How to make waterproof cork flooring

Advantages and disadvantages of cork flooring and cork laminate

Cork soil is obtained from the bark of the cork oak. It is hydrophobic, very elastic and poorly flammable. In fishing, for example, it serves as a float on fishing rods, it is also used as a sealing material in machines and devices and, as a cork floor, it beautifies any room when it is used as a floor covering.


General information about cork

Cork flooring as a floor covering for connoisseurs

Cork flooring promises a high level of living comfort. As a warm, soft and natural material, cork flooring brings comfort and a natural living atmosphere. Cork has properties that are beneficial for the air we breathe indoors. This makes cork, like other natural materials, particularly suitable for allergy sufferers. When laying cork as a floor covering, however, there are a few aspects to consider.

Cork flooring is not equally suitable everywhere

Cork is an organic natural material. Organic substances are naturally not designed for long-term existence, but are subject to permanent, natural decomposition processes. Cork is known for its waterproof properties. However, these are always accompanied by a high swellability of the material. Its use in humid environments is therefore a particular challenge. In the long term, rot and mold can also be dangerous for cork flooring. For a complete cladding of the floor of an apartment with cork flooring, special sealing measures are therefore required in the damp rooms. But a cork floor also has other limitations in its usability. These include, for example, the restrictions on underfloor heating.

Natural building material with tradition

Cork is a natural substance. The soft, rubber-like material is obtained from the bark of cork oaks. These grow mainly in warm regions of southern Europe such as Italy, Greece, southern France and Spain. The cultivation of cork oaks is a very lengthy process that requires a lot of experience. This makes cork materials relatively expensive and only available to a limited extent.

In interior construction, cork is used as a wall and floor covering. The raw material cork is crushed into granules and processed into the desired formats by means of a binding agent using a glue-press process. Used bottle cork is also used again. The size of the individual grain in the granulate is hardly decisive for the insulating and damping properties of the cork. This enables a wide range of manifestations. Coarse grain sizes are used to create the typical cork surface with its pleasant haptic properties. The finer the grain, the more varied the options for texture and color.


The selection of cork flooring

When it comes to cork floor coverings, a distinction has to be made between thin pre-fabricated cork parquet, cork mosaic and solid cork tile (also often referred to as "cork parquet"). In addition, there are numerous possible uses in interior construction in which cork is also used. The following formats are common on the market for building materials, laminates and tiles made of cork:

Rolled cork

Rolled cork are rolled mats made of glue-pressed cork granulate, which is used as impact sound insulation under laminates. It is an excellent alternative to plastic-based impact sound insulation. Rolled cork is therefore particularly suitable for users who value natural building materials. Impact sound insulation costs around 2.30 euros per square meter from a thickness of 2 millimeters.

Prefabricated parquet

Prefabricated cork parquet is an inexpensive way to enjoy the advantages of a cork floor. The parquet boards are now available as standard in the click board format. Thanks to its granulated structure, cork in particular offers the possibility of furnishing a large room without visible joints in the flooring.


The prices per square meter depend on the degree of processing and the thickness. The thickness always refers to the total thickness of the individual element. The cork part is only the top, visible layer.

  • 4 millimeters thick, unsealed, structured: approx. 11 euros
  • 4 millimeters thick, sealed, structured: approx. 15.50 euros
  • 11.5 millimeters thick, sealed, granulated: 14 euros
  • 8 millimeters thick, sealed, structured: 20 euros
  • 10.5 millimeters thick, bleached, sanded, polished: 32 euros

Cork floor tiles

Cork tiles consist exclusively and in full of solid cork. They are applied using the adhesive process. The advantage of the cork tile is that it has higher insulation and damping properties. Walking on thick cork tiles is particularly pleasant thanks to the resilient effect of the floor. As with prefabricated parquet, the price per square meter for the cork tile depends on the degree of processing and thickness.

Here are a few determined prices:

  • 4 millimeters thick, unsealed, unstructured: approx. 20 euros
  • 6 millimeters thick, sealed, structured: approx. 36 euros
  • 6 millimeters thick, sealed, structured, printed: approx. 43 euros

Cork tiles are limited in thickness to 6 millimeters as standard. In addition, cork sheets are available that can be used universally. Cork panels are available up to 40 millimeters thick and cost around 120 euros per square meter in the heaviest version. They are only offered untreated. Coloring and texture cost 10 euros per panel (approx. 0.55 m²) extra.

Cork floor mosaic

Cork mosaic consists of mats to which many small and uniform cork flakes are glued. They are laid like tile mats and then grouted. The prices for cork mosaic including glue and grouting material start at around 50 euros per square meter.

A cork floor offers the following advantages:

  • Natural material for a pleasant living atmosphere
  • Thermal insulation effect, especially pleasant when walking barefoot
  • Impact sound insulation, ideal for quick and subsequent installation
  • available in many colors and textures
  • perfect for allergy sufferers
  • Sustainable in cultivation, easy to recycle

Disadvantages of cork floors:

Cork can only be extracted to a limited extent. The natural limitation of the raw material ensures comparatively high prices. For comparison, here is the comparison of one square meter of floor covering

  • Laminate: 2-12 euros
  • PVC: 4-12 euros
  • Carpet: 5-30 euros
  • Ceramic tile: 5-30 euros
  • Cork: 30-80 euros
  • Real wood parquet: 50-200 euros

Cork is one of the high-quality floor coverings. Supplying an entire apartment with this material is a cost factor that must be carefully calculated. Here is a rough breakdown of costs (per square meter)

  • Prefabricated parquet (unsealed, unstructured): from 11 euros
  • Glue: 4.50 euros
  • Sealing: 2.50 euros
  • Notched spatula: 5 euros
  • Coating roll with handle: 10 euros

However, if the processing of the expensive material is to be left to a specialist company, the costs can be expected to double.

Cork has mechanical properties that must be taken into account when laying. Here you have to pay attention to the following:

  • Swelling in damp and wet conditions
  • Stretching when exposed to heat

Therefore, an expansion joint must be used for large areas and the cork floor must be sealed at least in the bathroom and kitchen.

What is a positive property of cork floor coverings in many areas causes major problems in other areas: The insulating effect of cork makes it unsuitable as a top layer for underfloor heating. This is especially true for the thick cork tiles. The porous structure of cork prevents heat transfer into the interior. In addition to the stretching effects described, there is also a great loss of energy here. In order to heat a room lined with cork tiles with underfloor heating, a very high heating output is required. This is not just a huge waste of expensive heating energy. The insulating effect of the cork covering can also lead to a build-up of heat in the underfloor heating.

After all, cork only has a limited compressive strength. Heavy pieces of furniture or point loads from small contact surfaces can quickly lead to damage.

For comparison, here are a few compressive strengths of floor coverings:

  • Real hornbeam parquet: 673 kg / cm²
  • Screed: 800 kg / cm²
  • Floor tile: 4000-5000 kg / cm²
  • Cork floor: 5 kg / cm²

Disadvantages of the cork floor

In summary, cork flooring has the following disadvantages:

  • Very expensive
  • organically susceptible
  • working mechanically
  • swells when wet
  • unsuitable for underfloor heating
  • Limited compressive strength

Differences in quality in cork floors

Pay attention to quality

High prices always attract providers who offer cheaper by compromising on quality. Cork is a high-priced material, but its quality can easily be checked. The following factors can be checked:

The concentration

  • 450 to 500 kg per m³ are the ideal value. This is on the packaging. Alternatively, the weight of a tile can be measured and the density calculated from its dimensions.

The mixture

  • If wood chips are visible in the cork, the volume has been increased by improper means

Thickness of the panels

  • Adhesive cork boards are at least 4 millimeters thick, cork parquet at least 11 millimeters thick.

The smell

  • Should be natural and not chemical, otherwise an inferior binder was used

The German cork industry has brought out its own logo that serves as a seal of quality. Products that have this seal of approval can be bought without hesitation.

Tips for fast readers

  • Inform about the costs
  • Seal the cork floor well in damp rooms
  • No cork floor on underfloor heating
  • Plan expansion joints for large areas
  • Pay attention to quality