Retro-Fit Joist Mats

Retrofit joist heating mats let you add radiant floor warmth from below without removing the existing flooring above. They’re designed for accessible joist bays in basements, crawl spaces, and garage ceilings and provide a simple way to improve comfort in cold rooms during a remodel or upgrade.

When to Choose Retrofit Joist Heating Mats

Unlike traditional heating mats, joist mats make it possible to add radiant heating beneath an existing floor without removing the finished surface above. The heating elements install between accessible floor joists from a basement, crawl space, or garage ceiling. They’re a great choice for homeowners who want heated floors without needing to rip up existing floors.

Because the system is installed from below, retrofit mats are especially useful for finished rooms with cold floors, additions, and spaces located above unheated areas. The heating elements warm the subfloor and finished flooring above to create warmth and comfort without needing to replace the current flooring. Compatible thermostats also allow the system to be scheduled and controlled based on how and when the room is used.

Is Your Floor a Good Fit for Joist Mats?

Retrofit heating works best when the underside of the existing floor is accessible and there is enough space between the joists to install the heating system and required insulation. Before making your decision, confirm that the joist spacing, subfloor, finished flooring, and available electrical supply meet the requirements.

Retrofit joist mats are commonly used for:

• Rooms above unfinished basements

• Floors above accessible crawl spaces

• Living spaces above garages

• Finished rooms in home additions

The finished flooring must also be approved for use with radiant heat. Tile, stone, engineered wood, laminate, carpet, and certain other flooring materials are usually compatible, but requirements may vary. Always review the flooring manufacturer’s guidelines before purchasing. If you’re unsure whether your space or floor type is compatible, the Warm Your Floor team is here to answer any questions and walk through the process with you.

What to Consider When Purchasing Joist Mats

There are a few major considerations to be made when it comes to retrofitting floor heating. Consider the following before purchasing a joist mat system for your home:

1. Measure the joist spacing. Measure the distance between joists and choose a product width designed to fit the available joist bays. Joist mats at Warm Your Floor are available in sizes for common joist configurations.

2. Calculate the area you want to heat. Retrofit products only warm the floor directly above the installed heating elements. Measure the joist bays beneath the room rather than relying only on the room’s total square footage. When measuring, remember to account for required installation clearances. These include 2” of space from recessed fixtures and ventilation openings, 8” from the edges of outlet boxes and junction boxes, and 6” from heat-sensitive items such as toilet wax rings and flexible ducting.

3. Check the flooring and subfloor. Make sure the existing flooring, subfloor thickness, and complete floor assembly are compatible with the heating system. Thicker materials may take longer to warm or reduce the amount of heat reaching the surface.

4. Plan for insulation. Fiberglass insulation installed beneath the heating elements is essential and helps direct warmth upward into the room instead of allowing it to escape into the room below.

5. Confirm voltage and electrical capacity. Choose a system that matches the project’s voltage and verify that your home's electrical circuit can support the total heating load. You’ll need to know whether you need a 120v or 240v system.

6. Select a compatible thermostat. A compatible thermostat allows you to control temperature and create heating schedules.

If you’re still unsure what type of mat or accessories you need, contact the Warm Your Floor team for assistance.

Add Warmth Without Replacing Your Floors With Retrofit Joist Mats

Retrofit heating mats offer an easy way to improve the comfort of your home without needing to destroy existing floors. Selecting the correct size, voltage, insulation, and controls is essential for long-term performance. If you’re a contractor working on a remodel project, upselling retrofit heating for existing spaces is also a great way to add comfort to your customers' space.

Warm Your Floor is an authorized dealer of SunTouch UnderFloor joist mats. Ordering your system from a verified dealer ensures you receive compatible products and a warranty for your system. Our team can help you compare retrofit options, confirm sizing, ensure system compatibility, and identify the components needed for your project. Shop our retrofit heating products and contact our floor heating experts with any questions.