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I am getting ready to install a new bathtub and shower.

After ripping everything out I noticed all the studs behind the original bathtub wall have cuts. See photo.

If anyone can explain why the studs are pieced together this way I would appreciate it very much.

[image of studs connected together with a zig-zag joint1

isherwood
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homegrown
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5 Answers5

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Those are called "finger jointed studs". These joints are weaker than regular 2x4 or 2x6. I do a lot of woodworking and when gluing boards together (for like a table top) the glue joints are actually stronger than the wood itself. But for some reason, that's not the case with finger jointed studs, they are just much weaker than the intact 2x. That and the alignment issue between the pieces make this product junk if you ask me.

The contractor that built my house started using them for interior walls. Some of the joints were off by as much as 1/4", which would have made sheetrocking much more difficult. My plumber said he hates them because unless you brace the stud when drilling, they'll break at the joint. To demonstrate, he got a short length (about 4') with a joint in it, elevated one end on a 2x and then proceeded to kick down on it. It broke right at the joint.

After a few interior walls were built with that crap, I inspected and found many cases where the joint wasn't at all even. I told the contractor to tear those walls and not use that crap anymore. He didn't like me for it, but later, when he used them on a project for himself, he admitted they were crap.

To answer, since they are already in place I wouldn't worry about it. The vertical load capacity isn't affected, esp. not an issue in a non-load bearing wall.

Sorry for going off like this, but finger jointed studs are just not a good product.

George Anderson
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  • Thanks for the response. It makes sense what you’re saying and yeah I am not going to be removing any of these studs but I surely wouldn’t buy anything like this either. To your point some of the joints are off as well and don’t seem to line up exactly. – homegrown Nov 15 '20 at 17:27
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    I've not seen these issues before. It's possible that you are commenting about the quality of the manufacture, not the product. And then the answer is to not buy cheap finger jointed wood. It's no different than regular wood, the less $ the more issues... – Ack Nov 15 '20 at 17:43
  • @homegrown I meant to mention that what you noticed, even in the pic you posted I could see misalignment or differing dimensions. A hand plane or power planer could fix that. Somebody DV'd me on my answer, dk why, oh well. No worries re your project...just me railing against finger jointed studs. – George Anderson Nov 16 '20 at 08:12
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    Is Steve Wellens the author of a deleted answer? Or some other pundit? In either case, we're missing context here, including what we're comparing ("cheaper and weaker") it against (some other joint, I presume?). Can you rephrase those first few sentences so that this answer is self-contained? – Toby Speight Nov 16 '20 at 11:19
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    I sympathise with your feeling on this, but it sounds like you're in a country that lacks minimum standards for building materials, vis some of the other users. In New Zealand we have https://codehub.building.govt.nz/home/resources/14911996asnzs/ and https://codehub.building.govt.nz/home/resources/8008int2014-asnzs/ which is "a specification for finger-jointed structural timber viewed as substitute for solid timber" and describes minimum values for everything you might measure. This is a different level to the local sawmill's offcuts pile and some wood glue that sellers peddle. – Criggie Nov 16 '20 at 11:31
  • I join the chorus in general support of finger jointed lumber. If you look at a glu-lam beam, they're usually made of finger jointed 2x4 that are then laminated to the thickness needed for the beam - my garage door header is made this way. I think it depends more on the quality of the particular mfgr than an indictment of the joint/process in general. – FreeMan Nov 16 '20 at 12:02
  • @TobySpeight Steve Wellens commented on Solar Mike's answer that finger jointed studs are "Done at a factory to make full use of shorter bits of wood. Just as strong and straighter than one long bit of wood." – Nosrep Nov 16 '20 at 13:31
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    @FreeMan there is a world of difference between a laminated beam (lots of glue area between the pieces, unbroken pieces next to the joints) and a single stud (barely enough glue area to hold the two pieces together until installed). To get something mechanically similar here, you'd have to glue a short length of wood on both sides of the stud joint. – Olivier Nov 16 '20 at 15:19
  • @TobySpeight I dk where Steve's post went, he may have deleted it. He said it was a good product and I had to disagree. I'll edit my post, delete the ref to him and re-phrase. – George Anderson Nov 16 '20 at 15:31
  • @homegrown If you have a hand plane (or power hand plane) you might want to take a swipe or 2 to even out the joint. Not a big deal, just a suggestion. – George Anderson Nov 16 '20 at 15:42
  • The only part of the joint that _needs_ to be flush is the one to which the wall surface is going to be attached. In this case, it's really hard to tell, but that one _looks_ to me to be smooth. Since this is a remodel, there _used_ to be wallboard (of some sort) over these studs and if the OP didn't have an issue with the surface not being good then, there shouldn't be an issue with it now. – FreeMan Nov 16 '20 at 16:06
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    _Notes that this is why "opinion" based questions are Off-Topic here. An "opinion" based answer has generated a fair bit of controversy... :)_ – FreeMan Nov 16 '20 at 16:07
  • @FreeMan Yes, I get your point. Thank you for the reminder. I usually don't opine much, but in this case, I just wanted to let people know of my experience with this product and it's not good. I'll try harder to contain my answers in a more factual basis rather than opinion. Thanks again. – George Anderson Nov 16 '20 at 16:14
  • No worries, @GeorgeAnderson we all need to vent sometimes! TBH, you do seem to be in the minority - maybe you've just not come across the best lumber. Finger jointing is becoming very common, not only for framing lumber, but for window/door jambs in a "paint grade" (to hide the joints) finish, as well. – FreeMan Nov 16 '20 at 16:19
  • This stud was behind the tub but the tub had “walls” that were attached to the original bathtub - not sure what the proper term for this is. So I’m actually not sure if some wallboard will go up nicely without planing some of these studs. I plan on installing hardiebacker or durock over this so I’ll find out if additional work needs to be done. I just wasn’t sure what the point of these joints were since this is newer house (2002) and my parents house did not have this (their house was built sometime in the 70s). Didn’t mean for this to ignite a heated debate! – homegrown Nov 16 '20 at 17:46
  • @homegrown No worries, I don't consider this a "heated debate" , but it is somewhat opinion based, which is generally frowned upon here. Still, I think it should be tolerated that if someone has experience with a product that they feel is inferior, they should have the opportunity to share that experience. If others disagree, well so be it, they can chime in as well. Take care and good luck on your remodel project! – George Anderson Nov 16 '20 at 22:19
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That is a join between two bits of timber.

The ends are machine cut and glued.

Solar Mike
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    Done at a factory to make full use of shorter bits of wood. Just as strong and straighter than one long bit of wood. – Steve Wellens Nov 15 '20 at 15:49
  • Thank you both for the explanation. I don’t think I’ve ever seen these sold at a Home Depot or other big box store but then again I may just have never noticed them before. – homegrown Nov 15 '20 at 16:19
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    They are becoming more common. The reason is scarcity of wood / less waste (more 'green'). These studs are in affect made from scraps or taking the quality pieces off of a solid wood stud that has bad unusable sections. – Ack Nov 15 '20 at 19:20
  • I see those types of joints a lot in trim wood, but never in a 2x4 wall stud. – SteveSh Nov 16 '20 at 19:07
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As others have said, this is "finger jointed" lumber. The quality of such lumber varies from quite good to kind of piddlin' poor. The purpose of the joints is to allow knots and other bad spots in the lumber to be cut out, producing a piece that is straighter and easier to work with than it would otherwise be (and of course allowing longer pieces to be produced from a given tree).

The care taken in cutting the joints plus the amount and quality of the glue used determines how straight and strong the joints will be, though the quality of the original lumber is also a factor.

And note that similar joints are commonly seen in wood trim, particularly in exterior trim. In exterior trim eliminating knots and splits is especially important, so the use of the technique definitely improves overall quality without running costs sky-high.

Hot Licks
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    I have to disagree. the softwoods (hem-fir, etc.) used can have substantially different movement during drying. If the manufacturer re-milled them after drying it would be better, but still not good. This is just a way to stick together leftovers and try to market an inferior product. They are garbage. I don't usually get this emphatic here as I totally respect others comments, usually they have a lot more experience than me. But having personal experience with finger jointed studs, I'm going out of my own bounds and calling them out as unmitigated crap.. – George Anderson Nov 16 '20 at 08:04
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Finger jointed studs are used because they can carry more weight without bending once you nail the plywood. They will always be straighter than regular studs; no bends means it takes more to break when bearing weight.

Glorfindel
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Caz
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    Do you have any evidence to support your claim of "always straighter" and "it takes more to break when bearing weight"? – FreeMan Jul 06 '22 at 18:42
  • They will not _always_ be straighter. Maybe on average, but there are plenty of straight solid studs and there will be some warped jointed studs. – isherwood Sep 12 '22 at 13:15
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I would prefer a solid stud if they were true #2 as they were in the past. Today, a lot of #2 lumber would be tossed aside in the past. There have been millions of homes built with finger-jointed lumber with no issues. They are more straight and offer the same amount of structural integrity in compression as a solid stud. There are even finger jointed rafters available. One of the reasons is fast growth timber, making it difficult to find long solid boards. You can refer to ICC's testing labs for an in-depth analysis of FJ lumber.

Zenhowie
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  • This doesn't answer the question. Please take the [tour] to learn how we're different from a discussion forum. – isherwood Sep 12 '22 at 13:15