Underfloor Heating Cost: What to Budget for a Bathroom Floor

So, how much is this actually going to cost you? Fair question, and honestly one that trips most people up because they think there's one magic number. There isn't. The ThermoGroup underfloor heating kits were listed at $381–$2,278 on myhomeware in November 2026, depending on the heated area — and that's before you've added a thermostat, insulation board, cable monitor, or the electrician and tiler who'll actually put it in the floor. Think of it less as one price tag and more as a stack of separate line items, each worth budgeting for on its own.

What Are You Paying For?

It's all too easy to have an idea of one underfloor heating cost and have your budget blow out due to another one being added later.

The first cost is the heating mat/cable. These are quoted by the size of the area they cover. The next cost is the thermostat. Some underfloor heating kits include the thermostat, others sell it separately. The next cost is the insulation board. We'll come back to that later. The final cost is the cable monitor. This is an alarm system that sounds when someone damages the underfloor heating cable when tiling or screeding. Not the most pleasant thought, but cheaper than replacing damaged cable after you've tiled!

The standalone thermostats were listed at $111 to $537 and the insulation boards were listed at $286 to $460 on myhomeware, and the cable monitor was just one fixed-price item. The actual price of the products you buy will depend on the area you're heating, the wattage of the heating cable (150 or 200 W/m²), whether you choose a manual, programmable or Wi-Fi thermostat, and whether you include insulation.

The installation cost is something that shouldn't be included in a supply quote. Supply and install are different services and must be priced separately — never add a labour figure to a product quote and call it the total cost. You should also factor in a licensed electrician to install the heating, plus a tiler/screeder and, if it's a bathroom, a waterproofer. In a bathroom the heating layout needs to be coordinated with the waterproofer beforehand, since the galvanised fixing profile used with some kits can be fixed to timber or concrete before waterproofing but cannot be fixed to a substrate that's already been waterproofed.

What Does Your Floor Cost to Run?

Here's a little-known fact. The day-to-day running cost of your underfloor heating has everything to do with your electricity tariff and how long your underfloor heating is switched on. A floor that's heating all day from 6am to midnight will have a different running cost compared to a floor that's set to heat for an hour before you shower.

It will also depend on the wattage. A 200 W/m² heating mat (common in bathrooms where the heating is in-screed) will draw more electricity than a 150 W/m² heating mat (common in living areas) over the same floor area. I'm not going to give you a dollar amount per day because no one selling you the mat knows your electricity tariff or usage pattern. If anyone claims they know what your annual running cost will be, I suggest you question them!

The Heating Itself

When creating a budget for the supplies for your underfloor heating, you start with the heating itself. Our underfloor heating kits are sold by the area they heat. Measure the open area of your floor where you want to have heating. Do not measure the entire room, as your installer will place the heating to avoid areas where fixed cabinetry and fittings sit. Here's a common mistake: the heating mats cannot be cut, shortened, or overlapped. Nope. The maker's recommendation is that it's better to underbuy than overbuy. This sounds weird until you realise you can't just roll up the excess matting like carpet. The kit descriptions say these kits include everything apart from insulation, which is available to buy separately. For a tiled bathroom floor, you'll want the undertile or in-screed mats and cables, whereas the Thermofoil mat is designed for carpet or floating timber floors, and shouldn't be laid under tiles.

Thermostats and Timers

Your thermostat will determine the latter factor. A Thermonet kit comes with one of our underfloor heating thermostats, which is a glass, dual-control or Wi-Fi unit, depending on what the kit description says, so it's already included in the kit price. Thermostat units are also sold on their own at ThermoGroup, which you'd need if you purchase a mat or cable without one. A programmable or Wi-Fi thermostat allows you to set a timer so it only warms the floor for the hours when you actually use the bathroom, rather than leaving it running all day like an expensive hobby. A floor-sensing thermostat limits the floor temperature to 28°C. For larger installations, your electrician may recommend a contactor, which is something they should advise you of, not you, prior to purchasing.

Why Insulation Is Worth Adding

When installed on a concrete slab, heat generated from the mat or cable will not only rise up through the tile floor, some of it will go downwards into the concrete. Our insulation boards sit between the slab and the heating element, and are available in a coated version suitable for wet areas like bathrooms, and an uncoated version designed for installation beneath tiles on concrete. The kit descriptions note insulation is not included, so you need to budget for the cost of the boards and fixing washers as a separate line item, not an afterthought. These also add either 6mm or 10mm to the floor buildup, so check the final floor heights with your tiler ahead of time to avoid a surprise step up into the shower.

References

Plumbing licensing requirements, state and territory plumbing regulators

AS/NZS 3000:2018 Electrical Installations (Wiring Rules) (incorporating Amendment 3:2023), Standards Australia

National Construction Code 2025, ABCB Housing Provisions, Part 10.8 Condensation management