Overview
Radiant floor heating warms the floor and then the room from the floor up. Instead of blowing hot air through ducts, it heats the slab or subfloor, which radiates warmth into the room and conducts it straight into your feet. The payoff is even, quiet, draft-free comfort with no dust getting kicked around and no cold spots near the windows, plus warm floors you actually feel. There are two ways to do it, and they are not interchangeable. Hydronic radiant runs warm water through PEX tubing and is the whole-house or large-area play. It is efficient, comfortable, and runs off a boiler, a water heater, or a heat pump. Electric radiant uses resistance mats or cables, and it shines for small areas like a single bathroom floor. It is an easy retrofit but expensive to run if you try to heat a whole house with it. Two things I will hammer on throughout: radiant is a heating system only, with no cooling, so you still need a cooling plan, and it only performs with the right floor covering over it and insulation under it.
Hydronic (Water) Radiant
Hydronic radiant circulates warm water through PEX tubing. The tubing either goes into a concrete slab during the pour, or it sits in or under the subfloor on a wood-framed floor using staple-up or routed panels. A boiler, water heater, or heat pump supplies the warm water, and a manifold with pumps and controls splits it into zones. For whole-house heating or large open areas, this is the efficient, comfortable option, and it is genuinely excellent over a slab in new construction where the tubing gets designed in from the start. The downsides are real. Install cost and complexity are high, and you are paying for a heat source, a manifold, pumps, and controls on top of the tubing. The slab is a big thermal mass, so the system is slow to respond. It takes hours to warm up and hours to coast down, which is fine for steady heating but bad for quick swings. A leak inside a poured slab is a nightmare to find and fix. This is the efficient whole-house premium pick, and it wants to be designed in, not bolted on later.
Electric Radiant
Electric radiant uses resistance heating mats or cables installed under the floor, almost always under tile, wired to a thermostat. There is no boiler, no manifold, and no plumbing. That makes it cheap and easy to install, which is exactly why it is the go-to retrofit for a bathroom or kitchen floor during a remodel. You roll out the mat, set the tile over it, wire the thermostat, and a small zone warms up fast. The catch is the running cost. Electric resistance heat is expensive to run, so it does not make sense as a primary heat source for a large area or a whole house. Think of it as spot comfort heat, not a furnace replacement. The classic use is warm tile underfoot in a bathroom on a cold morning, often on a timer, not heating the entire home. The other limitation is install access: you need the floor torn up to put it in, so it lands naturally on a remodel when the tile is coming up anyway. This is the easy small-area retrofit comfort pick, and warm bathroom tile is its sweet spot.
Floors, Insulation, and Install
The floor covering decides how well any radiant system performs. Tile and stone are ideal because they conduct heat well, which is why tile is the classic radiant pairing. Engineered wood and LVP are fine with manufacturer temperature limits respected, so you do not cook the flooring or void a warranty. Thick carpet and solid hardwood are the problem children; they insulate against the heat and fight the system, forcing higher water or element temperatures for less comfort. Just as important is what goes underneath. You must have insulation under the system, or it will happily heat the slab and the ground below instead of the room. Response time follows the mass: a poured slab is slow and steady, while thin electric mats warm a small zone faster. On the retrofit question, electric under tile is the doable remodel because you are already pulling up the floor, while hydronic-in-slab is really a new-construction or major-renovation move. For picking the covering itself, see our flooring-types-comparison guide on how tile, engineered wood, LVP, and hardwood actually behave underfoot.
FAQ
Can radiant floor heating cool the house too? No. Radiant floor systems only heat. Running chilled water through floor tubing risks condensation and does little for comfort, so you still need a separate cooling plan, usually a heat pump, central AC, or mini-split.
Is hydronic or electric better? They solve different problems. Hydronic is the efficient choice for whole-house heating or a slab, best designed into new construction. Electric mats are the cheap, easy retrofit for a single small area like a bathroom floor, but too expensive to run for a whole house.
What flooring works best over radiant heat? Tile and stone, because they conduct heat well. Engineered wood and LVP work within temperature limits. Avoid thick carpet and solid hardwood, which insulate against the heat and fight the system.
Can I retrofit radiant heat into an existing house? Electric mats under new tile are a realistic remodel-day upgrade when the floor is already coming up. Hydronic in a slab is really a new-construction or major-renovation job, since adding water tubing to an existing floor means tearing it apart.