Choosing Between Self-Leveling Compound and Thinset for Radiant Floor Heating
If you’re new to installing radiant floor heating, one of the first decisions you’ll face is whether to use a self-leveling compound or a latex-modified thinset. While both materials are commonly used in floor heating installations, the best choice depends largely on the type of flooring you’re installing over your heating system.
Before diving into the pros and cons of each, it’s important to understand what these materials are and how they perform. Latex-modified thinset is a blend of cement, fine sand, and additives that retain water to allow proper curing. It’s typically used to bond ceramic, stone, glass, or cement tiles to a variety of subfloor materials, including concrete and plywood.
In this guide, we’ll break down the differences between thinset and self-leveling compound, and help you choose the right one for your project.
Pros of Latex-Modified Thinset Mortar
Latex-modified thinset offers several advantages for tile installations:
• Durability and Crack Resistance: The inclusion of polymers enhances its strength and flexibility, reducing the likelihood of cracks due to substrate movement.
• Cost-Effectiveness: Generally more affordable than self-leveling compounds, making it a budget-friendly choice for many projects.
• Wide Availability: Easily found at most home improvement stores, ensuring convenience for DIYers and professionals alike.
• No Primer Needed: Can be applied directly without the need for a primer, simplifying the installation process.
• Dual-Purpose Material: Serves both to cover heating wires and to set tiles, streamlining the materials required for installation.
• Installation Membrane Compatibility: Both modified (ANSI A118.11) and unmodified (ANSI A118.1) thinset mortars are suitable for use with Prodeso Membrane installations.
Additionally, latex-modified thinset is versatile and suitable for various substrates, including concrete, plywood, and vinyl flooring. Its strong bonding capabilities make it ideal for securing ceramic, glass, metal, stone, and cement tiles.
Cons of Latex-Modified Thinset Mortar
While latex-modified thinset is a popular choice for tile installations, it’s important to consider its potential drawbacks:
• Inconsistent Mixing: Achieving uniform consistency across multiple batches can be challenging, leading to variations that may affect adhesion and curing.
• Difficulty in Leveling: Properly leveling the surface with thinset requires skill and attention, as it doesn’t self-level, potentially resulting in uneven tile placement.
• Labor Intensiveness: The application process is physically demanding and time-consuming, involving meticulous spreading and leveling.
• Risk to Heating Elements: When used with radiant floor heating systems, there’s an increased risk of damaging heating wires during application if not handled carefully.
Understanding these challenges can help in planning and executing a successful tile installation.
Pros of Self-Leveling Compound
When preparing subfloors for flooring installations, self-leveling compounds offer several notable advantages:
• Creates a Smooth, Level Surface: Self-leveling compounds naturally flow to fill in low spots and imperfections, resulting in a flat and even surface ideal for various flooring types.
• Faster Installation Process: These compounds are designed for quick application and drying, allowing flooring projects to proceed more rapidly compared to traditional methods like latex-modified thinset.
• Minimizes Risk of Wire Damage: When installing over radiant heating systems, self-leveling compounds encase heating elements smoothly, reducing the chance of damaging wires during the installation process.
By utilizing self-leveling compounds, installers can achieve efficient, high-quality flooring installations with durable and aesthetically pleasing results.
Cons of Self-Leveling Compound
While self-leveling compounds offer significant benefits in achieving smooth and level surfaces, it’s important to be aware of certain challenges associated with their use:
• Higher Material Costs: Self-leveling compounds are generally more expensive than latex-modified thinset, which can impact overall project budgets.
• Primer Requirement: To ensure proper adhesion and prevent issues like pinholing, applying a primer before the self-leveling compound is often necessary, adding time and cost to the preparation process.
• Potential for Heating Elements to Float: The fluid nature of self-leveling compounds can cause embedded radiant heating wires and mesh to become displaced or float if not securely fastened.
• Need for Secure Attachment of Heating Mesh: To prevent movement during application, the heating mesh must be firmly attached or stapled down at frequent intervals, which can be labor-intensive.
• Requirement to Dam Off Openings: Areas such as vents and doorways need to be properly sealed or dammed to contain the self-leveling compound within the intended area, necessitating additional preparation.
Being mindful of these considerations can help in planning and executing a successful flooring installation using self-leveling compounds.
Selecting the Appropriate Adhesive Based on Flooring Type
Choosing the right adhesive is crucial for a successful flooring installation. The suitability of latex-modified thinset versus self-leveling compound largely depends on the type of flooring material:
• Tile Installations: Latex-modified thinset is commonly used for attaching ceramic, glass, stone, and cement tiles to various substrates, including concrete, plywood, and vinyl flooring.
• Flexible Floorings (e.g., Vinyl, Laminate, Wood): Self-leveling compounds are preferred for these materials, as they create a flat and smooth surface, essential for the proper installation of flexible flooring types.
When installing vinyl or laminate flooring, achieving a smooth and level surface is crucial for stability and longevity. Self-leveling compounds are typically recommended for these materials, as they create an even base, reducing the risk of unevenness that can compromise the flooring’s integrity. On the other hand, using latex-modified thinset under vinyl or laminate may result in slight irregularities, potentially leading to instability. For hardwood floors, incorporating self-leveling underlayments between sleepers is generally advisable to ensure a consistent and level foundation.
Now that we’ve got the basics covered, you can make an informed choice. The next step is figuring out which floor heating system to install! You can get started with a free instant quote.
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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?
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
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.
I'm remodeling a bathroom that has under the floor radiant heat. The old tile floor had a lot of cracks so we decided to remove and re-tile. After lifting the tile, I discovered that the installer had used 1/2" plywood over the subfloor as the backer board and all of the cracks in the tile followed the seams where they had joined the 1/2" plywood together. The floor also squeaks which tells me it is probably flexing more than is good for a tile installation. The 1/2" plywood is nailed down. I'm trying to decide how to best approach this. One option is to keep the 1/2" plywood and just add a lot more screws to tighten everything up. Another is to take up the 1/2" plywood and replace it with cement backer board. This gets tricky as it looks like the 1/2" plywood was put in place before the plumbing and a hot water baseboard heater that was installed under the sink. What's the best way to deal with this? Thanks, John H
John, that's a great question and while we're reasonably certain that the cement backer board route that you outlined will ultimately be the best solution, our best recommendation for you is to have the floor evaluated by a flooring professional that you trust. There's obviously a lot of variables that would go into this assessment and there's no replacement for someone that can actually see the project up close. We hope that helps!
I'm trying to find an answer for my question and have thus been unsuccessful asking "only" concrete and "only" radiant flooring guys so here goes....building a house...we have (5"??) concrete poured on our main level. We are installing electric heat (instead of glycol) for our "full" house heating needs (no gas...just supplementing with a wood stove). To save $, we would prefer whatever we pour over it to be "the finished floor" (not putting plank, carpet, tile on top). Can thinset "be the floor"?? Can Self-leveling concrete "be the floor"?? any insight will be better than what I've got so far (big fat zero lol!). Thanks!!
Thanks for the very interesting question! It's a tricky one to answer without all of details but we can definitively say that neither thinset nor self-leveling cement would be serviceable final flooring surfaces. They're simply not durable enough for direct and continued foot traffic in that application (installed under a floor covering is a totally different story). Your best bet would be to use our Slab Heating Cables or Mats. These can be attached to your existing slab floor and then embedded in a new layer of traditional concrete, which can then be treated like any finished concrete floor. Hope that helps.
Hi, I am remodeling my bathroom and have put electric radiant floor heating in. I am now looking at just less than an inch between the level of the tile and the level of the tile in the shower pan. I am trying to do a same height walk in shower from floor to shower pan. My question is can I put about 1 inch of leveling concrete over my electric floor heating element and then tile over the top while not completely losing the heat? Thank you
Thanks for the question! Our official installation guidelines for our TempZone heating elements (the type that would be used under tile) stipulate that the heating elements themselves should be installed at a continuous depth that is no deeper than 1.5" inches from the finished flooring surface. Depending on how your floor heating is currently installed, it sounds like your project would be very close to exceeding this limit once you factor in the tiles and the additional thinset to adhere those to the self-leveling concrete. If you feel like this is the case, please don't hesitate to give us a call at a 1-800-875-5285. However, if the heating elements will be within 1.5" of the finished flooring surface, then the heating system will still be able to provide heat for the room because the heating elements essentially turn the embedding concrete/thinset into a "heat bank" that then evenly radiates heat upward through the room. You'll want to keep in mind, though, that since there will be more mass in a floor with 1" thick layer of self leveling concrete, it will take longer to reach the desired floor temperature than a system installed in a thinner level of SLC. Hope that helps!
Hi, we are looking to renovate a slab-on-grade house that has busy multi-coloured flagstone floors on top of a radiant floor system. Wondering if rather than ripping out the floors and risk damaging the heating system, I can skim coat over those floors with concrete?
You should be able to do a skim coat of concrete over the existing floors but you may notice a decrease in heat output (because of the additional material over the heating system). We would need more details about the heating system and how deeply it's installed currently along with the proposed depth of the skim coat to give you and idea of how much of a decrease that will be. Hope that helps and feel free to give a call (1-800-875-5285) if you have any other questions.
I have 440 square foot of tongue and groove osb over 1.5" foamboard. Relatively level. I am buying your electric radiant heat system. I already bought several bags of Allset thinking that I could level it over the wires. I've now read that floor leveler is easier to level. Any tricks I can use to help level the Allset? Is it going to be a lot more difficult than leveler to level, will it have some flowing and level a bit by itself?
Self-leveling compound (SLC) would be easier to level than All-Set (if you're talking about the Schluter product). The All-Set won't flow like SLC and any "leveling" it does by itself will be largely negligible. I would recommend either using SLC or if you want to stick with the All-Set you've already bought, I would see if the manufacturer has any videos or guidance about installing it with a heated flooring system and make sure that you're installing it according to their direction. Hope that helps.