Lap joint

Lap joint

In woodworking or metal fitting, a lap joint is a technique for joining two pieces of material by overlapping them. A lap may be a full lap or half lap.

In a full lap, no material is removed from either of the members to be joined, resulting in a joint which is the combined thickness of the two members. In a half lap joint, material is removed from each 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.


Half lap

Left to right: Half lap, mitred half lap, cross lap and dovetail lap

Half lap joints are used extensively in construction 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.


  • Frame assembly in cabinet making
  • Temporary framing
  • Some applications in timber frame construction

End lap

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.

Use for:

  • Internal cabinet frames
  • Visible frames when the frame members are to be shaped.

Cross lap

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. For a Tee lap, one of the members has only one shoulder.

Use for:

  • Internal cabinet frames
  • Simple framing and bracing

Dovetail lap

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

Use for:

  • Framing applications where tension forces could pull the joint apart

Mitred half lap

This is a variation of the end lap which shows a mitre on the face of the finished work.

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

Use for:

  • Visible framing applications where a mitred corner is desired

See also

External links

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Look at other dictionaries:

  • Lap joint — Lap Lap (l[a^]p), n. [OE. lappe, AS. l[ae]ppa; akin to D. lap patch, piece, G. lappen, OHG. lappa, Dan. lap, Sw. lapp.] 1. The loose part of a coat; the lower part of a garment that plays loosely; a skirt; an apron. Chaucer. [1913 Webster] 2. An… …   The Collaborative International Dictionary of English

  • lap-joint — lap joint, a joint connecting parts of a heavy beam, formed by overlapping the ends of two timbers and bolting, riveting, or strapping them together. lap joint «LAP JOYNT», transitive verb. to make a lap joint on; overlap …   Useful english dictionary

  • lap joint — n. a joint made by lapping one piece or part over another and fastening them together: also lapped joint lap joint vt …   English World dictionary

  • lap joint — lap′ joint n. bui a joint, as between two pieces of metal or timber, in which the pieces overlap, often flush • Etymology: 1815–25 lap′ joint ed, adj …   From formal English to slang

  • lap joint — type of joint where the parts lie parallel to each other and overlap each other Источник: ГОСТ Р ИСО 17659 2009: Сварка. Термины многоязычные для сварных соединений оригинал документа …   Словарь-справочник терминов нормативно-технической документации

  • Lap joint — Lap joint. См. Соединение внахлест. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • lap joint — noun joint made by overlapping two ends and joining them together • Syn: ↑splice • Derivationally related forms: ↑splice (for: ↑splice) • Hypernyms: ↑joint * * * …   Useful english dictionary

  • lap joint — užleistinė jungtis statusas T sritis radioelektronika atitikmenys: angl. lap joint vok. Überlappung, f; Verschachtelung, f rus. соединение внахлёстку, n pranc. joint rangé, m; recouvrement, m …   Radioelektronikos terminų žodynas

  • lap joint — lap jointed, adj. 1. Also called plain lap. a joint, as between two pieces of metal or timber, in which the pieces overlap without any change in form. 2. any of various joints between two members, as timbers, in which an end or section of one is… …   Universalium

  • lap joint — noun Date: 1823 a joint made by overlapping two ends or edges and fastening them together • lap jointed adjective …   New Collegiate Dictionary

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