I’m a new editor at Fine Homebuilding and am working on an article about wood screws. Instead of creating a historical tome I’m hoping to make the article as useful to as many of you as possible. So here’s the pitch. What do you want to know about wood screws and how do you use them?
Thanks.
Jim Kidd
Replies
how about info on shear streangth.
it often comes up on this site about using screws instead of nails.
DW screws are not wood screws, but...
bobl Volo Non Voleo Joe's cheat sheet
Do a search here at breaktime. It'll be a welcomed article. Define SR screws and we can avoid more screw wars. I think many guys and even retailers refer to any screw with a sharp tip and a Philips flat head as a sheet rock screw. SR screws will snap off easy as pie.
I like stainless square head for IPE' decks. GRK Torx heads for most other stuff, except SR, of course. You should touch on brass and bronze screws and their place and purpose.
charting shear strength and what it means is paramount.
Excellence is its own reward!
When I was a little kid, one of the most interesting pix I saw was of all the various screw heads/types with labels - slotted, toilet slot, robertson, square, phillips, reed-prince, lag bolts, hanger bolts, fillister head, cheese head, torx, clutch, combinations of all the above and others, etc. etc. Everbody has to learn the basics sometime in life, so I would recommend a pix like that along with a chart per your guidelines as to uses as a starting point.
Edited 10/15/2002 1:42:45 PM ET by JUNKHOUND
Did you drool over that hardware picture because of the variety of tips and bits or the models with tits and butts? We all know about hardware posters.
This could be FHBs first centerfold!.
Excellence is its own reward!
We all know about hardware posters. Remember Miss Makita? Tell us why you were really salivating over that hardware poster.
Was it all the variety of bits and tips or the models showing tits and butts? This could be FHBs first centerfold issue.
.
Excellence is its own reward!
Another new guy to break in!
Don't screw this up!
Boooo
Welcome aboard!
before you get any info you need to buy a round.
I will be having a tankard of the finest Ale!
Arrrrrrrrr!
Some of these guys don't know anything about screwin' so you should include stuff like pilot hole sizes and self drilling types.
Also I am curious as to how much pull thru resistance is gained by adding finish washers.
Mr T
Do not try this at home!
I am a trained professional!
There are two important things about screws:
1. They have far greater resistance to pulling out than do nails.
2. Most Building & Safety departments won't let you use them.
For remodeling it would be great if they'd let us use screws. They can be put in with far less impact and vibration transferred to the existing structure and old plaster. With an offset ratchet driver, you can put them in places where even a pneumatic palm nailer won't fit.
-- J.S.
John,
There was an article done on screws in the past, at least it compared nails to lag screws for plate to rafter connections. Nails only held 208 pounds (8p) while a 1/4 x 5 inch lag bolt held 1283 pounds and a 3/8ths x 8 lag bolt held 2783 pounds. only a simpson H6 connector was stronger.
The article was written by Stanley H. Niu
Further research along those lines convinced me to build my timber frame using lag screws as the primary connection fastener rather than trenails.
But my understanding is that in a timber frame the trenails are never supposed to be in a postion where they have to resist a pulling force, they are only used to pin joints together, so they only need to resist shearing, and in many joints the shear forces should be negligible unless you are experiecing a earthquake or hurricane.
I can understand using screws instead of nails for attaching SIP panels, but again most of these are in shear, not pulling.
Robert
But in the real world there's no such thing as pure shear. If there's any distance at all between the pieces being joined, or any crushing of the fibers adjacent to the fastener at the interface, the nail bends a little and therefore starts to get pulled to some extent.
-- J.S.
Robert,
In Europe trenails are not allow in current construction due to the fact that they provide a easy firepath and cause the connection to fail long before it would otherwise fail.
Thus causing heavy timbers to fall on people/ firefighters. The method used in European counties is to use metal connection hidden behind plugs which provide thermal insulation.
The logic of that method so appealed to me that is the method I chose.
A man I worked with, while looking you straight in the eyes and full of confidence, got upset when I wouldn't follow his recommended practice. He would hammer the screws in to within 1/4" of flush and twist them in the last few turns. He was irate that I would waste time spinning them in as he "had never had any fall out" when done his way.
You should have seen my eyes getting larger and larger while my mouth fell open reading that one..
Excellence is its own reward!
I do not like straight slotted screws.
=Peter
31. I is the longest one letter word.
How do they provide a fire path? Because they are not in the same grain direction as the beam they are hammered thru? Or because if they are left proud of the beam they can catch on fire easier and then burn into the beam? What about if they are level to the beam and either bottomed out, or all the way thru.
I understand now how you used lags though, I had this awful picture of lag bolt heads sticking out of beam and knee brace connections ;)
Robert
over time with the shrinkage and swelling of the seasons, trenails will loosen enough to provide an additional firepath. That additional firepath provides access to the relatively small cross section of the trenail. As you know a small piece of wood will burn long before a large timber and thus long before large timbers will fail they will fall apart because there is nothing holding them together.
I'm not familier with timber framing and would like to know what are "trenails".
Trenails are the wooden pegs used to connect large timbers together. there is actually much nice to say about them in that properly designed they can provide effective connection. In addition they are seasonally adjustable in the spring you loosen them up some to adjust for the swelling all wood goes through in high humidity and in the winter you tighten them up to adjust for the shrinking that occurs during the heating season.
Fire howeve,r is their weakness
Thanks for the info but why is "Fire howeve,r is their weakness". Unprotected steel will fail before wood timbers.
You are correct when you state that unprotected steel will fail prior to wood. However the design requirement of most european countries requires that the steel connection be "insulated"
That is achieved by "hiding" the steel connection behind a wooden "insulator" (false peg) the result is that fire must first burn through the "peg" and then the steel must reach a sufficant tempurature to cause it's failure. As there is still a wooden insulator surrounding the steel it takes a very long time.
I bow low to Mr Sprung for that specification!
Frenchy, what magazine was that article written in?.
Excellence is its own reward!
The GRK website has specs on their structural screws along with some reference to UBC code.
Framing roofs, part of the best of fine homebuilding series published by, hhhhmmmmm..... Oh yeh, Tauton press! ;-)
You'z guy'z wanna help the new guy out and try to consolodate all the info on one thread?<g>
http://forums.taunton.com/tp-breaktime/messages?msg=24000.1
Why? He's the one that started two threads on the same subject. I can tell we've got a lot of breaking in to do.
Excellence is its own reward!
Rut row...
Multiple postings may be the first sign he has a split personality.
Either that or he's been forewarned and is using the "divide and conquer" strategy...
maybe he's a transplant from JLC where the various forums are more segregated
LOL.
Excellence is its own reward!
me double post 2 - #41 in other post may have info of technical interest
A side thought - 95% of search returns for term "wood screw" in technical journals were for orthopedic and surgical devices!
But then we all know orthopedic surgeons are simply good carps or auto mechanics with a more extensive Latin vocabulary. <G>
What mystifies me most of all about screws is why you south-of-the-border types insist on using Philips drive screws when Robertson (invented by a fellow Canuck a few miles from my farm) drive screws are better in almost every way. I mean, every time I watch a DIY TV show and they are driving in a Philips head screw, I hear the bit and head being chewed up. Bring tears to my eyes. And completely unnecessary. Free yourself! Philips bad, Robertson good!
speaking for myself, its not that we perfer phillips head screws its just that theyre more plentiful easier to find, personally prefer square drive screws. They are starting to sel a hybrid screw , a phillips hd that will take a square driver but i havent tried them yet
At Darkworks cut to size made to burn......Putty isnt a option
That's one of those cases where compromise is not good, IMO..
Excellence is its own reward!
I hate those useless mongrel headed screws. Nothing fits them right even the special bit they sometimes give you in the box.
"Squipps" is what they're called around here...
"They are starting to sel a hybrid screw , a phillips head that will take a square driver but i havent tried them yet"
I HATE those stinkin' things. McFeely's snuck some of those in on me once. They're supposed to work with BOTH types of bits, but don't actually work with EITHER very well.
On McFeely's order form, there's a spot where you can check "May we substitute combo screws for square drive?" I always circle "NO" about 14 times, and write "HELL NO!" in big letters.
This seems to work - They haven't done it to me for years.I was more impressed by what came out the last time I blew my nose.
Boss- I remember talking in a thread along time back BP before pospero, speaking of making tools from the quality steel found in old leaf springs, wedges, chisels and the like. Well here's a new one. Ever see the narrow digging spades used for making small deep holes for transplanting trees and such. The bottom base spring is an exact fit in width and thickness from commercial grade products and depth can be to the builders desire as if in one wanted a deeper plunge. The rest is pipe and angle. There ya have it.
No applause just throw money.
Let the thunder crack and the waves roar.
We're going on.
Edited 10/19/2002 1:55:44 AM ET by rez
Boss-
In my experience those 'combo' screws at least work better with a #2 square drive than with a #2 Phillips. I've driven a lot of them with a 'quad' driver that fits the entire recess of the screw. Only problem is, I can't find the damn bits anywhere. Pisses me off when I need 2" yellow zinc and the only thing they have are the combo heads.
My vote's for Robertson or Torx.
Ken Hill
> Philips bad, Robertson good!
Torx better. Consider the amount of torque that a design can transfer before it fails, and divide that by the volume of the recess in the screw head, and you have a rough measure of the efficiency of a screw to installation tool interface. Of course this is more important in machine screws, where the materials being joined can take far greater forces.
-- J.S.
One more along John's train of thought - for machine screws attaching metal to metal where head to shank strength is the limiting factor vs. pullout or tear thru, External wrenching is best (hex or 12 pt washer head), philips is a close second, torx next, roberson or square next to last (70%), at the bottom (60% of strength) are hex socket which are prohibited in most aerospace applications.
Getting back to the wood screw question, most of the screw threads (cute, heh?) around here center around 2 topics: hanging cabinets and securing deck boards. I think maybe subflooring has come up once or twice, also. The consensus seems to be that drywall screws are bad for hanging cabinets, though most people around admit to having done it and none admit to ever having a cabinet fall off the wall (I've certainly done my share in the past few decades). I would certainly like to see some strength comparison between drywall screws, galvanized drywall screws (which I hear are better than drywall screws for structural uses), and the more expensive "correct" types of structural screws, just so we all know how much difference there really is. A comparison of the new types of screws for composite decking (Trex, etc.) would also be nice, with the increasing number of discussions devoted to these kinds of installations.
Just my 2 cents. Hope this helps. Good luck and welcome aboard. Rich.
> I think maybe subflooring has come up once or twice, also.
Also cute, and a bit more subtle than "screw threads"..... ;-)
Testing should include a statistically significant sample of screws from a variety of sources. My guess is that drywall screws will be very inconsistent, producing a much wider bell curve than better screws.
-- J.S.
LOL, You had to read deep between the lines for that one John..
Excellence is its own reward!
Jim, it is important that you be sure and define the term Wood Screw. All screws that look like wood screws (pointed with coarse threads) are not wood screws. There is an ASTM standard that applies to real wood screws. The load tables will not work with look alikes. Typical imposters are sheet metal screws, drywall screws, and deck screws.
Ignoring this fact kills people.
glenn