When installing wall shelves, there are two key factors to keep in mind: the span capacity of the shelf material and the vertical spacing between the shelves. These decisions depend on the types of items you plan to store.
To avoid shelf sagging, it’s important to understand the span limits of different materials. The “span” refers to the distance between the supports. Stronger materials can span greater distances between supports, while weaker ones need closer supports to hold heavy objects effectively.
Vertical spacing is straightforward—space your shelves based on the height of the items you’ll store.
Span Limits
The span limit is the maximum distance you can place between shelf supports. Different materials like glass, particleboard, solid lumber, and plywood have varying span limits.
These recommendations assume the shelves will hold a full load of standard-sized hardback books:
Plywood Wall Shelves
Plywood should be at least 3/4 inch thick. Plywood comes in various thicknesses, but anything thicker than 3/4 inch usually needs to be special ordered. Thinner plywood can be laminated together to create sturdier shelves.
- For 3/4-inch plywood shelves, the maximum recommended span is 36 inches.
1 x Lumber Shelves
1 x lumber, such as 1×8, 1×10, or 1×12 boards, is roughly 3/4 inch thick, despite its nominal measurements. For shelving, select-grade lumber is best as it has fewer knots and flaws.
- For 1×10 lumber, the maximum recommended span is 24 inches.
- For 1×12 lumber, the maximum recommended span is 28 inches.
2 x Lumber Shelves
2 x dimension lumber, like 2x10s or 2x12s, actually measures about 1 1/2 inches thick. Choose select-grade lumber for stronger and more attractive shelves, as it has fewer knots compared to construction-grade lumber.
- The maximum recommended span for 2×10 lumber is 48 inches.
- The maximum recommended span for 2×12 lumber is 56 inches.
Particleboard Shelves
Particleboard is made from sawdust and wood by-products bonded with glues and resins. It comes in various thicknesses (3/8 inch, 1/2 inch, 5/8 inch, and 3/4 inch). For single-layer particleboard shelves, use at least 5/8 inch thick material.
- The maximum recommended span for 5/8-inch particleboard is 24 inches.
- The maximum recommended span for 3/4-inch particleboard is 28 inches.
Glass Shelves
The span for glass shelves depends on the type, thickness, and size of the glass. Common types are annealed and tempered glass. Tempered glass is stronger and breaks into small pieces, while annealed glass breaks into large shards. It’s best to get a weight rating from a glass supplier for accuracy.
- 1/4-inch-thick x 11-inch-wide annealed glass supported every 24 inches can hold up to 29 pounds.
- 1/4-inch-thick x 11-inch-wide tempered glass supported every 24 inches can hold up to 117 pounds.
Recommended Shelf Height Spacing
Here are guidelines for determining the clear shelf height needed based on the types of items you plan to store on your shelves:
- Paperback books: 8 inches
- Hardback books: 11 inches
- Large hardback/coffee table books/catalogs: 14 inches
- Magazines: 14 inches
- CDs: 5 inches
- DVDs (movie cases): 8 inches
Clear shelf height refers to the space measured from the top of the lower shelf to the underside of the shelf directly above it. Adjust your shelf spacing accordingly to accommodate these items comfortably.