[Strawbale] RE Plywood vs. osb for gussets ?

[William R Bloom]

The forces in a stressed frame gusset to me would be 
similar to those encountered in a shear wall.  There are 
APA published values for thicknesses of plywood when used 
to resist shear taking into account the grade plywood, 
veneer configuration, thickness and nailing schedule.  I 
would think you could find the appropriate value for the 
plywood you have been using and select an oriented strand 
board with equivalent values.  I would assume that you are 
gluing the gusset, nailing only to hold the gusset while 
the glue set as is typical in truss construction, so a 
fastening schedule to develop the shear would not be of 
significance.  I just roofed an outbuilding where I used 
3/8 rated sheathing plywood gussets at the 2 x chord 
joints, butt glued the chords and glued and pneumatically 
nailed the gussets using polyurethane glue.  A very strong 
joint.

Bill Bloom
New Mexico



On Thu, 22 Feb 2007 16:38:23 -0700
  "Dr C Colegrave" <ccolegrave at hughes.net> wrote:
> Hello Ken
> Happy to comment but I am unsure which published article 
>from the APA you
> are using for your design. Could you give me the title 
>and I'd be happy to
> have a look at what the design is calling out for.
> Kindest regards
> Craig Colegrave
> Copperrock construction
> Central Alberta
> 
> 
> Date: Wed, 21 Feb 2007 11:39:34 -0700
>From: "Ken Simonelis" <>
> Subject: [Strawbale] Plywood vs. osb for gussets ?
> To: <>
> Message-ID: <000d01c755e7$a2ad2110$5fa0a2d1 at asdf>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Hello people, I was wondering if any one would care to 
>hazard a guess about
> the following. Come the spring ( it will come won't it ? 
>Been snow on the
> ground since Halloween this winter and cold to boot, a 
>very traditional
> Northern Alberta winter ), I will be making a small ( 
>400 sq. ft. ) cabin
> combining the techniques of using a wooden rigid arch 
>and straw bales for
> the walls. I've used these arches around the farm for 
>making small out
> building for the last 25 years and they have stood the 
>test of time very
> well so I thought to myself  it would be worth the 
>effort to combine  the
> system with s.b. and get that much closer to furnishing 
>shelter directly
> from the farm's collection of resources.
>    The arches themselves are straight walled with a 
>gable roof ( low slope
> ), sort of a 'whole house truss' if you will. The specs 
>come from
> information sheets available from the American Plywood 
>Association, and
> here's where my question comes in. Naturally enough, the 
>plans call for
> various sizes of thicknesses of plywoood to be used for 
>the connecting
> gussets. However since the hurricane season down in the 
>U.S. did not amount
> to much this past year, the cost of osb has dropped 
>,locally at least ,by
> about 2/3's, and having been caught short in the last 
>price spike, I bought
> several lifts of osb in anticipation of various building 
>projects in the
> near future. Plywood , however, is still way up there in 
>price, so I was
> wondering if, for this situation, I could substitute osb 
>for plywood when
> building the gussets for these arches ? If it's a dicey 
>situation with the
> numbers could I use osb of a greater thickness and 
>adequatly compensate for
> the difference in the two product ?  Cheers 
> 
> and thanks in advance to any who might shed a bit of 
>light on this matter.
> 
> 
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