As a woodworker, learning different joinery methods is a must. Before the advent of technology, woodworkers made sure every wood project was held together securely. One useful joinery method is the lap joint!
If you’re not familiar with the lap joint, you may also know it by another name: the overlap joint. You can use it for all kinds of materials. While commonly used in woodworking, plastic and metal projects benefit from lap joints!
The notion of a lap joint is actually quite romantic. Since they’re under “halving joints,” the notion that two halves can make a whole is a concept you can apply here! Basically, you use this joint to make two halves into one whole piece. However, aside from being a halving joint, a lap joint can also be a full one.
We can elaborate further down the article. Curious? We also cover applications, uses, benefits, and frequently asked questions! Look no further, and read our article on lap joints below:
An Introduction to Lap Joints
Lap joints or overlap joints can make two halves of any material into a whole piece. In regards to joinery, it’s one of the easiest joints to learn. You can approach this joint as a beginner! It’s easy to cut, easy to learn, and overall, easy to produce!
Lap joints can be full or half laps. Now, how do they differ?
A full lap joint is exactly as its name sounds. You don’t remove anything from the material of two work pieces. When joined together, they have a combined thickness.
Half lap joints are the opposite. You remove material from both of them! Once joined together, the thickest member makes up most of its width. The common practice is to get wood pieces of the same thicknesses. Half is removed from both of them, and then they’re joined together.
As we mentioned above, lap joints can be used for a variety of materials. When you use wood, you ideally use long-grain pieces and wood glue. Using wood is actually beneficial if you want something that resists shear forces! Usually, we know strong joints as mortise and tenon, but lap joints are on the same plane of strength. Remember this when you need something strong for your projects!
For metal projects, you overlap plate edges. While it may look useful, it’s not recommended! A single lap joint doesn’t resist bending, so it doesn’t have the structural integrity or flexibility that you’d want for your projects. However, if you just want to fit two metal cylinders into each other, it’d be good enough.
The Lap Joint and Its Applications:
Need a guide on where to use lap joints? We have a round-up! You can apply lap joints to woodworking projects like frame assemblies. You can use it for temporary framing, construction of timber frames, and tables!
The Advantages of Lap Joints
There are many reasons why you should learn to make and use a lap joint! For your convenience, we’ve rounded it up to three main reasons:
Easy to Do, Easy to Learn
Don’t let this joinery method intimidate you! Beginners can easily learn and execute the cuts needed for lap joints. If you’re a novice, you’ll learn fast enough. Halving joints in general, are easy, and you’ll be able to pull it off!
It’s a traditional joint you can learn online, upon observation, or from more expert woodworkers. It’s simple and has a lot of strength! If you’re a visually-inclined person, picture frames and mirrors work great with lap joints.
However, despite having enough strength, it’s also considered as one of the weakest traditional joints. In contrast, butt and miter joints work better with traditional glues.
Find the strength lacking? You can remedy the issue with dowels and wood glue! Get something expensive and high-quality to make the most out of your project. The right tools will get you there.
To isolate movement while using lap joints, you can incorporate other joints you know! There are ways that a lap joint can fail, so at least, you can have something to fall back on. If you have issues with alignment, strength, and durability, incorporate them for ease. However, it may fail on the aesthetics part. You have to accommodate aesthetics into it.
Let’s face it: woodworking can get expensive. You also have to factor in the time you use up investing in the material and expertise! But a lap joint doesn’t demand much from you, so you can use basic tools – and it won’t take up a lot of time either.
2 Major Lap Joint Categories
To make a lap joint work, you join together two pieces with the same material. Like we’ve mentioned before, you can use wood, metal, and even plastic! However, wood is the best choice for lap joints! It’ll have more flexibility. For the best results, join them at their ends, shins, or glue the entire bodies together. It all depends on your assemblage!
The way they become assembled, however, is best for them to withstand pressure and stress. When done correctly, the end result is more than that of a mortise and tenon joint!
Now, let’s get into the categories as a refresher before we get into more detail.
1) Full Lap Joint
- No material is removed
- Withstands a lot of stress, weight, and force
- Has the full thickness of each piece
2) Half-Lap Joint
- More common than lap joints
- Material is removed to assemble a joint
- Provides a secure bond
- It has a more even thickness
- Allows smooth transitions
Both joints can be done in different shapes: from Ls, Ts, and Xs. You can categorize them that way, too! L-shaped laps are end laps. The perpendicular positioning makes it possible to join the members’ ends.
Meanwhile, a T-shape is what we know as the half-lap. You position one wood piece onto the center and make a half-lap! The center can also be called the shin.
Next, we have the X-shape, or the cross lap. All the pieces are placed together at an angle! Typically, you place them on the shins or the center.
Proper positioning is crucial. The members are there for them to stay erect! Sometimes, you have to layer pieces one over the other to reinforce strength as much as possible. It’s similar to how log cabins are built – and those are close to nearly indestructible structures.
5 Different Types of Lap Joints
To have a better guide to lap joints, we put together a round-up for the versions you need in woodworking! You have to sift through them and find the one you need with proper strength. The project’s needs will be met adequately then. This way, you can also make sure everything is identifiable!
1) Half Laps
Remember: the positioning must be at the center. Some of the material is removed as well!
It’s best for woodworkers who need joints for transition or cabinetry! Beginners don’t need to worry – it’s easy enough to make in no time. It also provides a lot of strength for long grain wood through the surface. Racking won’t mess it up too much, so it will resist diagonal distortion. When needed, fasteners, dowels, or other reinforcements can be used.
2) End Laps
It’s a kind of lap joint that joins end to end, creating either a parallel, perpendicular, or right angle. It’s also called a pull lap or a corner lap! You will always notice this in frames – it’s probably the most common one out there.
However, if you’re using half-laps, you might know it as a half-lap splice. It’s a better choice for scarfing or shorter pieces! They have shoulders and cheeks, usually one for each piece.
Framing! Use these lap joints for internal frames or visible, shaped frames.
3) Cross Laps
The joint is in the middle of the pieces! Right angles are still made, but a wood piece may terminate by the joints itself or move through it. If ever one of the pieces terminates at the center or the shin, then you may be more familiar with it as the tee or middle lap.
For bracing and framing purposes! Use it anytime.
4) Dovetail Laps
If you cut the housing at an angle, it’s called a dovetail lap. The cross-piece resists the stem’s withdrawal! You’ll have a flashback to the times you complete a puzzle piece. Vulnerable frameworks are there for this kind of lap.
If you have any frames you deem structurally unsound, you can apply this frame! That way, the joint won’t be pulled apart by any stress or tension forces.
5) Mitred Half-Laps
It’s a lap joint with a mitred corner. The angles are there to accommodate mitered joints, but sadly, it can turn the frame weak. There’s less of a surface area, so you can’t glue as much.
Make frames with mitered joints! It’s professional, and if you use half-laps, then you can reinforce it to make it stronger. Visible framing applications are great for these joints, too!
Well, there’s little to no effort with this kind of joint! It’s one of the simplest ones out there.
First, you have to use a chisel. You also need measuring tools to measure out the depth of the notch you can make. Make sure it can accommodate the receiving piece.
Notches are typically in shapes – like a square or a rectangle. Once a notch is made, learn two terms right away: the cheek and shoulder.
The cheeks are basically the bottoms of the notch. Their depths can range from a centimeter to five inches! The notch is always parallel to the piece.
Meanwhile, the shoulder is the length of the depth to the edge of the piece. Measure out the notched floor to the top of the piece, and you’ve got yourself the shoulder!
Making notches is possible with basic woodworking and measurement tools. While accuracy is always important, the measurements are more or less forgiving. However, precise cuts are necessary if you need aesthetics!
FAQs: The Lap Joints’ Uses, Benefits & Other Questions
Here are some frequently asked questions you might have about lap joints, all answered:
When can I use a lap joint?
Any time, to be honest, as long as it applies to your project. It’s a timeless tool! Build cabins, tables, chairs, toys, and frames. The possibilities are endless.
What do you do with a flange?
A lap joint flange is used for metal. With metal lap joints, another ring to the wood piece is added for rotation.
Why should I use a lap joint?
It’s simple, useful, flexible, and best of all, very resilient! It can help wood pieces that exist in vulnerable temperature areas as well.
Should I get similar-sized pieces?
Nope! It’s not a requirement for lap joints. However, you do increase the chances of straining if one is smaller than the other – and they might not last long. That’s fine for some woodworkers and for some projects!
Lap joints are basic, simple, and easy to use and learn. With this guide, you can easily pick out the lap joints you need for your projects!
We hope we helped you out! Lap joints’ applications are versatile, so refer back to this guide if you ever feel confused.
Jason is a 40-year-old woodworker, carpenter and author who have been involved in the woodworking and woodcraft industry with 17 years of experience. He is expertise in technical aspects, woodcraft and furniture building projects.