How can I figure the amount of weight a piece of plywood, probably 3/4 or 1"
.... how much weight it would hold? It would be 24" x 60" and supported on
both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side. I could use butcher board or block, whatever it is.
Thanks ...

"AKA gray asphalt" wrote in message
news
How can I figure the amount of weight a piece of plywood, probably 3/4 or
1" ... how much weight it would hold? It would be 24" x 60" and supported
on both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side. I could use butcher board or block, whatever it is.
Thanks ...

This may help
http://www.woodbin.com/calcs/sagulator.htm

"AKA gray asphalt" wrote in message
news
How can I figure the amount of weight a piece of plywood, probably 3/4 or
1" ... how much weight it would hold? It would be 24" x 60" and supported
on both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side. I could use butcher board or block, whatever it is.
Thanks ...


Over time it will sag noticeably of its own weight. You need more support
for a shelf or platform that size.

Don Young

Don Young wrote:
"AKA gray asphalt" wrote in message
news
How can I figure the amount of weight a piece of plywood, probably 3/4 or
1" ... how much weight it would hold? It would be 24" x 60" and supported
on both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side. I could use butcher board or block, whatever it is.
Thanks ...


Over time it will sag noticeably of its own weight. You need more support
for a shelf or platform that size.

Don Young



You must be using plywood made from cardboard.
3/4" plywood on 24" studs (essentially what the op
is doing) is never going to sag by itself.

The Sagulator, shows that a 1400 pounds would
result in a deflection of 0.1 inch. a sag of 0.1"
wouldn't be a problem even if visual was important.

George E. Cawthon wrote:
Don Young wrote:
"AKA gray asphalt" wrote in message
news
How can I figure the amount of weight a piece of plywood, probably
3/4 or 1" ... how much weight it would hold? It would be 24" x 60"
and supported on both 24" sides and one of the 60" sides? The
weight would be evenly distributed but there wouldn't be any
support in the center except along that one side. I could use
butcher board or block, whatever it is. Thanks ...


Over time it will sag noticeably of its own weight. You need more
support for a shelf or platform that size.

Don Young



You must be using plywood made from cardboard.
3/4" plywood on 24" studs (essentially what the op
is doing) is never going to sag by itself.

The Sagulator, shows that a 1400 pounds would
result in a deflection of 0.1 inch. a sag of 0.1"
wouldn't be a problem even if visual was important.

I don't think your reading the OP's specs. It is 24X60 shelf supported on
both ends and along one of the 60" sides leaving one of the 60" sides
unsupported it will deflect and sag under it's own weight with that
configuration over time. Time to recalculate with the "sagulator".

Rich

George E. Cawthon wrote:

"AKA gray asphalt" wrote

How can I figure the amount of weight a piece of plywood, probably 3/4 or
1" ... how much weight it would hold? It would be 24" x 60" and supported
on both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side...

The Sagulator, shows that a 1400 pounds would result in a deflection
of 0.1 inch.

That's what it says for a 24" wide and 60" deep 3/4" shelf...

But a 60" wide x 24" shelf would initially sag 3.89" with a 1400 lb load.

Nick

On Mon, 8 Jan 2007 16:15:36 -0800, "AKA gray asphalt"
wrote:

How can I figure the amount of weight a piece of plywood, probably 3/4 or 1"
... how much weight it would hold? It would be 24" x 60" and supported on
both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side. I could use butcher board or block, whatever it is.
Thanks ...



You search on the keywords "plywood span table"
and get something like this:

http://www.greatnorthernlumber.com/simpplyr2.html


Lots. I have to say, the
arrangement you describe seems destined to
sag on the loose edge, and dump whatever
you're trying to hold up. You're probably
better off fastening the crap out of the two
ends, and leaving off the supports on the
long side, so it can sag evenly. I doubt
you'll be able to make the plywood fail
in that configuration before whatever you're
attaching it to comes loose.

What are you trying to do?

--Goedjn

Rich wrote:
George E. Cawthon wrote:
Don Young wrote:
"AKA gray asphalt" wrote in message
news How can I figure the amount of weight a piece of plywood, probably
3/4 or 1" ... how much weight it would hold? It would be 24" x 60"
and supported on both 24" sides and one of the 60" sides? The
weight would be evenly distributed but there wouldn't be any
support in the center except along that one side. I could use
butcher board or block, whatever it is. Thanks ...


Over time it will sag noticeably of its own weight. You need more
support for a shelf or platform that size.

Don Young


You must be using plywood made from cardboard.
3/4" plywood on 24" studs (essentially what the op
is doing) is never going to sag by itself.

The Sagulator, shows that a 1400 pounds would
result in a deflection of 0.1 inch. a sag of 0.1"
wouldn't be a problem even if visual was important.

I don't think your reading the OP's specs. It is 24X60 shelf supported on
both ends and along one of the 60" sides leaving one of the 60" sides
unsupported it will deflect and sag under it's own weight with that
configuration over time. Time to recalculate with the "sagulator".

Rich



Sorry, I apparently read it wrong, thinking it was
supported along the two long sides. Don't think
the sagulator will help. It won't sag along the
24" sides or the one 60" side. 24 inches wide is
pretty wide, so with enough weight it will sag.
It will not sag on it's own from my experience.

I have 10" wide shelves 30" long supported only on
the end and they don't sag with a full load of
large books. I also have a bookcase with 9" wide
shelves 48" long and supported with nails through
1/4" plywood on the back edge and these shelves
don't sag with a full load of magazines. Each
shelf supports 140 pounds (I weighed a 6" section
of magazines).


The only way to tell how much the ?shelf? will sag
is to support a 2 x 5 shelf on 2x4's (on the
floor) and step on the shelf along the unsupported
edge and in the middles of the long length (and on
other parts of the shelf). That will give a
decent idea of what the shelf will support. I
suspect that the shelf will support at least 300
pounds distributed evenly over the shelf with
little sagging.

wrote:
George E. Cawthon wrote:

"AKA gray asphalt" wrote

How can I figure the amount of weight a piece of plywood, probably 3/4 or
1" ... how much weight it would hold? It would be 24" x 60" and supported
on both 24" sides and one of the 60" sides? The weight would be evenly
distributed but there wouldn't be any support in the center except along
that one side...
The Sagulator, shows that a 1400 pounds would result in a deflection
of 0.1 inch.

That's what it says for a 24" wide and 60" deep 3/4" shelf...

But a 60" wide x 24" shelf would initially sag 3.89" with a 1400 lb load.

Nick

Yeah I used the wrong dimensions, however your
numbers are with both long sides unsupported. The
sagulator doesn't calculate with one long edge
supported. If you support one long edge, sag will
be reduced a lot. Elsewhere I suggest that the
shelf would likely support 300 pounds ok. ,
Deflection would likely be less than 1/4" at the
center of the unsupported edge, but certainly no
more than 1/2 inch.

George E. Cawthon wrote:

... a 60" wide x 24" shelf would initially sag 3.89" with a 1400 lb load.

Yeah I used the wrong dimensions, however your
numbers are with both long sides unsupported. The
sagulator doesn't calculate with one long edge
supported. If you support one long edge, sag will
be reduced a lot. Elsewhere I suggest that the
shelf would likely support 300 pounds ok. ,
Deflection would likely be less than 1/4" at the
center of the unsupported edge, but certainly no
more than 1/2 inch.

Certainly? :-)

Nick

what the OP is posing is that he is building a shelf with two supports
on either end and one in the back the length of the board. looks like
this:

------------------------------------
| |
| |
| |


where the ----- side is 60" and the | sides are 24".

I made a 54"x20" shelf from 1/2" MDF for linens and such, and it
doesn't sag at all because we supported the back with a furring strip
54" long.

Since you want a lot of weight on it, it's probably going to be utility
use and appearance is second concern. I'd use OSB tongue and groove
flooring (the yellow painted edge stuff) I think it's 3/4" thick. If
you think about how that stuff mounts in homes on trusses and how much
weight it holds without warping.

You could also use corrugated tin and roll the edge over in front if
you're holding something like paint cans. ugly, but it won't deflect
even if you jump on it.

good luck.

wrote:
George E. Cawthon wrote:

... a 60" wide x 24" shelf would initially sag 3.89" with a 1400 lb load.

Yeah I used the wrong dimensions, however your
numbers are with both long sides unsupported. The
sagulator doesn't calculate with one long edge
supported. If you support one long edge, sag will
be reduced a lot. Elsewhere I suggest that the
shelf would likely support 300 pounds ok. ,
Deflection would likely be less than 1/4" at the
center of the unsupported edge, but certainly no
more than 1/2 inch.

Certainly? :-)

Nick

Yes. Note that the op said the weight would be
equally distributed. 10 square feet, each foot
would support 30 pounds. Place 30 pounds on each
square foot that has a supported edge and you
would not see any obvious sag. That leaves only 3
square feet in the middle of the unsupported edge.
How much would one expect the thing to sag if
you place 30 pounds on each of those square feet?

The whole thread is a bit silly. If weight
carrying and shelf sagging were an issue, any
reasonable person would simply face the
unsupported long edge with a 3/4" x 1-1/2" piece
or place the sheet atop 2x4's supported at the
short ends.

replying to Edwin Pawlowski, snowangel7 wrote:
http://www.woodbin.com/calcs/sagulator.htm
Thanks so much for posting this, very helpful!


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