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Building Green

Started by jemmy, December 22, 2020, 02:25:11 PM

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jemmy

Any issues that I need to consider when building a steel barn with green lumber? If I mix species am I asking for problems? My idea is to do a standard pylon system, with a free spanning rafters. I understand everything will shrink 5-8%.I just do not know how this will translate complications in the structures and how these complications should be combatted. My first thought is to use screws everywhere, is a possibility to use nails? In Ohio you do not need permitting to build an agricultural building, so using sawn lumber is on the table. 
Plan for the worst, hope for the best, and take what comes with a grin. - Grandpa Chuck

Don P

Green oak and steel can be a problem. Regular nails in green wood that then dries lose about 70% of their withdrawal strength, ardox type pole barn nails are the exception. Never a great idea to build green but sometimes you gotta do what you gotta do.

jemmy

https://www.mazenails.com/nails/6/35/ARD*/spikes/log-home/ardox-spiral-spikes

Are these what you are talking about? 

And Im planning on using plating with lag bolts, I imagine these wont lose their holding value?
Plan for the worst, hope for the best, and take what comes with a grin. - Grandpa Chuck

Don P

Those are the nails I was talking about. Whenever possible a "deformed shank" either ring or spiral shanked is going to be better in withdrawal, and of course driving through and clinching even better, which is where the phrase "deader than a doornail" comes from, a clinched over nail in a door batten strip.

Now you made me dig out the book  :D. A lag installed at above 19% moisture that dries to below 19% (that's just the general break line for green/dry) does not lose withdrawal strength. If installed green and stays wet use only 70% of the published withdrawal for dry wood.

Looking at that table under shear, a dowel type fastener, which is any of these we are talking about, installed green and then drying, if over 1/4" dia has 40% of published shear strength, if under 1/4" it has 70%. hmm, that seems quite a spread.

The better place to get those numbers is probably the connections calc over at awc.org. I think it'll have all this with the design strengths, moisture adjustments, whether you are using a metal plate, etc, built into the calc. I took a short day class taught by "Dr Nail  :D", there is actually as much going on with fastener selection as with beam sizing. holding stuff together is another big part of building engineering.

jemmy

Thank you Don for the help and wisdom. This means a lot to me!
Plan for the worst, hope for the best, and take what comes with a grin. - Grandpa Chuck

kantuckid

Quote from: Don P on December 22, 2020, 05:39:27 PM
Green oak and steel can be a problem. Regular nails in green wood that then dries lose about 70% of their withdrawal strength, ardox type pole barn nails are the exception. Never a great idea to build green but sometimes you gotta do what you gotta do.
That said and all above is so true- I can still testify to the difficulty of tearing down a bunch of green built houses and barns all nailed long before I was born. My big red crowbar has been beat to crap tearing down stuff built green. Screws are great where they serve a special purpose, nails are lots cheaper though. Framers still use hammers and nail guns. I wish my home had more screws around areas like doors and windows where, over time you replace glass, change stuff out, so on. Plus screws pull things together via threads, a nice idea sometimes. 
If I drive down the road near me many of those buildings-barns and old common houses the folks live in-they are nailed green wood. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Don P

Just a comment on screws. The typical deck or drywall screws are brittle things. They work good in withdrawal but are brittle so they break unpredictably in shear, at relatively low stress. If you want to use screws structurally, use a structural screw. Usually you will find that stated or an "ESR" number on the box and often a small chart or flyer with the box giving design strengths.

Ductility pics, drywall and deck screws break pretty readily in bending, that black structural screw, well, I folded it over and broke a come along about the same time that I broke the screw. The nail, very ductile, it isn't likely to snap unexpectedly.



 

With any of these "dowel type fasteners" if you are splitting wood that is not good, at that point it is fine to predrill a pilot hole 70-90% of diameter or root diameter of a threaded fastener, no reduction of design strength.

In a relatively weak per unit area material like wood many smaller fasteners often work better than fewer large fasteners. You won't break a bolt but the bolt can certainly break the wood if heavily loaded, where many nails spread over a larger area spread that load out over more wood area. Losing one nail is probably not catastrophic where breaking out one bolt can be. The gang nail plate in modern light trusses is an example of this.

In all work one thing to think about is to avoid brittle failure, you never want a building to fail by the Snap! Whump! path. A building should have ductile failure, visibly distorting, screaming as it pulls nails and rends wood, buying time for you to run.

kantuckid

I'd like to sell off my stash of slotted screws. I might have enough to build everybody something? Torx screws give slots the finger in the screw world. I only use slots in brass for furniture and brass hinges I have on hand. They are always mild steel but also never cooperate much. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Walnut Beast

GRK fasteners/screws are the ones I really like. I've found all galvanized dipped smaller screws like Don P give examples of to always snap off 

Don P

Yeah, I walked out of Lowes the other day with $200 worth of them and fastenmasters. I didn't need a bag, they are proud of those things.

kantuckid

I've wasted enough time chasing larger torx screws to score deals on many of the larger ones I have chomping at the bit to become part of my cabin. The larger ones are seriously tough stuff. 
And not long ago, I thought a pole barn nail was hot to trot.  :D Them and the timber screws like to stay where they first traveled. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

mudfarmer

Quote from: Don P on December 26, 2020, 05:08:22 PM
Yeah, I walked out of Lowes the other day with $200 worth of them and fastenmasters. I didn't need a bag, they are proud of those things.
>$1 each for 8" timberlok by the 50 pack here. yes proud but when you walk the walk you get to talk the talk I guess ;D
The GRK are really nice but the head is ugly, even my wife agrees and she married me and stuck around all these years  8) The black 5/16" hex head seems easier to hide and less obtrusive in visible spots.

Walnut Beast

I don't think the head looks that bad. I don't know right off hand but Don P probably knows. The trim screw that has the pencil top head hides pretty good. I really like there concrete screw/anchor 

Don P

All depending, head pull thru can be another problem with small headed fasteners so do think about your failure mode. I don't particularly like looking at any of them, I have a full set of plug cutters and, all depending, hide exposed ones if it is going to be exposed in the finish.

zinc oxide

best prices I've found, especially in bulk.

Construction Screws - Jake Sales

I think it was in eighth grade shop class where we learned about 'counter boring' and 'countersinking', and I seem to recall that the screw actually just clamps the board.

 These screws, in addition to the washer head, have the type #17 point, and  helical ridges (mostly obscured by my fat thumb) for the counterbore, if that is the proper word, long time ago. The gentleman I spoke to specifically mentioned not to pre-drill, although I neglected to ask about hardwood applications. End of year sale going on, so I may try to call today and find out. They typically just come in a plastic bag in a cardboard box. I then transfer them to plastic coffee cans, and spray and toss with silicone spray for future use. Figure it couldn't hurt, and I have noticed there is no squealing when driving the screws. I have also finally learned to keep the spare appropriate size bit tips in the same container, typically use an old snuff can, which I pray will soon be at a premium, LOL, New Year's resolutions. I have also found that it helps to use the labeler to cut down on time opening cans to see what's inside.

Almost any type of screw you could imagine, in addition to a variety of 'specialty items', like high-quality roof boots for new and retrofit construction. Very reasonable prices.




 

A local lumberyard has started carrying grabber® XT-II exterior grade deck screw with the same type  #17 point.

It has been my experience that unless you pre-drill, regardless of how tightly the piece is clamped, you get a loose joint with virtually all drywall type screws. The XT-II Eliminates the pre-drilling entirely for rough construction such as 2 x 4 shelving frames. Actually pulled through and split a 2 x 4 that I screwed to a 4 x 4 just for test purposes.

Don P

With some screws and lags I've had a pilot at 70-90% of root diameter, a predrill at 100+% of thread diameter and a counterbore at 100+% of the diameter of the head or washer. For some stuff you can use a fuller bit with a countersink on it.

When I'm running in without any prebore, with modern screws this is most often, If the screw pushes the pieces apart as I go in I'll reverse till the pieces set back together and then finish screwing in, that'll usually do it.

I've been trying to find the paper on green oak I was thinking about @jemmy , it isn't loading for me right now, lunch is over and there are windows in the shop waiting for me to bring epoxy down, but I believe this is it;
https://forestry.gov.scot/images/corporate/pdf/green-oak-in-construction-2007.pdf

zinc oxide

what the...?

My apologies for the widely varying font sizes if that is what it is called. Didn't mean it to appear like I was 'shouting' in web parlance. From now on, I will start and complete a post in its entirety instead of jumping around to other applications... My best guess.

Thanks, Willy

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