Questions and answers

Do you have any questions about underlays? We have the answers for you. You can find some of them here in our FAQs. If anything is still unclear, please contact us on an individual basis. We are always happy to help yo.

What do I need to consider with regard to installation on underfloor heating?

Since both laminate as well as wood flooring are good insulators, the merits of laying either product over an underfloor heating system should be carefully considered.

The important thing is that the entire floor system (insulation underlay + laminate / wood flooring) should not exceed a thermal resistance of 0,15 m²K/W (the thermal resistance of the underlay can be found on each product page in the technical data). The lower the thermal resistance, the higher the efficiency of the underfloor heating.

We recommend using the following products for laying on an underfloor heating system:


Which underlay can I use on wooden floors?

On wooden bases, installation takes place without the moisture protection film in principle. If the base is very uneven, we recommend using special wood fillers (partly fibre-reinforced) or particle boards, which are installed on top of the old wooden boards with an intermediate layer of PE foam. Then install the impact sound insulation on top of this without moisture protection.

When do I need moisture protection?

If you are laying flooring on screed or concrete, moisture protection is absolutely essential. Otherwise, rising residual moisture from the base can cause serious damage to your laminate or wood flooring.

All our products with AquaStop™ technology offer suitable moisture protection in the form of a laminated AquaStop™ film surface. The advantage of this is that it eliminates the need to install a vapour barrier too.

Can I install it on carpet?

We generally advise against installation on existing carpets. For high-pile velour carpets, you risk breaking the click connections due to lack of pressure stability. In addition, there is a high likelihood of mould formation with installation on carpet.

The EPLF Merkblatt also recommends removing existing carpet (Paragraph 5.4.5).

Can I lay double layers of underlays?

In general, we do not recommend the use of double layers of underlay. The 2 layers impair the pressure stability of the underlay and the resulting friction may lead to undesirable floor noises.

What do the individual test marks mean?

TÜV Cert DIN EN ISO 9001

Zertifikat: 01 100 84025
The TÜV-Cert certification body of TÜV Rheinland certifies SELIT for the scope “Development, production and sale of innovative insulation materials for ceilings, walls and floors and the introduction and application of a quality management system in accordance with DIN EN ISO 9001:2008.

SELIT stands for quality and reliability – for more than 30 years!



The mark of conformity in the German Federal States identifies regulated and non-regulated construction products that comply with the underlying technical regulation, the national technical approval, the general supervisory authority test certificate, or the approval in individual cases.

In Germany, this is also known as the “Ü mark of conformity”. The equivalent mark in Austria is the “ÜA mark”. The conformity mark identifies the permitted use of a construction product in Germany.

All SELIT products have the Ü mark of conformity and therefore the national technical approval.


FSC® 100 %

Zert.-Nr. GFA-COC-001689
The Forest Stewardship Council® confirms that “ÖKOLIT® 5 mm wood fibre” is a product made with raw materials from forests managed to the highest standards“ and thus a material origin “from forests certified according to the environmental and social standards of the Forest Stewardship Council”.

This product is certified as contributing to sustainable forest management.

What should I take into account in the case of heavy items of furniture or heavy loads?

Where there are high surface stresses or heavy loads, the pressure stability of the insulating underlay is the decisive criterion. Products made of polystyrene (such as SELITAC® and SELITPRO® Serie) are the first choice in this case.

Do underlays also provide thermal insulation?

For cold floors, especially in basement areas, underlays contribute to thermal insulation. The rule is: the thicker the material, the better the insulation. Even underlays as thin as 5 mm, such as SELITAC® 5 mm, provide significantly increased foot warmth. SELITFLEX® 10 mm Thermo achieves top performance in terms of thermal insulation.

How do I find the best underlay?

The easiest way to find the right underlay is to use the “SELIT Product Advisor”, which is our app. This app is for iOS and Android and enables you to scan the flooring you have purchased and find the perfect underlay for it.

You can also find a product advisor tool here on our website. Just answer a few questions and get a recommendation straight away.

Can the underlay be affixed with adhesive?

underlays like SELITPRO®, SELITAC®, SELITFLEX® and SELITBLOC® are designed for the floating installation of laminate, wood flooring and vinyl click flooring and must not be firmly affixed to the base.

For easier installation, you can use SELITstop® Aluminium-Foil Sealing Tape.

Do underlays need to be acclimatised?

Unlike floor coverings (laminate, wood flooring and vinyl), underlays do not have to be acclimatised in the room but can be installed immediately after purchase.

Decorative floors must be acclimatised in the installation room for at least 24 hours and 48 hours is preferable. Please follow the instructions provided by the floor manufacturer.