A bed frame with slats is a platform bed, as opposed to a panel bed. A platform bed supports the mattress with a series of evenly spaced slats, usually made of wood, and there is no box spring under the mattress. A panel bed is designed for use with a box spring, which provides its own support for the mattress and therefore does not need slats. If you're building a platform bed for a queen mattress, or you have an old platform bed that needs new slats, determine the number of slats you need based on the slat width. The slat spacing is generally standard. You can use a variety of wood types for the slats, but some wood species work better than others.
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Standard Slat Spacing
Slats on a standard platform bed (with no box spring) should be spaced no more than 2 1/2 inches apart. This allows for adequate air circulation under the mattress while providing sufficient support for most types of mattresses. However, some mattress warranties specify design requirements for platform beds, including slat spacing, so it's a good idea to check with the manufacturer for specific rules that apply to your mattress model. Some mattresses may need spaces smaller than 2 1/2 inches.
Calculate the Slats
Calculate the number of slats you need based on the width of the slats and the standard spacing. Slats typically are made with 1 x 3 or 1 x 4 lumber: 1 x 3s are 2 1/2 inches wide, and 1 x 4s are 3 1/2 inches wide (both are about 3/4 inch thick). A queen mattress is 80 inches long. If you space the slats no more than 2 1/2 inches apart, you need the following number of slats:
- 1 x 3: 17 slats
- 1 x 4: 14 slats.
In both cases, the spaces will be about 2 3/8 inches. This assumes you have a slat, not a space, at each end of mattress. Therefore, if you have 17 slats, there will be 16 spaces; if you have 14 slats, there will be 13 spaces.
Basic Wood Types for Slats
Most do-it-yourselfers building a platform bed for their queen mattress will go the local lumberyard or home center and pick up slats in whatever standard lumber species is available. This most likely will be an inexpensive construction grade of softwood, such as pine, larch, Douglas fir or spruce. If you choose this route, you should use 1 x 4s rather than 1x 3s (1 x 4s are stronger), and choose boards that are kiln-dried so they're less likely to warp and relatively knot-free, because knots are often weak spots. Also, pick through the stock to find straight, flat boards.
Better Wood Types for Slats
If you're building a furniture-grade bed, or if the cheap slats on your old bed have failed and you want to upgrade, you're probably in the market for hardwood slats. Bed manufacturers make slats from a variety of wood species, including beech, birch, poplar and oak, as well as many others. The properties that make good slats for a standard platform bed are the bending strength and the stiffness. Bending strength measures how much the wood can bend before it breaks. Stiffness is how much the wood resists bending. Common hardwoods that score relatively high in both categories include:
- Birch (yellow)
- Oak (red, white)
- Yellow pine.
Yellow pine is actually a softwood but scores as well as many hardwoods. Other species of pine, such as sugar, Ponderosa, and white pine, do not score as highly.
Use a Center Support
Queen beds are 60 inches wide, and no slat of any wood type will span that distance without eventually sagging in the middle. Therefore, all platform queen beds with slats should have a rigid center support running from the head to the foot of the bed. With a center support, the slats span only about 30 inches rather than 60 inches. Keep in mind that for a regular platform bed, you really don't want the slats to flex, so the stiffer the slats, the better.
There is a type of slat system called a bowed slat that uses steam-bent European birch slats mounted onto rubber bushings. This is a precisely crafted system with very specific design characteristics; in other words, don't try this at home. Stick to a stiff slat, and include a center support to give your mattress a solid foundation and to prevent sagging over time.
Philip Schmidt is author of Install Your Own Solar Panels, The Complete Guide to Treehouses, and 18 other home-related how-to books. A former carpenter, he has been a full-time writer and editor for over two decades, teaching DIYers about houses and everything we do with them.