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Specing the plywood for bookshelves

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Forum topic by simonov posted 12-20-2018 07:36 PM 539 views 0 times favorited 6 replies Add to Favorites Watch
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simonov

63 posts in 925 days


12-20-2018 07:36 PM

I need to build some bookshelves for my home. I had some very nice ones made for my previous home:

These are made out of 3/4 inch hardwood veneer plywood with matching hardwood face frames. I have made some similar bookshelves with birch plywood and pine for the office here:

One thing I’ve noticed working with 3/4 inch plywood is it is heavy! The bookshelves I need to make for my house will be 60 inches tall by almost 48 inches wide, which is pretty big. If they were to sit on the floor up against the wall there would be no problem, but mine will hang from the wall, on French cleats. A bookcase that large made from 3/4 inch plywood, plus the books, seems like a lot of weight to hang from the wall.

So I was thinking about using 1/2 inch plywood, but I’m not sure whether it will strong enough to support the weight of the books. The rear and side walls will be dadoed to accept the shelves and of course the face frame will support them in the front. The face frame will also disguise the true thickness of the plywood.

Does anyone have any experience using 1/2 inch plywood for a project like this?

-- Nunc est bibendum.


6 replies so far

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ocean

164 posts in 1253 days


#1 posted 12-20-2018 08:42 PM

I would stay with the 3/4 ply to get proper support. Also being 48” wide you will need all the support you can get. Try using two or even three cleats on the back. The cleats should also be located behind where the shelves are located. I’m assuming the back is only a thin 1/4 veneer ply or less. If you need to get an idea of weight, stack 12” of some average books you have and weight them and multiply by total inches of shelves. You will be blown away at the weight. Stay with 3/4 ply.

-- Bob, FL Keys

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PPK

1433 posts in 1229 days


#2 posted 12-20-2018 09:33 PM



I would stay with the 3/4 ply to get proper support. Also being 48” wide you will need all the support you can get. Try using two or even three cleats on the back. The cleats should also be located behind where the shelves are located. I m assuming the back is only a thin 1/4 veneer ply or less. If you need to get an idea of weight, stack 12” of some average books you have and weight them and multiply by total inches of shelves. You will be blown away at the weight. Stay with 3/4 ply.

- ocean

+1

1/2” plywood isn’t gonna be a good idea. I also agree with the multiple cleats. I’d be more wary about your walls bowing with that much weight hanging off them. 2×4 or 2×6 walls?
Also, I use 1/2” backs on my cabinets. Works much better than 1/4” backs, and is often cheaper, believe it or not…

-- Pete

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bondogaposis

5453 posts in 2771 days


#3 posted 12-20-2018 09:49 PM

Sorry, but I would not hang that much weight from a wall. Build a base cabinet and set it on that. Forty eight inches is a pretty long span for 3/4 plywood and unless you reinforce them with sold wood, they are going to sag.
No way 1/2” plywood is going to work.

-- Bondo Gaposis

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Phil32

579 posts in 323 days


#4 posted 12-20-2018 11:37 PM

I recently made a bookcase for my wife’s cookbooks – it is 9 feet long (wide), but the span of the shelves is only 28 inches. The shelves are now packed solid with books, with books on books – with no sag. The bookcase rests on the floor. The shelves are dado’d into the upright end panels, but the intervening uprights are cut, providing full support to the shelf. It is all 3/4 inch stock.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

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Kazooman

1325 posts in 2372 days


#5 posted 12-21-2018 12:00 AM

As far as the shelves themselves, you can use the “Sagulator” to get an idea about what to expect from the load.

https://www.finewoodworking.com/2007/01/05/engineer-shelves-with-the-sagulator

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

The crosspieces from the face frame can add a lot of stiffness to the shelves as can a matching cleat along the back (for fixed shelves).

However, I agree that the real issue is the sheer weight of the unit and how well you can suspend it on the wall. The cabinet portion of your French cleats would be anchored either into the edges of the vertical plywood section (not a strong base for screws) or into whatever you choose as the back panel and that is likely to be attached to the frame by simply setting in a rabbet. Even with glue and screws there is a limit to how much that can withstand.

Just thinking off the top of my head (without the benefit of hindsight or too much careful consideration) I suppose you could make a stronger unit by also incorporating a rear “face frame). That could get you some vertical members of wood anchored securely to the wall and then the plywood sides could be glued (and screwed) into dados. I really doubt that this would result in the visual appearance you are looking for.

Bondo has it right, build a base cabinet. I am thinking something with a nice pair of semi-transparent beaded glass doors and perhaps some interior lighting to display your collection of 12 -18 year old single malts. Invite us all over to see how well it turns out!

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ArtMann

1396 posts in 1236 days


#6 posted 12-21-2018 12:44 AM

I have used 1/2 inch plywood for a French cleat system in my shop but I completely agree with Bondo. I strongly suggest you reconsider hanging something that massive from a row of studs. 1/2 inch plywood will not be adequate but even if it were, there is still the enormous weight of books.

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