Plywood thickness thos 3/4 or that 1/2

[Craig D Peltier]

When do you use 3/4 verse 1/2 inch. I did search for plywood 175 hits and one hit for plywood thickness.Nothing helped me but I do remember seeing it in a post here.
I know long shelves 3/4 is better or a hardwood face on 1/2 will help.

But for vanities and dressers? built in sides and tops? Id like to know where I can cut cost.

Thank you

[Todd Jensen]

Hello Craig, from Covington/Maple Valley. :) For vanities and small dressers, I think 1/2 is fine for sides as well as cross-members. Anytime I go much bigger, I really like to use 3/4", particularly for shelving. Another important factor is what ply and grade you're using, though it is kind of a moot point when discussing costs as a high-grade 1/2" is going to cost more than Home Depot/Lowes 3/4" maple or oak ply. I'm sure someone on here has a better answer, but in the end situation will dictate more than anything and come down to what the design is, what kind of spans are involved, and how much weight the overall piece and particular sections will be designed to support. For 'most' applications, I'd rather be safe than sorry and spend the extra $10-15 a sheet for sturdiness. I think its easier to use biscuits, fasteners, etc. with 3/4". Of course, just my 2 1/2 cents - hope this helps.

[Eugene A. Manzo III]

If you try to "Cut Costs" when you are building something you may be better off selling your tools and buying particle board furniture from the big stores for cheap. I build it so the people that lift it after me swear because its to heavy :rolleyes:

[John Huber]

Choice of thickness depends a lot on how the stock is to be used. Hinges and knobs seem to be sized for 3/4" stock. It's hard to find much selection of hinges and knobs for 1/2" stock. Also adjustable shelf standards that are inset into the sides are difficult to mount on 1/2" stock.

For drawer carcass stock, 1/2" seems fine for the sides, if you glue 1/4" plywood across the back to strengthen against racking.

[Byron Trantham]

If you try to "Cut Costs" when you are building something you may be better off selling your tools and buying particle board furniture from the big stores for cheap. I build it so the people that lift it after me swear because its to heavy :rolleyes:

I agree! Cost of a project is usually directed towards the material you want to use, cherry, oak, birch, etc. Thickness of material is usually directed towards strength/construction considerations. Cabinet carcasses and shelves are usually 3/4" while drawers are usually built with 1/2" material. Costs will surprise you. 1/2" red oak plywood more often than not, costs more than 3/4". I recently had to get 2 sides good, red oak, 1/4" plywood and it cost $52 a sheet! Thickness, therefore, does not necessarily save money.

[Ed Falis]

Choice of thickness depends a lot on how the stock is to be used. Hinges and knobs seem to be sized for 3/4" stock. It's hard to find much selection of hinges and knobs for 1/2" stock. Also adjustable shelf standards that are inset into the sides are difficult to mount on 1/2" stock.....

I remember running into exactly that problem when I built a utility cabinet for the kitchen a few years ago. The Euro hinges were a &***$% - well, you know what I mean. In the end, it all worked out ok.

[John Schreiber]

I generally build based on what others have done and what looks and feels right. For confirmation, especially on shelves, there's a website which has a program which will do some engineering calculations. Try the sagulator (http://www.woodbin.com/calcs/sagulator.htm).

[Art Mann]

The ability to choose plywood thickness requirements, as well as solid wood dimensions, is a skill that is developed with time and experience. I have never seen a book of hard and fast rules on the subject, although there are such things as sag calculators on the internet. My advice to you is to stick with purchased plans (or adaptations and alterations) or copy the design of similar commercial items until you develop a feel for what is appropriate. If you have an idea for a specific project but don't know what to use, you can always post a question here. Lots of guys have lots of experience and are more than willing to help.

[Bill Wyko]

I would say 1/2 is more for shear strength where as 3/4 is more structural. I wouldn't use half for anything that is going to support weight. It is good for keeping something square, like the back of a wall unit of book shelf. As far as 1/2 supporting shelves or doors, I'd rather be safe than sorry. IMHO.:)

[joe greiner]

Not to pick nits, but shear strength is structural too. Thinner material for in-plane loads, including maintaining shape; thicker for loads perpendicular to the sheet. That said, fiddling with details to marry thinner materials is not without cost, considering the value of your time. In structural engineering, the rule of thumb is "When in doubt, make it stout."

Joe

[Craig D Peltier]

Thanks for all the replies, its been very informative.I havent been on the forum in a bit I was out of town.
Im building a vanity with only two sides 3/4 american birch ply and then face frame with 2 doors. Back and Bottom I was thinking 1/2 russian birch.
Ill post pics, here when done.

[Von Bickley]

Craig,
At one time, I spent a lot of time around residential construction. I have been around many kitchen cabinets, bathroom vanities, bookcases and utility cabinets. On the residential jobs that I have been around, I have never seen 1/2" plywood used anywhere. This may be different in other parts of the country, but all I ever saw was 3/4" plywood.:D :D :D

[Jim Becker]

Von, I'm sorry I didn't take detailed pictures of the "custom" cabinets that I ripped out of our kitchen when I renovated in 2003. Almost no plywood. Just 3/4" oak frames and hard-board...stapled together. By what was at the time a local cabinet shop. And to add insult to injury...they were blue. :eek:

But they came apart really easy!!

Ok, the uppers had a little plywood here and there. 1/2". :o And they were blue, too.

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That all said, with good construction, 1/2" plywood could be employed for cabinet carcass construction in many ways with good results. But there often wouldn't be any cost savings given that 3/4" (or 18mm) plywood is priced pretty aggressively as compared to the less-used 1/2" stock. And the 3/4" material is a bit stronger, overall. That's especially good given the current trend to use heavier stone counters even in more modest settings these days.

[Steve Clardy]

I use 3/4 on all of my cabinet boxes and shelves.

Around here, the same grade ply in 1/2" costs more than 3/4" ply.

Due to supply and demand. Not much demand for 1/2" unless its baltic birch ply