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Solid floorboards on underfloor heating

Installing a wooden floor on underfloor heating is not an easy task and requires considerable experience from both the heating installer and the floor fitter. Wood, as a natural material, reacts to changing environmental conditions such as humidity and temperature, and underfloor heating significantly increases fluctuations in these factors. Therefore, this type of heating must be designed with the work of a wooden floor in mind and provide very even and gradual heat distribution across the entire floor surface. Two properties are required from floorboards:

Two properties are required from floorboards for underfloor heating:

low thermal resistance, affecting the efficiency of the entire installation,
high dimensional stability, which reduces the risk of permanent deformation.

When choosing a natural wooden floor, one key decision is whether to select engineered or solid floorboards. Engineered floorboards have only a thin top layer of hardwood, which can significantly limit the number of times they can be refinished. Solid floorboards, by contrast, are made entirely from one wood species and can last for decades. They can be sanded several times, restoring the surface with each renovation. Which type is better suited to underfloor heating?

Board stability

Some experts in the engineered-flooring industry claim that solid floorboards installed over underfloor heating will eventually deform. This view, however, often reflects experience with products from less reputable manufacturers. Scientific research shows that premium products such as WALCZAK solid floorboards perform differently.

"(...) the specific properties of the oak floorboard [by WALCZAK] give it the attribute of a flooring material with enhanced dimensional stability" – Dr Eng. Jerzy Majka, Poznań University of Life Sciences

— dr inż. Jerzy Majka, Uniwersytet Przyrodniczy w Poznaniu

This ensures floor stability even in the case of increased humidity and air temperature fluctuations caused by underfloor heating. WALCZAK solid floorboards achieve this thanks to their construction with transverse and longitudinal notches on the underside, which by increasing flexibility enable precise installation and guarantee floor stability during use. The innovativeness of this solution is confirmed by a protective certificate granted by the Polish Patent Office. The notches are also an important element of the production process itself and, combined with WALCZAK's proprietary drying and wood processing techniques, have eliminated half of the forces responsible for board movement during changes in environmental conditions.

Thermal conductivity

The second aspect of using floorboards on underfloor heating is their thermal conductivity. The value of the thermal conductivity coefficient for wood depends primarily on its density. Solid floorboards are made entirely of a single wood species, usually oak or ash, i.e. a species with high density and thermal conductivity. In the case of engineered boards, low-density wood (birch or coniferous species) is usually used under the thin top layer, meaning lower thermal conductivity.

Recent scientific research has shown that:

a 16 mm thick WALCZAK solid oak floorboard has the same thermal resistance as a 14 mm two-layer board,
a 14 mm three-layer board has 32% higher thermal resistance than the two materials above, even though the test was performed without foam underlay, which is most commonly used for this type of board; foam would further worsen the result.

Facts versus myths

So is a solid floorboard suitable for underfloor heating? Scientific research and the opinions of many floor fitters prove that YES. When choosing boards for underfloor heating, we should be guided more by the manufacturer's reputation than by whether the board is engineered or solid.

"From our many years of experience, properly prepared solid floors, such as WALCZAK floorboards, perform better on underfloor heating than 3-layer floors." – Wioleta Gańcza, wooden floor showroom owner, floor fitter

"(...) we have repeatedly installed WALCZAK floorboards, parquet or mosaic parquet on underfloor heating substrate and this material has performed excellently" – Agnieszka Adamczak, master floor fitter, expert

Companies installing solid floorboards over underfloor heating

Below is a list of experienced flooring companies that install WALCZAK solid floorboards over underfloor heating.

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