Reviewed by George Baral
Updated October 10, 2024 | Published April 21, 2020
There’s nothing worse than stepping out of your nice warm bed onto an icy cold floor. That’s when radiant floor heating seems like an especially good idea. It is, without question, one of the most comfortable ways to heat your home. Read on to learn everything you need to know about radiant floor heating systems.
Radiant floor heating is installed under the floor, warming your house from the bottom up. Have you ever seen an old Roman bath? They had heating under the floors. Very clever, those Romans. Various forms of radiant heat have been popular in Europe for years.
How does radiant heat work, though?
Many radiant floor heating systems circulate hot water through flexible tubing installed beneath the floor. Others use electrical heating elements. Either way, the floor warms up and heat radiates throughout the room. The air temperature at the floor will be about 24 °C. Since that nice, warm air rises, there’s no need for a furnace to kick in and blow air through the room. The air at eye level is about 20 °C, depending on your thermostat settings.
Another plus: there are no restrictions on where you can put your furniture, as you don’t need to worry about the placement of baseboard heaters or air registers. The system is also silent, efficient, and dust-free.
Because it warms from the bottom up, radiant heat warms the room where the people are. And it maintains the heat over a long period of time, unlike a forced-air system, which feels great when the hot air is blowing into the room. But, as soon as the fan shuts off, the room begins to cool. With a forced-air system, the hot air rises to the ceiling and quickly dissipates. Your head may be warm, but your feet can still be freezing.
Conversely, a radiant floor heating system is totally invisible, heats the room evenly from the floor up, and can help you save on energy costs. There’s no need for a blower, so your air quality is much better with no dust or allergens being circulated around your home.
Cristina Miguelez, a Remodeling Specialist with Fixr.com, notes three key benefits to radiant floor heating:
“First, directly heating the people and objects that come in contact with the floor is a method known as conduction,” says Miguelez. “This makes you feel warmer even if the air is cool.”
She continues, “the floor may also radiate heat, which means that it will warm items and objects inches to feet directly above it. And finally, it also heats the air that touches the floor, which rises, heating the rest of the room.”
This process is known as convection, and is much more energy efficient than forced-air systems and other alternatives.
“You can actually set the thermostat lower and use less energy to stay warm,” says Miguelez. “There are no drafts or energy loss, so you stay more comfortable as well. Because it remains on consistently, no hot and cool feeling occurs when the forced hot air turns on and off.”
Radiant floor heating isn’t perfect, of course. One of the trade-offs of having better, more efficient heat is a higher price.
“Radiant heating can be a lot more expensive to install,” says Miguelez. “[Hydronic heating] requires a boiler and tubing that is ideally laid in concrete. While dry installations are available, sandwiching the coils between two layers of plywood tends to be a little less efficient at holding heat long-term. Therefore, unless this is a new build, installing radiant heating requires very invasive construction throughout all the flooring of the home.”
The time it takes to install radiant floor heating depends on the type of system and the scope of the project.
Most radiant floor systems are hydronic, meaning they use hot water. These are complex and have multiple components that you need to install in layers, not to mention adding a boiler if your home doesn’t have one. As part of a new building or a larger renovation project, installing the radiant floor heating system may only take a week or so. However, if you’re installing a system in your existing home, you need to budget time to tear up the existing floor, prepare the subfloor, install the system itself, and install the floor on top. It can take several weeks of arduous work.
To cut down on time (and cost) some people elect to only install floor heating in certain spots such as the bathroom or bedroom.
The layers of material necessary for radiant floor heating systems has another unfortunate (but manageable) drawback:
“Radiant floors also raise the height of your floor,” says Miguelez. “They consist of a layer of compacted sand, followed by insulation, and then the tubing and concrete. This will add up to 3 to 4 inches to the height of your finished floor.”
There are two main types of radiant floor heating: electric and hydronic.
Electric cables, usually in a mat, are installed above the subfloor, in thin set mortar. One of the advantages of electric radiant heat is that it is cheaper to install than a hydronic system. And it heats up quickly, as soon as you turn up the thermostat. However, due to the high cost of heating with electricity, this is usually just used in small rooms, or for supplemental heat. It’s commonly used in bathrooms or kitchens. It heats up quickly and, because it’s in a small room, doesn’t use a lot of energy.
Water is heated by a boiler or water heater and travels through flexible plastic PEX tubing. The tubing can be set above the subfloor in grooves, clipped to the underside of the floor, or buried in concrete. It is more expensive to install than an electric system. However, it’s less expensive to operate, and therefore, is often used to heat whole houses. It provides a very high level of comfort and can be your home’s primary source of heat.
Boilers come in various sizes, and can use just about any kind of fuel, such as natural gas, oil, propane, or coal.
It’s acceptable to install hardwood floors over a radiant heating system, but constant changes in temperature can cause the wood to expand and contract more than it can handle; it may suffer buckling or gapping. If you want a wood floor, choose engineered hardwood instead (see below).
Engineered hardwood flooring works much better than solid hardwood above an in-floor heating system. Engineered hardwood is more dimensionally stable, meaning it doesn’t swell and contract as much in response to heat and moisture.
Porcelain or ceramic tile floors are a great match for radiant heating systems. They conduct heat well and don’t suffer from the temperature fluctuations.
Laminate floors aren’t the best choice, but they’re not the worst, either. They’re thin, so they radiate heat quickly. However, they’re easily damaged if moisture escapes from a hydronic heating system, and high heat can damage the laminate. If you choose laminate flooring, make sure your in-floor heating system stays below the temperature noted by the flooring manufacturer.
There are different types of bamboo flooring, many of which are appropriate for use with a radiant heat system. When choosing a bamboo flooring product, make sure to review the manufacturer guidelines. Most will specify if they can withstand the strain of under-floor heating systems.
If you have a thick carpet with lots of underlay, you’re actually insulating the system so you won’t be getting the benefit of the under floor heat. If you are a carpet lover, this may not be the right system for you.
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Radiant floor heating systems aren’t cheap.
“To install hydronic radiant floor heating in every part of a 2,000-square-foot home, the average cost ranges from $14,000 to $48,000, with most homeowners paying around $28,000 for the project,” says Miguelez.
Those figures include the costs of tearing up existing floors, however. Installing radiant floor heating in a new build is often notably cheaper.
There are also different methods of installation, some more expensive than others. There’s no way around it though: hydronic radiant heat flooring systems are pricey.
Check out Bob Vila’s website for detailed information on all the different installation methods. Also, see This Old House for more info on heating your whole house, and various methods of installation.
In-floor systems, though, can save homeowners a lot on their energy bills. Miguelez says there are three factors that determine what kinds of energy savings you can expect:
“The first is your boiler. Your boiler is what heats the water, and it requires energy to do so. Like furnaces, boilers have multiple degrees of efficiency, with more efficient boilers costing more. They can be powered by gas, oil, propane, or electricity, so exact costs vary.
Next, you need to consider whether you have a concrete subfloor for the radiant heating or a dry layer of plywood. Concrete provides better performance so that you can maximize energy usage.”
“Finally,” says Miguelez, “how well-insulated the room is and what you set your temperature to also impact your savings.
How much cheaper, though, is in-floor heating compared to competitors like forced-air systems?
“According to the Radiant Professionals Alliance, most homeowners see an energy savings of between 10 to 30% a year on average,” says Miguelez.
By all accounts, things rarely ever go wrong with a radiant heat system. Before you decide to install one, though, there are some things you should consider:
Radiant heat works best in a home that is well insulated.
Even if you’re pretty sure your home had good insulation when it was built, insulation can degrade over time. Identifying and fixing poor insulation can be an involved process, but a quick and easy thing to check is your attic: if you can see the top of the joists in your attic over the insluation, chances are you need to improve the insulation in your ceilings.
Make sure you select a fuel source that is cost efficient in your area. If using electricity, you may be able to get a break on your electric bill if you use it mainly during off-peak hours. Large concrete subfloors can be heated up (or charged) using electricity at night and may not need more electricity during the day.
One of the easiest things you can do to check if your thermostat is working is to see if there is any electricity reaching it. The safest way to do so is using a non-contact voltage tester. If you find that there’s no power reaching the thermostat, you may have tripped a circuit breaker. If there is power, but your thermostat still appears to be malfunctioning, you should refer to your manufacturer’s instructions for troubleshooting.
Some floor coverings work better with radiant floor heat than others. For instance, ceramic tiles warm up nicely and distribute heat evenly. However, carpets act like insulation and will make it more difficult for heat to get into the room.
Some experts advise using rosin paper as opposed to tar paper underneath a laminate floor when you are installing a radiant floor heating system. As tar paper warms up, it can off-gas, causing an odour in the home.
If your new in-floor heating system is heating the floor unevenly, the culprit may be poor installation. It’s not worth the savings to cheap out on radiant floor heating systems. If your system isn’t installed well, the only solution is to re-install it.
Fortunately, uneven heating is much more likely caused by malfunctioning equipment, like a boiler that’s run into issues or trouble with a manifold. You will need to call a professional to diagnose and repair most issues.
If air gets trapped in the pipework running under the floor, it can cause that zone to stop heating up. Depending on your system, purging the air can be a bit of an undertaking. Since you’re dealing with a pressurized system, you may want to have a professional do it for you.
Like any other heating system, you should plan on yearly maintenance by an HVAC professional. Even though the pipes will last for the life of the house, there are mechanical parts, such as pumps and boilers, which should be checked. Normally these parts are silent, so it they start making noise, it could indicate a problem. The technician can clean the pump, while also checking the pressure valves. If they are beginning to wear, they can be replaced before any serious problems occur.
One of the benefits of radiant heat is that there are no filters or ducts that require regular cleaning. And there is no need for venting outdoors.
Yearly maintenance should include a thorough inspection and a test to check pressure which could indicate the presence of leaks. Leaks could mean that oxygen is getting into the system which can lead to corrosion. Low pressure can also indicate that the system is not operating as efficiently as it should, leading to higher utility bills.
Your service provider may be able to set you up on a preventative maintenance contract to ensure that everything is taken care of on a timely basis.
When it was first introduced to North America by soldiers returning from Europe after the World War II, copper tubing placed in concrete was used. However, copper within concrete will corrode fairly rapidly, so the lifespan was relatively short. Today, high-tech plastics are used and can have a lifespan of over 100 years. The mechanical parts of the system, such as the water heater, pumps, etc. may need to be replaced more often.
You can extend the life expectancy of water heaters and boilers by keeping the temperature a little lower. Proper yearly maintenance will also help to extend the life expectancy of your system.
Home insurance companies will want to know what type of heating system your home has, the type of fuel, and if it’s a hydronic radiant floor heating system, the age of the unit used to heat the water. Home insurance policies generally cover water damage caused by burst pipes, so it is important for your insurer to know what type of risk they are taking on. The type of system you have, as well as the age, can have a bearing on whether you can obtain home insurance, and at what cost.
These systems do seem to last a long time, but proper maintenance is key to keeping any system in good working order. If your heat goes out during the winter, there could be some serious water damage due to frozen pipes bursting. It’s in everybody’s best interest to make sure your heating system is in good condition.
Be sure to review your home insurance policy in detail, and consult with your agent if you have any questions or require clarification. Most policies have exclusions for water damage caused by frozen and burst pipes if you’ve been away from home during the winter. Or, from damage caused by continuous water leaks over a period of time. Some companies may require you to have your home checked regularly (or even daily) if you’re gone during the usual heating season. Otherwise, any damage caused by freezing will not be insured. Just imagine coming home to a big frozen mess, and then finding out your insurance will not pay for the repairs. It’s important to know exactly what the requirements are, so you can properly protect your home, and rest easy while you’re away on vacation.
When purchasing home insurance, make sure you know all the details about your home, including the heating system, so you can provide accurate information to your insurance agent. They need to know the type of risk they’re insuring, and you need to know the type of coverage you have, before anything happens.
You use radiant floor heating much like you would a standard furnace system: with a thermostat. Set the temperature you’d like, and the system will turn on automatically when the temperature drops lower than your choice.
Most hydronic radiant floor heating systems are set up in different zones, which lets you set the temperature separately in each part of your home. Each zone will have its own thermostat.
Installing a hydronic radiant floor heating system in an existing home is a big project, but it’s possible to do at least some of it yourself. It depends on your level of comfort running pipes and tubes, plus tearing up and re-installing flooring. You’ll also need to install a boiler system, which most likely requires the help of a professional. While installing a hydronic system yourself is possible, it’s not recommended unless you’re certain you can handle the massive project.
Electric systems are a little easier to DIY, as long as you have the skills to install electric components safely. It’s still a big job though, as there’s no alternative to ripping up the floor.
Underfloor heating systems take up to 3 hours to warm up completely from cold, so it’s best to leave the system on most of the time, at least at a low temperature.
The best radiant floor heating systems have highly programmable thermostats that allow the system to stay very low while you’re at work or asleep and start warming up again 30-60 minutes before you need it.
There are some limitations on what furniture you can place atop underfloor heating.
You should avoid any furniture that has a wide base and no clearance. For example, don’t place a mattress directly on the floor. You should also avoid using rugs.
These types of objects can trap heat underneath them, reducing the efficiency of the system and in some cases damaging the floor.
Furniture with at least 2-3 inches of clearance is okay. That gives the hot air enough space to circulate properly.
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About the expert: George Baral
George Baral has an MBA and a masters' degree in chemistry. He spent almost 35 years inspecting and evaluating heating and air conditioning systems before retiring. He obtained a California general contractor's license to start a company focusing on energy-efficient construction, became certified as a LEED AP and earned a NATE (North American Technical Excellence) certification, which provides advanced training for HVAC technicians.
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