Terms of the Trade: What Is a Tongue and Groove Joint? Terms of the Trade: What Is a Tongue and Groove Joint?
The tongue and groove joint allows for two flat pieces of wood to be joined together to create a new flat surface. For the joint to work, each piece of wood needs to have a slot (the groove) along one edge and a thin ridge (the tongue) on the opposite edge. Usually this allows for a tight fit and glue is not needed.