Laastitasoitteet

Laastitasoitteet are mortar-based leveling compounds used to create a flat, smooth floor surface before installing final floor coverings. In Finnish construction terminology, the term covers both self-leveling underlayments and traditional leveling mortars. They are designed to correct irregularities, fill minor gaps, and even out substrates to meet the tolerances required by the chosen finish layer.

Composition and variants include cement-based self-leveling underlayments, which are typically polymer-modified cementitious mixes that flow to a level surface and cure with good hardness. Gypsum-based leveling compounds are used on dry, non-moisture-sensitive substrates. Some products are lime-based or contain additives to improve adhesion, flexibility, and shrinkage control. Thickness ranges vary: self-leveling products commonly cover about 2 to 20 mm per layer, while traditional leveling mortars can be applied thicker when needed.

Application and preparation involve proper substrate readiness: the surface must be clean, sound, dry, and free of contaminants. Absorbent substrates are primed with a recommended primer. Mixing follows manufacturer guidelines to achieve a uniform consistency with a workable pot life. The material is applied by pouring and screeding or by troweling, with self-leveling products spreading under gravity to reach the target thickness. After application, drying should be protected from rapid moisture loss or temperature fluctuations, and flooring installation is performed once the product has achieved sufficient hardness per the product’s instructions. Compatibility with the chosen final floor coverings and any moisture requirements should be verified for each specific laastitasoitte.