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Nails vs. Screws - Testing them out

xxPaulCPxx's picture

For years I've built with only screws.  I have a background in theatre, where we used screws for everything - crappy drywall screws to boot!  Well, after years of building the platforms I performed on, I've found better screws and never really learned how to use a hammer.  Well, except to hang pictures and demolition, of course.


Well, the building inspector told me that screws were not approved by Simpson for use in their Strong Ties.  I examined their literature - sure enough, they say it in big letters - NO SCREWS.  USG connectors do allow #8 1.5" wood screws though.  So does a stair tread bracket manufacturer.


Hmmm.


Simpson says no - others say yes.  Maybe Simpson knows best - I decided to test them out.  I bought their 1.5" galvanized nails, as well as some 8d Bright Common and 16d Bright Common nails (Grip Rite).  I then built a test mechanism: One 2x8x14' attached horizontally to another with a strap hinge.  The top board was kept off the ground by 4 legs, the bottom one was a lever that i would use to pull away from the top board - the hinge at the end being the fulcrum. 



I then used a piece of piece of 18 ga Simpson strap to go across both boards at differing points, usually 6", but sometimes 9" or 12" from the fulcrum.  I would attach the strap to the boards using nails or screws.  The screws I used, BTW, were McFeely's #10 1.5" round washer head, Grip Rite #8 3" Primeguard Plus, and Phillips Deck Mate #9 3.5" screws. 


I'm wondering how you guys in the field might call this.


1.5" 8d nail vs. 1.5" McFeely's screw - Winner?


2.5" 8d nail vs. 1.5" McFeely's screw - Winner?


3.5" 16d nail vs. 3.5" Deck Mate Screw - Winner?  (Hint - the shear force was over 2500lbs)


 



Rebuilding my home in Cypress, CA


Also a CRX fanatic!


Edited 6/12/2005 1:38 am ET by xxPaulCPxx


Edited 6/12/2005 5:32 pm ET by xxPaulCPxx

YAY!  I love WYSISYG editing!  And Spellcheck!

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(post #66552, reply #1 of 60)

Could you have found any smaller of a font?


 


Matt
Matt

(post #66552, reply #2 of 60)

I'm wondering how you guys in the field might call this.


Doesn't matter how I think those might turn out. The specs from the manufacturers, and the statements in the code, and the judgement of the inspector -- those count for a lot more than my opinion.


And the reasoning is simple. Big companies like Simpson have a building full of engineers, probably a million or so in simulation software to show them what's what.


And I have a saw and a hammer, a hardhat and a pair of safety glasses.


Although your test fixture is interesting and thought-provoking, how well do you think it holds up against a building full of engineers?


 


 


Unless you're the lead dog, the view just never changes.

. . . I can't live proud enough to die when I'm gone, So I guess I'll have to do it while I'm here. (Phil Ochs)

(post #66552, reply #20 of 60)

who ya gonna believe, your own eyes or a building full of engineers?
Remember, engineers built the Titanic, the Tacoma Narrows bridge......
All the simulation software in the world doesn't beat one good hands on test......
Just my two cents worth.....

(post #66552, reply #42 of 60)

All the simulation software in the world doesn't beat one good hands on test......


Perhaps you are correct. And that's why we allow some portion of our taxes to be used to crash vehicles and assess the results.


But the point here is that the test being done by the original poster may or may not have anything to do with the specific strengths and weaknesses that must be assessed in order to determine if nails, screws, or other fasteners, are better for any specific purpose.


"One good hands on test" could lead some to think that they have the answer. I prefer to rely on the hundreds of tests -- some hands on, some in a lab, and some simulated -- that an engineer will sign his/her name to.


And here's an example. The original poster has revealed his results -- they show that screws do better. But I've done demolition work where studs were fastened to plates with screws, and others with nails. Getting the screwed studs out is a breeze compated to getting the nailed ones out.


So -- how valid the hands on test is, is a much more relevant question. And that's a big part of the reason for the building full of engineers, and the millions in simulation software.


 


 


Unless you're the lead dog, the view just never changes.

. . . I can't live proud enough to die when I'm gone, So I guess I'll have to do it while I'm here. (Phil Ochs)

(post #66552, reply #48 of 60)

All true...I just thought you were a bit harsh on the original poster...
Partly as a consequence of the age old difficulty man seems to have dealing with "science", I think some people (not you!) have the idea that some engineer(s) with the right formula(s) figure out everything, & then we mere mortals follow their instructions...
In fact, theory & practice dance together....emperical knowledge and theory build on each other to give us the "engineered systems" we use today.....

(post #66552, reply #3 of 60)

We have this discussion about every 6 months here. Someone has decided screws are better to frame with and doesn't understand why everyone doesn't agree with them.

What the last poster said is right on. What you or I think doesn't mean squat. To be able to use screws, you need indepentent testing and code approvals. That costs big bucks.

So for now, you're stuck with tried and true nails, like it or not.

If you can't be a good example, then you'll just have to be a horrible warning.

(post #66552, reply #5 of 60)

Although heat-treated wood screws have the shear strength (actually much more than nails in some cases), I spoke to a Simpson person and he said they are not recommending screws because they are not sure how well they will hold up long term, being more brittle than nails.

I still think the kinds of nails that I see at lumber yards etc are garbage. Bend and corrode at the drop of a hat. Can only order Maize nails by the crate.

I recently had to pull out some 1-1/2" 10d joist hanger nails. Oh boy, scary how easily those babies came out....

(post #66552, reply #8 of 60)

"...heat-treated wood screws have the shear strength..."

It's not the strength of the screws/nails that's important - It's the area of the wood they bear on. That's a common misconception.

When I was young, I was put in a school for retarded kids for two years before they realized I actually had a hearing loss. And they called ME slow! [Kathy Buckley]

(post #66552, reply #11 of 60)

both

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #66552, reply #4 of 60)

You are a madman. Can I come over and play? But I think YesMaam gave very sound advice. I would suspect their nails will at least match any of the others you used. Sometimes I get some younger guy working for me with progressive ideas, good carpenters around 30 seem to know everything. Its annoying at times but I think a good sign. I knew everything by 30 now I don't know sh*t. I had one last year that insisted the top of door jambs need not be rabbeted. That's when I coined the phrase. "You're telling me you all of a sudden got smarter than 300 years of carpentry tradition." Said with a smile and he right tone it gets the point across. But today with the progressive fasteners and new materials, glue etc. Maybe thes common sense diversions away from tradition have some merit. I digress. I don't know if you see a parellel. But the inspector probably will fail a strap without the proper fastener.
Next time you want to hang a truck, or blow something up let me know.

Mad?  You call me MAD?  HA (post #66552, reply #53 of 60)

Mad?  You call me MAD?  HA HA!

Just a little off topic, when I was rebuilding my car some years back I needed to do a bunch of welding on the bottom.  Taking a spark shower under the car didn't sound like much fun, so I designed and built this:

It's all 2x4 or scrap wood, only the bracket to the car frame and pivoting axle are metal.  Rock solid, and I could spin the car one handed!

Rebuilding my home in Cypress, CA

Also a CRX fanatic!

YAY!  I love WYSISYG editing!  And Spellcheck!

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(post #66552, reply #16 of 60)

My suspicions were true.

(post #66552, reply #27 of 60)

Well, that's a pretty cool test IMHO. Pretty cool car spinning contraption, too! (How'd you find the exact center of gravity on the length-wise axis, though?).

I'd vote for the screws--just because I think a room full of (government approved) engineers will almost always find the wrong answers..

You ought to check out the Coral Castle down in Miami. A 4-foot tall dude built this thing out of 2-3 ton sized coral blocks he cut, excavated, and positioned...by himself..only at night under a full moon. There's a revolving door there that weighs a couple of tons which he's got perfectly balanced on a coke bottle so it spins with one finger.

The whole castle was built without ANY simpson ties or...nails. Or anything else which might connect the blocks. And no building codes were followed at all. I think it was built about a hundred years ago. I'ts still there. He's all gone.

(post #66552, reply #30 of 60)

Thanks!  I balance it by attaching the brackets to the front and rear, then using a jackstand as the balance point on the bracket and moving it back and forth until worked out right - marked it and welded on the axle.


I realized later that the with a driver behind the wheel, the car would be perfectly balanced down its center axis... as long as you had the Right Hand Steering that England and Japan have.  Nice bit of engineering!


Rebuilding my home in Cypress, CA


Also a CRX fanatic!

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

(post #66552, reply #38 of 60)

That car "spinner" is REALLY COOL! I was falsely impressed with my spinning solid doors. I assume you used screws in your end brackets.

I used to do "glue tests" but never elaborate screw/nail tests like you, but I was sure from reading your first post the screws won hands down. Sometimes we use a wench to rack i.e. a sagging old garage and you quickly learn to use screws.

To him who only has a hammer all the world is a big nail.

(post #66552, reply #40 of 60)

Hey, I like your door rotisserie.  I think I'll rip it off!  I've got a ton of doors to paint... sometime.


And you bet I only used screws.  Didn't want 1/2 ton of fun dropping on my foot unexpectedly!


Rebuilding my home in Cypress, CA


Also a CRX fanatic!

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

(post #66552, reply #41 of 60)

Paul,

Just read this thread. The founder of Velux, the Danish roof-window company, was told by the experts (in the late 1940's when Velux began) that all roof windows must inevitably leak. He proved them wrong. The company motto is something like, "One experiment is worth more than all the expert opinions." I'm sure it is on their site, but this is from memory.

I think there are a host of reasons the Code prefers nails to screws, including:

1. Tradition. "It has always been done this way."

2. Technology. Older screws were weaker/more brittle/less uniform than modern screws.

3. Verification. There is less to be done wrong with a nailed installation than with a screwed installation.

4. Redundancy. Since the nails are weaker, more of them are needed, and so the risk is spread over more fasteners, tending to more overall reliability.

5. Terrible results with Piffin screws. Left a bad taste in the craw of Code authorities, resulting in a mindset of, "We gotta be sure THAT never happens again."

I am surprised you did not test the Simpson Strong-Drive #8 by 1-1/4" screws. They are rated by Simpson's hall of engineers for respectable loads. Too bad they offer nothing between that and the 1/4" Strong-Drive lags.

I do remodeling, and I agree with the poster who noted the lack of collateral damage in older structures when using screws. The codes need to catch up to the technology so that we have more legal options in our quest for construction excellence.

Thanks for introducing this topic.

Bill

(post #66552, reply #49 of 60)

"I am surprised you did not test the Simpson Strong-Drive #8 by 1-1/4" screws. They are rated by Simpson's hall of engineers for respectable loads. Too bad they offer nothing between that and the 1/4" Strong-Drive lags."


Funny you should mention this.


I once compared the 1 5/8" Simpson hanger screws to Deckmaster 1 5/8" screws.  Both were plenty strong in shear, but the Deckmasters had better tearout resistance.

(post #66552, reply #50 of 60)

Hmmm, interesting... I just read this on the Simpson FAQ:


Q: Can I use nails other than what you have specified? How about using screws instead of nails?

A:
Some of our connectors (generally straight straps and face mount hangers) can be installed with alternative fasteners but usually with reduction in load capacity. Please refer to the Simpson Strong-Tie catalog or this chart for a list of viable substitutions. As for screws, because of their smaller shaft diameter and shorter penetration distance they usually have lower shear capacity than common nails. This is not to say that you can not use screws with our connectors. Just keep in mind that there is going a reduction in the published load values, and if this reduction is acceptable, then there should be no problem using them.


I think this is going to help me make my case with the inspector.


I never really took the Simpson screws seriously, as they were phillips head instead of square drive.  I'll do drywall in phillips, but I'll stick with being square for everything else if I can get it!


Interesting note about pilot holes and nails... though in the test with the toenailed 16d, I did predrill them with a 7/64 bit to prevent splitting - same as I did with the screw.  It still gave quite easily - however I did not drill the pilot hole the full length of either fastener, only about 1.5 inches.


Rebuilding my home in Cypress, CA


Also a CRX fanatic!

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

(post #66552, reply #6 of 60)

Are you testing how much force it takes to break a nail vs a screw?  Or are you testing how much movement is permitted before total failure?


Are you testing shear only?  Or are you testing shear with some bending force also?


It's not really a question of which one is "stronger" in a particular test (although it is interesting).  It's really a question of which one performs adequately in the real world.  My understanding is that the use of screws for structural fastening is not permitted because it doesn't take a lot of movement for them to fail.


-Don

(post #66552, reply #7 of 60)

You are not as crazy as everyone else is claiming.

Only 50% as crazy <G>.

Some screws have been tested.

http://www.grkfasteners.com/selection_guide.htm

But they have not published a substitue guide showing how many/which size screws can be substitued for how many/which size nails.

Possibly it is too application dependent to do that.

At this point it would still take an engineer, but all of the data needed is there.

. William the Geezer, the sequel to Billy the Kid - Shoe

(post #66552, reply #9 of 60)

"test fixture is ......, how well do you think it holds up against a building full of engineers"


In defense of the original poster, Pretty well - I work in buildings full of engineers, and despite all the millions of software and calculations, there IS NO SUBSTITUTE for testing - why do you think airplane wings are bent hundreds of thousands of time in tests before the plane ever flies passengers??  (edit PS - a truly valid test for screws vs nials would need to  include fatigue testing - thousands of cycles at least. )


The is another factor comes into play, and that is skill of the installer or installing the wrong screw (e.g compare an NAS1303 screw to a HF bin special in strength, etc).  A loose or wrong type screw is more common than a nail not driven in fully, which becomes a factor in a full up who screwed up on installation type of test. There are many threads on this board about piffin screws not being structural but many still think to use them as such.


In another building related case, a crimped wire connection is actually more reliable (by test results) than a soldered connection or a crimped and soldered connection- why? because of the much more probable incorrect soldering technique being performed by many differnt installers of varying skill levels. (BTW, my own house has soldered crimps as i did all the soldering myself)


Edited 6/12/2005 9:11 am ET by JUNKHOUND

(post #66552, reply #23 of 60)

Off topic question.


"Crimped connections stronger than soldered or crimped and soldered."


Learned most wiring skills from USCG regulations for Small Passenger Vessels.  I was building inspected boats for charter service and had to wire to USCG specs.


USCG specs say stranded wire and crimped connections only and are subject to random pull tests during inspections.  Good system but has a tencency to invite corrosion in a salt water environment.  USCG allows solder or silicone type sealants after the crimp is made.


Curiousity requires me to ask if you understand how soldering an already made crimped connection weakens the final connection.


Thanks for any insight.


Jim


Never underestimate the value of a sharp pencil or good light.    

Never underestimate the value of a sharp pencil or good light.

(post #66552, reply #39 of 60)

Had to go back and read my original post to be sure I did not say something I didn't think I said, so half your answer is that you misquoted me and mixed apples and oranges and different technical attributes.


What I said was


"crimped wire connection is actually more reliable (by test results) than a soldered connection or a crimped and soldered connection"


What you quoted was


"Crimped connections stronger than soldered or crimped and soldered."


 


Well, soldered is probably always stronger**; however, electrical  'reliable' is a lot different than 'stronger' (sorry Luka <G>) -  as for the reasons, they are myriad, including  expansion & contraction during soldering giving a lesser electrical weld of the crimp, wrong flux and resulting corrosion, solder or tin whiskers (esp in high altitude or space environments), workmanship, etc.  Perhaps the most egregious example personally experienced was a technician who had infomred no one how severe his arthritis was getting - he actually left big enough solder points on connector pins in a mil38999 connector that there was a pin-pin short, only one I've ever seen on aerospace hardware built by qualified personell (tech was qualified decades before the arthritis acute set-in and re-qualed as recently as 6 mo earlier).  


edit** unless wrong flux, which can eat thru the wire resulting in no mechanical strengh either.


Edited 6/12/2005 10:49 pm ET by JUNKHOUND

(post #66552, reply #43 of 60)

Thanks for the info.


Jim


Never underestimate the value of a sharp pencil or good light.

Never underestimate the value of a sharp pencil or good light.

(post #66552, reply #10 of 60)

I meant madman a sincere flattery.

(post #66552, reply #12 of 60)

OK, tally so far:


DIRISHINME  = pokes fun at my posting skills = dodged the question


YESMAAM27577  = Asks a different question = dodged the question


Boss Hog = Pointed out the history of the question = dodged the question


quicksilver   = "I would suspect their nails will at least match any of the others you used" = Votes Nails


Taylor = "had to pull out some 1-1/2" 10d joist hanger nails. Oh boy, scary how easily those babies came out" = Vote Screws


Don D  = Asks for test criteria clarification = vote withheld


Bill Hartmann  = Pointing out contrary info supporting screws (Thanks!) = dodged the question


JUNKHOUND  = Supports actual testing and points out possible test variables = dodged the question


Nails = 1, Screws = 1, Clarification required = 1 Not answering the question = 5.


Well, not a landslide for either side yet.


I wasn't asking what government officials or a roomful of engineers thinks would do better, I'm asking what  you think would perform better.  I respect you opinions based on years of experience, and I've learned a lot in my readings here - that’s why I'm posing this question to you.


OK, I'll expand on my procedure a little more here.  The purpose of my test was to find out at what point one fastener would fail and the other would not under equal circumstances.  I do realize that there is a lot of variation out there in screws, as a matter of fact I was very disappointed in one of my screw brands that I tested.  But I am testing particular screws in this case.  The fastener would be considered to fail the test if it A) broke or B) freed itself from the wood it was fastened to.  If the wood failed (cracking the wood in half, for instance) without the fastener being deformed, it was considered a wood failure and a null result.


I also made another test mechanism using 4x8x5' beams to test the longer fasteners, so I could test them at their full depth.  Since it was shorter, I had to use my own body weight to apply sufficient force for the tests.  I call this the "Fat #### Test" as I weighed myself at 221.5 lbs. 


I also did a brief test with toe nailing joist hangers, this test had 2 16d or 2 #9 3.5" screws in the bottom beam and the joist hanger being face attached to the top beam.


Anyone like to change their votes (or weigh in):


1.5" 8d nail vs. 1.5" McFeely's screw (face fastened to 2x8) - Winner?


2.5" 8d nail vs. 1.5" McFeely's screw (face fastened to 4x8)- Winner?


3.5" 16d nail vs. 3.5" Deck Mate Screw (face fastened to 4x8) - Winner? 


2 3.5" 16d nail vs. 2 3.5" Deck Mate Screw (toenail fastened through wood filled joist hanger to 4x8) - Winner? 


 



Rebuilding my home in Cypress, CA


Also a CRX fanatic!


Edited 6/12/2005 1:41 pm ET by xxPaulCPxx


Edited 6/12/2005 5:32 pm ET by xxPaulCPxx

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

(post #66552, reply #13 of 60)

Since you think I dodged the questions, here is what I think would perform the best.


NEITHER!!


For maximum strength limited only by the hanger and the wood, you will need a steel doubler on the other side of the supported and supporting member, thru bolts, preferably 10-32 NAS1303 screws or BACB30NE bolts , and another doubler on the hanger side. Then, adhering to Boss Hog's comments about compression capability of the wood, there may have to be 1/2" or larger dia steel sleeves around those bolts to distribute the compression stress on the supporting beam. Following that, you will need to do shock tests to simulate earthquake loads or overloads and allow for Class I to III hole tolerances and the zipper effect (remember the Kansas City hotel?). Now you are left with yield of the hanger flanges on the supporting member, so you will have to add a bolted stirrup across the top of the beam - whoops, ok there, went beyond the initial hanger failure, so. 


My vote: BOLTS, doublers, and compression spreaders.


Edited 6/12/2005 2:00 pm ET by JUNKHOUND

(post #66552, reply #14 of 60)

LOL! 


Thanks for pointing out the STRONGESTpermutation, but you are still dodging the question.  If nails are code and Simpson approved, and I test screws and nails side by side on a fairly basic test using Simpson products, which do you think come out on top?



Rebuilding my home in Cypress, CA


Also a CRX fanatic!


Edited 6/12/2005 5:33 pm ET by xxPaulCPxx

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

(post #66552, reply #17 of 60)

I think the screws won every time. Now what are your results?

 


Jon Blakemore

RappahannockINC.com

Fredericksburg, VA

 

Jon Blakemore

RappahannockINC.com

Fredericksburg, VA