Glueing Beams together

alex trent · November 25, 2011, 08:28:24 PM

I have seen on here that when joining two beams to make a thicker beam..like 2..2x10's to make a 4x10 more of less...the beams are glued as well as nailed and also some put plywood at the places where they butt to other beams. If I have beams butting together over a post with 3 inches bearing on each end, does this really need to be done? I guess cannot hurt, but what does it do?

PEG688 · November 25, 2011, 11:15:08 PM

Your mixing more than one process into a situation that may not fit.

If your building a built beam or laminated beam there are good reasons to stagger the splices in the build up rather than just butt built up beams end to end which is what it sounds / reads like you intend to do.

A beam that's laminated doesn't really need the plywood in between the 2 by's , that's normally done on 2x4 wall headers mainly as a quick and easy means of flushing the two 2 by's out to match the 3 1/2" width of a standard 2x4.

So IF your building a built up center beam I'd say stagger the splices over the posts , forget the plywood between and forget the glue.

Generally when people glue up 2 by's the chance that the lumber is dry enough , the glues applied thick / consistently enough, the temperature is 'right' all contribute to how well the glue works, and generally the glue IMO is a waste of time and money .

A built up beam nailed properly is as strong as a site glued up beam that isn't nailed properly. The glue is over kill , that is IF it works due to other factors.

So what exactly are you doing? Lets go back to that , if my answers don't seem to fit what you're attempting to do.

What sort of post are you using if your getting 3" of bearing on each bean end joint?

November 26, 2011, 02:47:25 AM

Quote from: PEG688 on November 25, 2011, 11:15:08 PM

A built up beam nailed properly is as strong as a site glued up beam that isn't nailed properly. The glue is over kill , that is IF it works due to other factors.

Most site built beams I see on this site are both glued and nailed. Pegg are you referring to a specific nail pattern or edge nailed like every foot or six inches? Thanks Rick

alex trent · November 26, 2011, 08:27:54 AM

My question refers only to using two 2x10s (or the like) on top of posts on which joists sit for a first floor base. To clarify, the first part is...

1)The beams are doubled up for additional strength. Let's say you can span it all with one beam. Do you need to glue then 2x's together and/or use plywood between?

2) Any beam...doubled up or not used in this situation..on top a post for framing first floor to hold up joists... meet over a 6x6 post. Does where these beams butt up to one another over the post need the plywood/glue splice or is tying each of them to the post enough.

I am referring just to this one situation and not laminated beams or other uses.

Staggering the beams where they meet over a post is another matter from this...right? I am not sure this would properly be called a splice, since the beams are not really spliced...they just butt to one another over a post. To me a splice would be when the beams were joined not over a support, but to make a longer span between supports. That is not to nit pick the definition...but I think it may be the cause for some confusion.

For a 20 foot total run with post set to span 5 feet and 10 foot beams, are you saying it is better to have the first 2x10 of a doubled pair end at 5 feet and the other at 10 feet nd the pair that butts do the same thing and so on?

PEG688 · November 26, 2011, 12:30:15 PM

Quote from: rick91351 on November 26, 2011, 02:47:25 AM
Most site built beams I see on this site are both glued and nailed. Pegg are you referring to a specific nail pattern or edge nailed like every foot or six inches? Thanks Rick

A good standard nail pattern, on 2x6 I do two one two one two , spaced about 4 to 6 inches apart. 2x8 / 2x10 step up to three two three two again spaced 4 to 6 inches apart. 2x12 four three four three .

Engineers now will spec on specific member a ridiculous 2" OC nail pattern , extreme example 3 or 4 " OC is pretty common. This close a pattern tends to split the framing member , even if you try to go side to side into the stud.

November 26, 2011, 12:58:34 PM

Quote from: alextrent on November 26, 2011, 08:27:54 AM
My question refers only to using two 2x10s (or the like) on top of posts on which joists sit for a first floor base. To clarify, the first part is...

1)The beams are doubled up for additional strength.
Well one 2x10 wouldn't be considered a beam, so your a bit off with that sentence.

Let's say you can span it all with one beam. Do you need to glue then 2x's together and/or use plywood between?

So when you say "one beam" are you saying you'd like to use one 2x10 20 feet long and call that "one beam"?

Lets start over you have a 20 foot span , the plans call for a 2x10 double for a center beam. Is that right?

If so sure you could order 2 / 20' 2x10 , again I forget the plywood between as you're not attempting to flush out the face of this "beam" with a wall. Generally the plywood sandwich is a used for headers over doors and windows , it makes a 3" doubled up 2x header 3 1/2" thick.

Another thing you could do for your beam is use 4 x10 stock to replace the doubled up 2x10.

As to your posts , 6x6 is over kill for a short post in a crawl space, unless you have a tremendous point load bearing on it. Highly unlikely in a small house or cabin. Those type of loads come in multi story buildings with , generally, deep crawl spaces , high ceilings , 10 or more feet on multiple levels .

Another place a 6x6 post might be wise to use is if the post is over 6' in length, a highly sloped lot day light basement exterior deck post that would be long.

2) Any beam...doubled up or not used in this situation..on top a post for framing first floor to hold up joists... meet over a 6x6 post. Does where these beams butt up to one another over the post need the plywood/glue splice or is tying each of them to the post enough.

A post cap from Simpson some times can work , a AC66 or AC44 , generally in a crawl space the post is attached to the beam with a 1x4 or 1x6 , maybe 3/4 CDX plywood scrape.

This gusset should be nailed to all three members, the post and both ends of the beam. Any intermediate posts should also be attached with a gusset post to beam cap , etc.

The post should be attached to the concrete footing with a strap , or some type of clip that attaches is , the strap can be poured into the concrete or bored in later with a roto-hammered / via a concrete anchor.

I am referring just to this one situation and not laminated beams or other uses.

Staggering the beams where they meet over a post is another matter from this...right? I am not sure this would properly be called a splice, since the beams are not really spliced...they just butt to one another over a post. To me a splice would be when the beams were joined not over a support, but to make a longer span between supports. That is not to nit pick the definition...but I think it may be the cause for some confusion.

For a 20 foot total run with post set to span 5 feet and 10 foot beams, are you saying it is better to have the first 2x10 of a doubled pair end at 5 feet and the other at 10 feet nd the pair that butts do the same thing and so on?

A splice beam would be a built up beam where you staggered the butt joints when you are done you have one long bean that in theory could be moved as one piece. It takes a few guys to move the beam into position as it's not stiff single piece. Once it's positioned over the posts and the joist are attached it makes a stronger whole than you'd get out of doubled up 2x10's butted end to end.

Again glued up "beams" done on the job site have about a 50 / 50 chance of having the glue add much to the final outcome unless you build in a bubble , weather conditions , temperature , wood moisture content all have to much to do with the outcome, generally all of those are beyond the control of the builder.

PEG688 · November 26, 2011, 01:19:58 PM

Check out the Simpson site you'll see the connectors,

http://www.strongtie.com/products/connectors/AC-ACE-LPCZ-LCE.asp

Post to beam connection, all in plane with each other.

Reason to use a 6x6 posts,

THis is a temp beam , but the gusset idea is about what you'd see under a house in a crawl space, note the 6x6 posts on the RH side of the photo , those are "real" posts again the use of 6x6 posts was needed due to length of post , load above and in this case just for visual mass of the posts , 4x4 would have looked to small.

Don't get frustrated you can do this, working thru the terms and the why of it all is a good. We'll all learn something.

alex trent · November 26, 2011, 08:48:09 PM

Thanks.

Think I got it. Glue is a waste of effort.

I will simply nail my 2x10's together and rest them on the post and use a Simpson device to hold them. The 2x10 pairs (my beam, so to speak) will just butt agains the other pair over the 6x6. The pass over a 6x6 before they get to the place where they butt...11 foot over three posts, span is 5.5'.

My posts are 6x6 a bit for looks, but also have 5.5 feet above grade back to front on 30 feet.

Don_P · November 26, 2011, 10:43:11 PM

Just to help with semantics. A joist is a beam, it is just one case of a beam. In the field no one calls it a beam but the engineering that sizes it is the same formula that sizes a girder, a header or a rafter. A girder, whether built up or solid sawn is another case of a beam, technically a girder is a beam that supports other beams.

Generally I like to "weave" built up girders into a continuous beam by alternating the breaks across the posts. It makes for a stiffer assembly and ties the building together better. In some cases it can be a bad idea and a series of simply supported beams is better, but then they need to be well tied to one another by steel straps or something.

Glue does make things stiffer but I normally don't glue built up girders. Like PEG, I tend to think it is hard to get a good job so I nail it well. Next week I might have a different opinion, I go back and forth on this one.

November 27, 2011, 07:13:29 AM

Thanks for the definition...sounds simple but as you see, can cause confusion.

Questions..

1. If the 2x10's splices are staggered to make up the final girder and all the splices come over posts, do you need plates at the splices...metal or otherwise at the splices, or just good nailing all over.

2. This is opinion, I know but since I am buying wood and air drying myself I will not get to pick all the straightest lumber after it is dry. So, do I buy shorter pieces for the beam build up and have three pieces in a 30 foot total length, longest being 13 feet OR buy longer and have just two pieces in each final beam....longest piece of 2x here is 18 and 17 feet. While fewer splices is good seems to me I run a greater chance of getting warping in the drying with the longer ones.

Don_P · November 27, 2011, 08:18:27 AM

If you make splices over the posts and stagger them and nail it all together well no hardware needed in the splices. I was also forgetting that this is rough sawn, glue isn't going to do a thing. Personally, if you can swing it I'd buy long but buy enough to go short in case you get alot of drying degrade and have to cut out twists,splits, etc. I'm trying to think of what the excess can be used for either way, if short maybe railing pickets, if long, benches, furniture, another building, etc. I'm not sure about how your woods act as they dry. My high specific gravity woods tend to go through alot of movement on the way to dry with greater losses than lightweight wood. Local knowledge there is probably worth much more.

The nails can make a big difference use pole barn, ardox nails... ring or threaded shank, these hardened nails will work much better and maintain strength through moisture fluctuations. If this is full dimension start with 20d and go from there up in size for the project. You'll need a cordless drill and a bunch of 1/8 and 3/16" bits I'd imagine.

PEG688 · November 27, 2011, 12:34:13 PM

So what type of wood are you getting? It being R/S must be in another thread, other than Don's mention of it?

And seeing Don's sort of wondering what type of wood your using where are you located?

Ah, I see Nicaragua, so you'll be using some tough to nail wood I'd guess? Most tropical are hard as the nobbs! Do you know what species you'll be using? I have a book called "Woods of the World" .

I also see you'll be up against so interesting issues with getting materials.

G/L PEG

Don_P · November 27, 2011, 01:33:12 PM

Hey PEG,
In another thread Alex mentioned using cedro macho, a common name. The common name I know is andiroba. I've used a little but not enough to know anything.
http://www.fpl.fs.fed.us/documnts/TechSheets/Chudnoff/TropAmerican/html_files/carapa1new.html

The main index for the tropical techsheets is here;
http://www.fpl.fs.fed.us/research/centers/woodanatomy/techsheets_display.php?geo_category_id=4&genus_commonname_criteria=c&sorting_rule=1a

Judging from the techsheet I'd borate green from the saw with solubor or timbor and count on some losses.
The durability comment has changed as I look at my mid '50's and mid 70's wood handbooks and now this techsheet. Not sure if this is the tree changing through second growth or simply wider experience.

PEG688 · November 27, 2011, 01:43:31 PM

My book says :

Pre-boring is necessary .

Moderately durable and resistant to preservation treatment.

Under uses it lists:

Boat and ship decking and superstructures , light construction , flooring and rafters, high class joinery and furniture , and turnery.

Looks pretty in the sample they show, sort of like Mahogany.

November 27, 2011, 07:01:57 PM

Thanks for the info.

The wood is, in fact, Andiroba. The most common wood for light construction here. I compared the properties to SYP to have a baseline and it looks like 20% more strength in key attributes. My work up to the floor will be rough and the rest finished..except maybe the siding. Will need pre-boring, but labor is cheap and they like to use the battery drill. The nail info is especially useful and to get anything but bad stuff, got to make a run to HD which I will do next week when in the states on business. Same nails for joists which will be layied on top of the beams?

Here is a decent site for info on this and some other wood. I considered guapinol....harder and tougher and will use it on the floor. But not worth the extra cost and trouble for framing and turns dark red.

http://www.lumbermax.biz/index.php

Cedro macho..local name... is used untreated here above ground and has good termite and insect resistance. There is no PT available. I will borate as soon as it is sawed. Bora-Care on the posts and beam joist lumber and Timbor on all the rest.

Don, I think I will take your advice and buy some extra pieces for the beams and joists to take care of big drying warpage which may happen. My local people tell me not a big concern...but that is to be seen. Their "concern" about things is not always a good indicator. I bought some a while back to use and never did...2x8x16 and some 2x4 x14 and 4x4x8 and now after three months under plastic in the rainy season dead straight. Just checked today. Of course, no where near dry, but still a good sign...I estimate likely 40% and the final air dry here will be 20%..which is pretty much EMC. Floor will be kiln dried to 13%

Availability of materials is, indeed, a challenge. It is getting a lot better though, but all the bells and whistles stuff...like specialty nails, connectors, is just not here yet. I have to place my wood order tonight as if not I miss my suppliers window to get wood that has been licensed to cut. They are finally trying to enforce regulations here to reverse deforestation. Missing that means waiting another month, which puts me really behind in starting the build in mid January. This will give me 6 weeks of air drying and will get me to an OK place with that. Just.

Some good news is I located a young man who has experience with wood and building with it. Has some engineering knowledge, but is mostly a designer. Biggest plus will be he has contacts with somedecent builders who can hel[ as this is not possible for me to do alone.

Don_P · November 27, 2011, 10:27:57 PM

For drying, shrinkage only begins below fiber saturation point, ~25%. That is also where mechanical properties begin to change, the wood gets stiffer and stronger. I doubt you will see more than hints of what drying might do in 6 weeks, but if you rush it and try to dry it too fast it will misbehave by checking and splitting.

On the nails, basically when you nail green lumber (>~19%) and then it subsequently dries it takes a big strength loss using regular nails. Hardened deformed nails do not experience this strength hit so if you can use ring or spiral shanked nails, hardened if possible. And for myself I'll add galvanized to the wish list as well to avoid corrosion or staining as parts of this will remain exposed. As for my comment on nail size, it sounds like some of this is rough, some dressed. What you are looking for to develop full strength of the nail is at least 10 diameters penetration into the main member. US lumber is dressed to 1.5" thick, a 16d sinker nail is .149" diameter... multiply .149 x 10=1.49", it is what it is for a reason.

On the borate, Disodium octaborate tetrahydrate, DOT, the ingredient you want, is in all of these formulations. Borate diffuses into wood that is above fiber saturation point. It travels through a wet cell wall from areas of high concentration to areas of low borate concentration. If the wood is fresh and green borate is all that is needed, it will diffuse without help. If the wood is dry then it needs some help saturating the cell walls and keeping them wetted out while it moves into the wood. Glycols dry very slowly and perform that function. Bora-care is simply DOT and ethylene glycol (anti freeze). Timbor is straight borate and is cheaper than Bora-care. So on your green timbers don't waste your money on boracare, unless you want to. On the dry wood you need to use bora care, or some form of DOT with a glycol.

Solubor is chemically identical to Timbor but is listed as an ag chemical and is cheaper (boron is a micronutrient used by plants). I use solubor and water for treating green timber and add antifreeze to that mix for dry timber. You can use a low tox antifreeze, the glycol is simply to wet out and slow drying. I build a wooden trough and soak timbers, rolling them over to get all sides.

All depending on what your shuttle vehicle is, we had one homeowner weld a removeable front pipe rack for his jeep that dropped into slightly larger pipe attached to the bumper. He could then haul ladders and small amounts of lumber up top.

alex trent · November 28, 2011, 05:53:29 AM

I am on my way to the States today and will certainly buy some of these nails.

I have read on line about using green framing lumber and seems like a lot do it and some even swear by it. Hope it works here as there are no lumber yards for this type of wood and from what I read air drying 2x's a long process to get the to EMC or close. This is the ideal time here to air dry as 90's and as low humidity as we get. The mill is stickering and letting me keep in their big shed which has good air circulation and generally a nice breeze. In any case, if I want to build anytime soon, not much alternative. She has a kiln and I may consider asking her to give it a week at the end in there. I believe she knows how to use it and the right schedules to avoid problems.

I already have both kinds of borate, so will save some of the liquid for when (if) i run into some dried lumber. No one seems to have or want to order the rough size coupling for me. I will call the customer service line but if you knw of a supplier, help is appreciated.

I plan to use the one with the bolt in the concrete (ABU, I believe is the code). We plan to pour in mid december, but not attach posts till mid January. So I can wait on the units and all I need right now is the right bolt. Says 5/8 HDG, so I assume this is a normal heavy duty bolt that I can put in (straight) as we pour.

Don_P · November 28, 2011, 08:19:22 AM

HDG... hot dipped galvanized
I'm running late so don't have time to check specs, just make sure that you have the location of the bolt hole (I assume this is a J bolt) in the bracket before placing the bolt in the pour.
Safe Travels

alex trent · November 29, 2011, 07:08:39 AM

Yes...to be sure. I am pondering this closely as I travel. Mispositioning one or more would be a real bear to fix. But lots of string and measuring a lot of time should help. In closely checking the ties, I see that the rough sizes for 6 inch have a lot less uplift than the ones available as regular. I am going to buy regular and notch the post to fit at the base. I take it trimming out a half inch will not markedly alter strength. I am going to take the bolts back (hopefully) so we can pour in late December and I have someone who will bring ties in in early January. To me, the Simpson CBSQ which goes right in the concrete and does not use a bolt looks sturdier than the ABU but also needs absolute precision in placement. I would stlll likely use them but means waiting to January to pour. Any harm in pouring now to within a foot of the top and having rebar in place all the way up and then filling in the rest later. The CBSQ needs 7 inches of concrete depth. This allows me to get a lot of it done now and still use the CBSQ if I get brave enough to insert them rather tan use a bolt with some room for adjustment.

Don_P · November 30, 2011, 07:33:36 AM

Dapping the bottom of the post to accept the CBSQ would not be a problem but I suspect the weak link would not be uplift. I think you'd fail laterally before uplift would become a problem with the ABU. IMO I'd pour the pier as one piece.

November 30, 2011, 04:53:02 PM

I am in Canada in the sticks and have had the chance to look at some Simpson connectors in some big hardware stores, so getting some comfort level now that I have put my hands on them. I think the ABU with the bolt is the ticket. Have to order and can get them brought down in January. I will plan to put bolts in in the pour and so it as one shot. Do I need j bolts? I want to take back with me and none here, and if none in HD, what is a good substitute? All thread? A 10" 5/8 bolt? On each I could put a nut and washer on the end I insert into the concrete ad that plus the threads should provide enough "hold? I assume this all needs to be galvanized...they all look like it, but not HDG.

Don_P · November 30, 2011, 05:57:03 PM

Yes you can use a bolt with a large washer, allthread with nut and washer would be a bit weaker but I wouldn't have a problem with it. The HDG is the main thing I would be trying to get, and at that diameter it isn't strictly needed.

alex trent · December 04, 2011, 10:17:15 PM

Found j bolts so I am ready to pour columns on return.

Nails are a problem. I am looking for spiral nales since wood will be greenish. For attaching the 2xs for the beams to one another ( two 2x10's) the only HDG spiral nails I could find are 16d Grip Rite S/T Patio/Deck. Length seems OK but I see the diameter of the nail is less than a common nail..like 0.114 vs 0.145 inches. So, is it OK to use these and just use more of them...say 6/lineal foot? Have really hunted and cannot locate any other spiral or ring nails of any size. These look good except for the diameter.

Then for the 2x8 joists to the beams... four 10d of the same type on each beam coupling?

What about 4" Prime Guard wood screws for joining the 2xs for the beams? Does it have to be nails/ I thought that when the load was the way it is in joining...pulling out, so to speak, screws were better than nails.

PEG688 · December 04, 2011, 10:50:41 PM

Most screws don't have shear strength , stick with nails. Withdrawal isn't the issue , shear is.

Seeing you're getting your stock milled why not just have 4 x 10 milled for the beams? Maybe you already addressed that , maybe they can only cut 2" stock.

Don_P · December 04, 2011, 11:13:12 PM

Somewhere on here I have pictures of prime guard wood screws that some had sheared under just the load of drying decking. I went back this year and replaced more, they were supposedly ACQ rated and I could get the head out but not the rest that was in the joist. We ran new screws into the same holes as an experiment fully expecting to hit the old shanks and having to put in more holes. No worries, the screws had dissolved, no crunching or grinding, they were gone.

Those spirals are fair, like you said it will take more to do the work. The trouble I've had is those ones fold up pretty easily when pounding into dense wood. You're at a judgement call point, I sure don't want to hear my name being screamed from the middle of a jungle $:-\$ .