phase was skipped.
Why an Acid Etch Cannot Meet the Standard
Acid etching is cheap: a bucket, a brush and a hose. It eats into cement paste and leaves the slab feeling rougher, but rougher is not the same as clean or profiled. Acid does not dissolve sealers, old paint or motor oil, because those are not cement paste — they sit on top of it.
Whatever remains becomes the bond line. A sealer or an oil slick acts as a release layer, so the film rests on the concrete instead of inside it. In a Reno garage the stresses only have to beat that release layer, and hot tires in July or a hard January freeze will find it.
What Reno's Ground and Weather Do to a Bond Line
The ground under the slab and the swing above it are the other half of the story. USDA-NRCS describes the Reno series as well drained with a duripan at 50 to 100 cm and low saturated hydraulic conductivity, so water perches instead of draining. The Washoe series carries 35 to 50 percent rock fragments. The Flex series is only 15 to 30 cm deep to weathered volcanic bedrock on the hills of northwest Reno.
Climate adds cycling on top of that. Reno records run from 108 °F to −16 °F, with mean highs near 45 °F in January and 90 °F in July. A film that is not mechanically anchored moves with every one of those swings.
How to Verify Prep Before the First Coat
You do not have to watch the whole job. Confirm three things in writing first: that the method is mechanical — diamond grinding and shot blasting, not an acid wash; that the stated target is an ICRI profile of CSP 3 to 4; and that dust is captured at the tool with a HEPA extractor rather than blown through the garage.
Then ask for the numbers that decide whether the slab can be coated. Typical requirements are moisture below 5 lbs per 1,000 sq ft on ASTM F1869 or 75% RH on ASTM F2170, concrete at 2,500 psi minimum, and 28 days of cure on a new pour. Ask for readings, not a summary.
Frequently asked questions
What does CSP 3 to 4 mean on a spec sheet?
It is an ICRI Concrete Surface Profile rating for a coarse, uniformly open texture. CSP 3 to 4 gives a 20–35 mil epoxy build enough pore structure to key into without trapping air under the film.
Can a slab be acid etched instead?
Not for a double-broadcast system. An acid etch is hard to control and hard to verify, it does not remove sealers or oil, and it does not reliably reach CSP 3 to 4.
How do I know the specified profile was hit?
Ask what equipment was used and how the profile was checked. A shot blaster for the field, planetary and hand grinders at the edges, and a HEPA extractor running throughout is the expected method. The perimeter should feel the same as the middle.
Do local soils change the requirement?
They can change the system, not the profile. Slabs on Truckee-series ground sit over poorly drained soils with a seasonal water table present three or more months in most years, so the slab is more likely to read high on moisture and the build gains a moisture vapour barrier.
What happens if prep is missed?
The floor usually looks right on installation day and peels in sheets a season or two later, most often from the edge inward. Repair means removing the failed film and re-profiling the slab. As an independent matching service we do not install or inspect floors; we help homeowners find providers who work to a written profile spec.
Sources
- USDA-NRCS Official Soil Series Description: Reno series
- USDA-NRCS Official Soil Series Description: Washoe series
- USDA-NRCS Official Soil Series Description: Flex series
- NWS Reno climate products (Reno–Tahoe International Airport)
Related
Epoxy Flooring services in Reno
Garage Epoxy
A Reno garage slab works harder than any other floor in the house: summer surface heat, winter ice-melt brine, and a car that parks in the same two spots every night.
Basement Epoxy
A basement floor in Reno is a moisture question before it is a finish question, and the answer is decided by the slab, not by the coating.
Commercial Epoxy
A commercial floor is bought in hours of uptime, not in square feet of resin.
Metallic Epoxy
Metallic epoxy is a design floor built on an engineering system: the swirl is the topcoat's business, the bond is the slab's.
Polyaspartic Coatings
Polyaspartic is the coating that made the one-day floor possible, and it is the layer that decides how a Reno floor ages under a high-desert sun.
Concrete Coating Sealing
Raw concrete is a working surface, not a finished one, and sealing it is the cheapest way to stop dusting, staining and moisture at the surface.
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