Why Teco Nails?


For years I've wondered why we are supposed to use teco nails for joist hangers. Wouldn't a screw do a better job on holding things together in an earthquake or what ever?
Thanks, RO
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Robert Olin
Bob\'s Water & Septic LLC
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Yes, some screws would probably be better than hanger nails but hanger nails are bettter than a lot of different types of screws. If screws were allowed ......then someone, sometime, would be "out of the correct screws" & then drywall screws (or whatever they had in their pouch, truck or local hardware store) would get used.
Drywall screws would be the worst of the worst but many screws exhibit brittle behavior. Nailed connections are know quantities, nearly always exhibit ductile failure.
Drywall screws are for hanging drywall but I see them used for just about any application imaginable.
So I guess the hanger mfrs just stick with nails " 'cuz that's the way we've always done it". Plus nails install faster?
cheers Bob
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But, why are teco nail so short? You would think a 16d would hold a lot better.
RO
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Robert Olin
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The wood can split. Many of the applications may call for teco or 16s common or 10s common. Look up the nailing in the Simpson Strong Tie Book, You may be surprised to find out that the nail you are using is not the nail that is recommended. Anyway, some joist hangers and H-1 or others use 16s or 10s common. Strapping takes some differing nails..... Again, it is the "shear" of the nail not the holding......... jloomis

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RO wrote:

Because the nailed item is less than 1/16" thick for the most part. That gives you almost 1 1/2" penetration. Much of the hanger,holddown,nail pattern logic defies common sense. We will see when the BIG ONE comes. However I do trust the math. Its the nailing patterns I wonder about. tonyg
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We do use some hex screws in PHD's I know the reason is the strength. The nail has great "shear" strength. And as the other reports, some screws are hardened, and break. I like to use Hot Dip Galvanized tecos.... Some of the teco nails just seem not to have holding power.(brights) jloomis

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The only "hex screws" for use in Simpson PHD's are the Simpson SDS screws...using anything else is asking for trouble....unless you really know the screws & the particular application.
I know the SDS's are a little spendy but they're worth it. I used them for strucutral testing of plywood shear panels (to attach fixture to panel), we got many uses out of them, no problems, no failures....more than I can say for HDepot (any where else) cheapo "lags".
Where have those black lags screws from the 50's & 60's gone? :( When lags had 1/3 grip & 2/3 thread....not all over the map....no or minimal grip?
cheers Bob
cheers Bob
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RO wrote:

Yes, but only rated screws. Drywall screws are too brittle and would snap in shear.tonyg in p.t.
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The idea isn't usually to hold something together, but holding something up, in a way that the shear strength of the nails is way more important than the holding friction keeping the nails in place. The nails can be short, since the shear strength of a 2" teco nail isn't much different than a 16d framing nail.
The shear strength of most screws is way lower.
JK
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Thanks guys, for all the info. From the Simpson site, it sounds like you can use 16d's into the support header, on say a 2x10 floor joist hanger. I can see how a shorter teco nail make more sense when nailing the joist hanger to the joist. RO
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Gotta read the Simpson footnotes for each connector. All sorts of hidden gems. :) Different connectors spec different nails. Their nail patterns baffle me & I did structural testing on wooden specimen for over 10 years. The A35 is crazy.
Even the SDS's have a footnote that pre-drilling might be needed! Most overlook that.
Simpson tried to get SDS concept to work in greater than 1/4"...just wouldn't work reliably. :( So SDS only in 1/4"....too bad awesome screws.
cheers Bob
cheers
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RO wrote:

If you nail hangers to a built up beam say 2,2x10s nailed together than you should nail the hangers with 16d sinkers or the 2 1/2" teco nail. The idea is to get penetration into the far piece. The the load is on both pieces. T
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