pohjatyö

Pohjatyö, literally "base work," is a term used in Finnish construction and civil engineering to describe the preparatory works that prepare a site for the main construction. The aim is to create a stable, well-draining, and accessible foundation platform for the structure, and to address any geotechnical or environmental constraints before building begins.

Typical pohjatyö activities include clearing and stripping topsoil, grading and levelling, and excavation to the depths required by the foundation design. It also includes geotechnical investigations, soil testing, and analysis that inform the choice of foundation type. Earthworks such as compaction of soils, stabilization of weak layers, and the installation of drainage and moisture management systems are common. Preparation of trenches for utilities, installation of geotechnical layers (geotextiles, drainage pipes) and the setup of formwork or temporary supports for foundations may also be included. The objective is to achieve adequate bearing capacity, controlled settlement, and a dry, stable subgrade for construction.

Project design and local conditions determine the exact scope of pohjatyö. It is typically carried out early in the construction sequence, after site clearance and access is established, and may be defined as a separate contract package with its own cost and schedule. Permitting, coordination with other trades, and quality control such as compaction tests are important components.

Climate and ground conditions influence pohjatyön approach. In cold climates, frost action is a key consideration, leading to frost protection measures or deeper foundations, such as piles, or frost-protected shallow foundations. Groundwater management may also shape the methods chosen for drainage and subgrade treatment.