What are the electrical requirements for an in-floor radiant heating system in a bathroom?

An electric in-floor radiant heating system in a bathroom requires a dedicated electrical circuit, a GFCI-protected connection, a wall-mounted thermostat with floor sensor, and installation by a licensed electrician with an ESA inspection — all non-negotiable requirements under Ontario's electrical code. This is one of the most popular upgrades in GTA bathroom renovations, and for good reason: stepping onto a warm tile floor during a Toronto winter morning transforms the bathroom experience.

The heating element itself is either a pre-made mat (heating cable woven into a mesh that rolls out over the subfloor) or loose cable (individual heating cable that the installer routes in a serpentine pattern with controlled spacing). Mats are the standard choice for rectangular bathroom floors — they come in fixed widths (typically 12, 18, or 24 inches) and roll out quickly. Loose cable is better for irregularly shaped floors, around toilet flanges, and in small or oddly shaped GTA condo bathrooms where a standard mat does not fit the space.

Circuit and Electrical Specifications

Most residential bathroom heated floors in the GTA operate on 120 volts for areas up to approximately 150 square feet, which covers the vast majority of GTA bathrooms. Larger bathrooms and master ensuites exceeding 150 square feet may use 240-volt systems for greater efficiency. The system requires a dedicated circuit — typically a 15-amp or 20-amp circuit depending on the floor area and wattage. A standard electric radiant floor mat draws approximately 12 watts per square foot. For a typical GTA bathroom floor of 40 square feet (deducting the area under the vanity, toilet, and tub where heating mats are not installed), the total draw is approximately 480 watts — well within a dedicated 15-amp circuit.

The circuit must be GFCI-protected, either with a GFCI breaker at the panel or through the thermostat (most modern heated floor thermostats include built-in GFCI protection with a test/reset button). The thermostat mounts on the wall — typically in the same location as the light switch or in a multi-gang box alongside other bathroom switches — and includes a floor-temperature sensor (a small probe embedded in the thinset between the heating mat and the tile) that monitors actual floor temperature and cycles the system to maintain the set temperature.

Installation Sequence

The timing of heated floor installation within a bathroom renovation is critical and requires coordination between trades. The sequence is: subfloor preparation → electrical rough-in (circuit from panel to thermostat location, thermostat box installation, conduit to floor) → heating mat installation and testing → floor sensor installation → thinset over the mat → tile installation. The heating mat must be tested with a multimeter (ohm reading) before thinset is applied, after thinset is applied, and after tile is installed — three separate tests to verify the cable was not damaged at any stage.

Cost Breakdown for GTA Bathrooms

For a typical GTA bathroom (approximately 35–50 square feet of heated area), expect these costs:

• Heating mat/cable: $300–$700 depending on brand (Schluter Ditra-Heat, Nuheat, SunTouch, and WarmlyYours are common brands available through GTA tile and flooring suppliers)
• Thermostat with floor sensor: $100–$300 (programmable models with WiFi connectivity run $200–$300)
• Electrical installation (dedicated circuit, thermostat wiring, GFCI protection, ESA inspection): $500–$1,200
• Total electrical and material cost: $900–$2,200, on top of the tile installation cost

The heating mat is typically installed by the tile installer as part of the floor preparation, with the electrician handling all wiring connections, thermostat installation, and the ESA inspection. Both trades need to coordinate timing — the electrician rough-in happens first, the tile installer lays the mat and applies thinset, and the electrician returns to make final connections and test after tile is complete.

All heated floor electrical work requires a licensed electrician, an electrical permit, and an ESA inspection in Ontario. The mat installation itself can be done by a tile installer or general contractor, but the electrical connections are strictly the domain of a licensed electrician.