Tongue and Groove
Tongue and groove (T&G) is a joint profile where one board edge has a protruding ridge (tongue) and the mating edge has a matching channel (groove), allowing panels to interlock for a tight, self-aligning connection without unsupported edges.
In Detail
Tongue and Groove Joints
T&G profiles are milled into the long edges (and sometimes short edges) of panels and boards. When assembled, the tongue of one piece slides into the groove of the adjacent piece, creating mechanical interlock that distributes loads between panels.
In structural applications like subflooring, T&G edges are critical because they prevent differential deflection between adjacent panels — one panel can't deflect independently and create a visible ridge or hump under finish flooring.
Common Applications
- Subflooring: T&G plywood and OSB (3/4" panels for 16" or 24" o.c. joist spacing)
- Roof decking: Exposed T&G boards in timber-frame and cathedral ceiling applications
- Wall paneling: Interior T&G pine, cedar, or hardwood accent walls
- Exterior siding: Some engineered siding products use T&G for weathertight joints
Related Terms
Edge Swell
Edge swell is the permanent expansion of panel edges — particularly OSB edges — that occurs when the panel absorbs moisture, creating raised ridges at panel joints that telegraph through roofing, flooring, and other finish materials.
Veneer Grade
Veneer grade is the quality classification of individual wood plies in plywood, ranging from A (smooth, paintable, minimal defects) to D (interior use only, knotholes up to 2-1/2" permitted), as defined by PS 1-09.
Related Materials
CDX Plywood
This is a test description for CDX plywood as we work on the technical backend of the website.
OSB (Oriented Strand Board)
Oriented strand board (OSB) is an engineered wood panel made from compressed wood strands bonded with waterproof resin. It is the most widely used structural sheathing panel in North American residential construction, offering uniform strength properties and lower cost than plywood.