OSB or Plywood for Truss Gussets?

[BHD]

depending on the truss there is compression and tension forces on members of a truss, thus the gussets are doing more than just keeping the lumber aligned,

at one time split rings were used on many field built trusses, and bolted together,

modern factory built trusses use steel plates, and machine rated lumber, which is superior to common lumber.

one could use light steel plates. either home made or commercial prepunched units, like below, in 16 gauge plate

Gusset Plates (G-Series & GP-Series) | ClarkDietrich Building Systems

 

[MacLawn]

Can't remember what I used when I built my trusses in '92 for my shop. But as usual, I'll agree with old Eddie. And s219. If done right, I don't think there'll ever be a difference if ye use OSB or plywood.

 

[LD1]

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

Sorry I dont have any good links to explain it. But think about this.....

When discussing what has a bigger impact on beam deflection (and how much load it can hold), Picture an i-beam. Picture one that is "square". Like 8" high and 8" wide, or 6x6 or 4x4 or whatever. IF it was the vertical member (web) that had all the strength, the beam would be stronger if laid on its side. Cause that would make it have 2 vertical members instead of one, and probabally thicker too.

Take a common W8x31 I-beam. Its commonly used for center beams under houses in my area. It is 8" high and 8" wide. The modulus of elasticity (basically the beams resistance to deflection), is 31 if the beam is laid on its side like the letter H. But 110 if kept upright. So almost 4x stronger.

Another example is look at a W10x19 beam vs a W10x22. Both 10" beams. The W10x19 has a .250" thick web and 4" flanges. The W10x22 has a smaller .240 web, but ups the flanges to 6" wide. That increases the strength by over 20% even though the web is thinner material.

OF course that is with steel, cause that is what I know better. But the same applies to wood. When a beam is loaded, the same types of forces are at play. Also look at those roof joists/trusses you see in commercial buildings. That are Two angles top and bottom, with round bar for webbing. The webs are mostly open cause the strength lies in the flanges. The bottom is trying to tear apart and the top is trying to compress.

If you are in for tons of reading, google modulus of elasticity, and beam properties, and the like.

 

[Gary Fowler]

I totally agree. Someone posted that OSB has more compressive strength than plywood so if that be true, then that would explain how wooden truss type beams use OSB. Regardless of the loading the web is always in compressive mode so OSB would be good for that. Gussets in a roof truss might see compression but more likely it would see elongation stresses from side to side and lengthwise.

Personally I think the metallic plates work best. You cant tear them out of a piece of wood without breaking the wood. You can bend it in any direction and the wood breaks before the connection. I don't think you will find that to happen with either plywood or OSB joints.

 

[PILOON]

""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."

No way can a person compete!

The truss mfg uses every little piece so there is no wastage, his wood is KD #1, he gets the biggest volume discount and his labor is non union.

 

[LD1]

Up to this point, I havent commented on the plywood vs osb debate for trusses.

Something I dont think I have seen mentioned yet is, for lack of a better term, nail retention.

But not so much the pull out strength. but the strength of the fibers themselves.

Take a piece of OSB. Cut it about 4" wide. But a few nails in one end and try to twist (like trying to shear off a nail). Then do it with plywood. The way osb is constructed, nails tear up the material and tear through it easier than plywood.

Now I have no scientific data to back this up, this is just observations based on many things I have torn apart.

 

[mikehaugen]

Up to this point, I havent commented on the plywood vs osb debate for trusses.

Something I dont think I have seen mentioned yet is, for lack of a better term, nail retention.

But not so much the pull out strength. but the strength of the fibers themselves.

Take a piece of OSB. Cut it about 4" wide. But a few nails in one end and try to twist (like trying to shear off a nail). Then do it with plywood. The way osb is constructed, nails tear up the material and tear through it easier than plywood.

Now I have no scientific data to back this up, this is just observations based on many things I have torn apart.

I think the glue is really where the strength come from... but with that said, I would still use plywood, or steel.

 

[300UGUY]

When I built a pole barn, I could buy trusses cheaper than the lumber. And the delivered. Big time saver also.

 

[LD1]

I think the glue is really where the strength come from... but with that said, I would still use plywood, or steel.

Possibly. But I have seen trusses built 30 years ago absent the glue, with plywood gussets, that are still holding.

Not denying that glue makes a big difference. But, I would trust a truss built with nails alone before I would trust one with only glue.

 

[bcp]

The web of a beam can be almost completely removed.





Bruce