Accidentally cut the bottom chord of truss. It happens on the corner of the stud and not fully cut through as picture showing. If I would like to fix it, which contractor should I contact? And would the repair make it even worse since there may need to use screws? Great thanks. enter image description here

  • All these truss questions lately are terrifying. But there seems to be some question about whether this is actually a truss. Can you slide a tape measure up there and get the dimensions of the lumber?
    – JimmyJames
    Dec 21, 2020 at 21:23

3 Answers 3


No contractor needed. Cut a piece of 1/2" plywood 3-1/2" X 12", drill 10 screw holes in it, slather it with glue and screw it on there. Might be overkill, but should do the job.

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    Agreed with both Ecnerwal & JACK. That's a pretty minor problem. Like JACK said, if you want to sleep at night and not worry about it, I'd just sister on a piece of plywood like Ecnerwal said and call it a day. Also, it's close to the support so even less of a problem than if it were in the middle of the beam. IMHO, Like Kris said, I wouldn't even fix it. You're fine. Dec 20, 2020 at 15:29
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    Or omit the screws and just clamp it. I'd use an epoxy with bonding fillers, that comes out about ketchup consistency... wet both surfaces, push 'em together, smallest possible wood screws just to get the surfaces to clamp together hard. The screws are irrelevant after the epoxy cures. The epoxy is doing all the heavy lifting. A million years later, a civilization doing archaeology will find bare copper wires, and that thin layer of epoxy. Dec 20, 2020 at 17:45
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    When it comes to peace-of-mind "there is no overkill" (the rest of the quote doesn't apply here)
    – Criggie
    Dec 21, 2020 at 6:25
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    DIY building repairs are how you get your insurance company denying payments if something goes wrong. If that beam is load-bearing and the roof collapses because he did a dodgy DIY job, good luck getting your insurance to pay up.
    – nick012000
    Dec 21, 2020 at 12:46
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    @nick012000 This is a DIY site.
    – Kris
    Dec 22, 2020 at 13:55

If you need to fix this so you can sleep better at night, any carpenter would be able to sister this truss for a repair. In my humble opinion though, no repair is needed. If you look around up there, there' a good chance you'll see notches cut all the way through for cables, conduit, pipes, etc.

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    If the description is accurate, this is a truss so there shouldn't be notches in the flanges at all. Having said that, the picture sure looks like a solid joist, not a truss, so I think you're right that no repair is needed. Dec 21, 2020 at 17:32

WHOA. Oh my lord! I hope nobody was injured.##

Did you hear any snapping/cracking after that cut? Have you checked measurements of the ceiling to measure lag/deflection. It may not be safe to remain there.

... and you're right to be worried about the effects of screws on the integrity of the remaining wood grain!!!

For something like that you will need to adhere two steel L-brackets to the chord's surface, and use threaded fasteners to recover the structural tension previously contained by the destroyed wood fiber.

example l bracket

Don't worry, It's not too hard though:

  1. Begin by removing all adjoining ceiling/drywall.
  2. Clear any insulation that may be in the way and clean the surface of the wood.
  3. The brackets should be at least 3/8 inch thick stainless. The photo above was for general example only.
  4. They should match the width of the beam, and be at least 18 inches long.
  5. Drill several bolt holes in the "L" to accept properly torqued fasteners.
  6. Make sure they're welded, not bent, as you don't want them bending back under tension. Any reputable local metal shop should be able to whip these right up for you NO PROBLEM.
  7. Make sure the backside is sanded with texture, not smooth, for maximum adhesion. The shop may be able to impart a pattern with CNC as well for you.
  8. Apply ample construction adhesive to the brackets, line them up and clamp them in place temporarily leaving an inch or two between them for closure of the gap.
  9. To help the adhesive dry, install a dehumidifier in the area, and allow it to run for several days. You need maximum adhesion for this repair.
  10. Return and install the bolts/washers.
  11. Tighten first by hand, then by crescent wrench until it gives resistance.
  12. Then use an impact driver. (Pneumatic or electric should be fine) and fasten until you hear the wooden beam crack. This will take up the slack created by the laceration in your photo.
  13. Then reverse one eighth to one quarter of a turn.

At this point, the ceiling should return to straight and level, and you can finish the job by covering any exposed threads, nuts, bolts, washers with construction adhesive to prevent them from slipping loose in the future.

So you see, not that big of a deal. Enjoy your repair, and Relax, this is totally fixable!

  • 13
    If this is satire, it's inappropriate. If this is a proposed solution, it's inappropriate.
    – isherwood
    Dec 21, 2020 at 16:34
  • "Have you checked measurements of the ceiling to measure lag/deflection." - that's about the only decent part of that answer. Pretty clear from the photo that in this case there wasn't any. Dec 21, 2020 at 17:00
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    You forgot to mention 'sell the place within the next week'. And 'Use at least ten acroprops immediately'.
    – Tim
    Dec 21, 2020 at 17:11

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