Shelving span advice?

Check out "the sagulator" here - it should answer your questions;
http://www.woodbin.com/calcs/sagulator.htm
"John Sellers" <[email protected]> wrote in message
news:[email protected]...
>
> Greetings wreck,
>
> I need some closet shelving, and am wondering if a 22-inch span is too
> long for 1x lumber (3/4-inch dressed). I'm thinking not, but wanted
> your input before committing to the cuts.
>
> I don't expect any heavy loads, just SWMBO's closet crap, etc. Shelf
> spacing only 16 inches, so there's only so much she could pile on each
> one, except maybe the top shelf.
>
> Will I need to glue some edge pieces front and back? Or should I just
> use plywood? Will pine/poplar sag more, so that I need consider
> better wood?
>
> These shelves will be 16 inches deep. I'm thinking of using two, or
> three (maybe four?) pieces to make the panels. Also considering
> installing in pieces, without glue-up. This would make the install a
> bit easier. Shelves will be on cleats, in each side of the 22-inch
> deep closet, behind the door trim, so getting full dimension panels in
> there might be a trick without some edge gaps. I'm not going to
> finish this out to furniture grade (plans are to prime and paint), but
> won't make it shop quality either. (Don't infer that I'm less AR
> about the shop stuff here <g>.)
>
> Will piecing the shelves (no glue-up) make my span strength concern
> any worse? If so, it's better to use fewer pieces per shelf, correct?
> I think I'll still biscuit the edges in this case, just to keep the
> joints even. Will biscuits break if edges aren't glued? Would loose
> tenons or dowels be better here?
>
> Or - am I worrying about nothing? 22-inches isn't that big a span,
> right?
>
> Thanks for any suggestions,
> John Sellers
>

On Wed, 24 May 2006 19:21:53 -0400, "John Sellers"
<[email protected]> wrote:

>
>Greetings wreck,
>
>I need some closet shelving, and am wondering if a 22-inch span is too
>long for 1x lumber (3/4-inch dressed). I'm thinking not, but wanted
>your input before committing to the cuts.
>
>I don't expect any heavy loads, just SWMBO's closet crap, etc. Shelf
>spacing only 16 inches, so there's only so much she could pile on each
>one, except maybe the top shelf.
>
>Will I need to glue some edge pieces front and back? Or should I just
>use plywood? Will pine/poplar sag more, so that I need consider
>better wood?
>
>These shelves will be 16 inches deep. I'm thinking of using two, or
>three (maybe four?) pieces to make the panels. Also considering
>installing in pieces, without glue-up. This would make the install a
>bit easier. Shelves will be on cleats, in each side of the 22-inch
>deep closet, behind the door trim, so getting full dimension panels in
>there might be a trick without some edge gaps. I'm not going to
>finish this out to furniture grade (plans are to prime and paint), but
>won't make it shop quality either. (Don't infer that I'm less AR
>about the shop stuff here <g>.)
>
>Will piecing the shelves (no glue-up) make my span strength concern
>any worse? If so, it's better to use fewer pieces per shelf, correct?
>I think I'll still biscuit the edges in this case, just to keep the
>joints even. Will biscuits break if edges aren't glued? Would loose
>tenons or dowels be better here?
>
>Or - am I worrying about nothing? 22-inches isn't that big a span,
>right?
>
>Thanks for any suggestions,
>John Sellers


A 22-inch span is nothing to be concerned about for typical loads.
Three-quarter inch thick ply or solid wood will work. I'm not
certain about your plan of installing pieces, which will weaken the
shelving unless spline/glue or something else is used. A 1.5" solid
wood lip on the front will greatly add to the strength.

"John Sellers" <[email protected]> wrote in message
news:[email protected]...
>
> Greetings wreck,
>
> I need some closet shelving, and am wondering if a 22-inch span is too
> long for 1x lumber (3/4-inch dressed). I'm thinking not, but wanted
> your input before committing to the cuts.
>
> I don't expect any heavy loads, just SWMBO's closet crap, etc. Shelf
> spacing only 16 inches, so there's only so much she could pile on each
> one, except maybe the top shelf.
>
> Will I need to glue some edge pieces front and back? Or should I just
> use plywood? Will pine/poplar sag more, so that I need consider
> better wood?
>
> These shelves will be 16 inches deep. I'm thinking of using two, or
> three (maybe four?) pieces to make the panels. Also considering
> installing in pieces, without glue-up. This would make the install a
> bit easier. Shelves will be on cleats, in each side of the 22-inch
> deep closet, behind the door trim, so getting full dimension panels in
> there might be a trick without some edge gaps. I'm not going to
> finish this out to furniture grade (plans are to prime and paint), but
> won't make it shop quality either. (Don't infer that I'm less AR
> about the shop stuff here <g>.)
>
> Will piecing the shelves (no glue-up) make my span strength concern
> any worse? If so, it's better to use fewer pieces per shelf, correct?
> I think I'll still biscuit the edges in this case, just to keep the
> joints even. Will biscuits break if edges aren't glued? Would loose
> tenons or dowels be better here?
>
> Or - am I worrying about nothing? 22-inches isn't that big a span,
> right?
>
> Thanks for any suggestions,
> John Sellers
>
The usual suggestion for span is no more than 36 inches for 1x12 lumber.
You could attach a 1x4 to the wall to support the planks to add support.
The 1x4 will reduce the deflection and the internal stresses.

Pine will be fine. If you look at closets in most houses, that material is
what you will find (unless they really economise by using mdf).
Jim

I think the best way to answer this kind of question is to build a really
rough model and put representative loads on it. If the deflection is
acceptable .....great. I have a feeling that plywood will deflect more than
solid (soft) wood. You don't need biscuits.
Dave
>