tongueside

Tongueside is a carpentry term referring to the edge of a board that carries the protruding tongue in a tongue-and-groove joint. The opposite edge is the groove side, which contains a channel designed to receive the tongue. When boards are joined, the tongueside provides alignment and helps create a smooth, continuous surface across adjacent pieces.

The tongue is typically a thin projection milled along the board’s long edge. The size of the tongue and the corresponding groove varies by product and manufacturer, but they are designed to fit tightly enough to resist separation while allowing for small movements due to humidity and temperature. Tonguesides are used on many common materials, including solid wood, engineered wood, and some laminates.

Applications for tongueside joints include flooring, wall and ceiling panels, siding, and cabinetry. The joint is valued for its self-aligning properties and its ability to create a stable, flat face. In construction and finishing, proper milling accuracy, finishing, and installation practices are important to ensure a seamless appearance and long-term performance.

Installation considerations include allowing for wood movement, maintaining proper expansion gaps at ends, and choosing appropriate fasteners or adhesives. The tongueside should be oriented so the joint remains secure through environmental changes, with attention paid to moisture exposure and finish compatibility. While arthitectural and historical uses vary, tongue-and-groove assemblies commonly rely on the tongueside as a key element in achieving a flush, durable surface.

See also: Tongue-and-groove joint, Flooring, Paneling.