onderlatten

Onderlatten are horizontal wooden battens used in Dutch construction to form a support framework beneath another layer. The term literally means “under-slats,” and the battens are typically installed to create a stable base, distribute loads, and allow for ventilation and moisture management between layers.

In traditional wall construction, onderlatten can function as the lower part of a lath-and-plaster system. They provide a base for attaching the laths and help distribute plaster more evenly, while creating space for air circulation to reduce moisture buildup. In roofing and other cladding applications, onderlatten may serve as a foundational layer beneath higher battens or directly under roof coverings to anchor and align subsequent materials. The exact role and terminology can vary regionally and by construction method.

Materials commonly used for onderlatten are timber species such as pine or spruce, chosen for their workability and availability. Modern practices may employ engineered wood or metal battens in places where higher strength or durability is required. Dimensions and spacing are determined by local building codes, the specific load, and the function of the layer being supported. Typical considerations include ensuring straight, dry timber, properly aligned fastening, and adequate clearance for ventilation.

Installation involves attaching onderlatten securely to the underlying structure (such as studs or rafters) with corrosion-resistant fasteners, maintaining consistent spacing according to the intended layer, and ensuring compatibility with adjacent materials. Regular inspection for rot, insect damage, and warping is advised, with replacement of affected battens as needed to preserve structural integrity.

See also: latten, lath and plaster, roofing battens, floor battens.