Subfloor properties

A floating hardwood flooring can be installed on concrete, slate or a wooden floor, on top of plastic, linoleum or cork. Wall-to-wall carpeting must be removed. The subfloor must be level. When measured with a 200-cm ruler, the maximum deviation allowed is 3 mm. If the deviation exceeds 3 mm, the floor must first be levelled using either a suitable filler or board. An old wooden floor should be nailed down, if necessary, to make sure it is rigid. It is advisable to clean the old floor to prevent any unpleasant odours.

The relative humidity of a concrete floor without a moisture barrier must be less than 60%, and with the Tuplex underlay which acts as a moisture barrier, less than 85%. To check the humidity, use either a hygrometer or place a plastic sheet (approx. 1 m²) firmly over the floor for 4­ - 5 days. If there are water drops underneath the plastic sheet or if the concrete has turned darker in colour, the floor is too moist.

A durable moisture barrier (plastic sheet, PE) of 0.2 mm is recommended for use underneath the hardwood boards, and sound-insulation material if the floor is to be laid on top of concrete. An additional plastic sheet is not necessary for wooden subfloors and intermediate floors.

Before installation
The installation temperature must be a minimum of +18 ºC and the air humidity must be 40 - 60%. Keep the hardwood floor packages on a level surface, loosely placed in the room where the hardwood floor is to be installed for 1 - 2 weeks. Open the packages only as the installation work progresses.

How to choose the laying direction and the starting place
It is preferable to lay the boards in the direction of incoming light. However, if you lay the hardwood boards on a wooden floor, it is recommended to lay them crosswise.

Start from a solid wall. First check with a cord that the wall is straight. A straight and solid starting line is crucial for successful installation. When necessary, draw a line matching the shape of the wall on the first boards and cut them into that shape.

Expansion allowance
Remember to leave a 7 - 10 mm gap between the wall and the board, around pipes or column penetrations, etc. Cover the gap with a skirting or cover strip. In larger floors, the gap should be 1.5 mm per metre crosswise.

Expansion joint
If the floor covers a large, continuous area of more than 8 metres in width (crosswise), an expansion joint should be inserted into the hardwood flooring. To make an expansion joint, do not apply glue on the board’s long side, have a so-called dry joint instead. Alternatively, you can leave a gap of approximately 10 - 15 mm between the boards and cover it with a cover strip. If the boards are installed crosswise, cut them and leave a corresponding gap between them. The expansion joint should be placed, for example, into the doorway, a corner or other suitable place.

In some cases, even large areas can be covered without an expansion joint if there are no gaps or corners in the room. Always ask the salesman or the manufacturer for instructions.

Sound insulation
The Upofloor Tuplex underlayment inserted between the hardwood flooring and the subfloor insulates impact sounds, such as walking, excellently. In other than detached houses, the most important thing is proper sound insulation of the supporting ground structure.

For more detailed information see our Tuplex page

Floor heating
Hardwood flooring and floor heating complement each other. Installation instructions are available from the manufacturers and salesmen of floor-heating equipment.

When using floor heating, special attention must be paid to correct conditions: the humidity of the air indoors must be 40 - 60% and the maximum temperature of the floor surface +28 °C. The most even heat emission is obtained with a continuously-operated, water-circulation system. This does not raise the temperature too high, as may be the case with so-called storage systems. Continuously used, it also reduces the relative humidity of the air indoors. Wood insulates heat rather well, but in this case, the hardwood flooring gradually adapts to the conditions.

A couple of days before installation, the floor temperature should be lowered to approximately 20 °C, and only returned to normal a couple of days after the installation.

The different species of wood do not have significant differences in thermal conductivity, but the heat is directed more quickly to the surface of a hardwood flooring in a stuck down rather than a floating installation.

Changes in the temperature also affect humidity. Beech and Maple are the most sensitive to changes in temperature and humidity. For this reason, these woods are not recommended for installation over floor heating.

For more detailed information on how to install Upofloor RealWood floors, see our Installer's quide below.