We put some pressing questions to Michaël Wensky, Key Account Manager at Küberit-Parkettfreund, and Patrick Welscheit (Export Manager at the same company). Before we get started with the actual interview, both gentlemen reflect on a titanic job that their firm, which is purely focused on professionals, has brought to a successful conclusion in recent months. They worked hard on a new, updated catalogue, which will come into force on 1 January 2024. It can be requested from field sales or customer service.

New catalogue on 1 January 2024
"There was clearly a need for a new tool like this," states Patrick Welscheit. "Above all, we need to provide customers with a knowledge tool and explain that while ecological products may be more expensive, they put much better tools in their hands. To get the message right, we made quite a few changes, especially then in the first pages. We adapted the information and added a lot of information on ecological products and their recyclability, while also adapting the way they are presented. Among other things, customers will be able to discover this new catalogue at the upcoming Domotex, where we will be presenting a totally new stand concept."

Over to the subfloors themselves. For this, we focus on Mr Wensky, who as product manager for insulation materials and accessories for floor installation is the ideal contact for more technical questions. First of all, we sound out what he thinks are the most important requirements for a subfloor in combination with underfloor heating or cooling.

"In principle, many insulating subfloors are suitable for installation with hot water underfloor heating," explains Mr Wensky. "Actually, the following applies: the total thermal resistance should not exceed a maximum of 0.15m²K/W, and here I refer to information from the 'Association of Underfloor Heating Manufacturers'."

"In the case of an installation where cold water can be pumped through the underfloor heating system for cooling in summer, there are additional requirements. An automatic control must be installed under the floor covering to determine the dew point. This requires dew point sensors to be installed under the floor covering, which will switch off the cooling system before condensation occurs. Condensation can cause damage to the floor covering system and trigger deformation, stretching, cracking and so on. Remember here that the thermal resistance Rλ,B for the entire floor system for floor cooling should not exceed 0.10 m² K/W. An additional question is whether this suitability also applies to electric floor heating. Here you have to be aware that this depends on the top floor. Heat resistance can be a problem with most plastic materials because they deform at temperatures above 70°C, so the underfloor heating should not get hotter. By the way, this also applies when using XPS insulation under the underfloor heating!"

Improve acoustic comfort
A subfloor can help improve acoustic comfort. But how does this work specifically with laminate flooring?
"Laminate floors have a hard core and therefore transmit sound very well to the subfloor (screed) or through the walls to the surrounding rooms," he clarifies. "The right insulating subfloors can significantly reduce these noises, and here we distinguish between walking and impact noise reduction. Walking noise refers to the sounds heard in the room and the unpleasant 'clack-clack' effect of laminate can be greatly reduced by choosing the right product. Such walking noise is strongly influenced by the insulation layer and the rule of thumb here is that the greater the mass of the underlay, the better the walking noise reduction. Impact sound, in turn, describes the sounds that can be heard in rooms below or in adjacent rooms. Depending on the material design of the base, these can be reduced and up to 20 to 22 dB are possible. The best insulating underlays achieve an improvement of up to 22dB."

Moisture barrier?
It is common knowledge that a moisture barrier is not an unnecessary luxury with underfloor heating. What specifically is the importance of this?
"For mineral substrates, manufacturers of top floors prescribe the installation of a moisture barrier or vapour barrier. For products with a built-in vapour barrier, you can do without a foil," Mr Wensky explains. "Keep in mind that the vapour density must be at least sd > 75m. The thickness is at least 200µm according to VOB, but 120µm is sufficient when it is vapour tight. The products with a vapour barrier are all at sd>75m and if you put an insulating underlayment on wooden floors, you should not use a vapour barrier."
We reserved the most important question for last. How does Parkettfreund make customers aware of the importance of choosing the right underlay? Here, our interlocutors referred to their own catalogue on subfloor insulation.

"On the first pages of this product information, the interested user/customer will find a lot of information" concludes Patrick Welscheit. "We provide basic knowledge about the installation underfloor, clarify the needs and requirements of the insulation underfloor and dwell on the environment and sustainability. In addition, we explain the requirements of the EPLF and MMFA in detail and emphasise once again how Parkettfreund's field service staff receive continuous training and how Parkettfreund offers training courses for customers."