Need suggestions for "floating" shelves

[David Fagan]

I want to build some "floating" shelves in one of my rooms. They'll be going into a corner, so I can support them on two edges. I was thinking of building a torsion box type setup using either 1/4" or 1/2" plywood skins, then wrapping the edges that will show with solid wood. I was planning on lagging 3/4" x 3/4" supports on the wall, and then attaching the shelf "boxes" to the supports. These will be about 9.5" wide x 6' long. They will have to support books/magazines along the whole length. Do you guys think they will be sturdy enough, or should I use some other method.

Thanks.

[Lex Boegen]

I would make the mounting cleats larger than that, and I'd rip a 45-degree edge too (i.e., a french cleat). When it comes to torsion boxes, thicker is stronger that thinner. It's the distance between the top and bottom skins that provides the I-beam support. You could design the mating french cleat into the shelf itself, then slip it over the french cleat on the wall and the support would be invisible.

[Jamie Buxton]

That's a big load. Enough weight on the shelf just crushes the sheetrock at the bottom edge of the cleat. If you've going to fill the shelf with books and magazines, there would be little visual effect from putting tall ends on the shelf -- say ten inches tall. Now you have 10-12 inches of height to counteract the weight of the books trying to wrench the shelf off the wall. Much sturdier.