Wood joinery, as the term implies, refers to joining pieces of timber or lumber to create other structures. Crafting wood joints has its origins in antiquity—the dovetail joint, for instance, was used by ancient Egyptian sarcophagus builders—and the process remains essential to constructing or assembling many types of wood projects and fine furniture.
The hallmark of skilled woodworking is the ability to create tight wood joints, where the edges blend seamlessly, making two joined pieces look like a single piece. To successfully create most types of wood joints, you’ll need to make precise cuts. This requires correct usage of two basic woodworking tools: a jig and a fence. A jig guides cutting tools, such as saw blades or router bits, to ensure multiple precision cuts, while a fence is the rigid, straight edge on a power saw used to brace the material being cut.
If you’re serious about gaining woodworking skills, take the time to master the seven sturdy types of wood joints listed here. After all, the stronger the joints, the more long-lasting the results! You may have to practice some more than others, but once you learn them, you’ll have the necessary knowledge to tackle virtually any woodworking project.
THE MITER JOINT
A miter joint occurs when two end pieces are cut on angles and fitted together, commonly found in the corners of picture frames and the upper corners of some styles of doorway casing (trim).
For a standard 90-degree mitered corner, the two pieces are cut on opposite 45-degree angles and fitted together. When installing trim, the pieces are glued at the seam and then fastened, via nails or screws, to the framing material in the wall. When creating mitered corners for a freestanding object, such as a picture frame, the pieces are glued at the seam, and then additional finish nails or screws are used to fasten them together permanently to one another. For freestanding woodworking projects, nearly all miter joints require both gluing and the use of additional fasteners.
The word “miter” simply means “angle,” so while many types of miter joints are cut on 45-degree angles, other angles can be used as well. For example, you can create an octagonal mirror frame using eight pieces of wood cut on 22.5-degree angles.
Best for: Making outside corners on door and window trim and creating decorative frames.
Pro tip: For tight miter joints that fit snugly leaving no visible gaps, use a miter saw, a specialized power tool that allows the user to cut precise angles. Hold the piece you’re cutting firmly against the saw’s fence to keep it from moving while making the cut.
THE BUTT JOINT
Among the first types of wood joints you’re likely to encounter when installing trim in a home is the butt joint, which, true to its name, signifies two pieces of wood butted together. In a basic butt joint, the square end of one piece butts into the side or the end of the other piece. The pieces are not attached to one another where they abut, but rather are fastened by nails or screws to framing lumber in the wall (such as wall studs, which you can locate with a stud finder or without one). Butt joints are often found on window and door trim where vertical trim pieces butt into a header (horizontal trim piece at the top of the window or door) or a horizontal window sill.
A common variation on the basic butt joint is the mitered butt joint, which consists of cutting the ends of two pieces of wood (often trim pieces) on opposite angles so you can butt the mitered ends together and make them appear to be a single whole piece. For example, instead of butting square ends of baseboard pieces together, which can leave a visible joint, one end is cut on a 45-degree angle and the other end is back-cut at the same angle. An angled seam is less visible than a squared seam.
Best for: Installing trim and baseboard.
Pro tip: For tight butt joints, use a chop saw, which is designed to make precision square cuts. It’s difficult to get accurate angles with a hand saw or a circular saw.
Photo: flickr.com via Jordanhill School D&T Dept
THE LAP JOINT
Lap joints are simply types of wood joints where two pieces of wood overlap. The two most common variations are the full lap joint and the notched lap joint.
A full lap joint, in which one board overlaps another and is then fastened together with screws or nails, is often used to construct the structural frame of a home. Lapped joints are also used to reinforce other pieces of wood, such as lapping a diagonal piece of wood over vertical pickets in a gate.
Like the full lap joint, a notched lap joint is created by overlapping two pieces, but the notched lap joint adds additional strength because both pieces of wood are notched and then fitted together at the notched sections. The notch depth will vary, depending on the project.
Best for: Structural framing or to reinforce pieces of wood that would otherwise tend to sag or warp.
Pro tip: If you’re notching pieces for a lap joint, lay the pieces out and clearly mark both surfaces to be cut at the same time. This will prevent confusion about whether to cut the top or bottom side of the pieces.
THE MORTISE AND TENON JOINT
Mortise and tenon joints have been used to build hefty structures for thousands of years, and likely came about when ancient builders discovered they could create a stronger type of wood joint by tapering one end of a piece of wood and inserting it into a cavity carved in another piece of wood. The mortise is the cavity, and the tenon is the piece that fits into the mortise.
Mortise and tenon construction is common in today’s furniture making, often used to attach chair and table legs, along with other parts of the furniture. Creating a successful mortise and tenon joint is an intermediate-to-advanced craftsman skill but modern tools can make the process easier. A router can be used to cut away excess wood, leaving a square or rectangular tenon projection, and a matching mortise can be cut out with a drill press or a plunge router.
Best for: Joining perpendicular pieces, such as furniture legs.
Pro tip: Make a mortise socket slightly deeper (about 1/8”) than the length of the tenon, which will give the glue used to fasten the pieces together room to disperse.
THE DOWEL JOINT
The dowel joint is similar to the mortise and tenon in that a projection is fitted into a socket to strengthen a joint. The difference is that a dowel is a completely separate cylindrical object and both pieces of wood will need to have sockets. Many of the types of joints we’ve already discussed can be further strengthened by the addition of a dowel.
You’ll find dowel joints on woodworking items where visible screws or nails are not desirable, such as high-end cabinetry, bookcases, and custom stairways. Dowels can also create a rustic look when the dowels contrast with the wood—for example, walnut dowels in oak construction. Once crafted by hand, today’s dowels are purchased already shaped into cylinders, and the sockets for accommodating them are typically drilled with a power drill.
Best for: Wood construction where other fasteners are not desirable, such as bookcases, cabinetry, and handcrafted wood projects.
Pro tip: Glue and clamp the pieces of wood you’re joining and let the glue set overnight before drilling the socket for the dowel. This will ensure that the wood pieces won’t move when the dowel is inserted.
TONGUE AND GROOVE JOINTS
Tongue and groove joints are typically used to install materials that will lie flat, such as hardwood on floors or beadboard on walls and porch ceilings. Each board features a tongue, or ridge, running along one side and an indented groove running along the other side. Nails are inserted through the tongue, after which the grooved side of a second board is fitted over the tongue to conceal the nails. Called “blind nailing,” this results in a surface unblemished by nail heads.
While DIY tongues and grooves can be crafted along the sides of flat boards using a table saw and a shaper, today virtually all hardwood flooring and beadboard comes with tongues and grooves already cut. Your job will be to fit them together when it comes time to install.
– Best for: Hardwood flooring and beadboard installation.
Pro tip: Install tongue and groove boards tightly against one another to prevent gaps. To do, tap the boards together with a rubber mallet as you install them or, in the case of hardwood flooring, by using a hardwood flooring nailer that sets the boards snugly together and neatly inserts nails at the same time.
THE DOVETAIL JOINT
Dovetail joints are very strong and resist pulling apart through the use of wedge-shaped interlocking pieces (the wedges resemble a dove’s tail). Dovetail joints are found where the ends of two pieces of wood meet at a right angle, such as along the corners of drawer sides. The wedge-shaped assembly, which requires only glue and no other fasteners, is often a sign of quality workmanship.
One or more wedge-shaped sockets are cut into one piece of wood and corresponding “tails” are cut on the other piece of wood before the two pieces are joined with glue and clamped. Once crafted only by hand, most dovetails are cut today using a router.
Best for: Assembling the sides of drawers or wood boxes and lids.
Pro tip: If you plan to cut a lot of dovetails, invest in a dovetail jig for your router. Dovetail jigs are adjustable to let you cut sockets and tails that fit together perfectly.
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