How To Install Radiant Heat Flooring – Forbes Advisor

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  • Working time: 2 to 4 hours
  • Total time: Up to 3 days
  • Skill Level: intermediate
  • Project costs: $300 to $600 per 100 square feet for materials

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Is your floor giving you cold feet? Radiant floor heating is exactly what you need to make your cold floors pleasantly warm. For use as both primary and supplemental heating systems, underfloor heating can be installed during the construction of a home, but is usually added to existing floors with moderate ease and only a few tools. In this article, we’ll discuss how to install radiant heat floors in two different ways to cover 100 square feet of an existing floor.

Types of radiant heat floors

There are two types of radiant heat floors. These are hydronic (hot water) systems and electrical systems. Within these two types, there are different installation methods. Below are installation instructions for the easiest ways to retrofit both types into an existing floor. Both are cost-effective ways to make your floors more comfortable and inviting.

When to install radiant heat floors?

Retrofitting radiant heat into existing floors is common, especially during renovations. If you have the opportunity, it is best to install radiant heat before the construction of a home or new construction is complete. However, installing radiant heat floors can be done at any time according to these guidelines.

Safety Considerations

Standard safety precautions are the rule when using power tools. If you choose to install electric underfloor heating, you must work with 110 V electrical wiring. Follow all electrical safety procedures.

Hydronic underfloor heating systems require plumbing connections to your boiler or water heater. Making these connections is possible for a well-qualified do-it-yourselfer, but it’s better left to the pros for most homeowners.


  • Safety glasses
  • Highlighter
  • drill
  • Heavy Duty Stapler
  • Various hand tools

Hydronic Radiant Floor Heat Tools

  • PEX plumbing tools
  • 7/8 inch drill bit (spade or forstner)

Hydronic Radiant Floor Heating Materials

  • Oxygen barrier PEX tubing (about 150 linear feet for 100 square feet of floor space)
  • PEX plumbing fittings
  • Aluminum Heat Transfer Plates
  • Fiberglass insulation mats

Radiant Heat Power Tools

  • Mixing attachment for drill
  • 5 Gallon Mixing Bucket
  • Electrical Wiring Tools

Electric radiant heat materials

  • Radiant heat electrical cables or mats
  • Floor leveling compound (five 50-pound bags)
  • Thermostat compatible with underfloor heating

Hydraulic Radiant Floor Installation Instructions

The next method requires access to the joist spaces under the floor to be heated. It is best for houses with unfinished basements. You can remove drywall from the ceiling for access, but replacing them can be difficult or expensive.

1. Layout Pattern

From under the floor, in the basement, mark a layout on the ceiling with a marker. Make marks in six to eight inch increments where the heat hose will be placed. Also mark locations where the pipes will pass through the floor joists.

2. Drill holes

Drill 7/8 inch holes in the joists for the hose to pass through. Be sure to follow local building codes regarding the number and location of the holes. Skip this step if you have truss-style floor joists that are common in newer structures.

3. Install PEX Tubing

Insert the PEX tubing one by one into the aluminum heat transfer plates. Attach them to the underside of the floor with strong staples following your marked pattern. While you are at it, run the PEX tubing through the previously drilled holes. Leave about two feet of extra hose at each end to make hot water connections later.

4. Install Insulation

Friction fits and not the insulation mats in place with the printed side facing you. Leave the extra two feet of heat hose exposed.

5. Connect plumbing to heat source

Make the sanitary connections to your boiler system or a special boiler. Now is a good time to call in a professional if you are unfamiliar with hot water heating loops.

Electric radiant floor installation instructions

This method works best for homes where there is little or no access to the space under the floor. For best results, an existing floor should be removed down to the subfloor.

1. Prepare workspace

Remove the existing carpet down to the subfloor and wipe clean.

2. Lay down electric heating mats or cables

Lay out the electric heating mats or cables to cover as much of the floor space as desired. Do not overlap any part of the mats. Staple or tape the mats or cables to the subfloor according to the manufacturer’s instructions.

Place the thermocouple supplied with the mats at least 30 cm from the walls and as close to the center of the floor as possible.

Gather the wires from the thermocouple and from each mat. Run them along the wall to where the electrical connections will be made. Insulate three feet from each wire by taping them to the wall above the floor. This is important for the next step.

3. Level the floor

Following the instructions on the bag, mix and pour the floor leveling compound evenly over the entire floor. Keep adding to reach a thickness of ¼ inch or until the mats or cables are completely submerged. Allow the compound to cure undisturbed for 24 to 72 hours.

4. Connect electricity

Connect the wires from all mats to the home’s electrical circuit according to electrical building codes. Connect the thermocouple wire to the thermostat according to the wiring instructions provided. Now is a good time to call in a professional if you are unfamiliar with electrical wiring procedures.

5. Install a new floor

Your floor is now ready for its new covering. Tile, laminate, vinyl, linoleum, even carpet with a dense pad are all good options. Coatings can be applied directly to the leveling compound once it has cured. Avoid penetrating the new subfloor with adhesive strips or other fasteners to avoid damaging the electrical components.


Electric radiant heating cables and mats can also be installed in the joist spaces under the subfloor. Staple the cables or mats to the underside of the floor and wire as usual. Follow the guidelines above to insulate the joist spaces.

When to call a professional?

Doing most of the work yourself will save you about half of your underfloor heating costs. But most homeowners choose to hire a professional to connect new hydronic heating to the existing hot spring. Connecting electrical underfloor heating components to existing wiring is an easy process if you are experienced in wiring techniques. If not, hire an electrician to make the final connections.

In older homes, be aware of the possible presence of asbestos in old flooring materials. If asbestos is suspected, call a professional to test the floor and remove it if necessary.

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