Lap joint

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.

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The main difference between this and the basic half lap is that the joint occurs in the middle of one or both members, rather than at the end. The two members are at right angles to each other and one member may terminate at the joint, or it may carry on beyond it. When one of the members terminates at the shin, it is often referred to as a tee lap or middle lap. In a cross lap where both members continue beyond the joint, each member has two shoulders and one cheek.

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This is a lap in which the housing has been cut at an angle which resists withdrawal of the stem from the cross-piece.

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The mitred half lap is the weakest version of the joint because of the reduced gluing surface.

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