Perustasojen

Perustasojen is a Finnish term used in architecture, civil engineering and construction to denote the base-level floors or elevations of a building or structure. It refers to the lowest structural levels that connect the building to the ground and often includes foundation elements, basement slabs and other substructure spaces. In design drawings and documentation, perustasojen concept helps define a project’s reference elevations and how the building sits in relation to the site.

The word combines perustaso (base level) with the plural possessive form perustasojen, yielding a phrase that can describe multiple base levels or the base levels collectively. In practice, perustasojen may refer to actual floors such as basements or semi-basement levels, as well as to their elevations relative to a chosen datum or reference point. Designers commonly specify perustasojen korkeus (the height of the base level) at given values such as 0, -2, or -5 meters depending on the number of basement levels and site conditions.

Perustasojen is distinct from kerros, which usually denotes above-ground floors or storeys. In some projects, terminologies overlap, but perustasojen generally emphasizes the foundation and base-level part of the building rather than the progressively higher floors.

In geotechnical and site-planning contexts, perustasojen elevations are important for excavation planning, drainage, groundwater considerations and utility placement. The term is most commonly used in Finnish project documents and may be translated as “base level(s)” or “base floor(s)” in English-language descriptions. See also foundation, basement, ground floor, elevation, and datum.