Screws vs nails in wood. 4

[fastline12]

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.

 

[TheBlacksmith]

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.

 

[jmw]

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

http://www.ViscoAnalyser.com

 

[Compositepro]

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.

 

[moltenmetal]

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...

 

[jmw]

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

http://www.ViscoAnalyser.com

 

[drawoh]

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

 

[Tmoose]

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.

 

[ScottyUK]

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!

 

[MiketheEngineer]

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

Doesn't help me much!!

 

[ScottyUK]

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!

 

[moltenmetal]

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.

 

[SomptingGuy]

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

 

[jmw]

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

http://www.ViscoAnalyser.com

 

[moltenmetal]

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.

 

[dgallup]

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.

 

[MiketheEngineer]

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