A thin heating element sits beneath the tile. Current flowing through it produces heat that conducts up through the mortar and tile, warming the floor surface from below. It is designed to warm the floor, not to heat the room, so your furnace or other heat source still does the main work. Two product formats are common.
A mat is heating cable pre-spaced on a fibreglass mesh backing, sold in sizes that suit common bathroom floors. It is unrolled onto the prepared substrate and embedded in thinset or a self-levelling underlayment. Mats install quickly and suit standard rectangular floor areas.
Loose cable has no backing and is laid in parallel runs, often clipped into strips or an uncoupling membrane designed for it. The spacing sets the watt density (watts per square foot), which controls how warm the floor gets and how fast. Cable suits irregular layouts and floors that have to work around a toilet flange, vanity or doorway transition.
| Where the heat goes: Heating is laid only in open floor area. It never goes under a toilet, a tub or a built-in vanity base, so a 50 square foot bathroom typically has about 35 to 40 square feet of heated area. Price the mat or cable on the heated area, not the room size. |
This is the single most important fact about a heated floor, and the one homeowners most often learn too late. Once tile is set, the element is permanently enclosed. Adding heat afterward means removing the tile, which almost always destroys it, and re-tiling the whole floor. The correct sequence:
Without a programmable thermostat, a heated floor is just a resistive element that runs when you remember to switch it on. A programmable unit with a floor sensor turns it into a system that:
A good 7-day programmable or Wi-Fi thermostat with a floor sensor costs $150 to $400. Many include the required ground fault protection built in.
Electric floor heating needs a dedicated circuit from the panel. Size depends on total wattage, and continuous loads like floor heating should stay within 80% of the breaker rating:
| Heated Area (at 15 W/sq. ft.) | Load | Typical Circuit |
| 40 sq. ft. | 600 W (5 A) | 15 A, 120 V |
| 80 sq. ft. | 1,200 W (10 A) | 15 A, 120 V |
| 100 sq. ft. | 1,500 W (12.5 A) | 20 A, 120 V |
| Larger floors or multiple rooms | Varies | 240 V system, sized by the electrician |
Ground fault protection is mandatory. The Ontario Electrical Safety Code requires it for heating cables installed in floors, provided either in the thermostat or at the breaker. The circuit and connection should be done by a Licensed Electrical Contractor who files the notification with the Electrical Safety Authority (ESA), so the work is inspected and documented for your insurer and future buyers.
| Item | Typical GTA Cost |
| Heating mat or cable (per sq. ft. of heated area) | $10 to $18 |
| Mat or cable installation | Usually included in the tile scope |
| Programmable thermostat with floor sensor | $150 to $400 |
| Dedicated circuit, thermostat installation and ESA notification | $400 to $800 |
| Total for a 50 sq. ft. bathroom (35 to 40 sq. ft. heated) | About $1,000 to $2,000 |
The top of the range reflects premium mat brands, a Wi-Fi thermostat, a longer circuit run from a panel at the far end of the house, or an uncoupling membrane system with integrated cable. On a bathroom renovation that already runs well into five figures, the heated floor is typically a few percent of the budget.
Take a typical ensuite with 40 square feet of heated area at 15 watts per square foot: 600 watts. Running two hours a day uses 1.2 kWh. At the Ontario time-of-use prices in effect (9.8 cents per kWh off-peak, 20.3 cents on-peak), the numbers look like this:
| Scenario | Per Day | Nov to Apr Season (about 180 days) | Year-Round |
| All off-peak | About 12 cents | About $21 | About $43 |
| All on-peak | About 24 cents | About $44 | About $89 |
These are electricity supply costs only; delivery and regulatory charges on your bill add to them. The Ontario Energy Board resets prices each November, so check the current rates. In practice, a thermostat cycles the element to hold temperature rather than running it at full draw, so real use is often lower.
| Programming tip: In winter, weekday on-peak starts at 7 a.m. Schedule the warm-up to start around 6 a.m. and much of the morning heating happens at the off-peak rate, roughly half the cost. |
The comfort payoff shows up every day from November through March, which is why heated floors are one of the upgrades owners most often say they would choose again. Whether it earns its cost depends on the room:
Can you add it to an existing tiled floor? Not without removing the tile. The element sits beneath it, so a retrofit means a new floor. The practical time to add heat is during a bathroom renovation, when the floor is coming up anyway.
Mat or cable? A mat suits standard rectangular floors and installs faster. Loose cable suits irregular layouts and floors with obstacles a pre-sized mat cannot work around.
Maple Leaf Quality Renos discusses in-floor heating during the design stage of every bathroom renovation, then confirms the heated area, roughs in the circuit and tests the element before any tile goes down.
Contact us for a free, no-obligation consultation and a detailed written estimate.
📞 +1 (647) 496-3360
✉ contact@mapleleafqualityrenos.ca
Serving Toronto, Mississauga, Brampton, Vaughan, Markham, Richmond Hill, Scarborough, Etobicoke, Oakville, Burlington, Oshawa, Hamilton, Barrie, Kitchener and surrounding communities.