Bookshelf Weight and Stud Wall Bearing Strength
My concern (and maybe I am worrying too much) is the weight load on the wall. Thinking about the 9' side, assuming 8' of shelf loaded with hardcovers (just in case) and four or even 5 rows high, I could be looking at somewhere in the neighborhood of 800-1000 lbs on just that side. It is an exterior wall, most likely 2x6 16" on center. Any advice?
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One thing you may want to consider is your corners. You have a weakness in your design in this area (no support). You can add support a couple of different ways.
From contributor S:
I agree - know the specs on your hardware. Then, for what it's worth, a long time ago I read that a 3/4" plywood bookshelf needed to be supported in no less than 3' increments to withstand bowing from the load. Have always followed that rule with no issues whatsoever. Solid wood edges add stability incrementally depending on the dimensions of your edge and the type of wood.
I also agree that you might want to reconsider your corner treatment. Maybe just keep the brackets within 8" of each corner - then a simple miter and spline (or domino, or biscuit) of one shelf to the other would add enough stability. I think you could even forgo using glue if your shelves will be fixed to the brackets so that they won't pull away from each other. A much better and nicer option that gets a little pricey but would reflect well on your furniture skills, is to make corner pieces - angled across the front or shaped as right angles - that would be rabbeted on each end to rest on the matching rabbeted ends of the flanking shelves.
From the original questioner:
Thanks for the advice. Good to know that I am in fact worrying too much. I didn't think the house would collapse or anything, just didn't want her to call me back in a year saying: "Hey remember those shelves? Well now my sheetrock is cracked and here is the bill for my repairs." I will be sure to hit the studs, so I guess if they can hold the roof up (and the snow) they'll hold some books.
I might look into working an angled corner piece as was mentioned. If nothing else, just to make it look a little nicer. Thanks for that rule of thumb with "no less than 3 feet". If the measurements work out reasonably well (where the studs are located), I hope to have a bracket at each end, and every other down the length of the boards or 32". I met with her today to go over what it would take me to do it as is, and will have to get over and find the studs now and price out brackets before we really firm things up.
I also like the Idea (if I understand correctly) of a solid trim/moulding. I did this on a checkout counter, but it didn't even cross my mind on this one. I bet it would stiffen up the ply significantly, and look better than the sharp square corners. I will run it by her and see what she thinks. Probably red oak ply, so I should be able to buy or rout something fairly easily.
I know she will not load it up with the last decade's worth of Encyclopedia Britannicas, but I have never put that much weight on a wall. I guess after thinking about it, a 12' length of cabinets freighted with plates and glass is not too much different, but I wanted to bounce the idea off someone else first.
She has a lot of books, and might be interested in a large freestanding bookcase also, so we'll see.
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From contributor S:
If you decide to apply a solid shelf edge rather than edge banding, you will gain another option for detailing the corner. My proposal: whether you use a store bought or shop made profile or simple square edged stock - overlay the bottom edge of your shelves by at least 1/2" (preferably 5/8" to 3/4"). This will allow you to run one set of shelves into the corner and the opposing run of shelves into the first. At the butt, add a 1/2" ply gusset with glue and screws on the underside to overlay and support the two meeting shelves. Then apply your edge detail which will hide the gusset from the front. Your shelf edge can be butted or mitered at the corner. This makes a very strong and weight bearing corner. Of course you now need to edge all your ends too. Add at least 40% more to your labor and materials cost.
In addition to strengthening the corner however, you have also made building the corner simpler, added some visual interest to your project, hidden the ends of the shelf brackets, added a great deal of stability to your shelves, and yes, you can space your brackets further apart.
Check your corners for square. They will likely not be perfect and that will be exaggerated and you will be aggravated running 5' of shelves into 8' of shelves. A tip for dealing with the potentially not so square corners of the room is to clip off 1" or so off the back corner of the shelves going into the corner. This will clear any inevitable irregularities of the inside dry wall corner. Run your longest shelves into the corner then butt your short run into those. If you need to trim a slight angle to mate the butt edge, it will be easier handling the 4 shorter shelves.
From contributor G:
I have a house full of those shelves running 7 to 10 shelves floor to ceiling and filled solidly with very heavy books. They will cause your walls no grief if you have the standards adequately secured. I use a 2 1/2 inch drywall screw at every hole. 32 inch spacing on the standards. My shelves are 3/4 white oak, cherry, walnut and hornbeam 11 to 12 inches deep (notched around the upright standards. To join shelves I use two biscuits and use them in the overlap in the corners (this in addition to putting the first standard 16 inches or less coming out of each corner).
Each run of these shelves is finished by an end cap of the same shelving material run vertically from floor to ceiling and nailed into the ends of the shelves. (This end nailed panel serves as a support for up to 24 inches of shelf back to the nearest standard).
It is not high class cabinetry, but it houses the 10,000 plus volumes of our book collection quite well. The 10 inch shelf brackets disappear and the effect is wall to wall, ceiling to floor books without any obvious supports. Just ribbons of shelves and the endcaps at the ends of runs. You can break the runs for windows by running one shelf above and one just below the window and then run an upright cap between those shelves on either side of the window and again nail the upright cap to the shelves abutting the window on either side.
The only inconvenience, since I am too cheap to buy wides, is edge gluing all that hardwood stock up into the foot-wide shelf stock.
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