Glueing Beams together

Started by alex trent, November 25, 2011, 08:28:24 PM

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alex trent

She had 2xs ready to cut to lengthand not sure I could get 4x's.  I was mainly worried about getting some from a reputable supplier and might could have waited, but this is it for now. Better off now as I am getting more contacts.

Screws it is. The prime hard story is scary...you think things that are certified are good.

I will take what I have back. Still one more chance to get something else (thicker) as I have another visitor before we start to nail and will try to order online and have sent to them.  But good to hear these will work..although a bit thin.  I will pre drill everything anyway so that will ease the process...this looks like a 3/32 bit to me as 1/8 is just about the same size as the nail...???

And I will just put in 30 % more nails than what is called for with common 16d nails. Does 6 per lineal foot sound OK?




UK4X4

#26
Not code but could you not just bolt them together ? - more expencive but certainly secure

I have some hardwood furniture here at my house- which got damaged during shipment-I had to drill holes just to get nails in- without they just fold up.- so i ended up screwing glueing and plugging (just for looks)

so even when you get them in - using pre drilled holes they certainly won't hold as well as they should

These are 2x12's carriage bolted and construction adhesived together supporting the concrete tiled roof on my house in the UK- read very heavy

the upper beam is original - 115 years old ! (oops a century out )originally designed for a slate roof

the beams and uprights are what i put in after removing the original ceilings and multiple 2x4 supports, after I had a water tank leak and the ceilings disolved- wattle and daub- horse hair plaster etc etc.

After a dusty day stripping it all out - sat on the floor with a cold cider the wasted space above looked aswome through the joists- so out they came and I love the results- made a poky 13ft sq room open and bright



alex trent

Well, in the old days...before being on here, I would have bolted them and felt secure.  Now I get the feeling that is not a recommended practice, although it seems simple and like a strong connection. I could put in one every 3 feet or so. Not all that expensive for my distance.  If it is OK, I will likely do that as a lot easier than drilling and nailing.  But doing that is not the end of the world either. I need to get diameter of pre drill holes right as want it to be smaller than the usual as I anticipate some shrink after I nail so do not want to make it worse with the pre drilled holes. Nails are 0.114 and 1/8 is 0.125...so 3/16 looks like it is the size...unless I could bolt.

MountainDon

Quote from: alextrent on December 05, 2011, 06:14:14 PMNails are 0.114 and 1/8 is 0.125...so 3/16 looks like it is the size...

I'm not following that. ???  Maybe it's me?
Why would we want a 3/16" hole (0.1875"; it is so much larger than the shank diameter of the 0.114 nail?


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

Don_P

#29
I think that's a typo... 3/32" drill was mentioned earlier.
Let's back up, I think we're staring at our bellybuttons. A built up girder with  framing members sitting on top of it simply needs to be held together. Code calls for nails 32" oc along each edge, staggered. A built up header calls for 16" oc along each edge. I was assembling some 4 ply 2x12 girders today for that situation and looked back and I was running patterns of three .131x3.25" about every foot in a diagonal across the face.

If the joists are hanging on the sides on the girder then the situation is a good bit different. In that case we are trying to distribute the bending stress from the outer ply to the inner one. That takes a good connection.

Bolts are fine just be sure that a bolted connection isn't overstressed. The temptation is to use few bolts under alot of stress. The steel of the bolt can handle the stress but the wood around it might be overstressed. In general wood takes better to many small connectors spread over a larger area than one connector concentrating stress in a single point. But bolting works fine as long as it doesn't overstress the wood. Where I see people getting into trouble most of the time with bolts is highly stressed joints... trying to hang a ledger that carries a floor on an unnotched post or making a heeljoint connection with one bolt. I have several hundred lag screws and ledgerlock type screws in the current job. I guess the key point is that wood is not steel, spread the stresses out.

Just as a side note I've seen people try to mix fasteners thinking some nails will help a bolted connection. Typically connectors work in different ways. A bolt takes full load pretty much immediately where a nail slips and deforms a bit before taking full load. So in that scenario they don't help one another, one connection fails, then the next.

I was suggesting deformed shanks for any nailing involving green (>~19%) framing, it simply holds better. If the wood is subject to wetting, very green lumber, acid containing lumber, or if staining would be objectionable hot dipped galvy fasteners are a good idea. If you nail through and clinch, it isn't ever coming apart.

Also a tool that might come in handy if you have room is a power planer. If parts go a little whooppee on you as they dry you can plane the offending humps and bumps off before applying finish materials.


alex trent

Yeah, meant 3/32..it was early and also cold.

The items on what the nails are meant to do was to be my next question, as on the airplane back it occurred to me that...just as you said....there is little "shear'...just keeping them together since all the splices are over the posts. But, since my "logic" has been wrong about wood issues before, I thought maybe something was amiss with it.  I think the bolts maybe just trouble. I will use the 16d spiral HDG nails and double up on the quantity used, which gives me plenty of margin for error.  Nails are pretty cheap.

I will look into the planer as I am worried about what happens as this dries before I start putting it together.  I ordered some extra wood for this part, so hopefully that will help too. But, the wood is delayed a week now, so I likely will have to delay building to give it at least 6 weeks to air dry.

How accurate are wood moisture meters?  I have one and if it is decently reliable can use that as a guide.    If it is really wet at the end of my projected  time, I may have her put in the kiln for a week.  Costs a lot. Also, I was worried about her doing more harm than good with that, but the guy I am using to help with logistics here says she knows her stuff on that.

Don_P

Moisture meters run the gamut. Mine is a slide hammer model by Delmhorst. I was ready to throw it into the trash for giving wildly varying readings until I cleaned it up and coated all the exterior contacts with ox-guard, the contact paste that electricians use. It has been reliable since.

Air drying by time probably doesn't mean much. Wood will dry at its' own pace dependent on thickness, drying conditions, and species. As it dries from the the green, fully saturated state, it first loses the "free water". This is the moisture that is contained within the cell lumen, the hollow cavity enclosed by the cell walls. This moisture leaves fairly rapidly but has no effect on the shrinkage or mechanical strength properties of the wood.

At about 25-30% moisture content, mc, each cell croses through what is called the fiber saturation point. The lumen is empty, the free water is gone and what remains is a saturated cell wall, fully plump, that contains the bound water. This moisture is chemically bound to the cellulose of the cell wall by hydrogen bonds. The cell wall is comprised of many microfibrils of cellulose strands wrapping around the lumen. As the bound water leaves the microfibrils move, are pulled, closer and closer together. The piece of wood shrinks, the cells become stiffer and stronger.

The fresh cut timber end shows a dry shell and a core that is above fiber saturation. If you see the wet the meter is not needed, you're above ~25% and the wood is still quite green.


Notice I said each cell passes through the fiber saturation point. This is an important concept. The piece doesn't arrive at the FSP all at once, in general wood dries from the outside to the inside. The outer shell can be drying and shrinking while the core is still green and plump. If the drying conditions are too severe the shrinking shell splits because the saturated core will not let the shell move in. This is the trick when operating a kiln, running as fast and harsh as possible for economy while going slow enough not to turn the load into a pile of splinters. You can check or split wood by air drying in harsh conditions as well. In the early stages of drying if the outer shell is drying too rapidly either in the sun or just on a hot, dry, windy day the same thing will happen. A kiln is a controlled environment, air drying is pretty uncontrolled.

I was sawing a load of white oak for a farmer to use for fencing and stickered it onto my trailer as I was sawing. It was a beautiful June day and when I was done I drove over to his place. When I got there the load was surface checked pretty badly. I had run much harsher conditions than a kiln would ever think about. Over the next 30 minutes as we unloaded in his barn the core moisture diffused up to the surface and those cells swelled again. The checks closed and the wood appeared pretty again. Mind you it hadn't healed by any stretch, I had torn the fabric and just like ripping cloth, it might be hard to start a tear but once it begins it is more easily ripped. Covering a load of green lumber running down the highway is not to protect it from the rain, covering a load of dry lumber is.

This is a shot of my meter in a stud that has "seasoned", reached equilibrium moisture content. If you look at the EMC tables for the temperature and relative humidity shown on the thermometer/hygrometer it will confirm the meter readings.


People have built with green timber since time began. And even now I recieve wood that is at 19% yet EMC here is 8-12% so the wood still has some moving to do. We dry construction lumber to that point to keep mold and decay fungi from growing and to take some of the shrinkage out. As a side note, the fungi with a very few exceptions require FSP or above to grow. The old rule of thumb was not to apply interior finish until the wood was seasoned out. Don't place bolts on the two edges of a drying wide board and expect it not to split as it shrinks. Think about what the wood is going to do. Tighten things up, shim as needed, smooth any crowns and then cover and finish the interior. It is a matter of expectations and understanding. I sure prefer to build dry and things act alot better, but I've also built with wood that had bird nests in it the week before.

I need to move a few stacks of lumber up to the house at the job. It's the trim wood we got while sawing the heavy timbers, which I installed green. The trim wood has been air drying for a year while I built. The HVAC guy is going through my dehumidification kiln unit and I'll build a chamber in the basement to remove the last moisture that will bring the wood down to about 8% for interior use. In my house we lived with the trim stickered in the living room through a winter with the wood stove going. It also arrived at about 8%, one has to marry carefully to get away with that  :).

firefox

Thank you for the fantastic tutorial Don!!!!
It was very much appreciated,
Bruce
Bruce & Robbie
MVPA 23824

alex trent

I must have the galvanized nail market in NICA cornered. Spent today cruising hardware stores to be sure I was not carrying in what is here. Nada.

My question is that I am assuming the name of the Grip Right Patio/Deck nails is not relevant.  I am not using them for that and just wondered if that signified anything that would lead me to trouble in my other framing uses. They are just about right...16d is 9 gauge and a regular 16d is 8 gauge, so I am ok. These are the only Grip Rite nails that fit the spiral and galvanized criteria.  There are galvanized ring shanks in non-Patio/deck categories, but I am using them in pretty hard wood and these spirals are supposed to be better suited. Will have to pre-drill anyway, so the rings might work? From what I read, they have much more holding power.  On the other hand, the spiral patio/decks are available in Home Depots all over and the others not. If it is really worth while I could order.  If it were not for green wood nails would not be as big a problem, but i do feel compelled to use spirals/Ardox...maybe just getting compulsive.

Last, are these the same as Ardox?  I see Grip right has an Ardox as well as a spiral nail.


MountainDon

Quote from: alextrent on December 07, 2011, 03:26:01 PM

Last, are these the same as Ardox?  I see Grip right has an Ardox as well as a spiral nail.

I believe Ardox is a registered trade name for a spiral nail.

FWIW, the entire GripTite catalog is available online.



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

Don_P

If you're ordering, these are the real deal;
http://www.mazenails.com/catalog/catalog.php?page=PAGE24&group=THS
These are their ring shanks;
http://www.mazenails.com/catalog/catalog.php?page=PAGE24&group=THA

I had a discussion with a very knowledgeable engineer phd during a class. He did his engineering thesis on nails and was telling us that ring shanks were superior in holding power from testing he had done. I maintained that from field experience I felt a spiral was superior in withdrawal. He said that a ring shank has higher initial strength but once you get it popped and moving it comes on out similar to a common nail where a spiral doesn't have as high an initial strength but once it is popped loose it is harder to withdraw than a ring shank. I think that initial pop happens when someone drops something heavy during construction. He didn't disagree. The NDS is specifying the hardened ardox like the ones in the top link above as not losing capacity in wood that goes from green to dry.

Erin

QuoteBolts are fine just be sure that a bolted connection isn't overstressed. The temptation is to use few bolts under alot of stress. The steel of the bolt can handle the stress but the wood around it might be overstressed. In general wood takes better to many small connectors spread over a larger area than one connector concentrating stress in a single point. But bolting works fine as long as it doesn't overstress the wood.

When hanging our main carrying beam, Dad wanted to put bolts in it in order to get a good "squeeze" on 2x12s that are a bit wonkey, so the nails could grab.  But I pointed out that we didn't really want to be punching holes in the strength of the beam.  (Nails, of course, don't puncture, but rather spread wood fibers.  The strength of the fiber is still there, just moved around)

We decided to put our bolts right at the joints, over the posts, so as to have those weakened spots over the strength of the supporting posts. 
Just a thought.
The wise woman builds her own house... Proverbs 14:1

alex trent

Nails....Thanks for the tip on nails...I saw that site, but problem is for spiral they sell only 4 and 3 1/4 in 5's (rest are in 50's) but you can get the ring in 5's any size. In my reading I too am getting the feeling that in hardwood and green, spiral, not ring,  is best to use.  I wrote them asking if they could give me some local dealer where I have a potential traveler and also to the online store asking if they could do a special in 5's.

Good news is that today I went to my water collector that is built of pine..now dry as up for 4 months, and the Grip Rite 16d went in no problem with a hammer. I know pine is not what I have, but mine will be greener, so might be OK..if not I bought a lot of drill bits.  Do you think, aside from the fact that the Maze nails come in hardened, the Grip Rites are a problem.  Nice thing is they have all sizes in 5's at HD. But the classification as deck nails throws me. Mean anything...i don't know what a "good" nail feels like...these look OK, a bit on the thing side.

Bolts... good tip and i may have to if I get some real twisting.  I plan to nail if all goes well.

But I do plan to notch my posts (6x6) and put the beam (4x10) into the notch and bolt.  so that work for me.

I am going to switch my posts to my Builder Forum location Mtn. Cabin in Nicaragua as I am about to kick it off with some real work. This learning has been a blast, although a bit taxing at times.  I do love to learn new stuff, but also hate to do things with just enough knowledge to be dangerous. .. I really hate to think about having done it without getting on here first. so keep the advice coming, i have a feeling there is a lot more to come.

Don_P

I don't think they are a problem, they are simply not the ultimate nail.  The wet service factor that is applied to allowable nail loads gives factors to multiply the tables' allowable nail loads by. The allowable load of a nail in withdrawal that is installed in wood that is above 19% mc and then dries to below 19% is derated by 75%. In shear that fastener is derated by 30%. A threaded hardened nail is not derated in withdrawal under those conditions. You have a threaded mild steel nail. My feeling is that you have some derating in withdrawal and a 30% derating in lateral load capacity. So, use more nails. A nail gun has similar problems the shank diameter usually means that I must pull the trigger more times to get the same joint connections as common nails.

Erin's bolt comment brought up another topic, horizontal shear in beams. Take a phone book and bend it. Watch the pages slipping past each other as the shape of the book changes from straight to bent, you are seeing horizontal shear. The fibers of a beam do the same thing. Now lay the book down flat and draw vertical lines across the edge every few inches. Now bend the book like an exageration of a loaded beam again. Notice that the lines in the center have not moved much but at the ends where your supporting hands are the lines have displaced the most. Shear is greatest at supports. Not necessarily a problem just a counterintuitive concept to consider. Actually the best place to drill a hole in a beam is well out in the span, center of depth... in the neutral axis at a point of low shear. Kinda hard to bolt to a post there though  :D.


Erin

Not to mention the fact that joints in a built-up beam are ideally placed over posts... 

Also, at least in my case, the bolts penetrated the ends of two 2x12s, but were in the center of the third.  (Because the joints were staggered) 
We also used the skinniest bolts we could find. 
The wise woman builds her own house... Proverbs 14:1