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I am trying to install a bike hoist on my garage ceiling, and ran into this piece of metal when drilling through the drywall to the joist:

It looks like the material behind the metal plate is wood. Can you tell me what this steel is? Can I drill through it to the wooden joist?

Update:

Since this is in first floor garage, with Living room upstairs, it doesn't help to check from the attic.

I dug the hole a little more from both sides, it looks like, and I can feel, that it is the regular 2 by 4 wood stud behind the metal plate, and there seems to have no wire etc I can touch around. So is it safe to drill?

I need to screw with a 3" lag bolt through the metal, so I guess I will need a titanium drill bit to do the work?

Thanks a lot! studhoist

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    Metal plates are sometimes used as a warning device to warn of pipes or electrical wiring that is within 1-5/8" of the surface of the wall. The metal isn't immune to screws, it's only to make you aware you should probably proceed carefully. – Harper Jun 16 '17 at 4:40
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    Since you've already got a fairly large hole, I would just make the hole large enough to clearly see what the structure is. Then patch with a new piece of drywall. – longneck Jun 16 '17 at 15:56
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I wouldn't drill it. It's probably a truss splice plate. Can you get in the attic and look to see if it wraps up the sides of the bottom chord?

  • If it is a splicer, one screw hole won't be a problem. – isherwood Jun 16 '17 at 12:03
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    @isherwood OMG If that's a splice, then it's in TENSION and it will be a problem. If it was in compression, then it MIGHT NOT be a problem. – Lee Sam Jun 16 '17 at 13:11
  • There are already dozens of stamped holes in those plates. OMG one more small one won't do a thing, especially since a screw is likely to fall into an existing hole. Also, wherever they're in tension they're quite large. – isherwood Jun 16 '17 at 13:29
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    @isherwood Hmmm...three more reasons not to drill it: 1) You don't know the size of the proposed hole, 2) drilling it could disturb the surrounding teeth into the wood, and 3) those "stamped holes" are from the fabrication of the steel plate putting "prongs" or "teeth" into the wood. – Lee Sam Jun 16 '17 at 13:40
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It sounds like you have there a bottom chord of an engineered floor truss. You've encountered a butt joint. There may be a plate on the top side as well.

While it's a critical component, a screw hole will not be a concern. If you can, hit one of the stamped holes. If not, drill up to a 3/16" hole where needed just through the plate. There's enough overhead built into those trusses that this is not a concern for failure.

If you're using larger screws, consider moving a few inches to avoid damaging the plate with larger holes.

  • Even if you run the screw through an existing hole, if there is a plate on the top, you're likely to hit a solid point and push the plate up. I'd just move 6-8 inches one way or the other and avoid it. – Tim B Nov 13 '17 at 15:21

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