karmmått

karmmått is a Swedish term used in carpentry and building construction to specify the dimensions of a frame—often the jamb of a door or window. The word combines “karm,” meaning the structural frame or jamb, with “mått,” meaning measurement. It refers to a nominal size standard that helps builders ensure that framing components fit together correctly and meet structural requirements.

The concept dates back to the 19th century when Swedish builders developed a series of standard sizes based on the number of “karm” sections used in interior wall construction. These specifications were originally expressed in fractions of a meter, but over time they were adapted to a metric system for consistency with national building codes. The Swedish National Board of Housing, Building and Planning (Boverket) incorporated the karmmått into its building regulations, and the standard is now codified in the Boverkets Byggregler and in documents published by the Swedish Standards Institution (SIS).

Modern construction projects often use prefabricated framing systems that reference karmmått to guarantee seamless assembly of wall panels, doors, and windows. The standard also informs calculations related to load-bearing walls, acoustic isolation, and thermal performance. While the term has become less common in contemporary industry where overall metric dimensions are preferred, many traditional builders and architects still use karmmått when specifying custom or restoration projects. The persistence of this terminology reflects its historical importance in Swedish construction practices.