The shelf-maker's complete guide
However simple a woodworking project may seem, it pays to plan ahead. Shelving is no exception. Any board supported at two points qualifies as a shelf, but you quickly run into questions: Which material and span dimensions work best? What supports should you use? What choices do you have for making the shelf look good and match its surroundings?
To steer you through successful shelfmaking, we put together this guide. You'll find a chart covering 19 material and edging choices at five possible spans, 11 adjustable-shelf hardware possibilities, five options for placing fixed shelves inside a cabinet, pointers on attaching supports for wall-mounted shelves, and information about glass shelves. Whether you plan to build a formal bookcase for the living room or a place to store paint cans in the garage, you should find the answers to your questions.
Consider width, height, and spacing
Although shelves might hold a variety of objects over the years, tailor the dimensions to suit the first purpose you have in mind. To allow for spacing changes, use standards and brackets or shelf pins and a series of evenly spaced holes.
Shelf depth, however, is a one-time choice. It typically depends on what you intend to store or display. Measure the objects that you want the shelves to hold, whether it's a TV, audio equipment, or small figurines. Take a look at the handy chart below for the spaces that a few common items require.
For the height of your shelves, make sure they are within reach of the people who will use them. In general terms, a convenient maximum shelf height for adults is 68" above the floor; for teen-agers, 61"; for middle-schoolers, 55"; for kindergartners through third-graders, 51"; and for preschoolers, 48".
If you plan to use the shelves for electronic components, allow extra space for wires and cords, and provide holes to run cords between shelves or to a wall outlet. An electrical plug requires a hole at least 11⁄4 " in diameter.
The front edge of the shelf says a lot about your work
Let's start our materials discussion with the subject of edging. As you'll see later, solid wood glued to the full length of a shelf's front edge adds a great deal of strength. It's also essential for appearance's sake when you use plywood. And, edging made wide enough to extend below a 3⁄4 " shelf adds visual weight, which lends a solid, sturdy feel to large bookcases.
If you choose to apply edging, use 3⁄4 " stock cut to an appropriate width. The wider the edging, the more strength you add. Rely on a simple butt joint and yellow glue to secure the edging to the shelf. Also make sure the edging is slightly proud of the shelf's top face when you clamp it up. After the glue dries, trim the edging perfectly flush with the top face by using a flush-trim bit in a handheld router. See "How to flush-trim edging in a flash" at the end of this article for a simple jig that helps you complete this task without damaging the shelf surface.
Choose a tough-enough shelving material
Almost any form of sheet goods or solid lumber can serve as a shelf, given enough support points. However, the choice of material becomes all-important when you support a shelf only at the ends. To evaulate differences in strength, we performed a test. See the photo above.
To give our test materials a serious workout, we loaded each 11"-wide shelf with a full set of encylopedias—that's 64 pounds of books. We left the weight in place for half an hour, and then measured the deflection at the centerpoint. Of course, photographs or lightweight collectibles would place only a fraction of this load on your shelves. But it's a good idea to build in extra strength, just in case future usage requires it.
We tested 10 of the materials in two ways: with and without a 3⁄4 ×11⁄4 " edging glued onto the front of the shelf. We used oak, pine, and poplar for edging, matching the choice to the shelf and its most likely setting. In many cases, edging reduced sag by half or more. (The wheat-stalk fiber shelving comes from the factory with a bullnose profile that's not adaptable to front edging.) We used the same shelves at each span to avoid any variations in quality, cutting them shorter for each round of the test.
We didn't include all of the options, of course. If you add a second edging at the back of any shelf or a stiffener on the bottom, you'll beef it up even more.
Overall, 3⁄4 ″ Baltic birch with poplar edging outperformed all of the others, even the solid woods; it refused to sag over a 42" span. The main disadvantage of Baltic birch is availability. You're more likely to find it at a specialty woodworker's store or lumberyard than at a home center.
Somewhat surprisingly, edged pine beat out edged oak as the next one to achieve a zero-sag rating, that coming at 36" However, oak performed better than pine in the unedged categories.
Edged or not, none of the tested materials gave satisfactory results over a 48" span. If you need shelves of that length to hold books or other heavy objects, laminate two 3⁄4 " pieces together to make a 11⁄2 "-thick shelf. At 42", the solid woods with edging sagged approximately 4⁄64 " (1⁄16 ") at the centerpoint, which is visually acceptable. (The eye will notice a sag of roughly 1⁄32 " per running foot.) Consider, however, that a permanent installation probably would sag more over time.
When we tested our shelves at 36", often considered the maximum span for unedged material, sagging remained a problem for most of our shelves. Edged pine remained flat, however, and solid oak, both edged and plain, stayed within acceptable limits.
Edged oak plywood and edged medium-density fiberboard (MDF) become feasible choices at 30". By the time we shortened the span to 24", the notable entries were the ones that still failed to stay flat: particleboard, oriented-strand board, and wheat stalk board.
For a light, bright look, try glass shelves
Some display cabinets are more attractive with glass shelves rather than wood. See-through shelving creates a light, airy look and focuses attention on the objects on display. Glass shelving is easily supported with shelf pins or lightweight standards and snap-in brackets. If you consider glass, here's what you need to know about strength and profile options.
Build in muscle with fixed shelves
When you're quite sure about shelf spacing and don't expect to change it to suit different items, you might choose to build a cabinet with fixed shelves. Such shelves not only give the shelving unit a well-built look, but also add strength and stability.
Select among the options shown in these drawings when you build a cabinet with fixed shelves. Make your choice based on the style of the piece itself or to match surrounding furniture.
The key to any of these fixed-shelf methods is to make certain that the supporting dadoes at either end of a shelf match perfectly. To do this, locate them exactly the same distance from the bottom of the cabinet side, and perpendicular to the edges. Avoid butt joints, in which nails, screws, or biscuits provide all of the support. It's worth the effort to cut dadoes, which give much more support over time. For less formal work, place a simple cleat under each end of the shelf. This approach works best when the cabinet side is made of plywood or another manufactured material, so you don't have to be concerned with the screws restraining its movement. Fasten the shelves to the cleats with screws driven from below.
Make sure to provide all the support needed
The array of shelf pins shown belowrepresents the tip of the iceberg when it comes to supporting the ends of adjustable shelves. We picked some of our favorites for applications from utilitarian to elegant. If you plan to cover the wall of an unfinished basement with shelves, choose the ones that cost the least. For small projects, the price differences are less important, and you should use whatever style seems appropriate.
Note that some brass pins come with brass sleeves for the pinhole. Sleeves might seem like a small detail, but they lend a much more finished look to your project. They hide the exposed plies if you're drilling into plywood, they keep the pins from pressing into the lower side of the hole, and a classy circle of brass shows at the surface.
Metal standards designed for clips mount on the surface of the cabinet side. To add a quality look to your installation, cut a shallow groove for each standard to sit in.
Tailor wall-mounted shelves to hold anything
Sometimes you'll want to place shelves on a wall instead of inside a cabinet. This approach can speed construction, save floor space, or allow for the storage of lumber or other long items.
Wall-mounting makes it easy to increase the number of support points and increase the strength of the shelf. For shelving designed to hold lumber, paint cans, or other heavy materials, it's wise to place several brackets under each shelf, each one attached to a wall stud with the appropriate screws or nails. As a rule, use #12×21⁄2 " or longer screws for guaranteed strength. Check the bracket load ratings to calculate the number of brackets needed for your particular situation.
Slotted metal standards and brackets, such as those shown in the photo below left, offer flexibility in shelf number and spacing. The double-slot design increases side-to-side stability.
Install larger brackets, such as the one in the photo below right, in a permanent location for truly big jobs. For example, a set of these brackets will support a lot of lumber in your workshop.
How to flush-trim edging in a flash
After making a pair of Shelf-Edging Jigs, clamp them at the edge of your workbench. Next, clamp two edged shelves as shown, with their top faces against the jigs, to provide support for your router base. Install a 1⁄2 " flush trim bit in your router, and rout along one shelf, then the other to make the edging flush with the shelf surface.
When you use a solid-wood shelf, or apply wood edging to sheet goods, you have a wide range of profile possibilities. A simple round-over softens the appearance of the shelf, and a chamfer adds a bit of visual interest.
For elegant or classical projects, use an edge-forming router bit that suits your design. Use a series of light passes on your router table to shape the profile after applying and flush-trimming the edge.
For a quicker way to dress up the front edge of a shelf made with plywood or other sheet goods, simply attach flexible, pre-glued wood or melamine veneer. See the photos below for the correct procedure. Visit a home center for this type of veneer, which adds no strength to the shelf, but quickly covers a raw, unattractive material edge.