Icon - Arrow LeftAn icon we use to indicate a rightwards action. Icon - Arrow RightAn icon we use to indicate a leftwards action. Icon - External LinkAn icon we use to indicate a button link is external. Icon - MessageThe icon we use to represent an email action. Icon - Down ChevronUsed to indicate a dropdown. Icon - CloseUsed to indicate a close action. Icon - Dropdown ArrowUsed to indicate a dropdown. Icon - Location PinUsed to showcase a location on a map. Icon - Zoom OutUsed to indicate a zoom out action on a map. Icon - Zoom InUsed to indicate a zoom in action on a map. Icon - SearchUsed to indicate a search action. Icon - EmailUsed to indicate an emai action. Icon - FacebookFacebooks brand mark for use in social sharing icons. flipboard Icon - InstagramInstagrams brand mark for use in social sharing icons. Icon - PinterestPinterests brand mark for use in social sharing icons. Icon - TwitterTwitters brand mark for use in social sharing icons. Icon - Check MarkA check mark for checkbox buttons.
You are reading

Remodeling 101: 5 Things to Know About Radiant Floor Heating

Search

Remodeling 101: 5 Things to Know About Radiant Floor Heating

November 8, 2018

Can anyone resist the sensation of walking barefoot on a heated floor? If you’re just embarking on a renovation or building a new house, consider installing radiant heating (also known as underfloor heating), an energy-efficient way to keep warm throughout the cold months. As an architect who has supervised and survived many remodels, I have experienced radiant floor heating in other people’s houses and covet it in my own. Here’s the lowdown on the subject: Read on if you’re ready to rip up your floors in the name of cost-effective, energy-efficient heat.

In a rustic architect-designed cabin on the southern tip of Puget Sound, the heat comes up through the concrete floors. See more in A Puget Sound Cabin That Rests Lightly on the Landscape.
Above: In a rustic architect-designed cabin on the southern tip of Puget Sound, the heat comes up through the concrete floors. See more in A Puget Sound Cabin That Rests Lightly on the Landscape.

1. What is radiant floor heating?

Invented by the engineering-savvy ancient Romans, who had slaves fanning wood-burning fires under elevated marble floors, radiant floor heating is an under-the-floor heating system that conducts heat through the floor surface rather than through the air (as in conventional forced-air heating systems).

Imagine waking up and putting your bare feet on warm oak floorboards every morning in the winter. Photograph from The Dinesen Family House: A Historic Renovation for Danish Design Royalty.
Above: Imagine waking up and putting your bare feet on warm oak floorboards every morning in the winter. Photograph from The Dinesen Family House: A Historic Renovation for Danish Design Royalty.

2. How does radiant floor heating work?

The two most common types of radiant-floor heating systems are electric (heat via electric wires) and hydronic (heat via hot water tubes), both of which are buried underneath the floor. Here’s how the two compare: Electric radiant-floor heating systems are easier and more affordable to install, but more expensive to operate, making them ideal for heating small areas. Hydronic systems are less expensive to operate, so they work well for large floor areas and even entire houses. The caveat is that they come with higher initial costs because they’re more complicated to install and require heated water from a boiler or a water heater. For more on the pros and cons of each system and which might be better suited to you, see Radiant Floor Heating: Electric vs. Hydronic by San Francisco contractor Jeff King of Jeff King & Co., a member of the Remodelista Architect & Designer Directory.

An electric radiant heating wire system installation from contractor Jeff King & Co.
Above: An electric radiant heating wire system installation from contractor Jeff King & Co.

3. What are the pros of radiant floor heating?

Not only does radiant floor heating keep your toes warm, but it ensures that the rest of your body will be kept at a comfortable temperature as well. Waves of infrared radiation rising from the floor warm up the building mass, insuring that heat isn’t lost to surrounding surfaces. In a conventional forced-air heating system, heated air (along with dust and allergens) rises to the ceiling and drops back down as its temperature lowers, making it difficult to keep your toes warm, even if everything above your shoulders is boiling. “We experience pure warmth with radiant floor heating. As we heat up from our feet, we stay warmer at a lower temperature,” says contractor Jeff King. Delivering heat and comfort efficiently: what’s not to love?

The diagram on the left illustrates the principle of radiant floor heating in which heated surfaces transmit heat to all surrounding objects. There is no loss of heat because everything is at the same temperature. The diagram on the right illustrates how heated air in a conventional forced-air system rises to the ceiling and then comes back down as cool air. This explains how you can still be cold when the thermostat says 7
Above: The diagram on the left illustrates the principle of radiant floor heating in which heated surfaces transmit heat to all surrounding objects. There is no loss of heat because everything is at the same temperature. The diagram on the right illustrates how heated air in a conventional forced-air system rises to the ceiling and then comes back down as cool air. This explains how you can still be cold when the thermostat says 72 degrees. Diagram from Sustainability Workshop.
A remodel in Brooklyn, kitted out with radiant heating beneath new painted-oak floors. (The architects note that best-grade wood is minimize to avoid warping from the heat.) See more of the project in Nordic Beauty: A Brooklyn Townhouse Reinvented with Style—and Restraint.
Above: A remodel in Brooklyn, kitted out with radiant heating beneath new painted-oak floors. (The architects note that best-grade wood is minimize to avoid warping from the heat.) See more of the project in Nordic Beauty: A Brooklyn Townhouse Reinvented with Style—and Restraint.

4. What are the cons of radiant floor heating?

A radiant-floor heating system is difficult to install after a floor is already in place, and it’s really only feasible if you’re prepared to remove your floors or are building a new house. While there are new products, such as electric radiant pads, that can be installed between the joists underneath your floor, they require access from below via a basement or crawl space. Lack of one or the other is a deal breaker.

 Stone tiles work well with radiant floor heating because of the material&#8
Above: Stone tiles work well with radiant floor heating because of the material’s thermal conducting properties. Flooring at Philip Johnson’s Glass House in New Canaan, Connecticut, are heated. Photograph by Matthew Williams for Remodelista from 14 Lessons in Minimalism from the Glass House.
The Glass House’s floor is more indestructible than wood and it conducts heat well–the house has a hydronic radiant-heat system in which hot water flows through piping under the bricks. Photograph by Matthew Williams for Remodelista from  Lessons in Minimalism from the Glass House.
Above: The Glass House’s floor is more indestructible than wood and it conducts heat well–the house has a hydronic radiant-heat system in which hot water flows through piping under the bricks. Photograph by Matthew Williams for Remodelista from 14 Lessons in Minimalism from the Glass House.

5. Which flooring materials work best with radiant heat?

While all flooring materials can be used with heated floors, some work more effectively than others. Some general rules of thumb: Materials with thermal-conducting properties (stone, concrete, ceramic tile) conduct, transfer, and hold heat effectively while withstanding high temperatures. Solid wood floors can shrink and expand with fluctuating temperatures leaving unsightly gaps. If you’re in love with wood floors, however, an experienced wood-floor installer will be able to manage potential shrinkage. Vinyl and plastic laminate floors also come with temperature limitations, while carpets have insulating properties that potentially reduce heat flow.

The rooms at the Wythe Hotel in Brooklyn, New York, feature polished concrete floors with radiant floor heating. See more of the hotel at White Heat in Brooklyn: The Wythe Hotel. (See why concrete is a good match for radiant floor heating in Remodeling src=
Above: The rooms at the Wythe Hotel in Brooklyn, New York, feature polished concrete floors with radiant floor heating. See more of the hotel at White Heat in Brooklyn: The Wythe Hotel. (See why concrete is a good match for radiant floor heating in Remodeling 101: Polished Concrete Floors.)

Consider also, for the cold weather: Remodeling 101: Towel Warmers.

Ready to rip up your floors and install radiant floor heating? Read on in these other Remodeling 101 flooring features:

N.B.: This post is an update; the original story ran on November 14, 2013.

Have a Question or Comment About This Post?

Join the conversation

v5.0