A floor-rated sintered slab can work with either water or electric underfloor heating in a compatible installation. For a whole home heated daily, start with water-based heating, especially with a heat pump. For a small bathroom retrofit, start with an electric mat or cable. An existing water circuit, limited floor height and the complete installed cost can change that choice.
Which system fits your floor project?
Water-based, or hydronic, heating circulates warm water through pipes. Electric mats and cables generate heat under the surface. Both transfer warmth through the bonded slab; the choice starts with the work needed beneath it and the source of the heat.
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Whole-home or new floor
Start with hydronic and a suitable heat source. Plan the floor and heat source together for regular use across a large area.
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One small bathroom
Start with an electric mat or cable. A local zone is simpler to add without extending pipework. An accessible water circuit can change the economics.
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Renovation with fixed thresholds
Compare complete low-profile assemblies. Include insulation, levelling, bonding and slab thickness; compare the final doorway height, not just the heater.
A renovation does not automatically rule out water heating. Warmup’s retrofit range includes a 16 mm dry hydronic system alongside thin electric products. That is the named system’s depth: preparation, bonding and the selected slab still count toward the finished level.
Compare the same heat demand and the full installed cost
Water carries heat; the heat pump or boiler determines how much purchased energy produces it. An electric resistance boiler does not acquire a heat pump’s efficiency by heating water. Compare the same rooms, indoor temperature and heating schedule before comparing bills.
Worked comparison: 1,000 kWh of useful heat delivered into the same room over a heating period. Assume each floor delivers 90% of the heat entering it into that room, so each needs 1,000 ÷ 0.90 ≈ 1,111 kWh at the floor. Use electricity at €0.25/kWh and gas at €0.08/kWh. These are assumed inputs, including the shared 10% floor/distribution loss.
Direct electric mat or cable
€278
(1,000 ÷ 0.90) × €0.25 ≈ €277.78. Resistance heating converts the purchased electricity to heat; the common floor loss is already included above.
Water heating + heat pump
€98
Assume seasonal heat-pump performance of 3: (1,000 ÷ 0.90) ÷ 3 ≈ 370 kWh electricity. Add 20 kWh for hydronic pumps and controls outside that performance figure: [(1,000 ÷ 0.90) ÷ 3 + 20] × €0.25 ≈ €97.59.
Water heating + gas boiler
€104
Assume 90% seasonal boiler efficiency: (1,000 ÷ 0.90) ÷ 0.90 ≈ 1,235 kWh gas. Add the same 20 kWh auxiliary electricity: [(1,000 ÷ 0.90) ÷ 0.90] × €0.08 + 20 × €0.25 ≈ €103.77.
Costs above are rounded to whole euros in the headings and cover purchased energy. They exclude installation, maintenance and standing charges. Floor losses, seasonal performance and auxiliary use vary; replace all three with the proposed system’s estimates, and do not add pump energy twice if it is already included in its performance figure.
Under these inputs, heat-pump water heating saves about €180 per 1,000 kWh of useful room heat against direct electric heating. The close heat-pump/boiler result also shows why local energy prices matter. If a water system uses an electric resistance boiler, it loses the heat pump’s advantage and adds water-side equipment and auxiliary consumption.
Warmup’s heat-source guidance explains why lower water temperatures can improve heat-pump operation. The seasonal performance in your quotation needs to match the proposed climate, water temperature and system, rather than a favourable laboratory operating point.
What belongs in the installation quote?
Electric heating usually has the lower entry cost for one room. Hydronic heating introduces pipes, a manifold and water-side controls, and may require a heat source. A nearby circuit with spare capacity is a very different starting point from installing a new heat pump just for a bathroom. Compare these packages:
- Both systems: floor removal or preparation, insulation, levelling or screed, required membranes, slab fixing, controls, testing and making good thresholds.
- Electric: mat or cable, floor sensor and thermostat, plus the electrician’s circuit, protective devices and any supply upgrade.
- Hydronic: pipework, manifold, pumps or mixing controls where needed, connection and commissioning, plus any heat-source upgrade.
For one-room work, compare the additional connection cost to the existing heating system. For a whole-home replacement, compare complete systems. Include servicing and access: keep controls and manifolds reachable, record cable or pipe routes, and retain spare matching slabs for a repair that requires opening the floor.
Two projects, two different decisions
The following worked projects use stated assumptions to show how the decision changes. Annual heating demand is an input from a room heat-loss and usage estimate; room area alone does not determine the bill.
A 6 m² heated bathroom area in a local renovation
Assume 6 m² remains available after the bath and fixed furniture, the existing main heating stays, and there is no nearby water circuit. The annual useful heat requirement for the selected comfort schedule is estimated at 500 kWh. Using the same tariffs, 90% floor delivery and heat-pump performance of 3, direct electric energy costs about €139/year. Heat-pump water heating costs about €51/year when its allocated auxiliary electricity is 20 kWh/year.
Choose the electric mat or cable as the starting option. An €88 annual energy difference gives limited room to recover extra plumbing or a new heat source. If the complete hydronic quote were €1,000 higher, energy savings alone would take about 11.4 years to recover it, before servicing or financing. This is an assumed quote difference to show the calculation.
What changes the decision: an accessible water circuit with suitable spare capacity and a small connection cost can make hydronic worth comparing. Measure the full floor build-up against the doorway, and check wet-floor slip suitability and waterproofing before selecting the slab.
A 100 m² heated floor planned with a whole-home heat pump
Assume the floor is being rebuilt, insulation and levels can be coordinated, and the home’s calculated annual useful heat requirement is 10,000 kWh. At the same tariffs, delivery factor and seasonal performance, direct electric energy costs about €2,778/year. Heat-pump water heating costs about €951/year, including an assumed 100 kWh/year for separately counted pumps and controls.
Choose hydronic as the starting option. Here the assumed energy difference is about €1,827/year. An additional €6,000 in the complete installed quotation would take about 3.3 years to recover through energy savings alone, before servicing or financing. Compare the entire heating packages, including the heat pump if it is not already part of the project.
What changes the decision: a large retrofit premium, low annual heat use or weaker seasonal heat-pump performance can lengthen that recovery. If another system already heats most rooms and only one small floor needs comfort heating, compare that smaller job instead.
What changes beneath the sintered stone?
Compare complete floor constructions. A shallow electric mat can respond sooner than pipes embedded in a thick screed because there is less material to warm above and around the heater. A low-profile hydronic floor can also respond quickly; an electric cable buried deep in screed must warm that mass too.
Typical electric mat
- Sintered stone
- Adhesive / levelling with heating mat
- Insulation board
- Board fixing layer
- Prepared subfloor
Typical pipe-in-screed water heating
- Sintered stone
- Slab adhesive
- Screed with heating pipes
- Insulation
- Structural floor
For a known material, thermal resistance equals thickness in metres divided by thermal conductivity. Doubling the slab thickness doubles that layer’s resistance when conductivity stays the same; it does not double the whole floor’s warm-up time.
Choose a thickness approved for the floor loading, slab format and support, then compare the complete construction depth. The thinnest catalogue option is not automatically the best floor specification.
A change from a 9 mm slab to a 12 mm slab adds 3 mm to the finish before any change in adhesive or levelling. At doorways, compare that total with the adjoining floor. The tile thickness and installation build-up guide explains how these layers affect the finished level.
Can the heated floor replace the room’s other heating?
Either system can provide primary heating if its designed output covers the room’s heat loss. A room losing 1,200 W on its design cold day, with 12 m² of usable heated floor, needs 100 W/m² from that area. The heating designer checks whether the selected construction can deliver this at its permitted floor temperature.
Baths and permanent cabinetry reduce the usable area. A mat marked 150 W/m² states electrical input while energized, not guaranteed heat delivered into the room. Downward losses, the floor construction and temperature control affect delivery. Warmup’s room-planning guidance also bases suitability on usable area and calculated heat loss.
If the available floor cannot meet the room’s heat loss at its approved temperature, improve the insulation or add another heat emitter. Do not raise the thermostat beyond the floor system’s limit.
Protect the large slab through bonding, joints and start-up
Large sintered slabs need continuous support: a void leaves part of a brittle panel unsupported under foot or furniture loads. The adhesive, coverage and back-buttering method must suit the slab, substrate, heating system and format.
Laminam’s flooring guide, section 7.3.4, addresses heated screeds through commissioning, substrate and crack assessment, cooling before laying and movement accommodation. Its fixing guidance calls for full contact. Those details belong in the selected slab and installation-system instructions.
Keep specified perimeter and movement joints clear of rigid adhesive or grout, and coordinate structural joints with the slab layout. Fewer visible grout lines do not eliminate movement joints. Use the required membrane and bonding sequence where an uncoupling or anti-fracture layer is specified.
Separate heated-screed commissioning before tiling from adhesive and grout curing after tiling. ARDEX gives 21 days before initial heating for conventional sand/cement screed; proprietary screeds can differ. This is not a universal waiting period after slab installation. Record the specified cable or pipe tests before covering, then follow the approved cure and start-up schedule. Never use the heating to accelerate drying.
Funtek’s sintered stone installation guide covers the wider substrate, handling and fixing sequence.
Turn the heating choice into a slab specification
Once the installer has set the floor height and construction, give the slab supplier a definite material request. Record the product, finish, thickness and format together; add the room’s wet or dry use and a floor plan. The installer can then check one named slab against the design instead of working from “sintered stone” as a general category.
For example, Dior Beige and Lisk Grey both currently list 1200 × 2400 mm in 9 mm thickness, with 6, 12 and 15 mm options also listed in that format. A 9 mm listing gives you a specific starting point for the drawing and quotation. Have the installer approve that format and thickness for the actual floor support and loading before ordering.
Dior Beige Cement Look
Warm beige · Soft matte
Fine cement texture for a warm neutral floor.
Example listed configuration
1200 × 2400 mm · 9 mm
4 faces · Random match
Lisk Grey Stone Look
Light grey · Soft matte
Cloudy mineral variation for a cooler neutral floor.
Example listed configuration
1200 × 2400 mm · 9 mm
4 faces · Random match
Both colours have a soft matte surface and four faces with random matching. Compare the face mix and proposed joint layout as well as a colour sample. A large format still needs movement joints; for a wet bathroom, obtain the slip-test result relevant to the exact finish and intended wet-floor use.
Ask for the named slab’s floor-use and fixing instructions, and any available thermal conductivity or resistance data for that thickness. If thermal data is unavailable, flag that gap to the heating designer before the output calculation is signed off. Funtek’s technical data page provides a starting point for the material discussion; request documents tied to the selected product and finish.
Send Funtek the chosen colour, installer’s thickness requirement, floor plan or cut sizes, quantity and destination. The flooring supply service can develop that into size and cut-to-size options, samples, MOQ confirmation and a project quotation. The heating installer uses the confirmed slab specification in the final floor construction.
Get slab options for your heated floor
Send your floor plan or area, destination and installer’s thickness requirement. Funtek can provide slab options, sample information and a quotation for the selected sizes.