Installing radiant floor heating under the tile is a great option for homeowners who want to enjoy the benefits of this type of heating system while also adding a stylish touch to their home’s decor.

In this blog post, we will provide a comprehensive guide on how to install radiant floor heating under tile, step-by-step.

Types of Radiant Floor Heating Systems

There are three main types of radiant floor heating systems:

Electric Radiant Heating

This type of heating system uses electric cables or mats embedded in the floor. It is typically easier and more affordable to install, making it a popular choice for homeowners.

Electric systems are best suited for smaller spaces and are often used as supplemental heating.

Hydronic Radiant Heating

Hydronic systems utilize hot water circulated through flexible tubing embedded in the floor. This type of heating is more energy-efficient and better suited for larger spaces or whole-house heating.

However, hydronic systems are more complex and require a higher initial investment.

Air-heated systems

In air-heated radiant floor systems, hot air is blown through ducts installed beneath the floor. The air absorbs heat from the ducts and warms the floor, which then radiates heat to the room.

These systems are less common than hydronic or electric systems and are typically used in combination with solar or geothermal heating sources.

Pre-Installation Preparation

Before beginning the installation process, it’s crucial to prepare the area and gather the necessary materials.

Here are the important pre-installation steps to follow:

Cleaning the Floor and Priming the Plywood

First, make sure the subfloor is clean and free of dust, debris, or any loose materials. A clean subfloor ensures proper adhesion and reduces the risk of damage to the heating elements. If you have a plywood subfloor, it’s essential to apply a primer to help the adhesive bond properly. This extra step enhances the longevity of the entire installation.

Measuring and Selecting the Right Cable

Accurate measurements are vital for a successful heated floor installation. Start by measuring the total square footage of the area you want to heat. Remember to exclude any permanent fixtures, such as cabinets or appliances, from your calculations.

Once you have the correct measurements, you can select the appropriate heating cable or mat size for your space.

It’s essential to choose the right cable length to ensure even heat distribution and prevent cold spots. Keep in mind that the cable should never be cut or shortened, as this can damage the heating element and compromise its functionality.

Buying the Right Cable and Seeking Assistance from a Supplier

When purchasing a radiant heating system, it’s essential to choose a high-quality product that meets the specific requirements of your project. Consult with a radiant heating supplier to ensure you have the correct materials for your installation.

They can help you select the appropriate system, cable length, and thermostat based on your unique needs.

Remember, a successful heated floor installation starts with thorough preparation and the right materials.

By following these guidelines, you can ensure a smooth and efficient installation process that results in a comfortable and evenly heated floor.

Installing the Flextherm System (Electric Radiant Heating)

Installing an electric radiant heating system requires attention to detail and careful planning. Here’s a step-by-step guide to help you through the process:

Installing the Overlapped Wheel Locking System

  1. Begin by laying out the heating mats or cables according to your room’s measurements and design. Make sure to follow the manufacturer’s recommendations for spacing and layout.
  2. To join the tracks, use an overlapped wheel locking system. This ensures that the heating cables remain securely in place and prevents any movement during the installation process.

Laying Out the Wire

  1. When laying out the heating cable, consider whether the system will be used primarily for warming or as a primary heating system. This will help you determine the appropriate cable spacing and wire layout.
  2. For a warming system, you can use wider spacing between the cable runs. This provides gentle warmth, ideal for taking the chill off cold tile floors.
  3. For a primary heating system, use closer cable spacing to achieve the required heat output for the room. This is necessary to maintain a consistent room temperature during colder months.
  4. Follow the manufacturer’s guidelines for cable spacing and layout to ensure optimal performance.

Spacing the Wires Evenly to Prevent Cold Spots

Even spacing of the heating cables is essential to achieving consistent, comfortable heat across your entire floor. Uneven cable spacing can result in cold spots, which are areas of the floor that receive less heat than others.

  1. To avoid cold spots, carefully measure and mark the spacing between cable runs according to the manufacturer’s recommendations.
  2. Use the overlapped wheel locking system or heating mat to maintain consistent spacing throughout the installation process.
  3. Periodically check your cable layout and spacing to ensure that it remains even as you progress.

Installing Hydronic Radiant Floor Heating

Hydronic radiant floor heating systems use hot water circulated through flexible tubing embedded in the floor. This type of heating is more energy-efficient and better suited for larger spaces or whole-house heating. Here’s a step-by-step guide on how to install a hydronic radiant floor heating system:

Preparing the Subfloor

  1. Clean the subfloor: Ensure the subfloor is clean, level, and free of any debris, dust, or loose materials. A clean subfloor allows for proper adhesion and reduces the risk of damage to the tubing.
  2. Inspect the subfloor: Check for any signs of damage or unevenness. Repair or level the subfloor if needed.

Installing the Insulation Layer

  1. Choose the right insulation: Select an appropriate insulation material for your project, such as extruded polystyrene or polyurethane foam boards. The insulation layer helps improve the system’s energy efficiency by minimizing heat loss to the subfloor.
  2. Install the insulation: Lay the insulation boards directly onto the subfloor, ensuring they fit snugly together. Tape the seams to prevent any movement during the installation process.

Laying Out the Tubing

  1. Plan the tubing layout: Create a detailed plan for your tubing layout, considering the room’s dimensions and any obstacles such as walls, fixtures, or built-in cabinetry.
  2. Install the tubing guides: Attach the tubing guides to the insulation layer, following the manufacturer’s recommendations for spacing and layout. These guides help maintain even spacing and prevent the tubing from shifting during installation.
  3. Lay out the tubing: Starting at the manifold, unroll the PEX tubing or other flexible tubing used for hydronic systems. Carefully loop the tubing back and forth, ensuring it follows your planned layout and adheres to the manufacturer’s spacing guidelines.

Embedding the Tubing in Mortar or Self-Leveling Compound

  1. Prepare the mortar or self-leveling compound: Mix the mortar or self-leveling compound according to the manufacturer’s instructions. Ensure the mixture is smooth and free of lumps.
  2. Apply the mortar or self-leveling compound: Pour the mixture over the tubing, ensuring it fully covers the tubing and fills any gaps between the tubing and insulation. Use a trowel or screed to level the surface and remove any air bubbles.
  3. Allow the mortar or self-leveling compound to cure: Follow the manufacturer’s guidelines for curing time. During this period, avoid walking on the surface or placing any heavy objects on it.

Installing the Heating Probe and Thermostat

A crucial component of any radiant floor heating system is the heating probe and thermostat. The heating probe measures the floor’s temperature and sends this information to the thermostat, which controls the heating system. Here’s an overview of the installation process and some helpful tips:

The Importance of the Heating Probe

The heating probe plays a vital role in ensuring the radiant heating system functions effectively and efficiently. It detects the floor’s temperature and relays this data to the thermostat, which then adjusts the heating system accordingly.

This process maintains a consistent, comfortable temperature throughout your space while optimizing energy consumption.

Determining the Proper Location for the Probe

  1. Avoid placing the probe near heat sources: To ensure accurate temperature readings, avoid installing the probe close to other heat sources, such as vents, fireplaces, or direct sunlight. These heat sources can cause false readings, leading to an inefficient heating system.
  2. Place the probe between heating cable runs or tubing loops: Install the probe between two cable runs or tubing loops, ensuring it’s in direct contact with the floor. This placement allows the probe to accurately measure the floor’s temperature without being influenced by the heating cables or tubing directly.
  3. Follow the manufacturer’s guidelines: Adhere to the manufacturer’s recommendations for probe placement and installation to ensure optimal performance.

Laying the Tile Over the Heated Floor

Once the radiant heating system is installed and the embedding material is cured, it’s time to lay the tile over the heated floor. Here’s a step-by-step guide to help you through this process:

Choosing the Right Tile

  1. Consider the tile’s thermal conductivity: Opt for tiles with high thermal conductivity, such as ceramic, porcelain, or natural stone. These materials efficiently transfer heat from the heating system to the floor surface.
  2. Evaluate the tile’s durability: Choose tiles that can withstand temperature fluctuations without cracking or warping. High-quality ceramic, porcelain, and natural stone tiles are ideal options for heated floors.

Applying the Tile Adhesive

  1. Select the appropriate adhesive: Use a flexible tile adhesive designed for use with heated floors. This type of adhesive can accommodate the expansion and contraction of the floor due to temperature changes.
  2. Follow the manufacturer’s recommendations: Adhere to the adhesive manufacturer’s guidelines for mixing, application, and curing times.
  3. Apply the adhesive: Use a notched trowel to spread the adhesive evenly over the floor, ensuring full coverage and proper bonding between the tile and the heated floor.

Laying and Spacing the Tiles

  1. Plan your tile layout: Before installing the tiles, create a layout plan to ensure an even, aesthetically pleasing result. Begin in the center of the room and work outward, making necessary cuts and adjustments as needed.
  2. Lay the tiles: Carefully press each tile into the adhesive, using a slight twisting motion to ensure proper contact and adhesion. Check for level and alignment as you progress.
  3. Space the tiles evenly: Use tile spacers to maintain consistent spacing between the tiles. This spacing allows for grout lines that provide a professional, finished appearance.

Grouting and Sealing

  1. Prepare the grout: Mix the grout according to the manufacturer’s instructions, ensuring a smooth, lump-free consistency.
  2. Apply the grout: Using a rubber grout float, apply the grout to the tile joints, pressing it firmly into the spaces between the tiles. Remove excess grout with the edge of the float.
  3. Clean the tiles: After allowing the grout to set for the recommended time, use a damp sponge to clean the tile surfaces, removing any remaining grout residue.
  4. Seal the grout: Once the grout has fully cured, apply a grout sealer to protect it from moisture and staining.

Post-Installation Considerations

After laying the tile over the heated floor, it’s essential to consider some post-installation aspects to ensure the longevity and proper functioning of your radiant heating system.

Allowing the Cement to Dry

For the adhesive, mortar, and grout to cure properly, it’s crucial to give them adequate time to dry before turning on the heating system. Most manufacturers recommend a 30-day program during which the heating system remains off. This waiting period allows the materials to set and cure fully, preventing potential damage to the heating system or the floor’s integrity.

Storing Paperwork and Contacting Customer Service

  1. Keep documentation safe: Store all paperwork related to your radiant heating system, such as warranties, installation guides, and receipts, in a safe and accessible location. This documentation may be necessary for future reference, troubleshooting, or warranty claims.
  2. Register your product: If your radiant heating system requires registration, complete this process promptly to ensure your warranty remains valid.
  3. Seek assistance when needed: If you encounter any issues or have questions about your heating system, don’t hesitate to contact the manufacturer’s customer service team for guidance and support.


Radiant floor heating under tile offers an energy-efficient, comfortable, and aesthetically pleasing solution for heating your home.

By following the steps outlined in this guide, you can successfully install a radiant heating system that will provide consistent warmth and comfort for years to come.

Remember to consult professionals when necessary and follow the manufacturer’s guidelines to ensure a safe and effective installation.