Microcement and Lavasteen Seamless Floor are both seamless finishes applied in thin layers. As a result, they adopt the characteristics of the substrate. A stable, level and dry base is therefore essential. When the subfloor moves or is uneven, this can lead to cracks or damage.

Note: the substrate must always be clean, dust-free, stable and dry before you begin with the finish.

Anhydrite screeds — the most suitable subfloor

An anhydrite screed (gypsum-based poured floor) is often regarded as the best substrate for microcement and Lavasteen Seamless Floor. This floor is perfectly level, shrinks minimally and has excellent thermal conductivity, making it ideal in combination with underfloor heating.

Thanks to its stable structure, anhydrite forms a highly reliable base. However, it is important that the floor is completely dry before you begin with the finish: the moisture content may be a maximum of 0.5%.

Cement screeds as substrate

A cement screed is a commonly used substrate for microcement and Lavasteen Seamless Floor. This screed consists of sand, cement and water and forms a solid base. After sufficient drying time, it is a stable choice, provided it is finished level and crack-free.

The moisture content of a cement screed must be lower than 2% before you begin with the finish. Any unevenness should be levelled beforehand, so that the final finish remains tight and durable.

Other suitable substrates

Besides anhydrite and cement screeds, other subfloors can also be suitable:

• Concrete floor: perfectly suitable, provided fully cured.
• Tiles: possible after levelling or pre-treatment with primer.
• Gypsum fibre boards or fermacell: provided properly screwed down and without movement.
• Wood: only if stable and dimensionally stable. Movement can cause cracks.

The exact build-up differs per material, but the basic steps are comparable:

Microcement build-up

1. Primer: ensures adhesion to the substrate.
2. Microcement base layer: applied with a trowel for strength.
3. Microcement finish layer: provides the final appearance (colour, texture).
4. PU topcoat: protects against water, scratches and stains.

Lavasteen Seamless Floor build-up

1. Primer: depending on the substrate (with tiles often epoxy primer).
2. Lavasteen Seamless Floor layer: consisting of epoxy resin and lava stone aggregate, applied with a trowel.
3. Sanding: after curing to level the texture.
4. PU topcoat: provides protection, prevents yellowing and gives an anti-slip effect.

• Drying time: a cement screed or anhydrite screed must be fully cured and dried (minimum 4–6 weeks). Measurement is essential.
• Moisture content: excessive moisture in the substrate causes adhesion problems.
• Stability: no movement or working in the substrate; this prevents cracking.
• Pre-treatment: always level irregularities for a smooth final result.