onderwand

Onderwand is a Dutch architectural term describing the lower portion of a wall, typically the segment that lies at or below ground level and forms the interface with the building's foundation. It is distinguished from the upper portions of a wall (bovenwand) in plans and construction documents, reflecting differences in structural function and exposure.

In construction, de onderwand often corresponds to foundation walls, basement walls, plinths, or other load-bearing elements that transfer vertical loads to the footing. The materials are usually durable, such as concrete, brick, or masonry, and the assembly includes mechanisms for moisture control, insulation, and connection to the building's structural framework. Common features include damp-proofing or waterproofing membranes, thermal insulation at or near the ground, drainage considerations, and anchor or tie connections to upper floors or slabs. Openings in the onderwand are typically reinforced with lintels to carry loads above.

Variations exist depending on climate and building type; in basements, the onderwand may be partly below grade, while in ground-level walls the term may refer to the section that supports the structural roof and floors. The concept is primarily used in Dutch architectural and civil engineering contexts, and equivalent terms in other languages may describe similar lower-wall elements. The term is not universally standardized and may be substituted by more general phrases such as foundation wall or base wall in international contexts.