Nice floorings require good substrates

Blog Bodenbeläge

Many building owners have a clear idea of the flooring they want. However, the adhesives used to lay the flooring are unimportant to many of them. The right adhesive and pre-treatment of the subfloor are important criteria for permanently beautiful floor coverings.

The choice of the right adhesive has a direct impact on the quality of the flooring installation and its durability. The quality of the substrate is also crucial for a high-quality result. Among other things, the evenness of the subfloor is extremely important, depending on the floor covering.

Skilled tradespeople work therefore with tailored systems in which all components from the primer to the levelling compound and the adhesive for the desired floor covering are perfectly harmonized. This saves time and building owners benefit from high-quality floors that they can enjoy for a long time.

In this blog post, we provide you with detailed information about the different properties of the various floor coverings, which adhesives are suitable for which floor coverings and how the substrate should be prepared.

Overview

  1. What floor coverings are available?
  2. How must the substrate be prepared?
  3. Types of laying methods and types of glues
  4. Recommendations in case of underfloor heatings
  5. Conclusion

1. What floor coverings are available?

Floor coverings are functional elements of interior design and contribute to the individual charm of the interior. Thanks to the material used and the laying pattern, they create a feel-good atmosphere and give rooms their charm.

There is a variety of floor coverings made of different materials. These can be divided into three groups: textile and elastic floor coverings and wooden floors. Whether the choice falls on high-pile carpets, artfully-laid parquet or design flooring: For all floor coverings, professional installation is important for the appearance. Building owners should therefore rely on expert advice from dealers and skilled tradespeople for selecting the materials and their installation.

Textile floorings

Textile floor coverings include any form of floor covering made of textile fibers:

  • Tufting fabric
  • Woven fabric
  • Needle fleece
  • Ball yarn
  • Self-laying carpet tiles
  • Natural fibers

These floorings are often used where foot impact sounds must be reduced and a warm feel-good atmosphere must be created (for ex. in hotel rooms, office rooms and also children’s rooms.

Textile floorings should be bonded over the whole floor surface. A dispersion adhesive is generally used for this purpose (see chapter 3). The only exception is self-laying carpet tiles; these are fixed in place with a fixation to prevent slipping. This type of floor covering is of particular benefit in office buildings where access to the installation underneath is required in the case of cavity floors.

Elastic floorings

Elastic floorings are:

  • PVC floorings (homogeneous/heterogeneous)
  • PVC design (LVT)
  • CV floorings
  • Linoleum
  • Elastomer floorings (also known as caoutchouc or rubber)

So-called design floorings of polyvinyl chloride have become increasingly popular in recent years, particularly in residential spaces. They are applied onto thin underlay boards and sometimes printed with a wood or tile look
(Alternative names for designer flooring are LVT (Luxury Vinyl Tiles) or vinyl).

Linoleum is the all-rounder among resilient floor coverings and therefore deserves special attention. The material was developed in the 1860s and offers numerous advantages. The basic material today is still linseed oil, which is reinforced with cork flour and jute fabric. Thanks to the renewable resources linoleum is a particularly sustainable floor covering. Although this material requires rather high maintenance, its high durability and attractive appearance make it a popular floor covering for various living spaces. Linoleum is available in plain colours or with different patterns in a wide range of colours and qualities.

All resilient floor coverings should be bonded with a dispersion adhesive (see chapter 3). Click systems for design flooring are an exception; depending on the manufacturer's instructions, such systems can be laid loosely or are already coated on the back with an adhesive.

Wooden floorings

Wooden floors are among the classics among floor coverings and have been used by people for many centuries. They can be found in a wide variety of wood types, grades (rustic with many knots, without knots, etc.) and installation types (herringbone, wild bond).

Parquet and wood types are divided into:

  • Strip parquet
  • On-edge upright lamella parquet
  • Mosaic parquet
  • Multi-layer parquet
  • Multi-layer plank or solid-wood plank
  • Wood block

Solid-wood parquet and engineered parquet are equally popular; however solid parquet offers a significantly longer service life. The quality of the wooden flooring available on the market ranges from luxury models that last for several generations to inexpensive multi-layer parquet that can be refurbished one time only.

Wooden floors are either glued down or laid as a floating floor (see chapter 3). The floating installation is generally only used for click systems, such as multi-layer parquet, multi-layer planks or laminate. The subfloor should be levelled in advance to ensure a very even surface and to avoid cavity noises. An insulating underlay should also be laid to further reduce impact sound.

Tip: when pre-treating the substrate, use coordinated systems or ensure that the installation company does so. You will save time during installation and achieve optimum results. You also protect yourself from costly repair work and, in the worst case, even prevent costly dismantling.

2. How must the substrate be prepared?

Any floor covering is only as good as the subfloor allows. It is therefore always worth checking and preparing the subfloor carefully before laying. For perfect floor coverings, the substrate should be dimensionally stable and technically suitable.

Dimensionally stable = sufficiently level, flush, horizontal or at the planned gradient.
Technical = load-bearing, clean, dry, dimensionally stable and free from adhesion-impairing components.

Check of substrate

The first step is to assess the installation substrate in order to be able to select a suitable substrate pretreatment.

Major defects in the substrate can be detected by eye. However, you should not rely on your visual judgement alone: tools such as a folding rule, spirit level or laser levelling equipment will help you to determine the dimensional accuracy of the substrate.

In addition to the dimensional accuracy, the surface hardness or its pull-off strength should also be checked and the moisture measured. Unrecognized cavities can also lead to undesirable damage or footfall noises later on. Any impurities on the surface that reduce adhesion must be carefully removed in advance.

Primer and levelling compound are mandatory, not optional

When bonding floor coverings - but also when laying in a loose manner - it is recommended that the floor is always primed and levelled. Levelled subfloors offer many advantages: they are even, so no hollows can form under the floor covering. They also ensure an evenly absorbent substrate, which is particularly important for dispersion adhesives.

The levelling compound can be evenly distributed and smoothed to the required layer thickness, using a smoothing trowel or squeegee. Self-levelling systems, such as weber.floor levelling compounds are flow-grade and pumpable; they can be pumped directly to the application site using a hose. The levelling compound and the new floor covering should be separated from adjacent components (walls etc.) by an edge insulation strip to minimize sound transmission into next-door rooms.

A precise checklist for the substrate inspection is available here:

The quality of a floor covering depends on the condition of the subfloor to a large extent. If the subfloor does not meet the requirements for the surface covering (see checklist), it is essential to level it with a floor levelling compound before laying the flooring.

How to deal with old floor coverings?

When refurbishing and renovating old buildings, existing floor coverings are often used as subfloors for the new ones.
However, this should be avoided. Old coverings do not provide a good substrate for new coverings, as the adhesion between the old and the new covering is often insufficient and the joints of the old covering can sometimes be recognized in the new surface flooring.

In principle, all substrates should be dry, clean and load-bearing before application. In addition to the visual appearance, the quality of a floor covering also depends on the condition of the subfloor to a large extent. If the subfloor does not meet the requirements for a new floor covering (see checklist), it is essential to apply a floor levelling compound before laying the floor covering.

Modern systems, such as the high-flow smoothing mortar weber.floor 4031 or the ultra-flow smoothing mortar weber.floor 4032 can be applied manually or mechanically to various substrates, form a load-bearing substrate for all common floor coverings and score with very low emission of total volatile organic compounds (TVOC) with the Emicode seal (EC 1Plus). As self-levelling systems, they are also extremely easy to apply.

3. Types of laying methods and types of glues

Solid gluing, fixation or loose laying?

For the installation of floorings the tradespeople have the choice between three types of applications: solid glueing, fixation or loose laying.

Solid gluing

In this case flooring and substrate are tightly bound. The solid glueing is mostly recommended in many cases. This method avoids hollow spaces under the floor covering. If underfloor heating exists, this method is by far more efficient since the warmth transmission in the room is better.

Fixation

This method is best suited for so-called "self-laying floorings". Not an adhesive, but a bonding fixation is used to prevent the flooring from sliding, particularly in commercial areas such as offices.

Loose laying

In this case the flooring is laid loose without adhesive and fixation. An insulation layer is laid onto the substrate in order to minimize the foot impact sounds. This method is however not convenient for all floorings and must be approved by the manufacturer. Common floorings for the loose laying method are laminate, multi-layer parquet, multi-layer planks and design floorings.

Different types of adhesives

Wooden floor coverings have different properties compared with resilient elastic floor coverings, so the right flooring adhesive must be selected according to the properties of the material. It is important that the flooring adhesive not only forms a unit with the floor covering, but also with the substrate - it therefore works in two directions. This is the only way to achieve a high-quality result.

Since a flooring adhesive must therefore fulfil different requirements, it is important to know the right types of glue for floor coverings in advance.

Dispersion adhesives

Field of application: all elastic and textile floor coverings
These adhesives are suitable for all resilient (elastic) and textile floor coverings and are characterized by easy processing. They are single-component and do not need to be mixed in advance. Dispersion adhesives are only suitable to a limited extent for parquet flooring and similar floor coverings due to their higher moisture ingress into the installation area and their lower mechanical strength.

Reaction resin adhesives, 1-component

Field of application: all common types of parquet and floor planks
Single-component reaction resin adhesives are mainly used for laying parquet flooring and similar wooden flooring. The advantages are easy-going application and either elastic or shear-resistant bonding.

Reaction resin adhesives, 2-component

Field of application: all parquet floors and all types of wood as well as heavy-duty floor coverings, such as elastomer floor coverings
These adhesives consist of two components that are mixed directly before processing. While 1-component adhesives can cure to either an elastic or shear-resistant bond, depending on the adhesive, the 2-component variant always generates a so-called "shear-resistant bond". In this case, the adhesive is even stronger, which can be particularly important for demanding wood species and parquet formats.
A shear-resistant bonding greatly reduces the transverse curvature of the wood and the "curling" of individual elements. A well-levelled substrate is very important for this type of adhesive.

Fixation

Fields of application: dimensionally stable ("self-laying") floor coverings
Fixations (so-called adhesive dispersions) are applied to the substrate by a micro-fiber roller and harden to form a non-skid underlay for dimensionally stable floor coverings. In contrast to full-surface bonding, there is no tight bonding between floor covering and substrate; the fixing product just lay on the floor surface as non-skid material. The bonding effect is sufficient for normal loads such as in offices.

Note: products that are Emicode-certified should be used as a first choice so as to minimize indoor air pollution as far as possible.

What does Emicode-certified mean?

Emicode-certified means that a product has a very low emission of total volatile organic compounds (TVOC) without impairing its quality and effectiveness. When adhesives with high emissions are processed in close proximity to the product, there is a health risk. The lower the emissions of the adhesives, the less harmful gases are emitted during processing. High-quality flooring adhesives provide a tight bonding effect without polluting the indoor air.

The Emicode certification is divided into three classifications:

The prerequisite for the issue of a licence to use the EMICODE® mark is the conformity of products with the classification criteria of the "Association for the Control of Emissions in Products for Flooring Installation, Adhesives and Building Materials" ("Gemeinschaft Emissionskontrollierte Verlegewerkstoffe, Klebstoffe und Bauprodukte - GEV)". The tests required for conformity are to be carried out in accordance with the GEV test method. The correct categorisation of products is carried out by the manufacturer and is monitored by GEV.

  • EC 1 Plus: very low emission, <= 750 ug/m³ TVOC
  • EC1: very low emission, <=1.000 ug/m³ TVOC
  • EC2: low emission, <= 3.000 ug/m³ TVOC

Thanks to continuous research, Saint-Gobain Weber is able to increase the quality of its products and also noticeably reduce emissions. Almost all adhesives, as well as numerous other floor products of Weber, can bear the seal EC 1 Plus. If a product is EMICODE-certified, the seal is printed on the packaging and mentioned in the technical data sheets.

4. Recommendations in case of underfloor heatings

Underfloor heating is a popular alternative to conventional radiators. A floating installation should be avoided in order to utilize them to the maximum. In this loose installation, both the insulation underlay and the cavities act as unwanted insulation of the underfloor heating. Instead, the floor covering should be glued to the substrate to provide the best heat transfer. Indeed, the heat transfer from the underfloor heating to the room is considerably better when using the glueing method. Almost all common glues for floorings and parquet can be used in combination with underfloor heating.

5. Conclusion

For a beautiful and durable floor, the system should be designed from bottom to top: checking the substrate, balancing with a high-quality smoothing mortar and selecting the appropriate adhesive for the desired top floor covering. In the end, you can only see the top cover, but the more correctly the substrate has been prepared and the appropriate floor covering adhesive has been selected, the more beautiful and durable it is.

For all floor coverings and installation methods, the careful preparation of the substrate with a smoothing mortar pays off. The preparation work for levelling the subfloor prevents the formation of annoying hollow layers and thus has a positive effect on impact sound insulation. In the case of underfloor heatings, it also increases the efficiency of heat transfer.
A system-compliant system saves time during processing and unnecessary repairs. If the materials are coordinated with each other, also the manufacturer issues a comprehensive warranty and skilled tradespeople are assured of a responsible contact partner.