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During the course of the COVID-19 pandemic, there was a huge upswell in home improvement and renovation spending, which led to a pretty significant uptick in projects incorporating floor heating (WarmlyYours sales data saw floor heating sales increase 27.5% in the first half of 2021, when compared to prior-year-period). A huge portion of these sales were to homeowners and trade professionals, up 53.4% and 11.7%, respectively.

While it’s unlikely that these growth rates will continue at such break-neck speeds, it is likely that the greater level of consumer awareness for floor heating among both professionals and homeowners will help bolster floor heating sales in the future.

And even though other floor coverings like luxury vinyl and laminates have grown in popularity over the last couple of years, tile still makes up the vast majority of floor heating projects (82.2% of WarmlyYours floor heating projects so far this year have been tile, marble or stone floor coverings). This increased consumer demand will likely lead to many professionals taking a closer look at floor heating systems for tile and how to install them. In this article, we’ll dive into two of the most common electric floor heating systems -- rolls and cables with an uncoupling membrane.

Two of the most common electric floor heating systems are rolls (pictured) and cables with an uncoupling membrane. Photos courtesy of WarmlyYours (Click on image to enlarge.)

Floor heating rolls consist of a heating cable (single or twin conductor) attached to a mesh (often fiberglass) backing. The heating elements on the mesh backing are oriented in a serpentine pattern with consistent spacing between the runs of the wire. This ensures that the heating system will deliver even heat. Photos courtesy of WarmlyYours (Click on image to enlarge.)

Other Installation Options

Before we get into the nitty gritty of rolls versus cables with uncoupling membranes, it should be acknowledged that there are several other floor heating product types that can be used, including spot heating mats, floor heating cable with fixing strips and hydronic systems.

• Spot Heating Mats: These mats come in fixed sizes and are used to heat specific high-traffic areas of a floor (think the area in front of a vanity or outside of your tub/shower). This helps cut down on operating costs (and material costs), but there will also be “cold” sections of the floor, so it’s very important that you work with the homeowner to review the proposed footprint of the heating system so that there’s an understanding of which areas will be heated and which ones won’t.
• Floor Heating Cables with Fixing Strips: Typically, this is the most economical option as it only involves the cable and the strips. However, it is also the most labor intensive, and depending on your subfloor, the fixing strips can be a challenge to hold in place.
• Hydronic (“Hot Water”) Systems: These systems are very popular and have some advantages like a lower operating cost when compared to electric floor heating. However, this also comes at the cost of increased floor height, increased maintenance and the need for pumps and boilers. Hydronic systems also have more expensive upfront costs and are typically only used in new construction projects because it’s costly to retrofit them into most existing homes.

Floor heating cables with an uncoupling membrane usually consist of a floor heating cable -- almost always a twin conductor -- that is “snapped” into the channels of an uncoupling membrane. There are a number of different uncoupling membranes available in the marketplace, but they do typically share some key characteristics such as having a fleece backing and nodules or “studs” that secure the heating cable. Photos courtesy of WarmlyYours (Click on image to enlarge.)

Floor Heating Rolls

Floor heating rolls have been a mainstay in the radiant heating industry for decades. Typically, these products consist of a heating cable (single or twin conductor) attached to a mesh (often fiberglass) backing. The heating elements on the mesh backing are oriented in a serpentine pattern with consistent spacing between the runs of the wire. This ensures that the heating system will deliver even heat.

These rolls are then laid out with the wires facing toward the subfloor (this helps protect the wire from damage during installation). The roll is attached to the subfloor (often with staples through the mesh or hot glue) as it’s unrolled into the room. Then the mesh -- but never the wire -- can be cut and then turned to be laid out parallel to the previous run of the roll. This installation method, often called “cut-and-turn,” is very expedient and a very user-friendly way to make sure you’re maintaining consistent spacing throughout. It should be noted that the cut-and-turn installation method is most suitable for square or rectangular room shapes. If there are obstructions in the room such as a pillar or air vents the heating cable can be separated from the backing and then “free-formed” around the obstacle.

Then, the heating elements are embedded in either self-leveling compound or thinset. It is possible for experienced installers to embed the heating elements and backbutter the tiles to place them during the same step, however, most installers will allow the skimcoat of adhesive embedding the heating elements to cure before going back to install the tile. This makes the tile installation easier, but it necessitates that the project take multiple days to complete.

The positives for many flooring professionals regarding floor heating rolls is that they are an economical alternative to using cable with an uncoupling membrane and are the perfect option for large, square or rectangular rooms. The drawbacks are that floor heating rolls offer the least flexibility, in terms of being used for non-traditional room shapes, and they also typically increase the duration of the install.

There is a variety of other floor heating options on the market, including floor heating cables with fixing strips. Typically, this is the most economical option as it only involves the cable and the strips. However, it is also the most labor intensive, and depending on your subfloor, the fixing strips can be a challenge to hold in place. Photos courtesy of WarmlyYours (Click on image to enlarge.)

Floor Heating Cable with an Uncoupling Membrane

This combination usually consists of a floor heating cable -- almost always a twin conductor -- that is “snapped” into the channels of an uncoupling membrane. There are a number of different uncoupling membranes available in the marketplace, but they do typically share some key characteristics such as having a fleece backing and nodules or “studs” that secure the heating cable. The fleece backing allows for a secure thinset bond between the uncoupling membrane and the subfloor. The nodules/studs are then spaced so that you’re typically able to choose from a couple of different cable spacing options, which can raise (if the cables are closer) or lower (if the cables are more spaced out) the heat output of the heating system. For most 3 to 4 watt per linear foot heating cables, the spacing between runs of cable in the uncoupling membrane will range from 3 to 4 inches.

The combination of heating cable and uncoupling membrane has gained a lot of popularity over the past five years among both homeowners and trade professionals. For homeowners, the appeal is largely the long lasting benefits that an uncoupling membrane provides for relatively fragile floor coverings like tile. Because the uncoupling membranes are wider than the tiles, they prevent cracks in the subfloor from telegraphing upward by absorbing most of the kinetic energy and dispersing it over a wide area. Similarly, because the uncoupling membrane is adhered directly to the subfloor and thinset holding the tile “floats” in the dovetails between the nodules/studs, it allows for the floor covering to move “uncoupled” from the subfloor, which protects tiles from popping or breaking due to foundational movement.

The installation method starts with dry fitting the uncoupling membrane sheets in the project area. The sheets are then adhered to the subfloor with thinset and the heating cable is snapped into the membrane. Finally, the installer spreads thinset into the membrane to embed the cables and backbutters the tiles before placing -- meaning they don’t have to wait for the embedding thinset to cure before placing the floor covering. Unlike with rolls, this process is relatively simple and most installers will be able to complete an installation in a single day.

For flooring professionals, the number one advantage of using a cable and uncoupling membrane system is the speed of installation, but it also offers other benefits. For example, using an uncoupling membrane and waterproofing accessories can allow you to completely waterproof your subfloor, which is great for use in high-moisture environments like bathrooms or kitchens. The primary drawback is essentially that this combination is more expensive than using floor heating rolls.

Each heating system has its advantages and disadvantages -- what’s most important is identifying which product type works best for your needs and the types of projects you work on. Once you’ve figured that out, you’ll be able to provide your clients and customers with the comfort and luxury of radiant heating while also streamlining your installation process on the jobsite.