Solid floorboards for underfloor heating

Installation of wooden floors over underfloor heating is by no means an easy task. It requires a great deal of experience from both heating fitters and floor fitters. As a natural material, wood reacts to changing conditions such as humidity and temperature and underfloor heating significantly increases fluctuation of these factors, which is why this type of heating must be designed with wood contraction and expansion in mind as well as ensure even and non-abrupt dissipation of heat on the entire flooring surface. Floorboards, on the other hand, must have two major characteristics:

  • Low heat resistance influencing the efficiency of the whole installation
  • High dimensional stability decreasing the risk of permanent deformations

While deciding on natural wooden floors one encounters a dilemma whether to choose engineered or solid floorboards. Engineered floorboards have only a thin layer of the desired type of wood on top of layers of cheaper wood types, which significantly limits, or even eliminates the possibilities of renovation. When it comes to solid floorboards, they are manufactured out of one wood type, thanks to which they are likely to last many decades. They can be repeatedly sanded and after every renovation the surface regains its original shine. The question is: which type of floorboards is more suitable for underfloor heating?

Floorboard stability

Experts connected to the engineered floorboards sector tend to express an opinion that solid floorboards over underfloor heating are bound to deform sooner or later. This contention, however, results from their experience of working with floorboards made by highly questionable manufacturers and there's research to prove that this is not the case when it comes to the high-end products, such as solid floorboards made by WALCZAK.

"(...) particular properties of oak floorboards [from WALCZAK] give them the attribute of a floor material of increased dimensional stability" - Jerzy Majka, D.Eng, Poznań University of Life Sciences

It ensures the stability of the flooring even during increased fluctuations of humidity and air temperature caused by underfloor heating. Solid floorboards manufactured by WALCZAK achieve this effect thanks to their construction with transverse and longitudinal notches on the underside, which allow precise installation thanks to increased elasticity as well as guarantee stability of the flooring during use. The innovative character of this solution has been confirmed by a certificate granted by the Polish Patent Office. The notches on the floorboards are also important for the manufacturing process and together with WALCZAK's original drying and wood processing techniques made it possible to eliminate a half of the factors responsible for changes resulting from expansion and contraction of wood during fluctuations of conditions.

Thermal conductivity

Another aspect of using floorboards over underfloor heating is their thermal conductivity. Thermal conductivity of wood depends predominantly on its density. Solid floorboards are made entirety of one wood type of high density and thermal conductivity, such as oak or ash. In the case of engineered floorboards, wood of low density as well as lower thermal conductivity, such as birch or conifers, is placed beneath the thin, top layer. The negative effects of such construction of engineered floorboards have been confirmed by the latest research, which has shown that:

  • WALCZAK 's 16 mm thick solid floorboards have the exact same heat resistance as 14 mm thick two-layer boards
  • 14 mm thick three-layer boards have 32% higher heat resistance than the two materials mentioned above, despite the fact that the test has been conducted without the foam sheet, on top of which this type of boards are usually installed; the sheet would only aggravate this result.

Facts vs myths

Are solid floorboards, therefore, suitable for underfloor heating? Research, as well as opinions of numerous floor fitters, prove that THEY ARE. While deciding on floorboards for underfloor heating one should trust more in the reputation of the manufacturer, than whether the floorboards are solid or engineered.

"Our many years of experience have shown that solid floorboards, if prepared correctly such as WALCZAK's floorboards are, work better with underfloor heating than 3-layer engineered boards" – Wioleta Gańcza, the owner of the wooden floors showroom, a floor fitter

"(...) we installed WALCZAK's floorboards, parquets and mosaic parquets over floor heating numerous times and the material always worked perfectly" – Agnieszka Adamczak, expert floor fitter


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