A butt, or standard lap jopint is the most common joint in woodworking.
The lap joint is the most common and simple joint in woodworking. A hardwood lap joint is one in which the two pieces are joined wood to wood, with glue and fasteners, having no other mechanical means of fastening, such as pegs, tenons or biscuits. There are a variety of styles of lap joint.
Lap Joint
A lap joint, or butt joint is the simplest joint. In this joint, two pieces of hardwood meet at a right angle, with one overlapping the other, so that its end is flush with the far face of the second piece. The joint is fastened with nails or screws, driven through the face of the overlapping piece into the end of the other piece. Wood glue is typically added to create a stronger joint, and the joint is held in place with clamps until the glue dries for best results.
Half Lap Joint
A half lap joint is one in which the two ends of the joining pieces are notched, from the center of the board out to opposite edges at the thickness of the hardwood. This creates two rectangle pieces which nest into each other to create a 90-degree corner that fits snugly. Drive fasteners through each rectangle half lap, into the other to fasten them together firmly. Nails can also be driven through the upper half lap into the lower, directly into the corner.
Dado Lap Joint
A dado is a groove in a piece of wood that runs through the face from edge to edge. A dado along one end of a hardwood board is often called a rabbet. In a dado lap joint, one piece is dadoed, or rabbeted along one end. The dado will be the same width as the thickness of the material being joined to it, and the depth will be half the thickness of the material. The two pieces are joined together by fitting the end of one piece into the dado on the other. Fasteners are driven through the face of the dadoed piece, into the end of the other piece.
Shiplap
A Shiplap is very similar to a dado lap joint. In shiplap, the dado, or rabbet, is cut along the long edges of both pieces of hardwood, so that when they fit together edge to edge, they maintain the same thickness. The rabbet can be cut at any desired width, but is typically 3/4 to one inch. The depth of the rabbet should be half the thickness of the material. This lap joint is traditionally used in boat building and is common with flooring, paneling and siding.
