Tile or stone floors are great to look at, but they can be really cold to the touch - especially in winter months. One way of taking care of that problem, and also heating your home, is to install radiant floor heating.
Radiant floor heating comes from tubes running underneath your floor’s surface. These are heated either electronically or via heated water. It heats evenly and doesn’t blow air which can kick up dust and other allergens. Also, as warm air rises, your lower body receives the comforting heat while your lungs breathe in more comfortable, slightly cooler air up higher. This kind of heating is particularly useful in rooms with vaulted ceilings.
Many homeowners may not know how extensive a project this can be and have a hard time predicting what the cost to install a radiant heating system will be. Your first step should be to talk to a reputable professional who can explain the best course of action for your particular home and who can estimate what your particular project will cost. Be warned, though, that this is a very involved project. You can expect quite a bit of disruption while it’s being done, but many owners say the comfort is well worth it.
As with any home improvement project, there are no true straightforward costs. There are factors that will influence your cost one way or another. Be sure to keep these factors in mind as you research the general cost of this project.
Square Footage of Flooring
The square footage of your home will help to determine the price. Oddly enough, smaller projects tend to cost more per square foot than larger ones. For example, a 5,000 square foot area could cost $5.00 per square foot while a 400 square foot area might cost $9.00 per square foot installed. This is because a larger area is usually a lot more open and easier to work in. In small areas, such as bathrooms, some people opt for a heating mat in thin-set cement instead. This is used as a supplement to existing heating systems and not as a replacement.
Large or small, the most affordable way to install the system is to do it during new construction or during an extensive remodel, when the floors will be non-existent (yet) or are being torn up anyway. This will reduce the labor costs of drilling holes in your existing flooring and other modifications.
Type of Radiant Heating
Which type of system you use will also affect the cost. There are two types of radiant heating used in residential settings: electric radiant and hydronic (hot water). Electrically heated systems cost more than hydronic systems, about $8.00 per square foot minimum. Hydronic systems cost about $6.00 per square foot minimum.
If you currently have a floor in place, the cost of drilling into or removing the existing floor will add to your cost by varying degrees depending on what kind of floor you have (stone, wood, linoleum, tile, etc.) and how large a space it is. Also, if concrete needs to be added, your floor may need additional supports for the added weight. The installation for radiant heating will be the most affordable with new construction or during a remodel when floors are already removed.
If you are installing a radiant floor heater as a whole-house system, you may find some rooms require different amounts of heat to be comfortable. This may lead you to establish “temperature zones” where a living room might be kept at a warmer temperature than a bedroom. Larger rooms may require more heat than smaller rooms. This will add to the complexity of the system, require more equipment, or more elaborate equipment (such as multi-zone programmable thermostats).
Normal Cost Factors
As with any contracted job, factors that will affect your overall cost include:
Radiant heating has been around a very long time. Its invention is credited to Caius Sergius Orata, a famous Roman merchant and hydraulic engineer. His “hanging floors” were heated from underneath by fires tended by slaves. However, examples of a similar system predate these by about 2,000 years at the ruins of Mohenjo-Daro. Whichever the case, they greatly improved the comfort level of ancient people as they continue to do today.
Radiant heating works on the basic thermodynamic principle that says “hot air rises”. The lines underneath your floor generate heat by electrical or hydronic means. This heat rises up evenly from the floor, warming up the lower part of the floor and cooling gradually as it rises. Warm air is generally harder for your body to process than cool air because it has fewer oxygen molecules than cool air. With the floor warm, the bulk of your body (your legs, arms, and torso) stay comfortably warm while your nose and mouth can breathe in more oxygen-rich cool air.
Because the heat is being radiated, not “blown”, you should know about what types of flooring it works best with.
Ceramic Tiles – These work best with this kind of heating. They conduct heat wonderfully and store it for quite some time.
Wood Flooring – This can work with radiant floor heating, but the warming of the air can cause the wood to expand and contract as it goes through its cycles. Wood strip flooring fares better than plank flooring as the narrow strips don’t expand and contract as much. Laminated wood flooring has good stability for this application.
Linoleum – It’s best to contact the manufacturer for compatibility. Some may off-gas or discolor due to the heat.
Carpet – Carpets are actually quite insulating. They can prevent the warmth from coming through efficiently. The thicker the carpet, the more insulating it is. In fact, the oil crisis in the 1970s which made energy costs so high contributed to the popularity of shag carpet during that time for that reason.
Stone – Stone flooring will hold the heat for quite some time. It’s one of the more popular floorings for homes with radiant floor heating. Some stone may take quite some time to come up to the desired temperature. After the installation, it can take as much as a week to get up to temperature! However, once it’s there, it holds the heat for quite a while.
Worth remembering is that some floors use an adhesive to hold them in place. Make sure your adhesive is compatible with a radiant floor heater.
For residential settings there are two types of systems that are used, electric and hydronic. (A third type exists, air, but it isn’t as efficient and is mostly used in commercial and industrial settings). While the end result is the same, they deliver their heat differently.
Electric systems are essentially a large heating pad installed beneath thin-set cement. Because they use your electricity to maintain heat, they are costlier to operate than hydronic systems, but they are more affordable to install. Also, they can often be a DIY project depending on the size of the room.
Like the hydronic system, the temperature is maintained by a thermostat. This adjusts itself throughout the day as the programming dictates, ensuring a comfortable temperature in the room or rooms.
Installing an electric system can cost from $700.00 for a bathroom to around $7,000.00 for a 1,500 square foot house. Because it can be installed as mats, the installation cost is significantly less than a hydronic system.
Hydronic systems use a hot water boiler and then a pump to circulate that hot water through the tubing. If you are heating a small room, such as a bathroom, you might be able to tie into your existing water heater. A larger room might require its own water heater. The water heater will increase the cost of installation, but will still be one of the more affordable radiant heat options. A 50-gallon water heater can cost from $360.00 to well over $1,000.00.
Based on the programming of the thermostat, the water heater will send hot water through pipes that are installed beneath your floor to provide the warmth. The pipes used to be made of normal plumbing materials like copper. However, these pipes eventually corrode and leak. Modern systems use a flexible tubing called cross-linked polyethylene, or PEX for short. Early forms of this material used to leak oxygen and reduce the efficiency of the systems, but current PEX has been refined to remove this flaw.
Some sources state that a boiler is used instead of a water heater. The boiler contains a mixture of water and antifreeze and is most often used in very large settings such as commercial spaces or where it gets very cold. Boilers are far more expensive than water heaters, often costing around $6,000.00.
Installing a hydronic system can cost from $6,000.00 to $14,000.00. Operating costs are lower than electric systems because water conducts and holds heat very well, meaning there is less actual operating time.
Forced air systems concentrate the heat in the upper half of the room while radiant floor heating concentrates it at the bottom half. Most heat loss occurs in the upper half of the room. This is like pouring water over a leak. By heating the lower half of the room, warm air is allowed to drift upwards through where you will be standing, sitting, or otherwise living. It can only escape through the roof after it’s warmed you up. And of course, after the rising air cools and falls, it gets warmed up again!
Water can hold 3,500 times the heat that air can. This allows you to operate your hydronic system less and at lower temperatures. The amount of water running through a 1-inch diameter tube can carry as much heat as a 10 x 18 inch forced-air duct.
Temperature zones are already used in many heating systems to lower costs. They can also be used in radiant floor systems, which will lower the operating costs even further than they already are.
Because the floor will hold heat longer, you can run the heater during off-peak hours, when rates are generally lower, and enjoy it during peak hours when your system will be off but the heat will still be there.
If you don’t use radiant heat for your whole house, you may be considering specific rooms to use it in. Which ones are best will depend on which rooms are used more often, but here are some general guidelines:
Bedrooms (unless carpeted)
Living rooms (unless carpeted)
Any high traffic area
Hallways and utilitarian rooms like laundry rooms do not necessarily need floor heating. Clearly there’s no need to heat a closet floor, and putting it in an attic is practically useless. However, if you do a lot of work in the kitchen or have a rec room or playroom, you may find it more comfortable to install radiant heating here as well.
Just because your home didn’t come with radiant floor heating doesn’t mean that you missed out. Almost any home can be retrofitted with a radiant floor heating system. However, the cost will vary with what kind of floor you have and how much space you’re retrofitting.
Here are some other things to consider about radiant floor heating:
While most radiant systems are thought of for heat, you can also use radiant systems for cooling. Putting them in the floor will not be very cost effective because cool air falls. The best place to install a radiant cooling system is in your ceiling. They will need some added equipment, such as a chiller and possibly a dehumidifier.
PEX, the tubing used in hydronic systems, was developed in the 1930s, but for some time it was flawed. It allowed oxygen molecules to leak in and corrode metallic components. As the processes developed, this flaw was eliminated and for about 35 years now PEX has been the go-to material for tubing in radiant heat systems. Its flexibility allows it to snake around the room and be laid closer together where more heat is needed and further apart where less is needed.
Solar heating is also being used more and more for radiant floor heating. Solar collectors have a great efficiency for supplying the heat needed. As solar panels become more and more affordable, they are sure to see greater use for many such functions.
Finally, there is the recent development of subflooring pre-fitted with tubing channels. This reduces labor as the channels are already there for the tubing to go into without having to drill. Available as panels, some are aluminum-lined to allow for even better heat distribution. They tend to cost more, but are more efficient.
Overall, the cost to install a radiant heating system will depend on if you're putting it into new construction or retrofitting, as well as the type of system you choose. Just make sure to talk to at least three professionals to ensure you find someone you can trust.