Tips About Self-Leveling Concrete
Whenever 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.
The 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.
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:
- 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.
- 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.
- Have all your tools and supplies ready. Once you start to pour, you may only have about 10-20 minutes to work.
- Keep your leveler product dry – store the bags indoors and up off the ground.
- Do not mix product in extremes of heat or cold.
- Do not add water to the product as you’re spreading it. The mix ratio is critical.
- Clean all tools and buckets immediately when you’re done. If you allow the product to set it will never come off.
- 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:
- Shop vacuum, broom, and mop
- Mixing buckets or barrels, as large as you need (6-gallon minimum)
- Mixing drill and mixing head
- Gauge rake
- Kraft paper or plastic sheet
- Silicone caulk
- 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
Jason has 20+ years’ experience in sales and sales management in a spectrum of industries and has successfully launched a variety of products to the market, including the original Rapid RH® concrete moisture tests. He currently works with Wagner Meters as our Rapid RH® product sales manager.