Concrete Surface Profiles: CSP Explained
A profile is not a measure of how hard you ground. It is a texture the coating has to fill and then cover, which is why the right number depends on how thick the coating is going to be.
Concrete surface profile is the ICRI scale from 1 to 10 that describes how open a prepared slab is, judged by holding a molded comparator plate against the floor rather than by measuring anything. Most epoxy and polyaspartic floor systems call for CSP 2 to 3, but the number you need is the one printed on your coating’s data sheet, because profile and film build are a single decision. Too little profile and the coating has nothing to key into. Too much, and the peaks stand proud of a thin film and start wearing through the moment the floor goes into service.
What the number actually describes
A profile is a texture, and texture is hard to write down. Two experienced people will not agree on what a rough slab means, and neither of them can put it in a specification. The ICRI scale exists to solve exactly that: instead of describing the surface, you match it. Each profile on the scale has a molded replica, you hold the replica against the prepared floor, and you record the one your surface matches.
Two consequences fall out of that, and both matter on site. The first is that CSP describes a result, not a process. It says nothing about which machine made it, how many passes it took or how hard the concrete was. The second is that it is a judgement against a physical reference, so it is worth making that judgement in several places rather than once in the middle of the floor, and worth making it while the machine is still on site.
The scale runs from a barely opened surface at the bottom to a heavily fractured one at the top, and the floor coating end of the trade lives in the lower part of it. Heavy profiles exist for overlays and repair mortars that are millimeters thick, not for films measured in mils.
Why too much profile is as wrong as too little
Under profiling is the failure everyone knows: the coating has nothing to key into, so it relies on adhesion to a smooth surface and lets go later. Over profiling is the failure almost nobody plans for, and it is the reason this page exists.
Too little profile
- The coating sits on the surface rather than keying into it
- Usually paired with laitance still in place, because the pass that opens the profile is also the pass that removes it
- Fails as sheet peeling or as a film that lifts cleanly with no concrete on its back
- The fix is more passes, which is cheap while the machine is on site and expensive afterwards
Too much profile
- The peaks are barely covered, or stand proud of a thin film altogether
- Wear starts at the high points, so the floor ages from the top of every peak down
- The finished surface reads rougher than the customer was shown
- Material runs over the coverage rate, because the valleys hold coating that a flat surface would not
The second column is the one that turns into an argument on handover, because none of it looks like a defect. The floor is bonded, the coating is intact, and it simply is not the floor the customer was expecting. That is a specification failure rather than a workmanship one, and it happens when the profile was chosen from habit instead of from the system going on top of it.
Profile and film build are one decision
This is the idea the hero draws. A profile is a texture the coating has to fill before it can cover, so the useful question is never how much profile the slab has. It is how much profile the slab has relative to the film going over it.
Run that in both directions. A thin sealer over a coarse profile is the top row of the hero: the coating drains into the valleys and the peaks are left proud. A high build system over a fine profile has the opposite problem, in that there is nothing much for a thick film to grip and the extra build is doing no mechanical work. The profile the data sheet names is the manufacturer telling you which pairing their product was designed for.
This is also why the profile question and the coverage question have to be answered together rather than in sequence. What a product actually builds at a given spread rate is arithmetic, and the film thickness calculator does it from the solids figure on the sheet, while solids by volume and what a coating really covers works through where that figure comes from. A specification that names a profile and a spread rate without checking they belong together is two correct numbers that contradict each other.
Where your number comes from
In order of authority, and the order is not negotiable. The coating’s technical data sheet names the profile it requires, and that is the specification. Where the sheet is silent or ambiguous, the manufacturer answers the question, not the internet. ICRI’s own guideline is where the scale and its comparators are defined, and it is the reference to reach for when a specification names a profile and you need to know exactly what is meant by it.
What is not an authority is what the last floor was prepared to. Profile requirements move with the product, and a crew that grinds every floor the same way is right by accident on some of them. Reading a data sheet properly covers the rest of what that document is telling you, most of which is also conditional.
Cost the passes it takes to get there
The profile is a target, not a duration. Put the area, a rate for one pass and the pass count in, and the schedule falls out of it rather than out of a guess.
A trial cut tells you what your machine does on this slab, which no published rate can.
Open the live calculator →What the method does to the profile
Different prep methods land in different parts of the scale, and the ordering is a property of how each one works on concrete rather than a matter of opinion. Chemical etching barely opens the surface. Diamond grinding cuts it, and how far it opens depends on the tooling and the number of passes. Shot blasting fractures it, so it lands more open than grinding at the same effort. Scarifying and scabbling remove material aggressively and land at the coarse end.
The practical version is that the method sets the range you can reach and the tooling and passes place you inside it. That is why the same machine gives a different result on a soft slab and a hard one, and why the honest way to hit a profile is a trial cut in an inconspicuous corner rather than a rule copied off a chart. The prep pillar compares the methods properly, including where each one is the wrong choice.
One method is worth naming separately. Etching does not reliably remove laitance, so it can leave a surface that is textured and still unsound, which is the one combination a comparator plate cannot warn you about. A floor can match the plate and still lift, and that is not a failure of the scale, it is a reminder that the profile is one gate of four.
Checking the profile you actually produced
- Match, in several places. Compare against the molded replicas rather than by eye. Prep varies across a floor, particularly between the open field and the edges
- Check the edges separately. Edge work is done with different tooling and is the most commonly under prepared part of the floor. An edge at a different profile is a visible line in the finished surface
- Do it before the machine leaves. A profile that is too fine is another pass. A profile discovered to be wrong after the coating is down is a removal job
- Confirm the other three gates too. A water drop should darken the slab and soak in within seconds, the slab should sound solid, and the moisture result should be inside the coating’s limit
- Record what you produced. If a floor is ever disputed, the profile you prepared to and the sheet you prepared it from are the two facts that settle it
Where to go next
The profile is one of four gates, and how to prep concrete for epoxy covers the other three and the order the work goes in. For the film half of the pairing, solids by volume is where the real coverage of a product comes from, and the coverage per mil chart is the whole curve as a lookup.
For what an under profiled slab looks like once it fails, why epoxy floors peel separates the profile cause from the three that look identical on the day. And for planning the passes, how long concrete grinding takes turns a pass count into a schedule.
Frequently Asked Questions
What does CSP actually stand for and who defines it?
Concrete surface profile. It is a scale from 1 to 10 published by the International Concrete Repair Institute, and it describes how open and textured a prepared surface is, from barely roughened at the bottom of the scale to heavily fractured at the top.
The scale exists because roughness is hard to describe in words. Two people will not agree on what a rough slab means, but they can agree on whether a floor matches a numbered comparator, which is what the scale gives them.
What CSP do I need for an epoxy floor?
Whatever the coating’s own data sheet names, and most epoxy and polyaspartic floor systems call for CSP 2 to 3.
Treat the sheet as the authority rather than the habit. A thin sealer, a standard build epoxy and a high build or troweled system are three different answers, and a contractor who prepares every floor to the same profile is right by accident on some of them.
Can the profile be too aggressive?
Yes, and this is the half that gets missed. A profile is a texture the coating has to fill before it can cover, so a deep profile under a thin film leaves the peaks barely covered or standing proud of the coating.
That shows up in three ways: a floor that looks and feels rougher than the customer expected, wear that starts early at the high points, and material consumption above what the coverage rate predicted, because the valleys took more coating than a flat surface would.
How do I check the profile I have actually produced?
Compare it against a molded replica of each profile, which is what the ICRI comparator plates are for. You hold the plate against the prepared slab and judge which one your surface matches, in several places rather than one.
Do it while the machine is still on site. A profile that is too fine is another pass; a profile discovered to be wrong after the coating is down is a removal job.
Does the same profile mean the same thing on every slab?
No, and this is worth knowing before you promise a number. The same machine, the same tooling and the same number of passes produce different results on a soft slab and a hard one, so the profile is a property of the result rather than of the process that got you there.
That is why a trial cut in an inconspicuous area is worth the ten minutes. It tells you what your setup does on this concrete, which no published rate or tooling chart can.
Is the profile the only thing that decides whether the coating bonds?
No. Profile is one of four gates, and the other three will fail a floor on their own. The slab still has to be sound underneath, clean of anything that sits between the coating and the concrete, and dry enough that it is not pushing moisture up into the film.
A textured surface with laitance still on it is the specific trap, because it looks prepared. That is the state a chemical etch tends to leave, and it is why a floor can match a comparator plate and still lift later.