Broke truss when installing

[GMCGarage]

Yes, this^^^^^. Did anyone else read the spec to discover the maximum tension in this piece of lumber is 540 lbs (a relatively low result, there are other pieces with thousands of pounds tension)? Simpson makes nail plates for this purpose. New wood, plates, ring shanks, through and bend them over. If you know which end of the hammer to hold, you can make this hold 500 lbs.

I understood the OP that the truss broke off before Node 3 and Node 12. I read that the diagonal is still intact. It broke before the plates.

 

[Ironcrow]

OK, not clear. But, either way if you know how to read the drawing, you can see what forces you are constraining. The lower chord of the truss is under great tension of course. The original design also places a plate in the middle of this chord, so the technology is capable of carrying the design load. I'm not a subscriber to the idea that truss design is inscrutable black magic, not to be touched by the unwashed. It is really a trivial backwater of civil engineering. Sure there is significant confusion in a complex hipped gambrel roof with dormers, with trusses supported in 3 places, or cantilevers with huge uplift issues, etc, but this is a simple truss on a rectangular box.

 

[GMCGarage]

OK, not clear. But, either way if you know how to read the drawing, you can see what forces you are constraining. The lower chord of the truss is under great tension of course. The original design also places a plate in the middle of this chord, so the technology is capable of carrying the design load. I'm not a subscriber to the idea that truss design is inscrutable black magic, not to be touched by the unwashed. It is really a trivial backwater of civil engineering. Sure there is significant confusion in a complex hipped gambrel roof with dormers, with trusses supported in 3 places, or cantilevers with huge uplift issues, etc, but this is a simple truss on a rectangular box.

From the OP, "The truss fell snapping off one end just outside of the truss metal plates."

Trusses are engineered to the bare minimum. I agree that most laymen could fix a truss. The OP is worried that if the inspector sees a fix, and does not have a PE stamp for the fix, it will be rejected, and then more scrutiny on the rest of the project.

wood is very forgiving, if the OP fixes this with a scab piece and bunch of nails, if it fails it will more than likely not bring down the whole structure. The issue is, at what span, load, etc does it get out of the laymans knowledge and into requiring expert analysis and design.

You really want some fun, go do some repairs on a 100' bowstring truss. I worked on a repair design for on of these some time ago. More time was spent on the design of the supports and where to support than the actual fix.

 

[Jeepster04]

I've built my own trusses several times. Last time for this house, from #1 grade (mostly clear) yellow pine and 1/2" plywood gusset plates glued with structural glue and nailed in place. In Matt i's photos above it looks like ordinary "white wood" in the trusses. Look at the way the wood snapped in two in the second picture. That's just not very strong wood for a truss.

Ive always thought that glued/nailed plywood joints were much stronger than the plates that are pressed in. If it were mine, this would be my fix...

 

[tenlug]

I'm a long time framer and worked for a PE doing structure repair. If you haven't sheeted yet just get another truss.

 

[Rock knocker]

Ive always thought that glued/nailed plywood joints were much stronger than the plates that are pressed in. If it were mine, this would be my fix...

On an inspected and engineered job, one doesn't get to pull their repairs out of their back pocket.

 

[rburke65]

Just let us know what you did and how all this works out.

 

[Texan1]

I suggest trying to get in touch with the Designer that handled your project. If your lucky they will have basic repair tool functions enabled in their Mitek Engineering program and be familiar with how to simulate the broken member damage conditions you have described and generate repair details - either 2x4 scabs or ply/osb gussets sized by the engineering program. If they can get it to run on their end, they may be able to send that drawing in to Mitek (assuming they typically source their sealed profiles from Mitek) and get it sealed far cheaper and possibly even for no charge vs. you finding an Engineer to determine what the repair should be and then stamp it.
my 2 cents...