Can You Install Wood-Look Tile Over Underfloor Heating?

Underfloor heating, which many Americans call radiant floor heating, warms a room from the floor up. The flooring on top decides how well that heat reaches the room and how long the floor lasts. Wood-look tile is a good match: you get the look of wood, and tile handles the heat better than real wood does.

Here is how wood-look tile compares with wood over a heated floor, and what to check before you lay it.

Why real wood and underfloor heating are a difficult pair

• Wood insulates. It slows the heat moving up from the floor, so the system has to run warmer or longer to heat the room.
• Solid wood moves as it dries out and takes on moisture. Over a heated floor that movement shows up as gaps, cupping and crowning.
• Engineered wood is more stable, but most makers limit the floor surface to about 80°F (27°C) and ask for the heat to be raised slowly, often around 2°F (1°C) a day, when the system is first switched on.
• Engineered boards usually need an expansion gap of 3/8 to 5/8 inch (10 to 15 mm) around the room, and time to acclimate before they are fitted.

Why wood-look tile suits a heated floor

Heat passes through it

Ceramic tile conducts heat far better than wood, so warmth from the heating reaches the room faster and more evenly.

It does not shrink or cup

Metro's wood-look tile is glazed ceramic, 9 to 9.5 mm thick. Warming and cooling do not make it gap, cup or split, and it has no 80°F surface limit the way engineered wood does. Your heating system's own settings are the limit.

No acclimation wait

Tile does not need to sit in the room before it is laid, and it does not need the wide perimeter gap that wood needs. It does still need a narrow movement joint at the walls, which the baseboard covers.

Installing wood-look tile over underfloor heating

• Follow the heating maker's start-up schedule. A new screed or thin-set bed needs time to cure before the heat is turned up, and the heat should then be raised gradually. Your installer will have the times for the products used.
• Use a flexible thin-set. Choose a polymer-modified mortar rated for heated floors, and back-butter each plank for full coverage. Hollow spots over heat are where cracks start.
• Keep the joints right. Metro planks have a curve edge and are laid with a 3 to 5 mm joint, about 1/8 to 3/16 inch. Add movement joints at the walls and across large floors.
• Consider an uncoupling membrane. Many heated-floor systems are designed to sit under one, and it also spreads movement from the slab.

Can you lay it over existing tile?

Sometimes. Laying over an old tiled floor with heating underneath saves the mess of removal, but check these points first:

• Floor height: a second layer raises the floor. Doors may need trimming and doorways may need transition strips.
• Weight: tile is heavy, and a second layer adds to the load on the structure.
• Loose tiles: tap every existing tile. A hollow sound means it is loose and must be fixed or removed.
• Flatness: for long planks the floor should not vary more than about 1/8 inch over 10 feet. Level it first if it does.

Which sizes work over heating

All four of Metro's plank sizes work over underfloor heating: 6 x 36 inch, 8 x 40 inch, 8 x 48 inch and 8 x 56 inch. The longer the plank, the flatter the floor needs to be. Heating a bathroom? Our guide to wood-look tile in bathrooms and wet areas covers finishes and waterproofing.

Two designs worth requesting as samples are Belmond Obsidian and Belmond Pearl, both 200x1000mm (8 x 40 in) in Satin Texture.

The short version

If you want the look of oak or walnut over a heated floor, wood-look tile gives it to you without wood's temperature limits, and it lets the heat through. Lay it on a flat, properly cured base with a flexible thin-set and the right joints, and follow the heating system's start-up schedule. Questions about a project? Talk to our team.

Frequently asked questions

Can you tile directly over underfloor heating?

Yes. Tile is one of the most common floors over underfloor heating because it passes heat well. Use a flexible thin-set rated for heated floors and follow the heating system's start-up schedule.

What flooring is not suitable for underfloor heating?

Solid wood is the usual one to avoid, because it moves with heat and moisture. Thick carpet and heavy underlays also slow the heat getting into the room.

Can you put engineered wood over underfloor heating?

Often, yes, within the maker's limits: usually a floor surface no warmer than about 80°F (27°C), a slow warm-up and an expansion gap at the walls. Wood-look tile gives a similar look without those limits.

Does wood-look tile need expansion gaps over heating?

It does not need the wide gap that wood needs, but it does need a narrow movement joint at the walls and across large floors, filled with a flexible sealant.

What is the downside of underfloor heating?

The cost and time of installing it, and the added floor height when it is fitted in an existing home. It also rules out solid hardwood.

How long does underfloor heating last?

Electric systems are commonly quoted at 25 to 30 years and water-based systems at longer. A tile floor on top does not need sanding or refinishing in that time.