# Book shelves - stiff enough?



## dgaddis1 (Jul 5, 2017)

Hello everyone. I'm new to the forum, and fairly new with woodworking as well. I have no aspirations to build fine furniture, but I do want to be able to build simple book shelves, built-ins, cabinets, etc.

I'm still learning the lingo too...so correct me if I'm wrong somewhere haha.

So, current project - book shelves for the wife. I've started building a set of shelves, approximately 5ft tall, 4ft wide, and 1ft deep. My question is :: will my shelves be stiff enough so they don't bow a noticeable amount. The shelves are 48" long, 12" deep. That's big I know. If I *need* to put a divider down the center I will, but I'd rather not if there are other ways to stiffen the shelves.

The shelves and sides are made of 3/4" plywood, and there will be a 2x1 (nominal) red oak face frame. The face frame is attached with pocket screws. The shelves are non-adjustable, they'll sit in 1/8" deep dados I routed into the sides, and they'll be secured with pocket screws as well. The bottom shelf will essentially sit on a base frame, so it's fully supported and I know it won't budge. The other shelves will have the face frame on the front for added stiffness. 

Should I add another piece of 2x1 along the rear underside of each shelf as well? The shelves backing will be 1/4" ply that's nailed in with finishing nails, it's not really a load bearing piece.

I recently finished this little record player stand, the shelves will be a larger version. That's the plan at least.

Appreciate any advice/tips/etc!


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## Steve Neul (Sep 2, 2011)

You shouldn't make a shelf longer than 30" without a center support or a wide piece of hardwood on the edge like what you have pictured. Even with little or no weight on a long shelf it will sag without some kind of support.


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## Brian(J) (Feb 22, 2016)

dgaddis1 said:


> Hello everyone. I'm new to the forum, and fairly new with woodworking as well. I have no aspirations to build fine furniture, but I do want to be able to build simple book shelves, built-ins, cabinets, etc.
> 
> I'm still learning the lingo too...so correct me if I'm wrong somewhere haha.
> 
> ...


Plywood is quite bendy. Solid Oak shelves might be OK but not plywood. Adding something, and angle iron with the leg up behind the shelf is a possibility, will be required.


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## David_Siebert (Nov 15, 2016)

Steve is bang-on. A hardwood 1x2 glued on front bead, with maybe a 1x2 also glued, flat behind the one on the front edge should be more than enough unless you're going to put something like auto parts on them. 

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## GeorgeC (Jul 30, 2008)

Steve Neul said:


> You shouldn't make a shelf longer than 30" without a center support or a wide piece of hardwood on the edge like what you have pictured. Even with little or no weight on a long shelf it will sag without some kind of support.


\
I am not sure just what you said. Did you say what he pictured with the wide board on front is OK? or not OKI?

George


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## Steve Neul (Sep 2, 2011)

GeorgeC said:


> \
> I am not sure just what you said. Did you say what he pictured with the wide board on front is OK? or not OKI?
> 
> George


In the picture there is a piece of solid oak around 2" wide on the edge of the shelf. If there were such a piece of wood on a 4' long shelf that should prevent it from sagging unless someone put something unusually heavy on it so I would say OK.


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## dgaddis1 (Jul 5, 2017)

David_Siebert said:


> Steve is bang-on. A hardwood 1x2 glued on front bead, with maybe a 1x2 also glued, flat behind the one on the front edge should be more than enough unless you're going to put something like auto parts on them.
> 
> Sent from my SAMSUNG-SM-N900A using Tapatalk


What do you think about this? This is a cross-sectional view of a shelf. 1x2's are red, 3/4" ply shelf is white.

1x2 along the front edge as part of the face frame, and an additional 1x2 under the back edge for additional stiffening. The 1x2's would be both glued and pocket screwed to the ply.


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## David_Siebert (Nov 15, 2016)

Dgaddis1 solution is stronger still if you have that inch to give in the back do it. 

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## Leo G (Oct 16, 2006)

Also if you are using plywood make sure to orientate the grain to go with the length of the shelf. The way you have it in the small bookcase shown in the picture the grain is going against the length and will be more prone to sag. (no worries cause it's glued to a face frame)


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## dgaddis1 (Jul 5, 2017)

Leo G said:


> Also if you are using plywood make sure to orientate the grain to go with the length of the shelf. The way you have it in the small bookcase shown in the picture the grain is going against the length and will be more prone to sag. (no worries cause it's glued to a face frame)


Crap, didn't even think of that, and I've already cut the shelves. Does it really matter with plywood? Does every ply have the grain oriented the same direction?


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## dgaddis1 (Jul 5, 2017)

Well...why do when you can overdo, right? Decided to change the design a bit. Going to shorten the shelves to 40", but double them up with a divider in the middle (so effectively 80" long shelves with a support at the mid point), and still stiffen with 1x2s on the front edge and under the back edge of each shelf.

Stiffer shelves, no worries of sag, more shelf space, and I won't have to build another to house all the wife's books. This one (paired with the other shelves we already have) should cover us and still have room to grow.


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## dwcon1431 (Jun 16, 2017)

dgaddis1 said:


> Well...why do when you can overdo, right? Decided to change the design a bit. Going to shorten the shelves to 40", but double them up with a divider in the middle (so effectively 80" long shelves with a support at the mid point), and still stiffen with 1x2s on the front edge and under the back edge of each shelf.
> 
> Stiffer shelves, no worries of sag, more shelf space, and I won't have to build another to house all the wife's books. This one (paired with the other shelves we already have) should cover us and still have room to grow.


Regardless of how you build it, you're learning what works and what doesn't work. I started forty years ago when I didn't have the option of social media to find solutions. In time, I learned to rely on experts like Norm Abrams for advice. Comparatively, you are years ahead of where I was. Congratulations to you for your efforts! 

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## Terry Q (Jul 28, 2016)

If you are proposing to make an 80 inch long cabinet, 60 inches tall I suggest that if you ever want to move the bookcases that you make two 40 inch wide cabinets and screw them together. You can screw on a top on that bridges both cases making appear as one.


Enjoy yourself, life is short


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## FrankC (Aug 24, 2012)

Just enter your shelf dimensions into this calculator and go from there:

http://www.woodbin.com/calcs/sagulator/


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## mmwood_1 (Oct 24, 2007)

You can make long shelves like that without a center vertical or a 'stiffener', but you need to use solid wood and it needs to be 7/8" -1" thick. I've done some 42"- 45", one for storing LPs and they do not sag.


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## selfdef2k (11 mo ago)

Would choosing a stiffer wood help as well?
To my understanding there are species that are twice as stiff, so they should sag half as much (or at least less) for the same load?
Hickory seems to be stiff in what I see described online. ( Do not have direct experience, so offering this up as a suggestion for others to explain).


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