Pohjarakenne

Pohjarakenne (foundation structure) is the system of elements that transfers the loads from a building to the ground and provides a stable base for the construction. Its purpose is to ensure safety, durability and appropriate settlement, while also protecting the structure from moisture and frost effects. The design considers bearing capacity of the soil, horizontal forces, temperature changes and local climate.

The core components of pohjarakenne include foundations, load-bearing elements and the subfloor. Common foundation types are laattaperustus (slab foundation), sokkeliperustus or perustuksen seinä (foundation wall/plinth), and paalutus (pile foundation) used on weak or deep soils. In buildings with basements or crawl spaces, the alapohja and related waterproofing, drainage and insulation arrangements are part of the pohjarakenne. Materials typically used are concrete (in situ or precast), reinforced concrete, and in some cases timber or steel in specific constructions.

Design and planning rely on geotechnical information and standards. Key considerations are bearing capacity and settlement control, frost protection, moisture management, and drainage around the foundation. The interaction between soil and structure governs layout, depth of foundations, reinforcement details, and possible use of protective layers or insulation. Climate conditions, groundwater level and soil type influence choice of foundation type and detailing.

Construction and maintenance address proper excavation, compaction, waterproofing, and drainage to prevent moisture ingress and uneven settlement. Problems such as excessive settlement, cracks, or frost-related damage often point to issues in the pohjarakenne or its interaction with the soil, requiring assessment and potentially redesign or remediation.