Concreate, Inc. delivers concrete polishing and custom staining for both commercial and residential projects primarily in Virginia and Maryland (but also up and down the East Coast). We work hand in hand with with designers, architects, project managers, general contractors, tradesmen, and home owners alike from start to finish. We welcome the opportunity to serve your polished concrete needs in every way possible.

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Concrete Surface Profile: What the Numbers Mean

Concrete Surface Profile: What the Numbers Mean

A worker milling a concrete floor to achieve the proper concrete surface profile.

The coating you’re using determines the CSP number you need to attain during the preparation process

Key Takeaways:

  • Concrete surface profile numbers relate to the floor’s roughness
  • Lower numbers are smoother, and higher numbers are coarser
  • Different coatings require different CSP numbers to adhere properly
  • The surface preparation technique you’ll use depends on the desired CSP number

As a contractor works on your concrete floors, you might hear the term CSP surface profile and notice a number often accompanies it. The number you hear relates to the concrete’s coarseness and determines the coating you can apply to the surface.

CSP numbers range from one to ten, with one being the smoothest concrete and ten being extremely rough. However, some coatings will only bond to coarse concrete, and other coatings are only usable when the floor is smooth, so your contractor will have to prepare the surface to match the coating’s specifications. 

In 1997, the International Concrete Repair Institute (ICRI) released its surface concrete profile classifications to provide contractors with an industry standard. These guidelines make the job easier to complete and reduce the possibility of coating failure. 

Knowing what CSP numbers mean and the preparation method your contractor will use to attain the right one helps you better understand the job at hand. Here’s a look at concrete surface profile standards and what they mean for your project.

CSP 1 and 2 – smooth floors

The smoothest concrete profiles you’ll come across are CSP 1 or CSP 2, which are nearly flat. Your contractor will need smooth concrete like this when applying a sealer or thin films like epoxy or urethane. After preparation, the concrete will feel like sandpaper, at least until the application of the coating. 

In some cases, all that’s necessary to attain a CSP 1 profile is some scrubbing or low-pressure water, although grinding is the most common preparation method for achieving a CSP 1 or CSP 2. It’s also possible to use a process called acid etching, but acid is difficult to rinse and can damage metals and other items in the surrounding area. As a result, acid etching is usually the last resort when other preparation techniques fall short.

If a heavy-duty coating isn’t necessary for your floor, there’s a good chance a CSP 1 or 2 profile will be the choice for your contractor. 

CSP 3, 4, and 5 – getting a bit rougher

When your contractor goes with CSP 3, 4, or 5, it’s likely because they’re applying a high-build coating to the concrete. These sealers are typically acrylic, epoxy, or polyurethane and can be anywhere between 10 and 40 mils thick. You might also need CSP 4 or 5 when applying a self-leveling overlay that goes over the existing concrete to create a new surface.

Attaining a CSP 3 concrete floor could require grinding, shot blasting, or sandblasting. CSP 4 and 5 concrete calls for sandblasting, shot blasting, or scarifying, which involves steel rods mounted on a rotating drum that strike the surface. However, these more aggressive surface preparation techniques increase the risk of micro-cracking, which could require repairs before applying the final coating. 

CSP 3, 4, or 5 could be the choice when installing a heavy-duty sealer or overlay in a warehouse or other industrial setting that requires additional protection from abrasion or spills.

CSP 6, 7, and 8 – noticeably coarse floors

Getting even coarser takes you to CSP 6, 7, or 8, which are generally recommended when applying a polymer overlay to the concrete. These overlays do an excellent job of restoring old or weathered concrete as an alternative to replacing the slab. The result is a new-looking floor without the expense of removing the old one and reinstalling it. 

Of course, the bond between the old floor and the polymer overlay is paramount, and this bond is maximized by applying it to a rougher grade of concrete. Scarifying is commonly used to reach CSP 6 or 7, but ultra-high-pressure water jetting, steel shot blasting, and scabbling are also possibilities. Scabbling involves using a tool with multiple piston heads that drive into the ground and crush the surface. The result is a highly coarse and irregular floor. 

Getting into this level of roughness is only necessary if the existing concrete is in poor shape and requires extensive work, but you don’t want to go through the hassle of replacing it entirely. 

CSP 9 and 10 – the roughest concrete floors

As you might have expected, CSP 9 and 10 are the roughest of the bunch. This preparation method is sometimes necessary when applying a polymer overlay upward of a quarter-inch thick because the coating needs a rough texture to adequately bond. 

Reaching this level of coarseness could require scabbling, water jetting, shot blasting, flame blasting, or rotomilling, depending on the job. Rotomilling is similar to scarifying, except the drum drives rods with teeth into the concrete for deeper grooving. You can also equip a rotomilling machine with smaller teeth for a slightly smoother surface. Your contractor will select the method that works best in your specific situation. 

Because these techniques are so aggressive, there’s a good chance that repair to the concrete will be necessary before applying the final coating. 

Finishing your concrete floors

Concrete surface profile numbers are determined by the average distance between the peaks and valleys on the surface. While they’re an accepted industry standard, there’s a lot of room for interpretation because these distances are so small, and measuring them proves a challenge. Many contractors have tools and ICRI rubber comparators to help them measure the floor’s classification, ensuring they’ve reached adequate coarseness before applying a surface coating. 

Concreate can assist with your concrete floor preparation and coating application, ensuring your chosen urethane, acrylic, epoxy, or polyurea binds to the surface and provides long-lasting coverage. Our experienced team will make your project look great and minimize the repairs and maintenance you’ll need in the future by doing the job correctly. Visit thisisconcrete.com today for more information on concrete surface profile numbers and what they mean for your project.