"Can you have parquet over underfloor heating?" is one of the three questions we hear most often. The answer is yes — we have been doing it for years and the floors work. But "yes" comes with conditions: the construction has to be stable, the thickness chosen to suit, the installation glued down, and the heating brought up gradually. If one of the four is missing, the floor will show it in the very first winter. This article describes each of them the way we do it on our own projects.
Why wood and heat have to accommodate each other
Wood is a living material — it takes on and gives off moisture according to the air around it. When the underfloor heating is running, the air above the floor is drier and the wood shrinks; when it stops, the wood takes on moisture and expands. This movement is normal. The problem comes when the construction of the floor amplifies it instead of damping it — then gaps open up, the planks warp, and the lacquer cracks along the edges.
That is why the choice of construction is the first and most important decision. Everything else — thickness, installation, start-up — are the rules for using that construction correctly.
Which construction works
Engineered oak flooring — yes. This is the construction we recommend and the one we manufacture in Trud: a 4 mm top layer of European oak on a birch plywood core with cross-bonded layers. Every layer in the plywood is laid at 90° to the one beside it, so the shrinkage of one is offset by the expansion of the other. The result is a plank that barely reacts to temperature and humidity. More about the construction — in our comparison of engineered and three-layer parquet.
Solid oak flooring — we do not recommend it. A solid plank is wood through its full thickness, with nothing to damp the movement. Over underfloor heating it moves more than the joints and the lacquer can take. We do make solid oak flooring and we value it — but for rooms without underfloor heating.
SPC flooring — yes, over water-based underfloor heating. Velvet Stone has a stone-polymer core, which is not wood and does not react to moisture. For a bathroom or a kitchen with underfloor heating this is the right choice.
Herringbone and chevron — yes, in an engineered construction. We make them with the same 4 mm oak on plywood and in the same 16 and 19 mm thicknesses as the straight plank. Solid herringbone — no, for the same reason as the solid plank.
Thickness is thermal conductivity
Our engineered oak flooring is made in two thicknesses: 16 mm (12 mm plywood + 4 mm oak) and 19 mm (15 mm plywood + 4 mm oak). Both work over underfloor heating. But 16 mm is our recommendation when there is heating, for two reasons: the thinner floor lets the heat through more easily and more quickly, and it has less mass to expand. The top oak layer is the same — 4 mm in both cases, meaning the same up to 4 sanding cycles.
Choose 19 mm if the underfloor heating is secondary (only in the bathroom, for example) and in the other rooms you want the more solid feel of the thicker plank.
Installation — glued down, over the whole area, no underlay
There is no compromise here: parquet over underfloor heating is glued down across the whole area with a two-component polyurethane adhesive. No floating installation, no click system, no underlay beneath. The reason is simple — air is an insulator. Every layer of air between the screed and the plank stops the heat you have paid for. A floating floor on an underlay is exactly that kind of layer.
The adhesive does one more thing: it holds the plank tight against the screed, so the heat passes through directly and the plank has nowhere to move. The planks have a tongue and groove and lock into one another, and the adhesive locks them to the subfloor. Before the adhesive we lay a moisture barrier over the screed — it protects the wood from residual moisture underneath.
Before installation — the screed has to be ready
The most expensive mistakes happen before the first plank is laid. There are three things we always check:
- Moisture in the screed. A new screed takes weeks to dry. We measure the moisture with a meter, not by eye — a wet screed under glued-down parquet is a guaranteed problem.
- Heating before installation. The underfloor heating is switched on and brought up gradually, to dry the screed and "drive out" the residual moisture before the parquet covers it. After that it is switched off or turned down until installation.
- Flatness. Glued-down parquet needs a level subfloor. Where there are deviations we level it with a self-leveling screed before installation — otherwise the plank does not sit tight and air pockets are left underneath it.
The humidity of the air in the room has to be between 40 and 60% — both during installation and afterward. That is the condition in which wood stays calm.
After installation — gradually, not all at once
Once the parquet is glued down and the lacquer has dried, the heating is not turned on at full power. It is raised in steps, a few degrees a day, so the wood can adjust. The same applies in the other direction when you switch it off in spring. Sudden heating is the number one cause of gaps during the first winter — and it is entirely avoidable.
Underfloor heating is a low-temperature system. A wooden floor is not a radiator — if the system is set to run hot, both the floor and the bill will suffer. The surface temperature setting follows the specification of the heating system and of the parquet; when we do the installation, we provide it in writing.
Which wood species behave more calmly
Oak is the most predictable wood species for underfloor heating — dense, stable, with familiar behavior. All of our standard engineered oak flooring is European oak, in the Standard, Plus and Prima grades and in over 15 colors. For underfloor heating the grade makes no difference — the construction is the same.
We make walnut and iroko in the same engineered construction, and they work over underfloor heating just as well — it is the birch plywood core that carries the stability, not the top layer. The Tabu Collection — veneer dyed all the way through, on our own plywood, 14 mm total thickness — is compatible as well.
The four mistakes we see most often
- Solid oak flooring over underfloor heating. It looks fine the first year. Then the gaps open up and there is no way to close them.
- Floating installation over an underlay. The floor "floats", it thuds when you walk on it, and the underlay blocks the heat. The heating is running, the room is cold.
- Turning the heating on abruptly. From zero to maximum on the first cold day. The wood cannot adjust in time and gaps open across the whole floor.
- A thick rug over the parquet. The rug traps the heat underneath it, the wood below overheats and shrinks more than the wood around it. If you want a rug — keep it thin and small.
Construction by construction
| Construction | Underfloor heating | Why |
|---|---|---|
| Engineered oak 16 mm (12 + 4) | Yes — our recommendation | Cross-bonded plywood dampens movement; the thin plank lets the heat through |
| Engineered oak 19 mm (15 + 4) | Yes | The same stability, slightly slower heat transfer |
| Engineered herringbone / chevron | Yes | The same construction as the straight plank |
| Tabu Collection 14 mm | Yes | Veneer on birch plywood |
| Solid oak 20 mm | We do not recommend it | The wood moves throughout its entire thickness |
| SPC Velvet Stone 6 mm | Yes, water-based | Stone-polymer core, does not react to moisture or temperature |
Parquet and underfloor heating — frequently asked questions
Can engineered oak flooring go over underfloor heating?
Yes. Engineered oak flooring with a 4 mm oak top layer over cross-bonded birch plywood is the construction we recommend for underfloor heating. Choose 16 mm thickness, glued-down installation with a two-component polyurethane adhesive, and a gradual start-up of the heating.
16 or 19 mm for underfloor heating?
16 mm. The thinner plank transfers heat more easily and has less mass to expand. The oak top layer is 4 mm in both cases, so the life of the floor is the same.
Can solid oak flooring go over underfloor heating?
We do not recommend it. A solid plank is wood through its entire thickness and has no stabilizing base — over underfloor heating it moves more than the joints can take. For rooms with underfloor heating, choose an engineered construction.
Is an underlay needed under the parquet with underfloor heating?
No. An underlay is a layer of air that blocks the heat. Parquet over underfloor heating is glued down across the whole area directly onto the screed, with a moisture barrier underneath — that way the heat passes straight into the plank.
When is the heating turned on after installation?
After the lacquer has dried completely, and gradually — a few degrees a day, up to the working temperature. Turning it on abruptly is the most common cause of gaps during the first winter. The same applies when switching it off in the spring.
Does SPC flooring work with underfloor heating?
Yes. Velvet Stone is compatible with water-based underfloor heating. The stone-polymer core is not wood and does not react to heat or moisture — which is why SPC is the choice for a bathroom or kitchen with underfloor heating.
Have underfloor heating and are not sure which thickness and which construction to choose? Send us a plan and the type of heating system. We come on site, measure the moisture in the screed and give a written recommendation for thickness, finish and a start-up protocol — free and with no obligation.