hanging bookshelf questions

[Justin James]

I'm in the process of converting a spare room to a study, and would like to have bookshelves hanging on the wall above the desk/countertop. My plan was to basically follow the construction methods used for kitchen cabinets: top and bottom dado'd into the sides, plywood back, and hang it all from a French cleat.

Then I got to thinking about the weight of all the boxes of books the last time I moved, and I'm reconsidering construction. First, the box design. The original plan was for boxes (probably 36" tall and 32" wide) to be made of 3/4" plywood, with a 1/2" back set in a groove. The groove would be set in 3/4" from the back, leaving space for the cleat between the back and the wall. I'll probably put a nailer on the inside opposite the cleat, out of habit as much as anything else. Faceframes of 3/4" hardwood (still debating oak vs. maple) to finish it off.

There would be several of these on the same cleat running the length of the wall, with the cleat attached with screws where it crosses the wall studs.

Any suggestions/comments/warnings?

[Peter Gavin]

I did something very similiar but I used solid wood (white oak) and used sliding dovetails to attach the shelves to the sides. Also, I didn't attach a back. The back nailer was actually again dovetailed into the sides and split horizontally so that it looks like a solid nailer in the back.

It has been loaded completely full for about 6 months and I haven't noticed any sags yet. There is a web site that you can calculate the amount of sag to expect given a certain material and weight but I don't knwo where it is. The 'sagulator"?

Peter

[Justin James]

I'm not too worried about racking (it won't) or shelf sag--I just don't want the thing to fall down, especially while I am under it! :) The Sagulator is at http://www.woodbin.com/calcs/sagulator.htm With the anticipated shelf dimensions, I should have .07" of sag; since that doesn't include the solid wood lip I'm planning on adding I should be fine.

I may be overly-concerned about this, but at the lab where I used to work, we had one wall-mounted shelving unit fall. It was . . . disconcerting . . . to come in the next morning and see my desk buried under the wreckage. In that case, it looked like the back had pulled out of the sides; it was still (mostly) mounted on the wall.

[Howard Rosenberg]

I'd still dado the shelves into the back.

I'd stick with the shelf lip/face frame idea.

The housed joints on the gables and the back enhance the rigidity and the front lip maximize it.

You should be okay with that setup regardless of load.

My 2C.
Howard

[Nancy Laird]

Justin, are you going to run the shelves all the way to the ceiling? If so, why don't you forgo the French cleat and just attach the shelves to the wall studs and ceiling joists with 3 or 3-1/2" screws. Your 32" span will span three studs if you're on 16" centers, and by attaching the boxes to the studs/joists, you can rest assured that they will NEVER fall down. We have 7 sets in our laser shop attached this way, they are 48" wide by 36", and they are loaded with woodworking magazines, books, lasering supplies, marble, granite, and sheets of acrylic (which are heavy). We're getting a little sag in a couple of the shelves (3/4" ply - no faceframes), but those things are NOT coming down any time soon. Just my .02.

Nancy

[Justin James]

I thought about running them to the ceiling so I could do just that, then remembered why that room is a "spare room." Nothing is square, level, or flat, or even close enough to pretend! Ten foot ceiling (well, in one corner--the other is about 9'10", and I'm afraid to measure the other wall). If I ran the shelves all the way up, I'd never put anything away. (Still think it would be neat though.)

I'll keep that idea in mind for the shop though--its the only room in the house that actually has an 8' ceiling. That could work well out there--thanks!

The major reason I'm a big fan of French cleats is that I usually work alone. Its a lot easier to level and shim a cleat by myself than to hang a cabinet alone--especially where I can't get a jack in place.

[Nancy Laird]

I understand your reasoning, Justin, so I'll bow to your decision. Just make sure those cleats are screwed into studs and that you have a nailer inside the cabinet opposite the cleat--and held together with glue and screws! Don't want those books falling down on your head, do we????

Nancy