Electric Floor Heating in Melbourne: In-Slab and Under-Tile Explained
Melbourne has the longest heating season of any mainland capital. Overnight temperatures sit in single figures from May to September, and slab floors, tiles and polished concrete hold that cold well into the day. Electric floor heating puts the warmth where the cold starts, in the floor, and it does it without ducts, radiators or a boiler.
P.A.P. Heating Solutions has supplied ELEKTRA electric floor heating in Australia since 1988. This article covers the two systems that suit Melbourne homes, what each costs to buy and run, the all-electric rule for new Victorian homes, and how a Melbourne job is put together. The full page is at floor heating Melbourne.
Two systems, two stages of the build
In-slab heating (ELEKTRA VCD35) goes in during construction. The cable is tied to the top reinforcing mesh at 200mm centres before the slab is poured, with 50mm of concrete cover. The whole slab becomes the heater. It suits new homes, extensions and slab-on-ground builds in the growth corridors from Clyde North to Tarneit and Craigieburn, and it pairs well with polished concrete. The slab is rested for 30 days after the pour before the system is switched on.
Under-tile heating (ELEKTRA DM20) goes in after the slab or subfloor is in place. The cable is laid at 100mm spacing and sits within a self-leveller or sand-cement screed layer under the tiles, never in tile adhesive. It is the system for bathroom and kitchen renovations in existing homes, from terraces in Fitzroy and Carlton to brick veneer homes in Glen Waverley and Werribee. Warm-up is quick, so it works well on a timer for mornings and evenings.
Both cables carry a 20 year warranty.
The all-electric rule for new Victorian homes
Since 1 January 2024, new homes in Victoria that need a planning permit must be all-electric. Gas ducted heating and gas hydronic are off the table for those builds. Electric in-slab heating is designed into the slab from the start, runs on the same supply as the rest of the house, and pairs with rooftop solar. For builders in the growth corridors it has become the standard way to heat a slab-on-ground home.
What it costs to buy
Under-tile heating, supplied and installed including GST, is about $705 for a 2 square metre ensuite, $733 for a 3 square metre bathroom, $845 for 4.5 square metres, $908 for 5.5 square metres, and from $1,175 for 10 square metres and over. In-slab heating is priced per job from the slab plan, because the cable length, the number of zones and the thermostats all follow the layout.
What it costs to run in Melbourne
An average bathroom of about 3 square metres uses roughly 600W. At a typical rate of 27 cents per kWh that is about 16 cents per heating hour. Most owners run it four to six hours a day in winter, which is 65 cents to a dollar a day, and switch it off through summer. Whole-house in-slab heating runs longer but at lower floor temperatures, and homes with rooftop solar can run it through the day on their own generation.
Floor temperature is set by the thermostat. Most people run the low 20s, which is warm underfoot without heating the room like a radiator would. The full working is in the running cost guide.
How a Melbourne job works
Send P.A.P. the floor plan. A layout design and the load requirements for the electrical contractor come back, usually within 24 hours, at no charge. The layout keeps the cable clear of vanities, toilets and cabinetry.
For in-slab jobs the cable is tied to the mesh before the pour and megger tested before and after. For under-tile jobs the electrical contractor runs a draw wire at rough-in, the cable is laid on the floor in a couple of hours for a bathroom, the tiler covers it with self-leveller or screed, and the electrical contractor fits the thermostat off after the floor coverings go down. The cable is tested before laying, after laying and after covering, with a break alarm on every job.
A licensed electrical contractor makes the final connection on every job.
Which Melbourne homes suit which system
New builds and extensions on a slab, anywhere from the Mornington Peninsula to Wallan: in-slab VCD35, often for the whole ground floor.
Bathroom and kitchen renovations in established suburbs such as Brunswick, Northcote, Camberwell, Brighton and Doncaster: under-tile DM20 in the wet areas.
Colder hills districts such as the Dandenong Ranges and the Macedon Ranges: in-slab for new work, under-tile for renovations, with longer daily run times than the metropolitan average.
Polished concrete living areas: in-slab VCD35, tied to the mesh before the pour.
Supply to Melbourne
ELEKTRA cable, thermostats and accessories ship direct to site or to the electrical contractor anywhere in Victoria, and P.A.P. supplies through electrical wholesalers. Technical support comes from P.A.P., including fault finding with a thermal imaging camera on any brand of cable if a floor stops working.
Next step
Send plans to sales@elektra.net.au or info@papheatingsolutions.com.au, or phone (02) 6242 9310. The layout and load requirements come back at no cost.