Electric vs Hydronic Underfloor Heating: Which to Choose

The right answer depends on room size and floor build-up far more than on running cost alone.

Electric underfloor heating is a thin mat or cable set into the tile adhesive or a levelling compound. It adds only 3 to 10 mm to the floor height, installs in an afternoon, and costs little to fit. Hydronic systems circulate warm water through pipes in a screed, which adds 50 mm or more of build-up and needs a manifold, a heat source and a proper commissioning. The installed cost difference is large, and so is the disruption.

Room Size Is the Deciding Factor

For a bathroom or a small hallway, electric wins on nearly every axis. The area is small, the running hours are short, and the cost of losing 50 mm of ceiling height to a screed is not worth it for five square metres. For a whole floor, or any room you intend to heat continuously, hydronic becomes the sensible choice: the running cost per kilowatt hour delivered is far lower, particularly when paired with a heat pump, and the thermal mass of the screed evens out temperature swings.

The crossover point in practice sits somewhere around 15 to 20 square metres of continuously heated area. Below that, the capital cost of a hydronic system rarely pays back. Above it, electric resistance heating becomes an expensive way to warm a room.

What the Floor Covering Does to the Numbers

Underfloor heating outputs are quoted for tile or stone, which conduct well. Every layer of insulating covering reduces the heat that reaches the room, and thick carpet with a foam underlay can cut output by half. Engineered wood is usually acceptable up to a surface temperature limit specified by the manufacturer, typically 27 degrees Celsius; solid wood moves too much and is generally a poor match. Check the covering before sizing the system, not after.

Expert Tip

Insulate underneath before you spend anything on the heating itself. A system laid straight onto an uninsulated slab sends a large share of its output into the ground. Insulation board under the heating layer is the single highest-return component in the whole build-up.

Summary

Choose electric for small wet rooms, retrofits and anywhere floor height is tight. Choose hydronic for whole floors and continuous heating, provided you can accept the screed depth. Either way, insulate below the system and confirm your floor covering suits it. Our Flooring Calculator helps you size the covering area once the build-up is decided.