Building bookshelves.

apoemSeptember 28, 2005

I am going to cross post this on several forums. So please forgive me if you read this again. I'm looking at building some bookshelves of sorts. They would be boards (sanded and stained) and laid on those brackets (?). I hope that makes sense. I know that some people here have built bookshelves. I am hoping they will chime in and tell me how they keep them from sagging.

My questions are this:

How thick does my wood need to be to prevent sagging? And/Or how far apart do the brackets supporting the wood need to be to keep the shelves from sagging and holding the weight?

I recently saw this information - sunset magazine? Better homes and garden? I don't know and can't remember. I've searched frantically for it. Can anyone help?


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Hi Ginger,

I have put up tons of these shelves in the past. I usually put the strips into studs if I can find them. The studs are unevenly spaced and hard to find in my house now (old house), but I think usually they are about 18" -24" apart?? Make sure you anchor them really well - if you don't have a stud where you need it, use a molly bolt or other anchor.

    Bookmark   September 28, 2005 at 6:54AM
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I did a big bookcase project using those metal standards you bolt to the wall.

you can go to the Sagulator to see about width between brackets based on what you expect to put on the shelves.

But what if you are stuck w/ a bigger span than the Sagulator tells you will work? Or if you want to use plywood or pine instead of some expensive hardwood?

Remember that attaching a second board perpendicular to the front (like a lip, but on the bottom) of the shelf will strengthen it quite a bit--that's not reflected in the Sagulator's calculations.

Here's how it works: you cut your 3/4-inch-thick plywood to the length you want, and to the depth you want minus 3/4 inches. Then you get a narrow piece of wood--maybe a 1x2--and cut it to the same length as the shelf. You lay the 1x2 against the front edge, so it points down. You apply a solid smear of wood glue between them, and you nail it in place. (clamp or strap it if you can to improve the glue bond).

Maybe you can use a 1x1, which would probably be the same width as your shelf itself, but it wouldn't add as much strength as a 1x2.

Sometimes this reinforcing wood is attached to the UNDERSIDE of the shelf right at the front; again, it's glued and perhaps screwed (since the screw head won't be visible), to keep it very snug against the shelf.

Because this board is perpendicular to the shelf, it'll keep it from sagging (think about iti--ever tried to bend a 1x2 sideways along the wide face?)

You can often reinforce w/ a strip of L-angle metal; it needs to be toward the front and it isn't as attractive as a strip of wood. Stronger, maybe but not as pretty. You can use something a bit smaller than you might need if you use wood, which would mean it impinges on your storage space less..

If you're worried about your ability to clamp or strap the wood to get a good blue bond, you could use the metal L-angles, and then on the front of the L-angle, attach a strip of lattice.

One advantage of attaching that wood to the front of the shelf is that it will cover the raw cut edge of the plywood.

But if you choose the L-angle idea, you can get the iron-on edge banding to finish the fronts. They make a snifty tool to trim the edges of the edgebanding. That's what I did, and the shelves look great.

Plywood is the most economical way to get shelves the side you want. Trying to buy boards the exact width is more expensive than paying the lumber yard to cut the wood. I personally would avoid Home Depot bcs in my area, they won't promise to cut to exact size; I go to a lumber yard that will.

Also, I've had people tell me this, and then tell me it wasn't true: When you have your plywood cut to size, be sure the surface grain of the top layer of plywood is running the LONG way on the shelf. NOT the short way; it'll bow more easily that way. Maybe it's not true on the 3/4 plywood, but I've seen this be a problem on 1/2-inch plywood, and I wouldn't take a chance on any other width.

Another thought: remember that those brackets themselves take up space from the shelf below, so that front drop-down lip won't affect THAT much of your storage space. And, you might not want to have that many of those brackets across the span, just because they get in the way. So putting one on every stud might be a royal pain.

I know for our bookshelves, we went w/ the outside dimension we could possibly get.

OH, and to make it so the shelves would touch the wall between the standards, I cut out a notch where the standards would go. Next time, I'll get a hole saw for my drill and cut out a semi-circle at that spot; it'll be much easier. The 90-degree turns were a PITA.

Feel free to ask me any more questions, either here on this thread or by e-mail.

Here is a link that might be useful: Sagulator

    Bookmark   September 28, 2005 at 11:13AM
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Try the websites for This Old HOuse, the magazine and the PBS show. I know I saw the guidelines for the thickness of wood shelves in one of their magazines.

    Bookmark   September 28, 2005 at 12:20PM
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