Homemade Cottonwood Roof Trusses

[Dan_Shade]

why not staples?  the flooring and plywood that I've removed that was built with staples was a major hassle to get apart, the nailed in stuff comes up a lot easier.

[mike_van]

My 2 cents - For 24 x 30, why not skip the trusses, use a conventional framed roof? Size your framing lumber accordingly. You don't have to worry plane or not, glue or not?  You can add a collar tie to every pair of rafters if you want.

[Don P]

Collar ties should be at the plate if possible, they lose strength fast as they rise.
 dowel type fasteners are mostly about diameter of the fastener and density of the wood. in northern species through a 15/32 side plate;
.099 dia=35 lbs shear/fastener
.120=48lb/nail
.131=58 lbs/nail
.148=67 lbs/nail
Larger than that and its hard to get the 10 diameters penetration into the main member, although the codebook bumps the value up if you clinch a nail on the backside.

One thing Dr Woeste at VA Tech said was that with trusses especially many smaller dowels is better than a few larger dowels such as bolts. If you lose a nail things don't go into overload immediately, if you lose a bolt the failure may be fast. They like slow, noisy failure if its gonna go.

[IMERC]

why not staples?  the flooring and plywood that I've removed that was built with staples was a major hassle to get apart, the nailed in stuff comes up a lot easier.

because of shear...

[beenthere]

There was an article in a recent Fine Woodworking mag that tested different types of glue.  Surprisingly, the titebond type glues were superior in all tests.  The biggest surprise was the polyurethane glue (Gorilla glue) failed on many of the tests.  It was the poorest performer.  Of course, this was in a woodworking application and construction adhesives were not tested.  They might very well be vastly superior for trusses.  I would think planing would increase the strength of any glued joint.

When Gorilla glue first came out, with its many claims, I was aware of some glue block testing under very controlled conditions, and many of the claims were no better than its competition, and in some cases not as good. I think the sales and marketing program have boosted the Gorilla glue more than performance.  Not knocking it, but just not praising it either. 

[Haytrader]

I have made several trusses with waffer board, construction adhesive, and staples.
These are the only ones that aren't covered by sheetrock.
 
I have a Paslode stapler and a lot of 1 1/2 staples so my theory is use what ya got.
I have used various adhesives including Liquid nails and have not had any problems.

[TexasTimbers]

I fell for the marketing and I agree their marketing is effective, but I have had no failures with the glue. First time I used it on a dock was in 1999 and it is still holdin just fine.

[jrokusek]

Sounds like I'm on the right track anyway.  Now I can buy a framing nailer to build the trusses and then frame the rest of the building.  I believe the framing nails are .131 if I remember correctly.  Good thread!

Thanks for the info!!

Jim

[Don P]

I wrote the Am Ply Association's Help Desk, asking if osb could be interchanged with same thickness ply in the ag service plans seen on the net. Here was the response;

Allowable design properties of OSB are similar to those of plywood. Interestingly enough some of the important mechanical property characteristics of OSB are superior for gusset applications.
 
An engineer can design truss gussets from either plywood or OSB. Assuming that panel axial tension capacity is the critical characteristic we would expect specifications for gusset thickness and nailing to be the same whether plywood or OSB. However, we cannot make a blanket statement that OSB gusset panels can be substituted for specified plywood or visa versa.
Regards,
Merritt Kline
Product Support Specialist
Wood Products Support Help Desk
APA-The Engineered Wood Association
Southern Forest Products Association
Structural Insulated Panel Association

[IMERC]

just have IRL exposure to this ..

built trusses using OSB and ply and both with nails and staples...
and of course construction adhesive...
had to take some of them apart...
ply with glue and nails were the toughest to break down...