Tongue and groove is also known as tongue in groove. Tongue and groove is used in conjunction with wood floorboards, sheet paneling, wainscot, and any number of other applications where a tight, solid seam is required between separate pieces.
Tongue and groove means that each piece has a tongue side and a groove side. The tongue and the groove each run the entire length of the piece. One tongue fits snugly into the groove of the adjoining board.
Advantages of Tongue and Groove Joining
- Tight join, requiring minimal amount of nailing or gluing to hold together.
- Provides microscopic seams.
- With proper coating, tongue and groove can even be water-tight.
Disadvantages of Tongue and Groove
- Can be difficult to fit the tongue into grooves, especially with boards have become swollen due to humidity.
- Tongues can easily break off, unless special care is taken.
- Difficult, if not impossible, to disassemble pieces that have been joined with tongue and groove. Tongue and groove wood floors usually cannot be disassembled without significant breakage.

