Nails vs Screws

flyingvan · July 11, 2012, 09:20:51 AM

SO, JRR---is your home sewn together? That would sure provide plenty of flex

JRR · July 11, 2012, 10:57:27 AM

Quote from: flyingvan on July 11, 2012, 09:20:51 AM
SO, JRR---is your home sewn together? That would sure provide plenty of flex

Now, now!

It's glued ... just like my sneakers!

Glued and screwed! So stiff, if it ever breaks ... it will be in a thousand pieces!

July 14, 2012, 07:57:02 AM

I think I have a pair of sneakers like that

I bumped into this while searching for something else. This is another e course on connections;
http://www.awc.org/HelpOutreach/eCourses/DES110/DES110eCourseV02-2011.pdf
(>6 MB, I'm gonna go change the oil while it tries)

The American Wood Council library of e courses is here;
http://www.awc.org/HelpOutreach/eCourses/index.html

I did check lags and ledgerlocks at Lowes the other day, lags were $2.49 ea singly. Ledgerlocks were ~$38/25 (OK, I wrote it all down in the store but apparently the dog ate it) The ledgerlocks (that particular screw) had higher shear numbers than the equivalent 1/2" lag

. The timberlocks were a bit cheaper but have lower shear numbers. I think for many applications the different structural screws are definitely in the running.

JRR · July 14, 2012, 11:16:47 AM

Don_P,

Thanks for the links. I have read thru the first one ... all many pages! It is a good read. But it puzzles me why folks who put such effort in making such an elaborate presentation ... refuse to use spell check. Example: "stringer" on page 132/133. ... also, did they really mean to have the green check on page 113?

But I was most puzzled by the article on "wood bolts" on page 142/142. Are the bolts made of steel ... or wood? Are they "wooden bolts"? I thought surely they must be steel until I read "The wood bolts were actually a laminated beech product"

?? Not much info on an interesting concept.

Don_P · July 14, 2012, 12:21:40 PM

They could stand a good proofreader. I think I saw a sheer /shear mixup in there as well

.
I googled the trestle, they had very specific needs to use the wood bolts, pretty neat;
http://www.ece.unm.edu/summa/notes/trestle.html

July 14, 2012, 01:24:48 PM

Neat, indeed!

firefox · July 14, 2012, 02:05:32 PM

Thanks Don! That was really something!
Bruce

Ndrmyr · August 24, 2012, 07:51:32 AM

I, like others am a big screw fan.

Due to shear strength, there are places where nails and only nails should be used. However, screws can pull a joint tight, and create a compression strength in a way that a nail can not acheive. A screw can pull or align a joint, and, toe screwing from opposite directions creates an incredible joint. I suspect that a stud wall toe screwed together can pull the base plate and top plate together in a way, that reduces the shear risk of using screws. If your structure is subject to a catastrophic forces that bring into play shear strength, then perhaps the far greater pulling resistance of screws can come into play. That beng understood, I can understand, from a seismic perspective (earthquake), why code doesn't allow screws. For us as amateurs and hobbyists, screws have an unbeatable attraction. They can be undone, and, redone. If I had $1 for everytime I had unscrewed something and rescrewed it back successfully, why....drinks are on me! It is slower than a bunch of wood monkeys firing away with nailers, but with impact drivers and screw guns firing collated screws, the gap narrows. I like to think I understand when to use nails. But given a choice, I will always screw!

NM_Shooter · August 24, 2012, 08:55:38 AM

Mtn Don has an interesting line in his signature :

"Just because something has been done and has not failed, doesn't mean it is good design."

If something has not failed, it is only proof that it has not failed yet. I'm going to stick with code recommended practices as much as possible. The proper use of nails is to keep two things from sliding apart.

Keeping things from sliding apart is the basis for all home construction. Everything should be built to resist shear forces, seems like gravity should be the only thing providing compressive force (which is why building perfectly plumb is important).

August 24, 2012, 01:20:06 PM

There are screws that can pass code inspections. They may not be listed directly in the IRC, but GRK, Fastenal and others do have screws that have passed testing. There are charts with shear values for these. Armed with that a person may be able to get their local inspector to pass the structure. All too often though when somebody says they will be or have used screws, the screws end up being the more common and cheaper "deck" screw. Those can be dangerous to use as they are brittle and shear easily. The structural screws are great but also expensive compared to a common nail.

speedfunk · September 03, 2012, 02:55:39 PM

I vote for screws...hands down. I remember as a kid building forts how many nails it would take for me to build something .. I would just keep pounding them in...15 or 20 lol. All my projects seemed to suck.

Fast forward to modernish day jeff. Fist project when I got a cordless impact driver..i was sold. I told my dad...if I used this back in the day my forts would have been much better.

The advantages of screws are just so numerous.

Maybe a bit more costly..but when I am redoing something it takes me two seconds and by not wrecking the boards I save that back easy. Imagine if we built using screws instead of demoing houses we could easily dis-assemble them and re purpose that wood with out wrecking the building.

People new to building will instantly be able to build solidly without wrecking wood and banging thumbs. The learning curve for newbies is much better with screws.

This shear strength argument Im not sure I follow. Your going to tell me that a movement will have the same impact as a hammer. A hammer wont break a deck screw( based on my experience anyway). If that much stress was present in a building by shifting ( It seems unlikley to me anyway) I would think it would tear out of the wood first. Heck i
ve used sheetrock screws framing our cabin. The door is sticky now so its shifted a bit due to shallow piers (whatever). So there is obviously stress on the building...you know what ..its solid..this is with 3" DRYWALL screws!! It.just seems like a minor point compared to all the advantages. But i guess that says something that its the biggest item against screws.

As far as being brittle..even deck screws do bend...I've bent them. They dont just instantly snap when given the least bit of shear pressure. What is more shear pressure then slamming a hammer against them? This is also not as simple as my last sentence, b/c your not slamming a hammer against them. Your slamming malleable wood. Its a relationship thing. The wood absorbs some shear it does not all get transferred to the screw. Based on my experience the wood is what will take the stresses. Or if there was insane amounts of stress the screw stays put and the wood will pull out leaving the screw. I would like to see someone break a screw by bending two pieces of wood with a screw at the joint. The more I think about it the le3ss relevant the hammer against a screw example is. What we are trying to do is the classic example of science. Attempted to learn by isolation. Its not like that though...everything is in context of its environment. There is no hammer being slammed into the screw in your house... its not relevant.

I think this has more to do with what people are comfortable with. If you got good at hammering then you probably prefer that. I on the other hand think its a no brainer. Whatever cost increase easily is made up by being able to re-use the screws and the wood. This being said i hve used a combination in our build..but have over time gravitated toward a good screw..( sorry, had to do it!)

MountainDon · September 03, 2012, 06:15:09 PM

I will simply say that decades ago when we first moved to NM and I was looking for some sort of work I liked, I filled in the time with doing handyman repairs. I saw a numbers of projects from fences to utility sheds that a DIY'er had built using the very common gold colored zinc plated deck screw. I can not remember how many times I'd go to remove those screws and find them broken off between the head and where the threads started. Innumerable. I'm sure that some of those took a good few years before failure.

Then a personal project note. We have a wood walkway around a portion of the back yard. 2x sections screwed down to 4x beams. It is low to the ground, on ground in places, and the wood moves a lot with seasonal changes from dry to wet. The screws (the coated ones suitable for PT wood as well as the gold zinc) also snap off from time to time in the same fashion.

I have personally seen deck screws shear off when used for temporary bracing, as when lifting and standing an assembled wall. I now use either GRK structural screws or scaffolding nails.

We're all free to do as we choose; I just believe that deck screws in particular are not at all useful as a substitute for common nails when structural strength is important. There are screws that are suitable for structural use, but they cost even more. However, they come with a pedigree, there are charts that list their strength. Can't find that information for a deck screw. If anyone does, let's see it.

zion-diy · September 04, 2012, 04:45:19 PM

I'm a little confused.

(so what else is new) $:-\$ When someone is framing a house or cabin, what part of the framing is in shear? I always thought that studs were mounted in compression. Same with floor joists, when they're mounted on top of sill plates. It seems to me that these parts are the most important piece of the puzzle. So, what am I missing?

flyingvan · September 05, 2012, 09:35:54 AM

You're not wrong. The main force taken by studs IS a compressive force. In a perfect world you wouldn't even need a nail. You could just dry stack everything.....However--
Did you know when you walk across your floor your weight makes the walls bow in towards you ever so slightly? Have you noticed a stud left lying around awhile starts bending and twisting, while the ones in your wall pretty much stay put? That connection between a stud and plate endures side loads from wind, slamming doors, earthquakes, unpermitted additions, ledgers, etc.....So, those nails take quite a bit of force from many directions. When a tractor bumps into that wall in 60 years whoever's on the other side will appreciate good construction practices

September 06, 2012, 12:01:10 PM

Ok, that explains a lot to me. thank you.

UK4X4 · September 08, 2012, 04:30:26 PM

I have two tool box's at home - 1 large with tools and 1 smaller with small bits or stuff to build things with

there's two drawers of fixings plus various bolt divided box's

roughly 5 drawers 36" w by 24 deep

The only nails I stock in my collection are 1" panel pins

every other timber fixing is a screw...............

Mind you I have'nt built a house yet !

But if you took a look a for example a 48" wide shear wall built to code and used screws instead, I be very interested in what fell apart first.

every thing I ever built with nails- panel and frame if you pushed it hard enough on the diagonal the nails pulled out of the sheeting and then the frame collapses

The ones with screws I'd have to undu.

Ref the heads popping of deck screws- yep bent a few and poped a couple of heads- decks etc deal with expansion and contracting every day, where as framing is a dry relatively mild climate behind the siding

but I think I've bent more nails and had more pull out of what their meant to be keeping togther, than I've ever had with screws