How to Ensure a Successful Self-Leveling Underlayment Application 

&#;Self-leveling underlayment&#; (SLU) is a bit of a misnomer. Although this type of product is incredibly useful, it does require a thoughtful installer to ensure the best results. Follow these guidelines to prevent issues in your self-leveling underlayment installation.

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Select a product appropriate for the installation: Know your installation environment and familiarize yourself with the relevant ASTM standards for strength. A commercial floor subject to heavy rolling loads will require a higher-grade self-leveling underlayment (like TEC® Level Set 300 Self-Leveling Underlayment) than a floor in a single-family home.

Also, it is critical to understand your project timeline and choose a product that fits within the appropriate schedule. Some products may require 24-48 hours prior to installing floor coverings while other more premium products are ready to accept moisture-sensitive floor covering in 12 to 16 hours.

Consult product data sheets for information on tensile strength, compressive strength and flexural strength, as well as recommended cure times.

Generally speaking, there are two types of self-leveling underlayments &#; traditional and next generation technologies. The most noticeable difference between traditional and next generation SLUs are the flowability and the smooth surface profile of each product. Check out TEC's new high-flow SLU: Level Set 500 HF and for best practice tips for successful high flow SLU installations view our Technical Bulletin. 

Some installers prefer the attributes of traditional SLUs because of the working properties. Others prefer the new technology for its high flow properties and extended working time.

The job scope will dictate which product technology should be used for installation. Traditional SLUs work best for deep fill applications greater than 3/16&#;. The newer technologies are ideal for thinner applications.

Know your substrate: Most SLUs require that all surfaces are fully stable and structurally sound prior to the application of a self-leveling underlayment. For example, understanding your existing substrate porosity is critical to choosing the proper primer. (A simple water droplet test will determine the surface porosity per ASTM F). Equally important is to know the make-up of the existing substrate. For example: typically, sound concrete requires a single coat of primer. Unsealed Gypcrete may require additional steps, including multiple coats of primer prior to the application of cement-based self-leveling underlayment.

Prepare your substrate: Make sure to plug all floor openings, gaps and cracks and install termination dams to prevent any seepage. Consult with product manufacturers to determine moisture limitations of the floor covering, self-leveler, and adhesives to determine if moisture mitigation is needed.

If moisture mitigation is required, this must be done prior to installation of the self-leveling underlayment.

Self-leveling underlayments require the use of a primer prior to installation (like the TEC Multipurpose Primer). Failure to use product recommended primer may result in installation failure.  Primer retains the moisture within the self-leveling underlayment to allow proper curing. Secondarily, it acts as a bonding agent to ensure the SLU bonds properly to the substrate. Refer to the primer label for information regarding application methods and dilution per ASTM F.

Beyond priming, most self-leveling underlayments require that the substrate is free from any contaminants that may inhibit bond, including adhesive residue, sealers/curing compounds, oil, grease, loose or peeling paint, or other contaminants. Polished underlayments will require epoxy primers and/or a specific Concrete Surface Profile (CSP), and in these cases, mechanical abrasion (shot-blasting), is required.

Proper water demand: Mix your self-leveling underlayment within the water range specified on the bag. Overwatering will lower the strength of the underlayment and may cause cracking and disbonding. Additionally, a white film may form on the surface of the cured underlayment if the product is overwatered. Failure to properly mix the SLU may make it difficult to work with and lead to improper flow, cracking, or an irregular surface. Mix a minimum of two bags at a time when barrel mixing to ensure optimum efficiencies during the application process. In addition, some SLUs can be pumped. If pumping, special attention is needed to maintain proper water ratios and prevent overwatering. Follow equipment and product manufacturer&#;s recommendations when pumping self-leveler.

Product and ambient temperature: Make sure that the temperature of the room is within the manufacturer&#;s acceptable range. A climate that is too cold or too hot can affect the product, such as increased set time in cool temperatures or reduction in heal time in hot environments. Temperature and humidity will affect flow, working time and set time of the SLU.

Additionally, the temperature of the powder and the water is crucial. Leaving product in the sun, or in a hot environment may lead to flash setting. In situations where warm product is unavoidable, mixing with cold water may help combat installation issues. To maintain cold water temperatures in hot conditions, use blocked or bagged ice in your water barrel.

Whether the environment is warm or cool, acclimating the product prior to mixing is always a best practice.

Use as recommended: Manufacturers will specify the maximum thickness of their product. Some products allow for the addition of aggregate (pea gravel) to increase the depth of the pour, while others only allow their product to be used neat. Be sure to use the appropriate aggregate size and amount when extending a self-leveling underlayment in a single pour. Two separate pours or multiple lifts will achieve the target thickness without the use of additional aggregate. Once the SLU from the first pour becomes a walkable surface, you may proceed to apply the proper primer coat for the additional pour or lift. If a surface is extremely uneven in isolated areas with depressions greater than ½&#; deep (bird bath), you may treat these areas independent to the final pour. This will assist with the application process by using a consistent amount of self-leveling underlayment throughout the application. Always consult with manufacturers to determine the most suitable product for your application.

Protect your freshly poured underlayment: All self-leveling underlayments should be protected from direct air movement (drafts) during the initial curing process (2-6 hours) as they may cure prematurely which leads to cracking. Generally, most underlayments are not considered final wear layer surfaces. During the final curing process (2-24 hours) they should be protected from excessive construction. Traffic without protection can lead to gouging and irregular surfaces. Allow to cure completely to prevent any unnecessary surface damage, prior to the floor covering installation.

A common theme connects these successful self-leveling underlayment application guidelines: noting and adhering to the manufacturer&#;s instructions. You must read labels and product data sheets carefully to ensure products perform as desired.

Make sure to check out our entire line of Surface Preparation products. If you need assistance determining which product is right for your job, contact our Technical Support team here or by calling 1-800-832-, Mon-Fri 8 a.m. -  6 p.m. CST.

 

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Even for those of us who consider ourselves to be pretty handy within the home improvement world, the thought of pouring self leveling concrete IN OUR HOUSE is moderately terrifying. O.K., completely terrifying. Don't worry. You can do this.

The VCT floor I laid, on top of the cement I poured, over the self installed heated floors.

First things first. I ate a whole can of Pringles today. They were Salt & Vinegar and now my tongue feels like I ate a ball of sandpaper. That might not seem pertinent to the task at hand - and it isn't.

When I redid my kitchen a decade ago I really wanted to address my cold floors. So I ripped out all of my ceramic tile and laid down heated floor mats. That wasn't scary at all. Pouring buckets of self leveling concrete over them WAS.

The cement floor would encase the heating elements, allow them to radiate heat still, plus provide a level smooth surface for tiles. That was my reason for pouring cement all over my floors and working myself into a panic.

Whatever your reason, you don't need to be afraid. I say that because I was afraid. Really afraid. Letter from the tax department afraid. You don't need to be.

Using Self leveling concrete

Self levelling concrete is cement based like traditional concrete, but it flows much easier and sets up more quickly due to polymers added to it. It's used to create a smooth, level surface for laying carpet, ceramic tiles or other floor coverings on.

For use almost exclusively on interior flooring.

Self leveling cement (concrete) can be poured up to a 1 inch thickness.

Materials

• Self leveling concrete*
• Leveling primer**
• a cement mixing paddle
• a strong drill (rent an industrial one)
• 5 gallon bucket
• trowel
• filler (like Durabond 90)

* It may also be called self leveling concrete, leveling compound, self leveling floor resurfacer or self leveling underlayment. Make sure you get REGULAR instead of QUICK DRYING. Regular will give you more time to work and spread out the material before it starts to set.

** Primer is needed when you're pouring concrete onto a porous surface like an existing concrete floor. It isn't needed when pouring onto old tile.

Method

PREP WORK

1. Scrape up any loose debris or old tiles from the floor. 
2. Fill any cracks or holes with Durabond 90 and create a dam to prevent the runny concrete from seeping anywhere you don't want it to go.

Scraping Dam created with strip of wood and duct tape

3. Vacuum so you have a clean surface.
4. Gather your materials.

The brand of resurfacer doesn't matter so much as the type. There are 2 types.  Quick drying and regular. You want regular.

POURING

5. Add the required amount of water to the bucket FIRST. (the bag will tell you how much water to compound mix to use) 
6. Add ¼ - &#; of the powdered compound. Mix with water using the drill.  Continue mixing in the remainder of the bag bit by bit until it's all incorporated.  Mix for prescribed amount of time as detailed on the bag.

For one bucket of concrete a strong cordless drill will do the job, but if you have any more than 1 bucket to do you're in trouble.  The battery will die after 1 or 2 buckets.  Then you'll go for your corded drill, which will burn out and will get thrown in the garbage.

Save your anger, your sanity and your relationship and RENT AN INDUSTRIAL DRILL.  After the first day I rented a strong drill for $20 for half a day. 

7. Pour your leveling compound where you want it.
8. Trowel it. Using a trowel push and pull the mixture where it needs to go.  Push it into corners and pull it towards you.  Excuse my hair.  It appears I was having a Paul Weller moment.

9. Clean up your drips.
10. Wait 24 hours to walk on it.
11. Wait 3 days to place furniture back.

The mudroom went perfectly well. It couldn't have gone better so I continued onto the kitchen where things were a bit tricker.

Tips for Larger Rooms

A bigger room means you have to pour the buckets of concrete, run back to the mixer and mix up another batch (which needs to be mixed a longgg time), run through the house with a 50 pound bucket of cement and pour it where you left off.  And repeat.

1. Larger rooms are easier to do if there are 2 people working. One mixing the cement and one pouring it.

Contact us to discuss your requirements of Self Leveling Compound Basecoat Primer. Our experienced sales team can help you identify the options that best suit your needs.

2. Use a stiff squeegee on a long broom handle for pushing and pulling the compound into place.

NOTE: Wet concrete is caustic and can burn.

YOU HAVE TO WASH YOUR FEET IMMEDIATELY AFTER YOU WALK THROUGH IT. Do so after every time you walk through it. Also don't walk through wet cement if you have open cuts. 

3. If you find bits of unmixed lumps of cement.  Just mush them with your fingertips.

4. You may need to do a second coat if the first coat didn't cover. You could still see the heated floor mats I installed after the first coat, so I did a second.

First coat Second coat

It may look uneven, but it's just an optical illusion. The photo on the right is a levelled floor that is perfectly smooth.

5. After leveling if you have any issue with dips and bumps you can correct them with a bit of Durabond 90. (fill, let dry, then sand)

Would you ever want to pour self leveling concrete?

To level an uneven concrete floor.

If you have a wonky basement floor that's uneven you can use self leveling concrete to smooth everything out and get it nice and flat. It's even handy if your concrete floors are just filthy. A thin layer of this will give you nice, clean concrete floors.

To prep a floor for laying down tile or to encase radiant floor heating.

The reason I poured it in my kitchen, bathroom and mudroom was so I could put down radiant floor heating. There's no basement or crawlspace at the back of my house which makes the floors pretty darn cold in the middle of a Canadian winter.  

How much does a 50 lb bag of self leveler cover?

How much the cement will cover depends on how thick you will need it to be.  This mudroom is around 30 square feet and one 50 pound bag of cement just barely covered it at about ¼" thickness.

Quick drying self leveling cement

Starts to set up in 5 minutes. This is only used when you have a small area to do and are an experienced concrete finisher.

Regular drying self leveling cement

It starts to set up within 15 minutes. This gives the amateur user much more working time.  Those extra 10 minutes make a huge difference when you aren't exactly sure of what the hell you're doing.

Continue to Content

The Self Leveling Cement *Quick Guide*

Yield:

Level concrete floor

Prep Time:

1 day

Active Time:

6 hours

Additional Time:

3 days

Total Time:

4 days

6 hours

A quick guide to pouring self leveling cement. Refer to post for in depth instructions.

Materials

• Regular Self leveling cement*
• Leveling Primer**
• a cement mixing paddle
• a 5 gallon bucket
• a trowel
• filler (Durabond 90).

Tools

• Strong drill (I rented an industrial one)

Instructions

Scrape up any loose debris or tiles from the floor.

Build dams to stop the cement from going anywhere you don't want it to go.*

Fill any holes and/or cracks in the floor that the liquid cement could run down. I use Durabond 90.

Vacuum to get the surface perfectly clean.

Add water to your bucket (amount will be stated on your bag of cement)

Add &#; of the bag of cement into the water.

Mix with the drill and cement paddle, continually adding the rest of the bag of cement until everything is incorporated and then mix for the length of time given on the bag.

Here we go. Pour the self leveling cement into the desired area. Push and pull it into place with a trowel. It does self level but needs some help getting around.

And now you wait for it to cure. You can walk on it within 24 hours and place heavy objects back in 3 days.

Notes

*It may also be called self leveling concrete, self leveling floor resurfacer or self leveling underlayment. Either way make sure you get REGULAR self levelling cement. Quick Dry lets you walk on it within 6 hours, but you have a much shorter working time, and for an amateur it's better to have as much working time with the product as possible.

**Primer is needed when you're pouring concrete onto a porous surface like another concrete floor. It isn't needed when pouring onto old tile.

**It's very liquidy so make sure you don't skip this step or you'll have cement running under your dishwasher or down your stairs or into other rooms! I used thin wood, heavy cardboard and duct tape to make dams.

Self levellers can be poured to an inch deep.

If for some reason your cement isn't level, didn't turn out right or wasn't poured quite deep enough, you can re-pour more cement as long as you do it before the initial cement cures. Don't exceed the total recommended depth of 1".

OTHER TUTORIALS REFERENCED IN THIS POST

 p.s. I'm out of chips.

&#;Follow me on Instagram where I often make a fool of myself&#;

For more High strength cement self-leveling compoundinformation, please contact us. We will provide professional answers.