OSB or Plywood for Truss Gussets?

[PILOON]

I just Googled "truss gusset" and found that glue is more important. OSB or plywood both work but use a white / yellow glue and tight joints and not construction adhesive. The Purdue PDF used 3/8 plywood. One article said staples better than nails. But my research was too brief. I'd call a truss company and ask their engineer.

And be sure the glue is white/yellow and not the PL in a tube. UV seems to break it down as things I used PL on 10 yrs ago splits leaving a non adhesive powder.

Staple I understand, especially those that sport divergent points as when used the tips diverge left and right like a pair of fish hooks. I like 1/2" X 1.5"

 

[PILOON]

Yup and those webs can be utilized for hvac and plumbing traveling perpendicular.

Just like honeycomb used in aviation structures.

 

[Capricious]

I recently explored this topic while building the roof trusses for my boat house. I had planned on using pressure-treated plywood, and bought a couple sheets. About 50% through the first sheet and a heap of sawdust later, I noticed so many voids in the cut gussets that I gave up on the plywood, as I knew I couldn't trust it for this use (I never would have slept through the night).

So if you do use plywood, make sure it is a high grade that does not have internal voids (I forget the nomenclature, but there is a rating system for plywood that covers stuff like this -- most of the CDX grade plywoods used in construction will have voids).

I'd have no problem using OSB for gussets if they were out of the weather. It is stronger than plywood for applications like this. Glue is important, as well as the nails.

By the way, after I punted on plywood I switched to using 12 gauge triple-galvanized nailer plates and 1-1/4" galvanized joist hanger nails. Did that on a previous shed about 15 years ago, and it worked well then, so I knew I could trust it here. The plates cost about $2 each, and a box of nails was about $16. Put a plate on each side of the joint, with nail holes staggered. Here's a pic that shows the result:

View attachment 392896

How come we only get to see one photo of the boat house?

 

[Capricious]

And be sure the glue is white/yellow and not the PL in a tube. UV seems to break it down as things I used PL on 10 yrs ago splits leaving a non adhesive powder.

Staple I understand, especially those that sport divergent points as when used the tips diverge left and right like a pair of fish hooks. I like 1/2" X 1.5"

The only issue i have with glue is that the bond is to the outer veneer of plywood, and if the bond between the veneers is weak, the plywood itself can delaminate, leaving a nice layer of veneer glued to the chord/strut/whatever. Still, that is not reason enough, in my opinion to "spec" OSB over plywood, but rather to choose plywood carefully.

When glueing plywood, I mostly use epoxy resin, thickened as appropriate with fumed silica, although in certain cases I have used ureaformaldehyde (Weldwood "plastic" glue). In both cases, "sizing" usually increases the strength of the bond.

I pretty-much don't use "goop in a tube" except on very non-critical joints. I consider gussets of any sort to be critical.

 

[gdicks]

All great points for consideration guys, and for the most part backed up by evidence rather than pure opinions so thanks for that. Does anyone have opinions on the fasteners I should use? Ive heard round shank nails, roofing nails, galvanized nails etc. what has the best holding / sheering strength? What about prefrerred length, is there a minimum depth I should be shooting for or is longer better?

 

[Capricious]

"..Does anyone have opinions on the fasteners I should use?..."



Oh, I'm sure they do.


I would bolt these connections. But no one else here would.

 

[Gary Fowler]

I don't have an opinion on the best gusset material one way or the other as to which is stronger, but regarding the I beam construction. IF you cross section any I beam you will find that the flanges (top and bottom pieces) are very thick compared to the web thickness which would seem to verify that on engineered trusses, the flange doesn't have to be that strong as compared to the flanges. The web just has to keep the two flanges apart so that elongation and compression forces can act upon the flanges.

However on the material issue, I would use the plywood if building it myself.

Another thing to consider is this, can you build them cheaper than a truss manufacturing facility can? When I had my shop and house built, the contractor ordered all the trusses built, he said he couldn't buy the lumber for what he could get the trussed fabbed and delivered for.

 

[s219]

How come we only get to see one photo of the boat house?

I've posted a couple other threads with questions, but will do a good one with photos when it's finished.

 

[orezok]

Which particular statement? Or better, what part of what I said do you not understand?
.

Perhaps I worded that poorly. I'm not questioning your statement, I'm trying to educate myself.

 

[buickanddeere]

OSB is fine in any application where a wet cardboard box would do. I don't allow the stuff on my place .