5 Min. Read

Thinset vs. Self-Leveling when Installing Radiant Floor Heating

Self leveling cement being poured over concrete subfloor

If you’re not a pro and are new to installing radiant floor heating, you will likely face the obstacle of choosing either latex-modified Thinset or a self-leveling compound. Both have their advantages and disadvantages, but when choosing between the two of them, it truly boils down to the type of flooring that you are installing.

Before the installation process begins, it’s important to understand exactly what latex modified thinset and self-leveling compound is, as well as the pros and cons of each.

Latex-modified thinset is a blend of cement, very finely graded sand, and a water retention compound that allows the cement to properly hydrate. It is used to attach ceramic tile, glass tiles, metal tiles, stone tile, and cement tiles to all kinds of substrates like concrete, plywood, and vinyl flooring.

Pros of Latex-Modified Thinset:

  • Very durable and resistant to cracking.
  • Less expensive than self-leveling compound.
  • Readily available.
  • No primer is required.
  • The same material to cover the wires and mesh is used to set the tiles, so there is only one item to buy.

Cons of Latex Modified Thinset:

  • If a second batch is needed, it is difficult to create the exact same consistency as the first batch.
  • Can be difficult to level evenly.
  • More labor intensive.
  • More chance of damaging wires with the trowel.

When it comes to flooring, tile is always installed with latex modified thin set. If you were installing vinyl flooring, it would be more difficult to achieve a perfectly level and flat floor with latex modified thinset, so self-leveling is a better choice.

Speaking of level floors, self-leveling is more likely to give you a completely flat surface. Self-leveling compound is polymer-modified cement that’s typically used to create a flat and smooth surface with a compressive strength. It is used as an underlayment for many types of floor coverings requiring a flat surface, including sheet vinyl, vinyl composition tile, ceramic tile, carpet, and wood.

Pros of Self-Leveling:

  • It is flat (self-leveling).
  • Perfect for laminate flooring.
  • Faster installation process than latex modified Thinset.
  • Less likely to damage wires.

Cons of Self-Leveling:

  • More expensive than latex-modified thinset.
  • Primer is required.
  • Its thick density can cause the wires and mesh of the radiant heating system to float.
  • The mesh needs to be attached/stapled down every few inches.
  • Areas, such as vents and doorways, need to be dammed off.

The rule of thumb is when installing vinyl or laminate flooring; self-leveling is the ideal compound to use. By using latex-modified thinset under a vinyl or laminate floor you run the risk of the mortar being slightly uneven which can make the flooring unstable.

Now that we’ve got the basics covered, you can make an informed choice. So which one will you choose?

Pictured Above: Self-leveling compound, courtesy of All-Things-Concrete.com (All Rights Reserved)

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This is very useful stuff!

Well done! I personally use SLU exclusively. It provides the flattest tile surface while it protects and encapsulates the wire. If you need to change 1 tile or the whole floor you may do so without the collateral damage to the floor heat system.

Linnay, Thank you sooo much for your informative read! What brand/type self leveling material do you use? Laticrete has some good reviews but I wanted to get your opinion! Patrick

I appreciate the information on the benefits of self-leveling and the benefits of of Latex-Modified Thinset. I had no idea that the Self-Leveling was less likely to damage wires when installing. My brother is looking at dong some renovations to his home within the next year or so, I will be sure to share this information with him so he can make the right decision. https://tileprodepot.com/product/laticrete-nxt-primer/

I am planning on floor heating on a remodel of a Florida room which has a slab. My plan is to put down an insulation layer, then heat cable, then thin-set then latex tile adhesive and tile. See any issues with this plan?

WarmlyYours Responds...

Chas, that sounds like a good plan but you can also accomplish this with one less "ingredient." You can use latex modified thinset as your adhesive for attaching the insulation to the slab, for embedding the heating cable, and for setting the tile. We have a cross-section drawing of the depths that you can review here: https://www.warmlyyours.com/publications/TZ-FLOOR-HEAT-3-TILE-OVER-INSULATED-CONCRETE-THINSET-A and, as always, feel free to give us a call if you have any further questions at 1-800-875-5285. Hope this helps!

We are installing in floor heating in our sunroom. The subfloor is plywood and the builder put tape to seal the seams. My question is should we use the self leveling compound down first then lay the wires and then another layer of thin set over the wires then install the engineered vinyl plank flooring down? Heather Bondy

WarmlyYours Responds...

Heather, for most applications the layer of self leveling over the subfloor will be unnecessary. But it can be useful if your subfloor has dips or is not level, as it will provide an even surface for the rest of the installation. It can also make sure your heating element ends up 1-1.5" from the top of the flooring surface for optimal performance. If your subfloor is level, you can skip directly to adhering the heating element to the subfloor, embedding the heating element in either self leveling or thinset, and then attaching your flooring. We have some great videos outlining this process and our 24/7 Tech Support Team is always available to answer any additional questions you might have.

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