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It was a cost saving. May not seem like much, but over millions of sheets of plywood, that adds up to big money. The change in dimensions of plywood came at a different time than that for dimensional lumber. It has been relatively recent, in lumber years, since they had to start making undersize router bits to dado for the undersize plywood. Classically a 3/4 dado for 3/4 ply. Now a 3/4 bit means the undersize ply won't fit snuggly in the cut.
Plywood also comes from slow growth trees unlike OSB so that is probably a reason too. By shaving a 1/32 off conserves a ton of trees over the long run.
There are two different thickness definitions we need to keep in mind when talking about plywood; that of nominal thickness and actual thickness. Just like dimensional lumber, most plywood is rated at a nominal thickness; that is the thickness before it is sanded. The actual thickness is just like it sounds, the actual thickness of the plywood panels you buy, after sanding. Typically, the actual thickness of plywood is 1/32 inch less than the nominal thickness.
I bought BC construction grade 3/4" plywood in 1992, and it WAS 24/32nds and not 23/32nds thick. Because I used a 3/4" routing bit to make dadoes for tight crosslap joints.
A few years later, bought what I thought was 3/4" plywood BC construction grade, used the same router bit, and found that my joints were loose and wobbly. I re-measured the thickness and found it to be 23/32nds. (They now sell "special" bits for downsized lumber...)
FWIW, they shrank the "finished" size for most other lumber, too.
I doubt that they are planing / sanding more off of the nominal stock to make it that much smaller.
Is it just another case of the "Shrinking Tuna Can"?
Cans that were once 8 oz, then 7.5 oz, then 7.0 oz are now 5.0 oz and still shrinking....
They didn't lose 1/32 at all. The full thickness plywood is still available but retailers and lumber suppliers are also prone to selling what they can buy cheapest and make the most money. The difference is when the APA decided we needed a performance rated panel. It will structurally do the same thing as a full thickness panel will but at a reduced price, kinda like the difference between a BC panel and an AC panel. Both of those are made with exterior glue, both are finish grade but the BC allows for more face patches and is considerably cheaper. But still does the same function but at a cheaper price.The 23/32 or any of the other sizes you see for sale are "performance rated" panels and will not be full thickness. Full thick panels will be several dollars more per panel.
Want to buy some real expensive plywood? Try specing a 3/4" NB 7 core plywood. The N is extremely rare these days and means the face is flawless. In all of my years in the industry I've only seen it once and that was on a Jack in the Box. But then, those buildings are speced with an entire truckload of seismic anchors too that most of the nation will never see or need.
They didn't lose 1/32 at all. The full thickness plywood is still available but retailers and lumber suppliers are also prone to selling what they can buy cheapest and make the most money. The difference is when the APA decided we needed a performance rated panel. It will structurally do the same thing as a full thickness panel will but at a reduced price, kinda like the difference between a BC panel and an AC panel. Both of those are made with exterior glue, both are finish grade but the BC allows for more face patches and is considerably cheaper. But still does the same function but at a cheaper price.The 23/32 or any of the other sizes you see for sale are "performance rated" panels and will not be full thickness. Full thick panels will be several dollars more per panel.
Want to buy some real expensive plywood? Try specing a 3/4" NB 7 core plywood. The N is extremely rare these days and means the face is flawless. In all of my years in the industry I've only seen it once and that was on a Jack in the Box. But then, those buildings are speced with an entire truckload of seismic anchors too that most of the nation will never see or need.
A search results in hardwood cabinet grade plywood for 3/4" NB 7 core plywood.
I asked at Home Depot and Lowes if they would order full thickness construction plywood, and they claimed it is not available. . . but -hey- what do they know?
A search results in hardwood cabinet grade plywood for 3/4" NB 7 core plywood.
I asked at Home Depot and Lowes if they would order full thickness construction plywood, and they claimed it is not available. . . but -hey- what do they know?
Probably not available from their suppliers. Individual stores cannot just order materials "wherever ".
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