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I'm attaching a TV mount (1/8" thick slotted plate) to a wall that is 1" soft wood (redwood?) paneling over what I suspect are 3.5" redwood studs. The studs seem to be square. The mount takes five fasteners (3 in one stud, 2 in the next).

From what I've read the bolts should go 1.25" - 1.5" into the stud so I was thinking I would use 2.5" long, 5/16" diameter lag bolts. To my surprise, the mount came lag bolts that are 3.5" long and 1/4" in diameter.

So, wise folk who use more fasteners than I do:

  • Would you use lag bolts or a structural screws?
  • How long?
  • Do you have a preferred brand? (please don't say Everbilt)
  • If a lag bolt, what metal and diameter?

Thank you!

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  • You mention that the studs are “square “. Are they 1 1/2” x 1 1/2” ?
    – Lee Sam
    Nov 21, 2019 at 7:16
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    From looking in another part of the wall, i thought they were 3.5 square. Reading what people have said, however, I now wonder if I am just seeing a few double studs and they are dimensional 2x4s. I didn't realize dimensional lumber dated to 1906.
    – LoftyGoals
    Nov 21, 2019 at 11:33
  • @LoftyGoals Preferred brand is a shopping question and off topic for this site, so you are unlikely to get an answer to that question here. Personally, I can't say I've ever cared about brand for lags, but there are only a couple of structural screw manufacturers I've seen locally and they seem to all have a good reputation.
    – UnhandledExcepSean
    Nov 21, 2019 at 15:16
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    If a television pulls off the wall with 1/4" screws something was done improperly, like oversize piloting. They will hold just fine.
    – isherwood
    Nov 21, 2019 at 15:32
  • Brand is on-topic if one brand is going to cause the job to fail. For example, I will tell anyone anywhere that Everbilt is dangerous unless you know what you're doing. In this case it seems like the brand doesn't matter so even Everbilt is probably fine. That's all I was trying to sort out.
    – LoftyGoals
    Nov 21, 2019 at 16:11

2 Answers 2

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1/4 lags should be fine even in redwood, many homes were built with redwood in the north Bay Area. Redwood is soft and has a lower withdraw force, I have 4 ea 1/4 x 3 lags holding a 78” flat screen I would use the same in redwood.

I would use lags over structural screws for the higher shear force. No brand preference, just plain old steel, bright or hot dipped it makes no real difference if they are not visible.

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  • why do you say lag bolts have higher shear force than structural screws?
    – warren
    Apr 28 at 11:25
  • @warren the shaft of a lag bolt is the full diameter and this is where the sheer strength comes from.
    – Ed Beal
    Apr 30 at 19:03
  • building code (and engineering reviews) would seem to disagree with you :)
    – warren
    May 1 at 11:23
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Use steel or stainless lag bolts. The 5/16" diameter will offer much more holding power than a 1/4" lag bolt.

The key to proper use of lag bolts is to:

  1. Make sure to use a flat washer over the slotted hole where the lag bolt will be installed.
  2. Make sure to drill the proper sized pilot hole for the lag bolt. This will offer the greatest pullout resistance and avoid splitting the stud.
  3. Use a hand tool when screwing in the lag bolts so that you do not over tighten them.
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  • This is great. What length and brand would you use?
    – LoftyGoals
    Nov 21, 2019 at 6:23

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