If the IRC specs a 3.5″ nail for framing, why do so many use just a 3.25″ nail
Irishjake
| Posted in General Questions on
For over 20 years I’ve been using a collated 16d (3.5″) nail in my nailgun for framing walls. I’m in the market for a nail gun upgrade (changing brands) and found that many best nail guns only go to 3.25″.
The IRC states that (2) 16d nails are needed to nail studs to the plates, why then a 3.25″ nail and why do so many nail gun manufacturers not make a gun that shoots up to 3.5″
Can any of you expand on this?
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Replies
To comply with the code you have to shoot 3-1/2" nails, but it seems to me that many framers don't, and for whatever reason inspectors aren't making a big deal out of it. I have a couple of Senco nailers that shoot 3-1/2" nails for that reason. It would be interesting to know how much of a loss of strength there is when the nail is 1/4" shorter. A related question is, when there is continuous 1/2" CDX sheathing nailed on a 6"/12" pattern, how much of the wall's strength is derived from that. My guess is that the sheathing nails do quite a bit to keep the studs in place, and that the missing 1/4" of shorter framing nails is not an issue.
I know the inspectors around here aren't liable for a thing. I'm sure they just drive by the site and say it looks good.
Inspectors here are more concerned about sheathing nailing. They'll look at it, and perhaps ask what nails were used, but I've never been aware of a question about the framing nails.
I'm not concerned with inspectors....in fact where I live there are none! We as the home owner or builder are responsible for ensuring that all the building processes are done to current/adopted code.
Why is it that sooo many use just 3.25" nails? I don't want to upgrade my guns and possibly limit the size of the nail I can drive unless there is good reason to only use up to 3.25" nails.
Brad,
Canadian building codes take a more nuanced approach to nail length, specifying where you must use which nails. 3 1/2" are generally reserved for ledgers on beams, toe nailing joists and trusses, bottom plates and a few other locations.
Your code writers probably just decided that, rather than call out specifically where they thought them necessary, they would just say use them in every situation. Are there situations where the 1/4" makes a real difference? For a diligent framer placing their nails carefully I don't think it does.
That said I'd bet the primary reason for builders using 3 1/4' nails is the difficulty most guns have fully sinking the longer ones - especially into lvls. If you haven't had an issue with your nail length in 20 years i can't see any reason to switch.
I've found there are situations where 3 1/2" nails are a real problem. Attaching plies on a doubled header being one of them. I started using 3" nails for those after coming home for lunch covered in blood one too many times.
Malcolm,
I just angle the nails to prevent blowouts when nailing headers, and corners, etc.. I don't have a problem with LVL's when the right compressor and pressure is being used...either way I still hand drive them anyways to ensure the plies are sandwiched tight.
I've find it silly even ridiculous that tool manufacturers would make a gun to fire nails that don't "meet" code, and not provide for that .25" extra "required" nail length. I was hoping someone would tell me that I've got the code wrong or show me evidence that the 3.25" nail is just fine and shed some light on why so many nail guns only go to 3.25". I mean it's not like guys have two guns laying there using x nail here and y nail there, except when nailing hangers maybe.
Brad,
This issue comes up on building forums quite frequently with a very similar debate of the issues and no more resolution that you've found here. All I can think is that it isn't seen as a serious enough problem for inspectors to make a fuss about.
Malcolm,
Thanks.....to bad someone hasn't taken it to the code council to change it since it's so ridiculous, but then again, there is lots more to worry about than .25"
I never had any inspector question the length of the nails. The engineer specified 3 inch nails for all half inch sheathing since all exterior walls are considered shear walls. I asked if I could use 2.5 inch as the 3 inch could interfere with drilling for electrical in 5.5 inch studs with half inch sheathing. No problem. I told the framers what the engineer wanted but I noticed at some point they were using 2.25 inch. Some 2 inch were probably used in a few places as well. All the engineer looked at was the spacing. And all the inspector looked at was if the engineer had passed everything.
In the 2015 irc table 602.3(1) almost all framing elements have the option to use 3.25” nails.you just have to use more of them.
The option is for 3", not 3 1/4", but otherwise DWWILKEY has it right: https://codes.iccsafe.org/public/document/IRC2015/chapter-6-wall-construction.