Testing Toe Nailing vs. Face Nailing
The “framing methods?” thread raised a question that deserves its own thread:
Which is stronger, toe nailing or face nailing?
It should be possible to come up with ways of testing to get a numerical answer, any ideas? I’m thinking building ten examples of each, and loading them until they fail. But we’d want to consider tension, shear in the plane of the joint, shear perpendicular to the joint, maybe some other considerations? Hmmm — ten of each in three loading directions is already sixty joints to build and test….
Another consideration is that there are variables in the toe nailing process. Face nailing is all pretty much the same, but I’ve seen toenails started anywhere from 3/8″ to 1 1/2″ from the end of the two by. First we’d need to standardize on how to make the toe nailed samples.
— J.S.
Replies
Sounds like the beginnings of an article in FHB. Go for it.
OK, is there a possible article here? Or how about a toe nailing contest? Maybe have a proper structual lab do tests on a bunch of samples for the article, and give a subscription extension to the person who sends in the strongest toe nailed test piece?
-- J.S.
Here's my little take on why a toe-nailed joint is stronger than an end nailed one.
A]
The end nailed joint only needs to pull straight off the neil in one direction to release for the other piece of lumber. It only fights friction and displacement. The end of the nail slides more easily along the same axis as the grain of the wood. Ring shank or coated nails can increase this friction and larger sized nails can increase the dispplacement.
The toe-nailed joint has to pull against diagonally placed nails which function similarly to a diagonal brace in a structure. The wood must tear across the grain of the wood to release, in addition to overcoming friction a some amt of shear in the metal. This combination of forces creates the stronger joint.
B]
My own experience in demo work is that joists installed with toenails are harder to pull apart. I have been called to repair more decks which were built with endnailing in the frame than those toenailed.
C]
I have also read - tho I can't quote the exact source - that there are studies to show that a toenailed joint is preferable for horizontal applications such as decks and floors. I believe that article said that codes required toenailing over end nailing for any framing other than platform framed walls. I have never worked in codes jurisdictions so I neveer been compelled to demonstrate that point.
It could be a good article, given the number of decks that fail for various reasons. It could be a technical article on joints and nailing in general, or a sidebar to deck construction. A deck constructiion standards article could actually save lives. Think of the number of DIY s who read this magazine and who build their own decks!.
Excellence is its own reward!
Way back when. I had job as a carpenters helper. One of the carpenters tried to teach me to angle the end nailed plates, I'm talking about hammering 16d nails through the plate into the stud, in at about a 30 degree angle down and one each at about 20 degrees, a small enough angle to make sure they don't come out the side of the 2by4, alternated side to side. He claimed it was a much stronger joint for uplift. Another carpenter said it made no difference.
Would this strategy change the strength of the joint? How much? Would it be stronger than a toenailed joint? In shear? In withdrawal?
I will say that the joints seemed stronger for the very few we had to take apart and the procedure, once learned and practiced for a bit, didn't take any more time while hand nailing. No nail guns back then.
I would agree with his theory and as I thionk back, I'm sure that I instinctively but sub-consciously do the same thing..
Excellence is its own reward!
The perscriptive code has nail schedules that include both straight-nailing and toe-nailing.
NER-272 has perscriptive methods for clipped head nails used in straight-nailing and toe-nailing.
The NDS for Wood Construction has details for proper toe-nailing and approved engineering analysis.
Yes and all of those are based on testing the different types of nailing.
I would image that a search of the US Forrest Products Laboratory web sites might give you some of the results of those tests.
I think there's probably a greater range of variation in toe nailing. A lot depends on where you put the nail into the end piece. I've seen a lot of stuff done by guys who figured out that they could avoid splitting the wood by starting the nail close to the end, say 1/2" to 3/8" from the end. The nail then cuts across the fibers, leaving only the strength of a little triangle of wood 3/8" on a side by the thickness of the nail to hold things together. This little piece shears out pretty easily.
Of course, going to the other extreme splits the wood, or results in the nail exiting so close to the far side that it can deflect off the cross piece and bend. Code allows pre-drilling to 75% of the diameter of the nail in the first piece, to prevent splitting, but who can afford the time to do that in production?
If the joint is in tension, pulling the end piece away from the cross piece, and the toenails grab a sufficient amount of the end piece, I can see your point that that would be stronger. The face nails have nothing but friction to hold them, while with the toe nails, you also have to bend the nails in addition to overcoming friction. Fortunately, there isn't much tension in wood framing. That's what the codes mean by "nails in withdrawal", which is generally forbidden because they hold so poorly. Especially if the wood dries out and shrinks, such joints can be pulled apart by hand. I've even pulled nails using just my thumb and forefinger where the wood was dry enough.
It may be that you've repaired more decks done by end nailing than toe nailing because end nailing is generally easier to do, so more decks are built that way. The big hot button code issue is face nailing ledger boards to the house. A lot of fatal deck collapses have been caused by that. Of course, the Simpson hangers get face nailed to the ledger, I angle the hanger nails downward so the load doesn't act to pull them out.
Code here allows both face and toe nailing, for instance 2x4 wall framing can be either two 16d face nailed, or four 8d toenailed.
-- J.S.
End nail can be stronger then toe nail if done right
Me and one of my friends was talking about this the other day. He said that toe nailing was stronger then end nailing. I asked him how he know that to be the case. He said because if you end nail than it can easily be pulled apart because the nails just pull strat out but if you toe nail than it is harder to pull out because the nails are angled in to the wood. He is wrong and here is why. That what he said sounds right but it is not really right. End nailing is stronger if nailed the right way. If you angle the nails away from each other you can get the same angles as toe nailing and since it is easier to do you can get better angles than toe nailing. So toe nailing is not stronger end nailing is you just have to do it right.
John,
Good thread. Now I'm curious on one thing so far because no matter which way we all frame walls "California Style" (Face Nailing) or "New Jersey Style" ;-) (Toe Nailing)) how many framers or anyone else that frames thinks it's stronger to Toe Nail or Face Nail Rafters to the ridge?
I personally toe nail rafters and think it's stronger. This is how I was taught and also told by Architects and Engineers. I've tested both ways and pulling out a toe nailed rafter is alot harder to do then to pull out a face tailed rafter.
Like to to here from an Architect or Engineer also.
In New Jersey we don't worry about earthquakes so there is absolutly no straps, no special bolts or bracing, shear wall discussions etc.
Joe Carola
Edited 3/28/2003 6:50:04 PM ET by Framer
Joe,
I reread an article in JLC by Harris Hyman P.E. about nails. I'll post a screenshot of the paragraph about toenailing. If you have the JLC CD-ROM the article is in the Feb. 1994 "Holding it Together"
Here is the pic.
Edited 3/28/2003 7:49:36 PM ET by TIMUHLER
Thank you kind sir.
Ok, I deleted the picture to put a better one in my post, but couldn't so here it is.
When it comes to nailing rafters to ridges, it's important to consider that there are two kinds of ridges.
I've seen the term "structural ridge" used to mean the kind where the ridge is a beam that carries about half the weight of the roof. In this case, the rafters are supported vertically by the ridge beam and by the wall. They're sort of like joists on a big slant. Instead of outward spreading forces on the walls, you have tension in the rafters trying to pull them away from the ridge beam. The attachment of the rafters to the ridge has to resist this tension.
The other kind of ridge is just a piece of one by. It keeps the rafters for one side of the roof lined up with and pressing against the rafters for the other side. And it keeps the rafters from falling over before you get the sheathing on. In this case, the outward spreading force is a very big deal. The ceiling joists resist that force if they're running the same direction as the rafters. If they aren't, you have to put rafter ties perpendicular to them and right over them. But in this case, the attachment of the rafters to the ridge isn't particularly critical. The rafters are pushing against the ridge, the nails just need to keep them from sliding out of place. It's the rafter to wall plate connection that needs the special earthquake hardware.
-- J.S.
Might be a good project for a materials class at KU. How'bout it CAG?
You did not say..
you did not say what you were nailing? I would say which is better depends on what you are fastening and a bunch of other stuff.
Not all toe nais are creatred equal. Did you split the wood in teh process? Many times people do. Not everyone is able to do a toe nail well.
I would think a toe nail in a perfect world would be stronger for uplift.
then again you are talking about hundreds of studs so uplift forces are spread over hundreds or thousands of nails so they are not likely to collectively fail in that senerio.
But I think alot of toe nails are not done well. It is kind of like the fact that Fiber glass insulation if installed right is as good as spray foam. The problem is, it is rarely installed "well/right".