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-   -   Used wrong nails for joist hanger (http://www.diychatroom.com/f15/used-wrong-nails-joist-hanger-84566/)

odlaw 10-21-2010 02:52 PM

Used wrong nails for joist hanger
 
I used 1 1/2 in joist hanger nails in the joist of a double shear hanger. I questioned this and was assured by Lowes expert and other bystander contracter that 1 1/2 was the proper nail to use.
I now know that those nails are useless and I really needed a 3 in nail into the joists.
I have 44 hangers put up and already nailed. I am only hanging sheetrock for a ceiling off of these 2x4 joists. Any Thoughts??
Thanks

jlhaslip 10-21-2010 03:45 PM

1 1/2 " joist nails will be fine unless the joists are holding up more than a 2 x 4 will carry.

Did you fill all the holes?

Daniel Holzman 10-21-2010 04:10 PM

If you purchased a standard double shear joist hanger such as a Simpson or a USP, the specified nail is a 10d galvanized common (for outdoor use). These nails are typically sold by the 1 lb or 5 lb container, and are right next to the joist hangers in the aisle. The 10d nail is typically 1-1/2 inches long, and is specifically sized for the hole provided in the hanger. For example, a Simpson LU26 takes 6 10d face nails, and 4 10dx1.5 inch joist nails.

I have put up dozens of these hangers, and have never used a 3 inch nail, I don't know who exactly makes a 3 inch nail specifically designed for the hanger, but I have not seen a Simpson or USP 3" nail for that purpose. I wonder where you learned that a 3 inch nail was required?

Gary in WA 10-21-2010 05:42 PM

Are they double joist hangers? Do you need the shear hangers to hold everything together or on the plans?
http://www.strongtie.com/products/co...ace_ss-df1.asp

Gary

DangerMouse 10-21-2010 06:41 PM

1 Attachment(s)
Use the 1" joist nails to face nail the hangers,

and the 3" Galv. 10D commons to double shear/toenail (45) through the side slots.

DM

wnabcptrNH 10-21-2010 06:42 PM

Quote:

Originally Posted by Daniel Holzman (Post 520852)
If you purchased a standard double shear joist hanger such as a Simpson or a USP, the specified nail is a 10d galvanized common (for outdoor use). These nails are typically sold by the 1 lb or 5 lb container, and are right next to the joist hangers in the aisle. The 10d nail is typically 1-1/2 inches long, and is specifically sized for the hole provided in the hanger. For example, a Simpson LU26 takes 6 10d face nails, and 4 10dx1.5 inch joist nails.

I have put up dozens of these hangers, and have never used a 3 inch nail, I don't know who exactly makes a 3 inch nail specifically designed for the hanger, but I have not seen a Simpson or USP 3" nail for that purpose. I wonder where you learned that a 3 inch nail was required?

+1. I have worked on government run projects where everything is monitored and I have put up a ton of hangers and they were hanger specific shear nails about 1.5" long. How would a 3" nail change the shear factor?

Gary in WA 10-21-2010 07:03 PM

http://www.strongtie.com/products/connectors/nails.asp

Gary

Daniel Holzman 10-21-2010 07:40 PM

Turns out this is a lot more complicated than I ever dreamed. The Simpson catalog in fact specifies 10d nails that are 3 inches long, and allows 10d nails that are 1-1/2 inches long for certain hangers, but as near as I can tell only for the header nails, not for the joist nails. For many of the hangers, the correct nail is the 10d 3 inch long nail, or for some of the heavy duty hangers 16d nails are specified.

Here is where things get odd. Simpson has a load reduction table that specifies the reduction (typically to about 70%) if you substitute 10d 1-1/2 inch nails for 10d 3 inch nails. However, there does not appear to be a reduction table for using the shorter nails into the joist. As near as I can tell, Simpson does not want you to use the shorter nail into the joist, so they don't provide a table showing required load reduction if you do use it. I guess this means that Simpson is not going to tell you what reduction to take if you inadvertently use the shorter nails into the joist.

The strange thing is that at Home Depot, Lowes etc. the short nails are sold as "joist hanger nails", and you have to search the hardware aisle for three inch hot dip galvanized nails that meet the spec of Simpson and will withstand PT lumber. This probably explains why the majority of decks are nailed together with short nails, which by the way are easily identified by the 10 stamped on the head of the nail. I can't recall ever going into a Big Box store and finding 10d three inch nails next to the hangers, so this probably explains why hardly anyone uses the proper nail to put up a hanger.

All that said, the load capacity of a nail in pure shear has little to do with the length of the nail, and everything to do with the diameter and strength of steel. However, the Simpson catalog lists load capacity for floor loads (nearly pure shear on the nails), but also for uplift and seismic. Under seismic loading, nails may be subjected to pull out forces, and the deck could be subjected to torsional forces, neither of which are pure shear, hence the length of the nail could be very significant for that specific type of load. A similar argument could be made for wind load, as the deck could be subjected to twisting loads, and individual nails could be subjected to pullout forces. You might also make the case that short nails are more likely to get loose over time as the wood shrinks and checks.

Obviously the proper thing is to use the specified nail, however you already used the wrong size. The hanger capacity could be downrated to the Simpson value of approximately 70 percent for the header nails, which is probably well above the required capacity anyway. The issue with the joist nails is more complicated, since Simpson does not publish a reduction factor for the short joist nail.

I suppose you could pull all the joist nails and use longer ones, and compute the capacity at 70 percent or so. This is probably adequate, but can be checked. Pulling the nails is likely to be a PITA, but since the joist nails go through a tab, it might be doable.

Alternatively, you could leave the shorter nails in the joist, and take your chances, if the inspector lets you do so. If you don't live in seismic country, and you manage to avoid hurricanes and tornadoes, my guess is you will be just fine. However, I am not your local inspector, so my guess carries no weight.

Gary in WA 10-21-2010 09:12 PM

D, footnote #4 in post 7.

Gary

jlhaslip 10-21-2010 09:26 PM

Thanks for this information, GBR.

I stand corrected.

odlaw 10-21-2010 10:17 PM

Thanks for all the replies. I pulled all the nails out of the joists and replaced them with 3 in nails. The joist nails pulled out with just a pair of vicegrips and some muscle. I might have over reacted but I have piece of mind now.
Thanks again

RetiredRGM 05-27-2011 11:31 PM

What about hanging them with screws

DangerMouse 05-28-2011 06:49 AM

Screws should not be used for joist hangers. They do not have the needed shear strength.

Use the required 1" joist nails (#10 stamped on head) to face nail the hangers and 3" 10D Galv. commons to double shear/toenail through the side slots.

DM

RetiredRGM 05-28-2011 10:15 AM

The box the stepson hangars
 
The box of the stepson hanger said you could use #9 2 1/2" structural screws. Witch are 13.00 for 100 ea but it comes with a free bit (Wow). Is this just a manufacture wanting to make more money? Will these screws affect a structural inspection. I'm just adding full size blocking every 4' and a 2x4 blocking at 24".

DangerMouse 05-28-2011 10:26 AM

Quote:

Originally Posted by RetiredRGM (Post 656660)
#9 2 1/2" structural screws

If the mfg. states these are OK, then they are, of course, fine.
I was referring to plain screws, which are not. This has been asked before.

Most joists that DIYers hang will use nails.
I did however, (when I put in my joists) have need of two hangers that required structural screws. The rest were nailed.

DM


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