Construction of Laminated posts for Pole Barn

   / Construction of Laminated posts for Pole Barn #21  
Steve, you’re an engineer so I bow to your expertise as far as wind load. We tend to build with plywood or T-111 siding rather than metal and as you know that adds considerable shear strength. Do you agree that a laminated post will offer more strength than a solid 6x6? How do you feel about the construction detail of the pole itself? Wind load is not a big factor in the local codes where I work so I may be wrong making blanket statements. I do believe what I have said meets the codes of our area.

Richard, Wish we had ready made laminates poles around our area. I have never seen them. Are the ones you get pressure treated on the lower half only? That sounds like the best of both worlds to me.

MarkV
 
   / Construction of Laminated posts for Pole Barn #22  
>We tend to build with plywood or T-111 siding rather than metal and as you know that adds considerable shear strength.

Absolutely. Metal siding provides negligible shear bracing. Conventional bracing or strap bracing is needed when using metal siding.

Proper bracing no matter how it is achieved will reduce the bending load at the base of the pole (where it would be highest if not properly braced) due to wind load, which is a good thing. However, when you get into some of the taller buildings (18'+) windloads can genereate large bending loads near the vertical center line of the side walls. This probably isn't much of a factor in your 10 an 12 foot high buildings (using 6x6s), just your taller buildings as the bending load increases both due to increased load area and longer beam length as the side walls get taller.


>Do you agree that a laminated post will offer more strength than a solid 6x6?
Absolutely. Since only one material is being used in the laminate the better strength characteristics comes only from the minimization of impact of defects. Defects will be limited to each ply AND sterengthened by attachment to adjacent plys.

>How do you feel about the construction detail of the pole itself?
I would buy them from a glu-lam manufacturer. Nobody can do it better than them. They are PT on the bottom only and use finger joints at the end joints. I'll see if I can find the link to the manufacturer I saw in PA. All the PT & SYP comes from down your way, there should be something in your area.
 
   / Construction of Laminated posts for Pole Barn #24  
What some people here seem to be missing is that the perimeter poles are subject to both axial loads due to gravity loading, and bending moments due to wind loads and sometimes eccentric loading from the truss connection.

This is why continuity is so important in the poles. Making a built up column with splices a foot or two apart is asking for trouble. Glue laminated columns as stated earlier are the best, but are also very expensive.

Why don't you mechanically laminate full height members together? This would seem to be an acceptable alternate.

If you are trying to acheive the section modulus and moment of inertia of a solid 6x6, why don't you use (4) 2x6's and use that price to compare to the cost of the 6x6?

Just some suggestions.

Yooper Dave
 
   / Construction of Laminated posts for Pole Barn #25  
Mark,

You can buy them either way. You can get pressure treated all the way up or just pressure treated at the base.
 
   / Construction of Laminated posts for Pole Barn #26  
Sorta just for fun, but also to see how much $$ and work it would take to build a laminated pole for my pole barn project, I bought 3 (2"x4"x 8') and 3 (4"x4" x8'). They we on sale at the local HD. Also I bought a tube of Liquid nails and a box of 3" 12d gal ring nails.

I cut one of the 2x4's in half and glued this, starting at one end of the 4x4, and nailed every 18" and 2 and each end. I used me biscut joiner and put #00 biscuts in the ends of the 2x4's and glued and nailed the next full 2x4 to the 4x4. So I basically stagered the joints by 4' with glue, nails, and biscuts holding it all together.

So now I've got something that is a true 3.5" x 5" x24' and if I attach a 2x6 to the adjoining side, then I'll have a 5"x5" (after I plane off the extra edge of te 2x6).

I've already got 6 30' power poles that are a good 12" dia for most of the structure.

Does anyone know of a comparison eng rating chart for comparing load ratings for hardwood beams vs steel I beams, or LVL's, or the wooden I beams ?

thanks
gary
 
   / Construction of Laminated posts for Pole Barn #27  
>Glue laminated columns as stated earlier are the best, but are also very expensive.

I've never priced the poles myself but I have heard the glu-lam poles are reasonable if you are shopping for longer poles (>16'). I'm sure there is some length were the glu-lam posts become a no-brainer. Probably not for your 12', 14', or 16', posts though.

I used 16' solid posts on my last barn and ordered 6 extra "just in case". Boy was I glad I did that, a bunch were warped and or twisted, and couple had some big nasty cracks down the length of the pole. In the future it's nothing but glu-lams for me. I'll probably save money as I know I won't have to buy extra /forums/images/graemlins/grin.gif
 
   / Construction of Laminated posts for Pole Barn #29  
RE:>I would buy them from a glu-lam manufacturer<

I'd agree with you there. Back in my engineering days it was common to see failure of bonded joints that were created in the field. You CAN do a good job of it, but you need to pay very close attention to the adhesive you're using, the conditions you are using it under (temperature, humidity) and maybe most important, how well you can get the surfaces to mate while the bond is curing. The glu-lam guys do all this in big presses and know their adhesive qualities. It pays to watch the details. There's not many things uglier than a long delaminating beam or column only held together by nails.
 
   / Construction of Laminated posts for Pole Barn #30  
Marine grade PT is 2.4 as compared to the .4 deck material at the big box stores. Big difference. The stuff is heavy. Don't know what .8 is but anyone who builds docks or bulkheads in salt water wouldn't touch .4 or .8 stuff.

FWIW, I had no problem getting a quote on true 8x8 sized marine spec. 26' posts.
 
 
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