Tips About Self-Leveling Concrete

tips about self-leveling concreteWhenever you need to repair, smooth, or raise a floor, self-leveling concrete can be a fast, cost-effective solution to the problem.

Self-leveling concrete is a cementitious mixture much like concrete. But unlike concrete, it flows easier and sets up much faster. The product is mixed with water, pumped or poured into place and spread evenly with a gauge rake. Once it’s spread out, it continues to flow evenly and levels itself out. Depending on the product, it may set up smooth and flat within 1-2 hours. In about 6 hours, it may be completely hardened and ready for use, depending on the flooring material being installed on top. Self-leveling concrete can be used as an underlayment for tile, carpet, or other floor coverings.

Now, let’s clarify some things concerning product names. Instead of “concrete,” you might see products called “self-leveling underlayment.” This name means exactly the same thing as “self-leveling concrete.” They’re generally mixtures of Portland cement, polymer plasticizers, and other ingredients. They have the strength of concrete but they flow more easily and set up quickly.

Self-leveling concrete can be poured as thin as a quarter of an inch, just enough to smooth out small imperfections if that’s all you need. But if the floor has low spots and needs to be smoothed, even more, it can be poured as thick as an inch and a half without the addition of aggregate and 5 inches with the addition of aggregate (though make sure you follow all manufacturer’s guidelines).

Self-leveling concrete works especially well with radiant heating installations because it easily flows around the tubing. The thicker floor-leveling compounds, that must be troweled to achieve a proper finish, can’t do this.

Where Self-Leveling Concrete Is Used

Let’s say you’re upgrading an old, damaged concrete floor that’s settled or cracked. Or maybe you’re installing a radiant heating system in a floor. Maybe you’re building an addition and you need to match the floor to the floor in an adjoining room. Maybe you’re finishing a basement where the floor is rough and uneven concrete. Some other applications for concrete toppings include warehouse floors, light industrial applications, retail stores, and institutional facilities. Concrete toppings can also receive pigmented color dyes, stains, saw cuts or mechanical polishing to produce a decorative concrete finished wear surface.

Preparing to Use Self-Leveling Concrete

Before you install your new floor, there’s an essential consideration you need to address, and that’s moisture in the existing concrete floor. All concrete contains moisture, and if the moisture level is too high, it may cause the leveling compound to degrade over time. So you need to test the slab to be sure the moisture level is not too high.

This isn’t something you can do just by looking at the slab. No matter how the slab looks, moisture deep in the slab can migrate to the surface over time and cause serious problems. If the moisture level deep in the slab is too high, you need to take steps to remediate it before you can pour your new floor.

This is a well-known problem with a well-known and scientifically proven solution. The way moisture moves in a concrete slab has been studied since the 1960s, and researchers have developed a scientifically proven test for measuring moisture levels deep inside a slab. That test is called “the relative humidity test using in situ probes.” This is the basis for the ASTM F2170 standard. This standard governs the processes involved with obtaining results using in situ probes in concrete slabs. Despite the complex terminology, this test method is actually very easy and much faster than you would think. Wagner Meters provides an in-situ concrete testing system that conforms precisely to ASTM F2170 in probably the most simple and time-saving way possible.

Raid RH L6 testingThe Rapid RH® L6 system uses single-use sensors for speed, economy, and ease of use (for example, they come calibrated from the factory and don’t require continual calibration checks and new documentation). Once the L6 sensors are installed in the slab and equilibrated after the F2170 requirement of 24 hours, there’s no need to move them from location to location and wait for them to equilibrate again. Repeat readings can be taken without additional equilibration time. And unlike reusable probes, the L6 sensors never need calibration.

Rapid RH L6 concrete testing The Rapid RH Total Reader® reads, displays, and transmits temperature and RH data via Bluetooth® to the DataMaster™ L6 app. The DataMaster L6 app stores, displays, and reports the data on your iOS or Android mobile device. From your mobile device, you can email PDF format reports to your client and all interested parties. Backup copies of your readings are stored in the cloud and in the sensors that are permanently installed in the slab. This unbroken digital path from the sensor to the final report, plus automatic data backup ensures the highest data integrity, accuracy, and peace of mind.

If you find that moisture is a problem in the slab, you need to get a professional to handle the moisture remediation. You can also visit the International Concrete Repair Institute (ICRI) for more information on next steps or to find an expert to help.

Installing Self-Leveling Concrete

7 Tips for a Better Concrete Installation:

  1. Read and follow the manufacturer’s instructions to the letter. Don’t skip or skimp on any step. And if any of these tips conflict with the instructions, go with the manufacturer’s process instead.
  2. Buy more product than you need. A difference of a fraction of an inch thickness can mean several bags of product. You have to finish the job in one pour so you can’t go back to the store for more.
  3. Have all your tools and supplies ready. Once you start to pour, you may only have about 10-20 minutes to work.
  4. Keep your leveler product dry – store the bags indoors and up off the ground.
  5. Do not mix product in extremes of heat or cold.
  6. Do not add water to the product as you’re spreading it. The mix ratio is critical.
  7. Clean all tools and buckets immediately when you’re done. If you allow the product to set it will never come off.
  8. Be careful not to pour more product than you need. If you do, quickly and carefully scoop it up into a bucket and remove it.

Here’s a list of what you’ll need to do the job:

  1. Shop vacuum, broom, and mop
  2. Mixing buckets or barrels, as large as you need (6-gallon minimum)
  3. Mixing drill and mixing head
  4. Gauge rake
  5. Cleats
  6. Kraft paper or plastic sheet
  7. Silicone caulk
  8. Leveling product and primer

Takeaways for a Successful Self-Leveling Pour

Whenever you need to repair, level or raise a floor, self-leveling concrete can be a fast, cost-effective solution.

Self-leveling concrete can be used as an underlayment for tile, carpet, or other floor coverings.

For a successful self-leveling concrete installation, follow the seven tips in this article.

To ensure that your floor does not suffer from a flooring failure, it’s essential to test the concrete subfloor for high moisture levels according to the ASTM F2170 standard. It’s not that hard to do and you’ve got a great product from Wagner Meters that can help.

The Rapid RH L6 system is the fastest, easiest, most cost-effective system for RH testing concrete slabs in compliance with ASTM F2170. It will get you accurate results in a fraction of the time versus other methods, and it’s digital, with convenient wireless communication to your smart device. This helps you cut down on the paperwork and give you greater confidence in the documentation of your test data.

Last updated on April 16th, 2020

22 Comments

  1. Jason Spangler Jesse Ford says:

    Thanks for mentioning some of the equipment you’ll need to level concrete like a shop vacuum, broom, mop, mixing buckets, mixing drill, gauge rakes, and other things. My brother is thinking about hiring concrete leveling experts because he’s contemplating redoing his driveway next month. I think it’s a good investment that he hires a reputable company that has the necessary equipment for a concrete project if he decides to do the renovations.

  2. Jason Spangler Warren Concrete says:

    I haven’t seen the finished product of this kind of leveling agent, but it does look very nice in these pictures. I plan to learn more about the product and start offering the service in my business. Thanks for the info.

  3. Jason Spangler Joan says:

    My floor has glue from old carpet. Do I need to remove all the old glue first?

    • Jason Spangler Jason Spangler says:

      Joan:

      Thanks for the question. This is always going to be a question for the flooring adhesive and finished floor product manufacturer to give you direction on. I would recommend finding their number and asking them directly. Good luck.

  4. Jason Spangler andrew novick says:

    What are you using the silicone caulk for? It’s not mentioned in the steps.
    Is it for expansion gap?
    Thanks!

    • Jason Spangler Jason Spangler says:

      Yes, it would be for expansion joints or any non-moving cracks. It’s labeled specifically as silicone, but more correctly it would any type of product that would set to a rigid hardness.

  5. Jason Spangler gary kohl says:

    I have 12″ by 12″ glazed floor tile. I would like to put a lock in place vinyl floor over this floor. Will this concrete pour product level the grout joints and more importantly will it adhere to the glazed tile? The grout lines are very shallow. Approx. what is the coverage per sq. ft. for a pour of this kind?

    • Jason Spangler Jason Spangler says:

      Gary,
      Thanks for the question. Many times, you may be able to install over existing floors if the existing floor is sound and adhered thoroughly to the subfloor. Usually, a primer and some sort of leveling material would typically be the way to go, but I would consult some of the manufacturer’s like Ardex, Uzin, Mapei, Shonox, etc. (there are many others) to get their technical recommendations. Good luck.

  6. Jason Spangler Rod Taylor says:

    I have a 40 x 40‘ pad that was poured poorly and very uneven so I would plan to use this leveling system along with a decorative system on top. And with the need of up to 1 inch of filler in a few areas. Can this product be poured twice if needed. Where could I buy the product for this application?

    • Jason Spangler Jason Spangler says:

      Rod,

      Thanks for the questions. It sounds like products of this nature would be perfect for your needs. I would research companies like Ardex, Uzin, and Mapei to find the right product for your specific application. There are many others out there, so in your research make sure you reach out to each company specifically for your specific needs. Good luck.

  7. Jason Spangler Allan says:

    Im laying 10mm layer of SLC to cover underfloor heating wires on a ply substrate. Do I need an expansion joint around the perimeter? The T&G 19mm ply should have a 5mm gap to the wall bottom plate for expansion so I either need to fill that with sealant or PEF rod first so the SLC doesn’t flow into the gaps. I assume I could use a neoprene sponge sticky back seal tape around the perimeter which I can get in 15mmx9mm for the SLC expansion joint? That gives me a 9mm expansion gap and 5mm, (15-10) above the finished SLC which is my drywall gap. Does that sound feasible? The pour area is about 4 sq metres. Thanks

  8. Jason Spangler Manani Curutchet says:

    Can I use this product in a patio outside? Thanks.

  9. Jason Spangler Dusty says:

    I am planning to do a pour in our three-car garage – what is recommended to clean stains? I read that etching with muriatic acid is not advised. I really got a lot from your article, thanks for posting

    • Jason Spangler Jason Spangler says:

      Dusty,

      Thanks for the question. I would look for a concrete sundry supply house in your area. A place that does finishing tools, stakes, curing compounds, etc. and give them the specifics to the stains. Are they rust, oil, etc. They should be able to give you guidance. Depending on the types and amount of staining you might just use white vinegar or you may find a more concentrated commercial cleaner. Good luck.

  10. Jason Spangler Vicki says:

    We had flooring installed. They leveled the subfloor before laying the
    floating floor down. The issue is 5 days later I went down in the basement
    and realized the self leveling product they used leaked through the subfloor.
    I now have it running down the walls and on the carpet. My question is
    what did they do wrong did they miss a step? And how do you get off carpet and walls?
    Thanks

    • Jason Spangler Jason Spangler says:

      Vicki,

      Thanks for the question. Many subfloor/wall assemblies aren’t fully sealed in everyday life. When doing a self leveling product, the material will flow on the floor to the low spot of level and if there is any way for the material to flow out, it will. Many time, if they know there is a floor below, I have seen installers use something like a spray foam insulation to establish a perimeter around the area where the self leveler is to be poured. I would contact the installer or retailer and let them know what has happened.

  11. Jason Spangler Heather says:

    This is fantastic detail! Thanks! I see you use the caulk in wooden joints. On a slab, would you also want to draw a line of caulk around the edges (like under the walls) so the self leveler doesn’t flow into the breathing room of the walls, or underneath old (and not straight) sills. My house is a 1960 slab with no basement and brick exterior.

  12. Jason Spangler Alice Carroll says:

    Thanks for pointing out that cleats would be needed when it comes to concrete leveling projects. I’m thinking about getting a concrete leveling repair service soon because the steps leading to the gazebo in my garden are a bit crooked and uneven. I hope that making them look more symmetrical would elevate the aesthetic appeal of the gazebo.

  13. Jason Spangler Janice Frank says:

    Looking to level outside (under roof) porch. Is there a leveling product for outdoors?

    • Jason Spangler Jason Spangler says:

      Janice:

      Thanks for the question. I would look at Ardex or Mapei (there are others) and if that fails I would seek out a concrete sundry specific distributor in your area and see what they have. Good luck.

  14. Jason Spangler TREVOR BARRY WRIGHT says:

    After a self-levelling product has been applied, can the floor be painted with COO-VAR Floor Paint?

    • Jason Spangler Jason Spangler says:

      Trevor:

      Thanks for the question. This type of question is really best answered by the manufacturer of the self leveler or paint since they should know specifically how there products will react. Good luck.

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