Installation of Underfloor Heating Under Laminate

It is well known that the quality of room heating is directly proportional to the area from which heat is released. That is why replacing a traditional radiator under a window with a full-fledged heated floor, for example, under a laminate covering, is much more efficient in terms of heating the room and comfortable movement across a warm wooden floor, instead of a cold and slippery laminate surface.

Below we will examine the option of installing a water-based underfloor heating circuit under a laminate parquet. Since the heat emission surface of the floor is much larger than that of a radiator, the temperature of the heat transfer fluid (water or propylene glycol) can be maintained lower, thus reducing heating costs for a house or apartment.

First, let's determine where it is technically possible to install a water-based underfloor heating system under laminate. Let me clarify immediately — it is not possible everywhere. Installing a heated floor over a concrete base is quite problematic; in such cases, it is simpler to install an electric heating circuit rather than a water-based one. However, in frame houses, other private homes, cottages, or old apartments — in short, wherever floors are built on joists rather than concrete slabs — such an option exists.

Preparation for Installation: Materials Required

For a high-quality installation of a water-based heating circuit, the following materials are needed:

Installation Sequence: Preparation Phase

First, insulate the space between the joists — for this, line (if necessary) the joists from below with thin (18–22 mm) untrimmed boards and lay a 100 mm thick layer of insulation on this makeshift subfloor. If the joist thickness allows, the insulation layer can be increased to 150 mm — it will be warmer.

Next, prepare the subfloor. Cut 2 x 2 cm grooves on each board — not necessarily in the center, but for example along one edge, to reduce the number of cuts. From practical experience, it is easier to use boards 40 or 50 mm thick, 100 or 150 mm wide. The board length should match the joist spacing. For example, if the joist spacing is 60 mm, a 3 or 6 meter board will work — this way, there will be no wood waste. The grooves must be cut in the same location on all boards — this is where the heating tube will later be placed. If the tube pitch is disrupted, the floor will heat unevenly.

After the subfloor is prepared and grooves are cut (this can be done at home using a hand router), place the board on top of the joists and secure it to each joist using screws.

Installation Sequence: Tube Laying

PEX tubing is laid into the grooves of the subfloor. For bends, a semi-circular section is cut in a staggered pattern to connect adjacent grooves, ensuring the entire room is covered by a single tube without joints or connections — this is crucial for the system’s hermetic integrity. On one side (usually the short wall), a straight cut of the same size is made to lay the return tube.

Pre-cut foil is cut into 20–25 cm wide pieces, the length remains as in the roll — typically around 10 meters. These pieces are laid into the grooves. After placing the foil, the PEX tubing is inserted into the same groove and wrapped around on all sides with foil. The tube, wrapped in foil, is secured to the floor every meter to one and a half meters using steel clamping plates and a simple construction stapler.

On the main supply pipe, one inlet and one outlet are created using T-fittings and ball valves installed on them. In the future, both ends of the water-based heating loop will be connected to these. This is essentially the floor control unit, allowing regulation of the heat transfer fluid flow rate, and thus controlling the floor heating speed and temperature.

Finally, a 2–3 mm thick foam polyethylene underlayment must be rolled out over the laid tubing, and the laminate floor should be installed according to the manufacturer’s instructions. The proposed floor structure, in terms of strength and reliability, is no less suitable for laminate installation than similar constructions using plywood, OSB, or solid wood subfloors.