Plywood - stiffest configuration?
 

Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

Thanks in advance for your helpful replies.

Darro

"Darro" wrote in message
...
Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

In configuration 1 you mention joints.Are you laying out a series of sheets
and then staggering the second layer? Done properly, that would have
marginally more stiffness at the joints. Lots more labor and no assurance
the glue joint is as good as the factory ply. I'd go with the single
layer.

On 2005-05-15, Darro wrote:

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Assuming you are doing a large area with multiple sheets, how about
5/8" T&G CDX plywood?

Cheers, Wayne

Darro wrote:
Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

Thanks in advance for your helpful replies.

Darro



For what application?

Darro wrote:
Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

Thanks in advance for your helpful replies.

Darro

not enough info.

fwiw a wood frame sandwiched between the 2 would give even more
stiffness in some ways, less in some.

NT

"Darro" wrote
Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Darro

The local lumber yards here, sell 1/2" CDX with 3,4, & 5 ply. Five ply
will be your stiffest (and most expensive out of the 3 choices) plywood, the
plys are alternated when glued/compressed together.

IMHO, stay away from 3 ply for any application except when hung vertically
for exterior walls.

Darro wrote:
Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

Thanks in advance for your helpful replies.

Darro

All else being equal a single sheet composed of the same total number of
layers as two sheets half as thick and having half the total layers as the
single will be stiffer. However that difference is not likely as the total
number of layers will not likely be equal and you need to consider the
overlap of joints that will add overall application stiffness. In addition
there are many other factors relating to stiffness.


--
Joseph Meehan

Dia duit

Iff stiffness is the only consideration and water resistance is not a
factor, then wafer board offers greater stiffness than plywood, not overall
strength, just stiffness.

--


Remove the obvious to reply. Experienced and reliable
Concrete Finishing and Synthetic Stucco application in the GTA.
"Joseph Meehan" wrote in message
.. .
Darro wrote:
Can anyone tell me which of two plywood sheet configurations would be
the stiffest, or do they have the same stiffness?

Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Configuration 1:
A bottom layer of sheets of 1/4" plywood plus a top layer of 1/4"
plywood sheets overlaid in the centre of the lower layer's joints and
glued to the lower layer.

Configuration 2:
A single layer of 1/2" plywood with the same outside dimensions as
Assembly 1.

Thanks in advance for your helpful replies.

Darro

All else being equal a single sheet composed of the same total number
of
layers as two sheets half as thick and having half the total layers as the
single will be stiffer. However that difference is not likely as the
total
number of layers will not likely be equal and you need to consider the
overlap of joints that will add overall application stiffness. In
addition
there are many other factors relating to stiffness.


--
Joseph Meehan

Dia duit

"Josh" wrote in message
...

"Darro" wrote
Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Darro

The local lumber yards here, sell 1/2" CDX with 3,4, & 5 ply. Five ply
will be your stiffest (and most expensive out of the 3 choices) plywood,
the
plys are alternated when glued/compressed together.

IMHO, stay away from 3 ply for any application except when hung vertically
for exterior walls.

4 ply? that would be strange, grain would run different front to back. Guess
it would make no dif if installed across the joists or parallel to them.
Don't see much straight dif from 3 ply.

"calhoun" wrote
4 ply? that would be strange, grain would run different front to back.
Guess
it would make no dif if installed across the joists or parallel to them.
Don't see much straight dif from 3 ply.

Being _normal_ building grade sheets are 4'x8', it sure does make a
difference how it is installed.

Guess if you've never used the better grade of 4 ply compared to 3 ply, you
wouldn't see any difference.

In 4 ply, the two center plys both run the same direction.

Go figure.

Bob