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Cracked vertical truss/beam - replaceable or sister it?

Cracked vertical truss/beam - replaceable or sister it?


  #1  
Old 03-05-21, 09:25 PM
W
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Cracked vertical truss/beam - replaceable or sister it?

There is a cracked vertical beam, possibly a king truss, in this attic. It is cracked horizontally, without evidence of rot/termite/water damage; and is cracked at a knot in the wood.

How would this be repaired? I have had recommendations to just replace the beam (how is this done given the truss plates/nail plates above and below, with typical DIY tools?)?
I have also received recommendations to sister two 2x4s on both sides, how would that be done?

The truss if 6ft tall, 2x4.
Thank you!

Pictures:



 
  #2  
Old 03-06-21, 05:12 AM
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This is a prime example of why we stress not overloading, drilling or altering trusses. Can you imagine how much force it would take to physically pull a 2x4 apart, and split it? That vertical king post is under tension, and the likely cause is too much load inside the attic, which it was not designed for. Plus, judging by the piece of 2x4 laying on the attic floor and the missing struts, someone altered those trusses by cutting them. Likely it was the company that installed that giant hvac unit that is just to the right off camera.

If that is the case, I would never say that this is not a "critical repair". Just the opposite... this is a dangerous situation and whoever cut those trusses should be held liable.

This is beyond the scope of DIY repair and you need to consult with the truss mfg, a structural engineer, or both. This is VERY serious.
 
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Old 03-06-21, 08:07 AM
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I hate to say it but I agree with XSleeper. Engineered trusses are one thing my building inspectors are very strict about. You don't mess with them at all (no cutting, drilling, adding attic storage...) without engineering approval.

As an emergency repair I would sister a 2x4 on both sides of the broken member as soon as possible. Most trusses are made with a high grade yellow pine or other high strength wood while the 2x4 you buy at your local home center are going to be something like lightweight spruce which is not as strong. So, keep in mind that this is only a temporary emergency repair.

In your bottom photo I would expect to see another diagonal on the right, mirroring the ones on the left side of the photo. This leads me to believe those diagonals were removed for the AC unit. It would be easy for you to spot evidence that they were removed. If they were then I hate to say (because it isn't cheap) you need a structural Engineer to examine your roof and design a fix/repair.
 
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Old 03-06-21, 08:25 AM
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Thank you for the response. I apprecaite the concern. I have reached out to multiple SEs in the area and have not had success in finding one - they either do not respond, state they don't do that sort of repair, or would not certify the repair was done correctly. Leaves me in a pickle.

If I was to sister a repair to it, and unable to obtain a SE consultation in the future, how might that impact changes of resale?

I do not believe there is a missing web member -- the photo crop didn't show the one on the right of it, you can see it in this photo:


How

 
  #5  
Old 03-06-21, 10:22 AM
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Well that photo helps clear up some of my concerns, and I'm glad I was wrong about the cut webs and things that the initial photo left out... and I'm glad there isn't a big heavy hvac unit up there.
 
 

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