Can I lay wood or laminate over underfloor heating?

Which floor coverings work over UFH, the thermal resistance figure that decides it, and the commissioning sequence that stops a new floor being wrecked in its first week.

Difficulty: intermediate
Time: 30 min
Read: 5 min
Safety: caution

Short answer

Most engineered wood, laminate and LVT can go over underfloor heating; solid wood is the difficult one. The deciding number is the total thermal resistance of floor plus underlay, which must stay below the UFH system's limit, and there is a maximum surface temperature the floor must never exceed. Turn the heating off before laying and bring it back up slowly afterwards.

Underfloor heating works by pushing heat up through the floor covering, so the covering is part of the heating system rather than something laid on top of it. That reframes the decision: you are choosing a component with a thermal specification, and getting it wrong either wastes the heating or damages the floor.

Safety

Never fix anything into a floor containing underfloor heating without knowing exactly where the pipes or cables run — a screw through a UFH loop means lifting the floor to repair it. Keep the heating off while the floor is laid and bring it up gradually afterwards as the manufacturer directs.

Step by step

Find out what UFH system you have.Wet pipes in a screed, wet pipes in spreader plates between joists, or electric mat or cable. Each has different output, different response and different rules about what goes over it.
Find the system's maximum thermal resistance for the covering.The installer or manufacturer states a limit, expressed as a thermal resistance value. Everything above the heat source counts towards it — the floor, the underlay and any membrane.
Check the flooring is rated for underfloor heating.The pack or the data sheet will say explicitly. Products not rated for UFH may delaminate, gap badly or void their warranty.
Choose a low-resistance underlay.Ordinary thick foam underlay is an insulator, which is exactly what you do not want. There are underlays made specifically for UFH with low thermal resistance.
Understand where solid wood struggles.Solid timber moves a great deal with moisture content, and UFH cycles the floor's temperature and dries it. Some species and some board widths cope; many do not. Engineered board, with its cross-laminated construction, is far more stable and is the usual recommendation.
Respect the maximum surface temperature.Wood floors over UFH have a stated maximum surface temperature, and exceeding it is what causes shrinkage, gapping and delamination. The system should be limited to it, usually by a floor sensor.
Turn the heating off before laying, and let the floor acclimatise.The screed should be at room temperature, not warm, while the floor is laid. The boards need to acclimatise in the room as normal.
Commission the heating gradually.After laying, bring the system up in small steps over several days, and down again the same way at the end of the season. A new floor hit with full heat gaps and cups.
Make sure a new screed has been properly commissioned before anything goes on it.A screed over UFH has to be heated and cooled through a defined cycle before a floor covering is laid, and it must be dry. This is not optional and it takes time.
Keep rugs and large furniture in mind.Anything that insulates a patch of floor makes it hotter underneath. Large rugs over UFH can push the floor above its temperature limit locally.

Tips

Tile and stone are the best coverings for UFH thermally, because they conduct heat well and tolerate the temperature. It is worth considering where the heating performance matters most.
If you are choosing the floor and the heating together, tell the UFH designer what covering you want — the system output is calculated with the covering's resistance in it.
Carpet over UFH is possible but the total resistance of carpet plus underlay is often the limiting factor, and thick underlay usually rules it out.
Keep a note of the UFH layout drawing. It is the only defence against drilling into a loop years later.

Common mistakes

Using a thick insulating underlay — It is doing the exact opposite of what the system needs. Heat that cannot get through the floor stays in the screed, the room takes far longer to warm, running costs rise, and the system may never reach the design temperature.
Bringing the heating straight up to full temperature on a new floor — The boards lose moisture rapidly and unevenly, which produces shrinkage gaps, cupping and in laminates delamination. Gradual commissioning gives the material time to reach equilibrium.
Laying solid wide-board timber over UFH without checking — Solid wood moves across its width with moisture content, and UFH drives that moisture content down. Wide solid boards over heating are a classic source of large winter gaps and cupping, which is why engineered board is usually specified instead.

If it doesn't work

Room takes hours to warm up after a new floor

Cause: Total thermal resistance of covering and underlay too high — Fix: Check the figures against the system limit. If the underlay is the problem it can sometimes be changed; if the covering is, that is a harder conversation.

Gaps opened between boards in the first heating season

Cause: Heating brought up too fast, or a covering not suited to UFH — Fix: Some will close as humidity rises in summer. Commission gradually next season and consider a humidifier if the room gets very dry.

A patch of floor much hotter than the rest

Cause: Insulating rug or furniture over a loop — Fix: Move it. Persistent local overheating damages the floor covering and can exceed the system's temperature limit.

Questions people ask

Can I have solid wood over underfloor heating at all?

Sometimes, with narrow boards in a stable species, correctly acclimatised, over a well-controlled system with a floor temperature limit. It is a specification decision rather than a general yes or no, and the flooring supplier should confirm it in writing for their product. Engineered board is the safer route by a wide margin.

What thermal resistance figure should I aim for?

The number comes from the heating system, not from a general rule, and the total for floor plus underlay must be below it. Ask the UFH manufacturer or installer for their maximum, then add up the figures for the products you are considering.

Does a floating floor over UFH still need an expansion gap?

Yes, and if anything more attention to it, because the floor is being cycled through temperature changes as well as humidity changes. Manufacturers often specify smaller maximum areas over heated floors for exactly this reason.