Aluspuitkarkassi

Aluspuitkarkassi is a term used in Finnish construction to refer to a base formwork frame that supports the first layer of concrete during the creation of foundations, slabs, or similar elements. The word combines aluspuit, meaning base formwork, with karkassi, meaning frame or scaffold. The exact definition can vary by region and project type.

Typical versions are constructed on site from wood or metal. Wooden aluspuitkarkassi use sturdy sawn timber such as pine or spruce and are covered with plywood or other sheeting to provide a flat surface for concrete. Steel or aluminum frames are used for higher repetition or larger projects, offering greater strength and reusability. Frames are assembled to match the required plan and are supported by adjustable props or shores to ensure level, plumb, and correct alignment. After pouring and curing, the formwork is removed and reused where possible.

Design and use considerations include bearing capacity, exposure to moisture, ease of dismantling, and transport. Wooden systems are cost-effective for short runs but are more susceptible to rot and weathering; metal systems offer longer reuse but require more handling and protection against corrosion. Proper bracing and connections are essential to prevent deformation during concrete placement, and maintenance involves drying, inspection, and storage to extend life.

Etymology reflects Finnish construction terminology, with the components indicating a base formwork frame. Related concepts include formwork in general, scaffold frames, and concrete construction practices.