Lap joint

A lap joint or overlap joint is a joint in which the members overlap. Lap joints can be used to join wood, plastic, or metal. A lap joint or overlap joint is a joint in which the members overlap. Lap joints can be used to join wood, plastic, or metal. A lap joint may be a full lap or half lap. In a full lap, no material is removed from either of the members that will be joined, resulting in a joint which is the combined thickness of the two members. In a half lap joint or halving joint, material is removed from both of the members so that the resulting joint is the thickness of the thickest member. Most commonly in half lap joints, the members are of the same thickness and half the thickness of each is removed. This joint, made by overlapping the edges of the plate, is not recommended for most work. The single lap has very little resistance to bending. It can be used satisfactorily for joining two cylinders that fit inside one another. Halving lap joints are used extensively in transition and cabinetry for framing. They are quick and easy to make and provide reasonable strength through good long grain to long grain gluing surface. The shoulders provide some resistance to racking (diagonal distortion). They may be reinforced with dowels or mechanical fasteners to resist twisting of the wood. Also known simply as a pull lap, it is the basic form of the lap joint and is used when joining members end to end either parallel or at right angles. When the joint forms a corner, as in a rectangular frame, the joint is often called a corner lap. This is the most common form of end lap and is used most in framing. For a half lap in which the members are parallel, the joint may be known as a half lap splice. This is a splice joint and is an alternative to scarfing when joining shorter members end to end. Both members in an end lap have one shoulder and one cheek each.