Lap joint or overlap joint is one of the common type of joint frequently used in wood construction. It may be full or half lap. When constructing a full lap joint, no material is removed from either of the piece of wood that will be joined and in half lap, material is removed from both work pieces so that the thickness of joint will be equal with remaining part. Lap joints can be used to join wood, plastic, or metal. In addition, lap joint in woodwork construction are used for temporary framing, tabling, frame assembly in cabinet making and etc.

There are different types of lap joint used during construction. However, lap joint are selected due to the type of projects and the thickness or strength needed for a particularly job. Moreover, lap joint uses reinforcement such as, dowel or mechanical fasteners to add to their strength.

Types of Lap Joint

Halving laps

Halving lap joints are easy and quick to make. This type of lap joint provide strength at the long grain to the long grain gluing surface. It is used in cabinetry for framing and transition. Besides, halving laps have the ability to withstand racking, and may be reinforced with mechanical fastener or dowels to add to the strength in order to withstand twisting.

Fig 1: Halvin Lap joint

End lap

End lap is also called pull lap and it is often called a corner lap when the joint forms a corner, that is, a rectangular frame. This type of lap is used when joining work piece end to end either perpendicular or parallel. In addition, end lap is used most in framing and it is the most common form. Half joint which are members of parallel, May be known as a half Lap splice.

Fig 2: End Lap joint

Cross lap

Cross lap and half lap are similar to each other, their difference is that the joint occurs in the middle of both work piece, instead, at the end. The two pieces meet at right angles and one of the piece terminate at the joint or carry on beyond it. The joint is said to be tee lap or middle lap when one of the work piece terminates at the shin. Cross lap is used for simple framing and bracing.

Fig 3: Cross Lap Joint

Dovetail lap

In this type of lap the housing has been cut at right angle. Dovetail lap have uses of framing where tension forces could pull the joint apart. It has the ability to withstand withdrawal of the stem from the cross-piece.

Fig 4: Dovetail Lap joint

Mitred half lap

Mitred half joint is classified as the weakest lap joint due to it reduced gluing surface. It is on visible framing application where a mitred corner is desired.

Fig 5: mitred half lap