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Radiant Floor Heating In Bathroom: Benefits, Cost, and Installation

Have you ever felt the sensation of warm floors on a cold morning? It’s hard to beat, especially in the bathroom. In years past, heated floors were a luxury only the wealthy could afford.

If you are a do-it-yourselfer with a few tools and know-how, you can probably design and install your own electric floor heating system in your bathroom too. Today we will discuss the design and installation of a radiant floor heating system, and offer a couple of tips to make the project successful.

How Does Electric Radiant Floor Heating Work

Radiant floor heating works by installing heated wires under a floor. This heat radiates upward, warming the floor and surrounding area. Radiant floor heating can be installed under virtually any floor covering, but some methods are designed for a specific application. 

The amount of time it takes to heat a bathroom floor depends on a number of factors, like insulation, design, and room size. For example, a small electric system located in front of a bathtub will usually raise the ambient temperature by five degrees in about five minutes or so. Your floor type will also have an effect on how long the floor stays warm after the system turns off. Concrete, for example, tends to hold temperature better than engineered hardwood.

Radiant floor heating is safe to use, even in wet areas such as a bathroom. No physical contact is possible between the person and the heating element. 

A heated bathroom floor can also heat a room. But if the heated area of a bathroom floor is small in comparison to the room size, the effect will be small. However, as the ratio between the floor size and the area to be heated increases, so does the effect. 

Are Heated Floors a Fire Hazard?

Heated floors are not a fire hazard as well. Radiant floor heating is no more dangerous to use than any other electrical appliance.

What Are the Pros and Cons of Radiant Floor Heating in a Bathroom?

Pros:

  • Radiant floor heating is excellent for spot heating such as in front of a tub or shower.
  • Installing most forms of radiant floor heating is fairly easy and reliable.
  • The cost of radiant floor heating has come down from years past and kits are now available to make the process even easier.

Cons:

  • Radiant floor heating can be expensive to operate, especially electric versions.
  • Since a system goes under the finished floor, some amount of demolition and repair will be required.
  • Radiant floor heating is especially vulnerable to poor installation. A mistake made during installation can be expensive to repair.

How to Install Electric Heated Bathroom Floors

Today we will discuss the two most common designs of electric bathroom floor heating. Among the most popular are radiant mats and radiant membranes. A third, called single wire, is a more customizable style of radiant mat technology. 

Electric Mat and Electric Single Wire

Here is a list of tools you may need:

  • Concrete tools, such as a mixing paddle, drill, and trowel
  • Utility knife
  • Wood and/or masonry chisel
  • Tape and/or adhesive
  • Electrical tools, such as a wire stripper and crimper, screwdriver, and multimeter

Step 1. Perform Measurements

We’ll assume you have gained access to the concrete pad or wooden subfloor and are ready to measure. Measure the entire bathroom the system will be installed in. Now deduct the area occupied by a fixture, such as a tub, vanity, or pedestal sink. This will provide the area to be heated (if you are just heating a small area in front of a tub or shower, you can skip this step). Now that you have the square footage to be heated, you can select the materials or kit based on your project.

Step 2a. Install Electric Mat

Next, test your wire. The wires used in electric mat heating are relatively small, and can be damaged during shipment. These wires will be woven into the mat during manufacturing, so locate both ends. Using a multimeter, check for continuity from one end of the wire to the other. If your system fails this test, do not use it. 

Now lay the mat out on the floor and see what needs to be trimmed. Do not overlap the mats, as this will cause an uneven floor and cause problems with the flooring later. Using scissors, trim the mat so that the wire is no closer than 4” to a fixture or baseboard and no closer than 2” to another wire. This will prevent overheating of the wire and issues with the thermostat.

Step 2b. Install Electric Single Wire

Single wire systems work and install similarly to electric mat versions. The primary difference is the customizability of a single wire system. Trim the mat as previously described, but you will now connect the wire to the mat using connectors built into the mat. Staying 4” from fixtures and baseboards and 2” from other wires, route the wire in gentle loops around the desired area.

Step 3. Position Sensor

With most systems, a sensor will be located within the mat and connect to a wall-mounted thermostat. Often, this sensor will need to be recessed into the floor. If your application does, use a chisel and carve a groove into the floor just enough to recess the sensor flush with the floor. Extend this groove from the sensor to the wall. 

Plugin the sensor and tape it to the floor. You can now run the cable from the sensor to the thermostat and make the connections. If you are not comfortable working with electricity, hiring a professional to make the required final connections is recommended. 

Electric Membrane

Not all bathrooms have tile or sheet flooring. Electric membrane floor heating is often used in applications where a very flat, thin floor is needed, such as engineered hardwood or laminate. In most electric membrane systems, the membranes can be trimmed and connected together as well to heat a larger area. 

Here is a list of tools you may need:

  • Utility knife
  • Tape and/or adhesive
  • Electrical tools, such as a wire stripper and crimper, screwdriver, and multimeter

Step 1. Test continuity

Test your membrane for continuity. The membrane is much more durable than wire, but check for continuity anyway using a multimeter. If your system fails this test, do not use it. 

Step 2. Install membrane

In most situations, a membrane system will be installed in a bathroom as spot heating. This makes the installation essentially the same as with the electric mat, with the exception of the mortar work. Since this system connects directly to the subfloor or concrete pad, in most installations simply measure and trim the membrane to fit the area.

Using scissors, trim the membrane so that it is no closer than 4” to a fixture or baseboard, being careful not to sever the wire. Now extend the sensor cable to the wall and secure it to the floor with tape or hot glue and make the connections to the thermostat.

Pro Tip. Do not attempt to install radiant heating under traditional hardwood floors as they are mechanically connected to the subfloor via nails. These nails would damage the wires or mats irreparably. 

How Long Does it Take to Install Radiant Floor Heating?

Most radiant floor heating projects can be installed in a bathroom over a weekend. However, time requirements will vary depending on the system being used and the application. Radiant heating mats and membranes are typically the fastest, while single wire designs can add more time due to the routing of the wire and trimming of the mat.

What Temperature Should a Heated Bathroom Floor Be?

Generally, radiant floor heating is very efficient to operate. Most thermostats will be set at a range of 85-90 degrees Fahrenheit, however, any system will have safeguards to prevent you from accidentally making the floor too hot. As mentioned earlier, some floors hold heat better than others, so tinkering with the thermostat may be needed to achieve the desired comfort. 

How Much Does a Heated Bathroom Floor Cost?

The cost of the materials for an electric floor heating system will, of course, vary from region to region, but expect to pay between $8.00-$15.00 per square foot. If you plan to hire the project out, the project will likely cost an additional $15.00-$30.00 per square foot.

 As electric floor heating systems get larger, they become less cost effective, so bathroom projects are perfect for first time users. A typical electric system, for example, will likely cost only 6.00-8.00 per month to operate, because the area being heated is relatively small. A typical 10’ x 36” electric mat will cost 150.00-200.00 from a big box store, making this design very affordable to both install and operate.

Hydronic systems, in contrast, use circulating warm water to warm a floor. They are more cost-effective to operate, but the installation costs are much greater. Therefore, installing floor heating in bathrooms where the projects are small and the benefits are high, hydronic systems are rarely used.

Is a Heated Bathroom Floor Worth It?

Most people who have radiant floor heating in a cold climate would probably say the time and investment is worth the effort. The reason is that there really is nothing to compare to the effect radiant heat has on floors. There is no other way to achieve the same effect, so for those who have had heated floors before, the feature is usually high on their wish list.

How Long Do Heated Floors Last In a Bathroom? 

Radiant floor heating is considered a passive system, meaning it has no moving parts. There are no fans or motors to wear out, so the system will typically last 20-30 years. This is essentially double the lifespan of a similar forced-air system, such as a heat pump. Many owners leave the system on all the time, relying on the thermostat to keep the room comfortable.

Is Radiant Floor Heating For Me?

Given the lower costs, ease of installation, and effectiveness, electric radiant floor heating becomes more popular every year. Radiant floor heating is often the most popular feature in a home and can even add more value than it costs. As such, installing radiant floor heating in a bathroom is an investment that can pay big dividends for years to come.

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