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Screws vs nails in wood.
4

Screws vs nails in wood.

Screws vs nails in wood.

(OP)
This has been a long standing discussion I guess.  I am working on a pole barn for myself and strongly considering screwing all of my purlins and gerts instead of nailing.  I know some feel ring shank and glued nails hold as well but I commonly have told people to get their nail bar and remove a screw.  I also am considering the considerable seasonal dimensional changes of lumber.  Just because a nail is tight today, does not mean it will be tight in 20 yrs.  The same may be true for screws though but at least the threads will have much more bind than a smooth shank.  

I am curious of any other opinions on this matter.  I would be securing 2x4s and 2x6s.   

RE: Screws vs nails in wood.

Sure, screws are probably better.

But if nails are good enough then the betterness isn't really worth anything.

RE: Screws vs nails in wood.

Walk along any seaside boardwalk and you'll find plenty of screws.

"Art without engineering is dreaming; Engineering without art is calculating."


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RE: Screws vs nails in wood.

Over time both will loosen, but I think screws take longer time to loosen.  Hammerclaw removal of screws will result in more damage to the underlying wood that wouldn't necessarily get replaced in a refurbishment.

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RE: Screws vs nails in wood.

We have been building floating docks completely with screws for about 20 years and they hold up a lot better than nailed construction ever did.  The outside frame corners are bolted through angle iron but the rest is held by screws.

They get hauled out in the fall and go through a Canadian winter on land then go back in Lake Huron and get worked by the waves for about 6 months each year.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 

RE: Screws vs nails in wood.

Screws!!  Because if you "screw up" - pun intended - they are easier to remove!!!   Or if you ever want to move or rebuild the building.....

RE: Screws vs nails in wood.

I know it's not the same but after my first two years on the acreage and several miles of board fencing in my lifetime, and one very sturdy horse shelter, I would never choose nails over screws in anything I ever built.

Regards,

SNORGY.

RE: Screws vs nails in wood.

4
Screws have more withdrawl resistance than nails, but we usually don't design wood construction details to depend on withdrawl resistance for safety.  Most joints that hold anything up are pinned, with the fasteners in shear.

Screws excel where withdrawl resistance is key, i.e. holding down flooring or deck boards etc.  They're also great when easy disassembly is your biggest concern- that's not typically a big issue in permanent construction though.

Screws, when compared at the same outside diameter as nails, have GREATLY less section thickness to resist shear.  So when people replace #11 hanger nails with #8 screws, for instance, they're not getting a detail with the same strength.

Screws are far easier to install with long-term corrosion resistance.  Nails in ACQ-treated lumber, for instance- forget about it.  Coated or stainless screws are king in that service.

Screws are usually made out of greatly more brittle material than nails.  A typical #8 x 3" deck screw can be snapped off with a single hammer blow.  That matters in some details, and doesn't in others.

Screws cost more and take far more time to install than nails.  A proficient carpenter with a hammer, much less a pneumatic nailer, can easily out-pace a guy with an impact screwgun.

If you use enough screws of the correct size to be equivalent to the nails you're replacing, screws are a perfectly acceptable alternative to nails.

RE: Screws vs nails in wood.

Molten brings up some very good points.  IF I am building tract houses - give me a pneumatic nailer and I will go to town.  If I am building a couple of walls in my house - I screw it every time.

RE: Screws vs nails in wood.

I was laid off a couple of years ago and in between jobs worked construction, mostly wood stud framing.

The guy I worked for was a complete nutcase.  He wanted all the walls plumb to within 1/16", joists/trusses (not furring) shimmed to within 1/16".

After ripping out a wall or truss for the tenth time, I started doing everything with screws.  Easy in, easy out.  I never used another nail on the job.

I worked on the job for a year and we were still on the same wing of the house.  He was working on cost-plus so I guess he had these rich owners snowed for the time being.

RE: Screws vs nails in wood.

jgailla, just curious, how were you "able" to measure framing to that degree of accuracy?

Regards,

Mike

RE: Screws vs nails in wood.

Of course we were not "able" to measure the framing to that degree of accuracy.

We would use a laser level, set off a certain amount from the floor plate, say 3 inches, mark the ground, set the laser on the mark, and then measure with a tape off from the top plate to the laser beam and make the top plate 3 inches from the laser.

For horizontal elements, we used a transit laser and handheld receiver in conjunction with a tape butted to the horizontal element in much the same method.

Now, if you measure this way and move things around a little, you can make it "good" to within a 1/16" for anyone who has no conception of repeatability or precision.

The problem comes the next time anyone tries to check it.  The process itself is no good to at least 1/8", so the company owner would check it and send someone else to "fix" it.  You can see how this process could be repeated ad nauseam.

The guy who owned the company was an accountant with a rich father who for some reason unknown to me decided to get into construction.  When I worked for him he was on his third project.  At least one of the other projects was building a house for his father, which may explain how he was able to stay in business for a few years.

In addition to all this, the guy was emotionally unstable and would occasionally lose his temper for no reason and send everyone home without pay.  Meanwhile I can't quit because jobs are scarce and I still can't make enough money to pay the bills on a sharply reduced income.

Sorry for the rant.  This was a bad time in my life and I'm still bitter.

 

RE: Screws vs nails in wood.

Before I got a proper job I was a "nail driver" with a house builder in Georgia.

Balancing up in the rafters and measuring up for the fillers I called down a measurement accurate to the nearsets 1/16thof an inch to the sawman on the ground and the boss intervened.

"You're a god-damned nail driver, not a cabinet maker." He then corrected the measurement to the nearest 1/8th - you go to the nearest 1/8th and call it "full" or "shy".

This was in the days of manual hammers..... you know, that metal lump on a stick you bash the nail or screw with (yes, I know some people who install screws with a hammer).
You learn how to drive a nail with only one or two hits and leave an owl eye to lessen the chance of t sweating out.

(The only question I wanted to ask was why, in a country with so many termites, are so many building built of wood?)

Oh yeah.
Nails are quick and cheap and effective for framing.
But when it comes to roof work, or anything off the ground you tend to doubt the value of nails.
Scaffolding boards ("walk logs" in redneck) don't rest on scaffolding but on metal frames nailed to the side of the house.
Since this means the nails are subjected to pull forces rather than shear, every so often the top nails would pull out and dump the worker on the ground far below and shower him with "walk logs".
It was no accident (well, it was if you know what I mean) that the boss and his son were both on crutches when I started there.
It isn't helped when the frames are nailed to the studs through 1.5" polystyrene insulation.
Nails hold best when the two bits of wood joined are held tight together by the nails and under some compression.  

JMW
www.ViscoAnalyser.com

 

RE: Screws vs nails in wood.

If you are stabilizing scaffolding with nails - be prepared to die!!

RE: Screws vs nails in wood.

Great thread to read (and learn,have a good weekend!)

RE: Screws vs nails in wood.

(OP)
Obviously nails in shear perform well.  However, my post was targeting the purlin and gert installations on a pole barn in which the shear is not as important as the pull stress in a wind storm.  I am still trying to find video of one failing but I think it is fair to say an up draft or lifting force on the roof is usually what does them in in which the roof is removed.  The purlins will peel off super easy.  

I am considering "flush mounting" the purlins so instead of laying them on top of the trusses like is typical and easy, I would cut and saddle each 2x between the truss top chords where nails would then be in shear.  

however, I am not immediately convinced that is worth doing.  As one mentioned above, if it is not needed, it is not worth it.  I was looking to attach with screwed in which if you use a decking screw rig attached to a drill, the extra time will be measured in minutes.  

The trusses certainly are not coming off the main poles without a catastrophic failure so if I can keep the purlins and gerts on, that means the sheeting should rip off and I replace it as needed in a major storm.

Lets keep it relative though.  150mph is target.  More than that and I am just grabbing my angles because mother nature trumps engineering every single time.   

RE: Screws vs nails in wood.

The frame is like a shelf bracket you put on the wall.
To be fair they'd usually hammer in a bunch of nails through each hole and turn the ends over (I think the designers probably intended them to be fixed with coach screws).
At least when I worked with my Uncle he used proper scaffolding.
Oh, and If I said 12" and 7/16ths he wouldn't question it. He and his partner were highly sought after craftsmen. I learned a heck of a lot more working with them for a couple of weeks than with the building contractor all through that summer. (I also learned that a Georgia Summer is no time to have an out door job).
(Oh yes, I was not only a nail driver I was also a mud man when necessary. Mud is Redneck for cement).

One good thing about my Uncle was he only trusted what he knew from experience was safe and reliable, which included his blue Chevvy '57 pick-up. It's probably still running.  

JMW
www.ViscoAnalyser.com

 

RE: Screws vs nails in wood.

(OP)
Before we put this to bed looking at shear and pull, probably the most important factor is fatigue life.  Structures move so the fasteners will to.  I realize nails do much better in this area but not sure on screws.  I know they are harder which is not all that great.  I still wonder why they do not do an induction harden just on the head so they will drive, yet leave the rest alone for better fatigue life.  I guess probably the strength needed to drive the screw in he first place.  

The defense of nails is usually fatigue life but I have to wonder if modern screws have improved there?   

RE: Screws vs nails in wood.

The old hand forged square nails would cut into the wood and be gripped on all four sides.  The modern wire nail splits the wood open and is only gripped on the tangentsto the sides of the "split."  But short of taking up blacksmithing, screws are probably a better choice.

RE: Screws vs nails in wood.

Not at all sure about the quality of modern screws for DIYers. I mistrust the source which is recognised for the "quality fade" problem and because the retailers are gouging the costs as far as they can.

JMW
www.ViscoAnalyser.com

 

RE: Screws vs nails in wood.

Nails will have greatly improved pull-out resistance when they are toe-nailed or installed at opposed angles. It's sad to see a deck where the boards are lifting and all the nails are installed so they are in pure tension. As has been said, they are shear fasteners.

RE: Screws vs nails in wood.

I too worked on a residential wood framing crew for a time, back in the days when a pneumatic nailer was as unusual as a hard hat to a framer.  

We used common nails, not spiral, because it made fixing screwups much easier- and more importantly, it permitted the use of a printed head hammer- in our case it was a 28 oz framing "axe".  A printed head hammer doesn't just drive a nail- it insists that the nail go where you tell it to go.  

The best I could manage was to sink a 3 1/4" nail in three blows, and most of the time it took four.  The boss could consistently do it in two, all day long, never bending one:  one bump to set it, and one to slam it just a bit below flush.  He WAS a pneumatic nailer, without the need to drag around a hose or listen to that damned compressor run all day.  He could also confidently walk backwards on a 2x4 interior wall top plate while dragging a roof truss.  Fall protection?  Forget about it...

RE: Screws vs nails in wood.

I may not be the best, far from it, but streets ahead of most people I see hammering nails.
I cringe when I watch some who have no idea what they are doing.
"It's just hammering" they'll say but like everything else that looks easy when done by an expert, there is an acquired skill.

JMW
www.ViscoAnalyser.com

 

RE: Screws vs nails in wood.

Quote (jmw):


Not at all sure about the quality of modern screws for DIYers.
...

   I designed and built a shed in my backyard.  I nailed the frame together, but I screwed everything else.  Here, in Canada, we have Robertson sockets.  The screws worked fine.  If you are abusive enough, you can strip them.

   The wood screws I have problems with are brass ones.  They look cool, but they are very delicate.  

               JHG

RE: Screws vs nails in wood.

Nails rely completely on friction for withdrawal strength.  Once the board splits, that nail provides almost no resistance to any loading. Nailing closer than in inch or 2 to the end of a board without pre-drilling brings risk of splitting.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_08.pdf
"As a general rule, nails should be driven no closer to the edge of the side member than one-half its thickness and no closer to the end than the thickness of the piece."  

To resist splitting some folks go to the trouble to orient a common nail's chisel point to reduce wedge action that would split and instead force the cutting of fibers instead.  Some hammer the point to blunt it, to similarly cause cutting and reduce wedging/splitting.

I dislike having to babysit fasteners, having to rely on hope that the wood won't split today, or ever.

In my experience #6 and #8 drywall screws and deck screws are much less likely to split framing lumber. But I still predrill near the ends. Sometimes on quarter sawn lumber I pump a screw into a predrilled hole near the end thinking I'm making it harder for face nails or screws to start a split.  

RE: Screws vs nails in wood.

molten,

What is a printed head hammer? Google turned up a blank, other than a lot of dot matrix printer stuff. I guess it has a patterned striking face - cross-hatched perhaps?
  

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If we learn from our mistakes I'm getting a great education!
 

RE: Screws vs nails in wood.

Yes - cross hatched.  Helps to keep the head from "sliding" off the nail head - theoretically.

Doesn't help me much!!

RE: Screws vs nails in wood.

Thanks Mike. I've seen them over this side of the pond, even tried using one once. I think it was an Estwing - looked like an outsize joiner's hammer as I recall - but I never did quite get to grips with it.
  

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If we learn from our mistakes I'm getting a great education!
 

RE: Screws vs nails in wood.

Printed head hammer?  Think of a meat tenderizer, only smaller.  Grips the nail head very effectively in my experience, unless it's worn down.  Very effective for toenailing.  Only useful with common nails, not spiral for obvious reasons.  

By the way, if you've ever hit your thumb with a 28 oz printed head framing hammer, the analogy to a meat tenderizer will not be lost on you.  You generally only do it once.

RE: Screws vs nails in wood.

Was round "my" house a while back. I left all my tools there when she finally pushed me out.

I think she was trying to do something with one of the fireplaces. There was my cold chisel sitting next to my tack hammer. I nearly said something.

- Steve
 

RE: Screws vs nails in wood.

I think one aspect of all this is the change in the quality of wood used.
Today's timber seems to be rapid growth kiln dried and shrink wrapped.
I'm pretty sure it is rather drier than necessary.
Dry wood doesn't respond as well to nailing as wet wood.
Wet wood shows more "elasticity" and less inclination to split.
You could bury the head more effectively in wet wood, especially ovals and panel pins. When that last hammer blow strikes, it is nice to see a little moisture. Too wet isn't good either, of course.

A sharp nail separates the fibres which, once the head is below the surface of the timber, then close up again.
The last hammer blow should depress the surface of the timber enough to ensure the head is below the surface. Then the surface fibres recover sufficiently to cover it.
 
The risk of splitting ought only to be near the end of the timber but with drier timbers, anywhere along the length and close to the edge is a risk.

But maybe I'm wrong about this.
 
It is just my feeling.
When I take a piece of graded tested kiln dried lumber today it seems to weigh next to nothing and to be very splintery. Maybe that is the drying process and maybe it is the quick growth crap that is sold these days or both. I guess one reason for this is because the drier the wood the more consistent the finished dimensions.
But one thing is sure, if you don't get your timber used up quick in whatever framing you do, it will start to draw moisture from the air and then it starts to warp.

Even back in the 70's we'd sort through the timber and through out obvious warped timber (still useful for cripples and infills).
Then we'd frame the house.
Then we'd have to go round and take out any timber that had warped once in situ.
Maybe.  If sheet rock hid it, it stayed (not with my uncle but with the contractor I worked for later).

I hate to waste timber. Even little bits end up in the oddments bin.  
Salvaged timber is often heavier, has more moisture content, denser grain and less prone to split or for the nails to draw.
Some old timbers you have a trouble getting the nails out, especially if they start to rust a little in there where they are in contact with the moisture in the wood. No more than that.

I had the advantage of spending some time working with craftsmen (my uncle and his partner) as with general contractors.
A lot of differences I can assure you. A lot more care in the selection of timber, and its use.

PS I think also that if you don't strike the nail cleanly i.e. with the direction of the blow along the length of the nail, then it doesn't go in as cleanly or as easily and you may find some increased tendency to split the wood. If you are forever having to stop and straighten the nail you are not hitting it right. If you don't hit it right then you will have problems.
Also, you have to use the right nail for the job. There is a reason there are so many different types out there but I guess a lot of DIY types just choose the nail by length and price.

Oh yes, and toe nailing is essential when dealing with warped boards, especially when decking.
   

JMW
www.ViscoAnalyser.com

 

RE: Screws vs nails in wood.

Trees are harvested smaller and growing faster, for sure.  They're taking the KD wood to pretty much the same moisture content as they were 30 years ago in my neck of the woods, but 30 years ago you could find a 2x3 or 2x2 much less 1x3 strapping that was solid wood- now it's all fingerjoint crap.  

We never framed with green lumber.  If water came out when you nailed it in our day, it had been stored improperly.  The only green lumber I've ever seen, aside from what I've sawn myself, was pressure treated SYP from the 'States.

Ever compare a piece of old-growth white pine to the balsawood-like substance they sell as white pine these days?  It's as if they were different species.

RE: Screws vs nails in wood.

I've got a cabin that was built in the twenties with old growth wood.  The interior walls are just studs so you can see every stick in it.  The 2x4's actually measure 2" by 4".  That lumber has to be more than twice as strong as what you can buy today.  The studs & rafters are on 24" spacing but it's gone through ~90 Canadian winters with who knows how much snow on the roof and at least one 100+ mph storm.  The only time it's been damaged was when a big white pine fell on a corner of the porch and the porch roof blew off & landed down by the outhouse.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 

RE: Screws vs nails in wood.

Hope the outhouse wasn't too badly damaged. Might make for a Shi^^ty day!!

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