USDA Truss Design, your opinion ?

[Arky217]

The following link is a picture of a 24' span nailed truss design from the Department of Argriculture.
What is your opinion of this design for a home built nailed truss to span the indicated 24 feet ?
(you may have to open the image in Windows picture viewer to see details)

http://images43.fotki.com/v1328/photos/1/1404952/6773112/Truss-vi.jpg

Thanks,
Arky

[glenn kangiser]

I wouldn't worry about it with a few considerations.

Modified to add, that it likely won't be insurable unless using code materials and approved design stamped by an engineer.  He is then taking the blame if it fails.


It was designed by U of M for USDA when they were worth something and weren't dictated to nothingness by industry.

It was likely designed using non-graded lumber before they realized industry didn't like local sawmills competing with them.

It was designed using good quality lumber, stamp or no stamp.  Grade your lumber yourself by using common sense.  Use at least the species it was designed for or stronger. Reject large knot etc.

Without currently approved codes and design it won't pass in a code area.  You will not have paid off enough people.

I like to use screw or ring shank nails.  Joints could have glue added.  They could be plywood reinforced, but that would be second guessing an engineer's design. 

Some of the second growth we get today is not as strong as the old wood so read their spec carefully.

Doing this, quality and suitability are your responsibility.  For myself, if I wanted to and had materials I considered to be of good enough quality, I would do it.

[n74tg]

I've seen that same drawing (and others).  I also have a book of truss plans (Midwest Plan Service, I think it was about $7) that use the glued and nailed plywood gusset designs that Glenn mentioned.  I was going to build my own trusses because I can't get a crane in here to set them, I thought they would be really expensive to buy and since I'm building every other part of my house myself I thought why not build the trusses too.

And while I don't have to pass any building inspections (I live out in the county), the idea of being able to get the house insured (at a reasonable price) after completion is beginning to weigh on my mind heavier than before.   

Then, one day I found the local truss company number on my caller ID.  Somebody must have given them my number.  I gave them a call, and low and behold right now my trusses are quite reasonably priced ($54 apiece) and they only weigh 134 lbs each.  While that weight isn't light, it isn't anywhere near what I was expecting.  I've been toting the 5/8" OSB wall sheathing up to 110 feet from garage to build site, so half the weight of a truss won't be bad, especially if I put a big C-clamp on it to act as a handle. 

The idea of being able to get all my trusses set in a couple of days instead of a couple of weeks or a month or more immediately became quite appealing as it allows me to get the house in the dry a lot earlier than originally planned, and to do it pretty inexpensively. 

So, long story short, look over your project again to see if there isn't some way you can use prebuilt trusses.     

[glenn kangiser]

It is hard to beat the efficiency of a truss company and even with their engineering they are quite cheap. 

[Okie_Bob]

Why do I always agree with Glenn? Beginning to worry about self here!
Just as n74tg, I had basically the same thing happen. Was worried about building my own trusses and decided to stop in local truss shop and after about 15 minutes with their design guy sitting at his computer, he gave me a completely engineered design with prices I couldn't turn down and free delivery in less than 10 days! Then to top all that, the following Christmas I got a big box of the absolute best peanuts I have even eaten. (Even stopped back in to see where they get them but, they wouldn't tell me!!!)
Great people, low prices, perfect trusses, done when they promissed, delivered without a hitch. What more can you ask? I really don't think I could have built the trusses myself for the same cost when you consider I would have to go get the materials, usually several trip as I always forget something....etc, etc, etc. Plus being dried in much faster, it is a no brainer!
Okie Bob

[glenn kangiser]

When we're right, we're right, BoB.

Not to discourage anybody from building their own but the truss company buys massive quantities of 2x and many times the trusses will come from them cheaper than we can buy the wood along with the computer designed truss plan and stamped engineered design. 

[MountainDon]

Depends on
1. rules & regs you have to work under

2. how much your time is worth

I too looked into these and have the catalog of designs. They are very labor intensive. The plywood gussets must be glued. Air nailers can be used but each nail must be set manually as air nailers will not pull the materials together like a muscle driven 20 oz. framing hammer will.