Plywood thickness for benchwork

I have built numerous layouts over the past 50 years or so. I never have used anything thicker than 1/2" plywood for the base. Have never had any kind of warping problems. Now, I am preparing to build what will likely be my last layout. it will only be 4x8. I am using 1x4 framework, with 12" centers, and then overlaying that with 1/4" plywood. On top of the plywood I am placing a layer of 2" thick pink foam insulation board. I do not expect to have any stability problems using the 1/4" plywood with this type of spacing and overlay. I have also used 3/8" plywood in the past. That worked well too. The older I get, the thinner I want to plywood, due to weight of the product. My back can not handle what it used to.

You might be fine with a 1/2" plywood or Oriented Strand Board (OSB) product...one way to control the effectiveness and performance of the sheet product is  the below table frame structure and span.  I used  2 x 4's, 24" on center with 1/2" BC  plywood from a big box store without issue.  You'd save some money rather than using 3/4" and lifting and carrying the sheets is a easier on the back...

I think 3/4 inch is overkill.

I used 5/8 plywood on 2x3 framing (16" apart) 2x3 legs too

Most of the layout is over 30 years old, some 40.  No problems with warping. Held my 200 pounds when needed.

Stay away from cheaper compressed board - hard to screw into and heavy as heck! OSB is ok

I once built a 6x8x10 layout using nothing but 1" thick rigid foam insulation on a 2x4 base with 24" crossmembers. Admittedly, it was only a single perimeter run of RealTrax with dozens of ceramic buildings on it. Mind you, I don’t recommend it due to noise, but it held up for a few years and was moved between rooms and the garage several times. I took it apart when my intention was to build a more permanent layout before life intervened. Also, the late late Jim Barrett did a whole series in the magazine featuring 1/2" plywood on 1x3 framing. I believe it’s available in the digital section.

Hi ,  I used 5/8 ths inch thick plywood or as sold 19/32  inches  @ $ 28  a sheet at Lowe’s .     See my post under my SteamPossum name of my build / framing.    Also 1/4 inch foam for sound deadening.  

Thank you guys for the help. I appreciate it! My wife and wallet will be happy that I don’t need 3/4 inch.