How to Plan for In Floor Heating / Radiant Heat in Your Bath

It's one of the most asked for luxuries in a bathroom project - in fact I can't remember the last time it was not part of a major overhaul of a master bathroom.  Radiant Heating, also known as in floor heating, is becoming a standard for the modern luxury bath.  

Frequently asked questions about in floor heating:

1. How is it installed?

2. How is the temperature controlled?

3. Will my bathroom become too hot if I don't eliminate the existing heat registers?

4. Can I use radiant heat under my wood floors?

5. Do's and Dont's


1. At it's most basic premise, radiant heat is a system that heats the floor of a room.  Related to a bathroom, the preferred method is to use a self contained electric system.  There are several companies that provide these systems, but my personal favorite is the Schluter Ditra.  

It is a self contained electric system that comes in a single box.  Tile setters perform the installation but an electrician is necessary for providing the electrical connection.  Communicating the specifications and details in the early stages is very important to all sub contractors on your project. 

Whether you use the Schluter system or a similar one, the installation process is fairly straight forward.  These heating systems come in "mats".  The wires are either embedded in the mats or they are laid directly into the mats (as with the Schluter).  

The Schluter Dietra System is a mat and wire system.  First the mat is laid, and then the wires are placed at specific intervals for the areas that heating is desired.  In this system, you can dictate which areas receive heat and which do not.  

Whether you are using a pre-sized heat mat or the system noted above, it is laid on top of thinset above the sub flooring.  Another layer of thinset is applied on top of the mat when the tile is installed.  

2. The temperature is controlled by a thermostat that is placed on the wall.  Thermostats are now fully programmable, meaning you can have your heated floor turn on to a certain temperature at a specific time and then turn off after a specified time period.  So if a couple usually wakes up at 7AM, they can set the thermostat to reach a certain temperature by 6:55AM setting the floors to a perfect temperature before anyone ever steps foot into the room.  After the usual routine of bathing and grooming, the floors return to a "dormant" state, and the heat is turned off.  You can repeat this process several times during the day if needed. 

3. Each house is different, so assessing the current heating situation is vital prior to planning for radiant heat.  However, in most cases, radiant heat is sufficient for heating an entire room and no additional heat registers are necessary.  

4.  Always check with the manufacturer of the flooring as to its compatibility with radiant heat. Dependent upon the wood species, climate, and installation you should be able to utilize radiant heat under wooden floors. Generally speaking, engineered hardwoods perform best. 

5. Do: lay radiant heat under areas in front of each vanity sink, in front of the toilet, and around bathtubs.  Dont's: Do not lay radiant heat under the footprint of a cabinet, bathtub, or toilet.  Laying radiant heat under a toilet will cause the wax ring to melt and become a big issue in the future.  

The cost of radiant heat has come down dramatically over the past few years.  An installation can be completed in a day and the units themselves are not terribly expensive.  Radiant heat has become one of the most popular add on items to a master bath remodel with good reason. Who wants to stand on cold tile first thing in the morning?