Construction of Laminated posts for Pole Barn

yooperdave · Jun 27, 2003

Don't know what .8 is but anyone who builds docks or bulkheads in salt water wouldn't touch .4 or .8 stuff.

They are referring to the density of the preservative treatment being retained in the wood.

Green treated has the least, brown treated has more, and marine grade has even more yet. This is why the wood is so heavy.

Yooper Dave

Anonymous Poster · Jun 27, 2003

buckeye:

Are you dead set on the "pole barn" style? If not consider quonset. I have designed and built a couple smaller structures using laminated frames. Advantages include less material per sq ft of floor, stronger load factor (for same material) and cheaper (for same quality).

Of course, like a carpenter with a hammer in their hand (the old cliche), I have built sailboat - ply over frame - so everything looks like a sailboat. Very strong. Laminate frames using resorcinal glue (or liquid epoxy - I guess the West system is still around), notch for longitudinal stringers, and, if you really want it strong, build up your own plywood using cheap door skins (one layer in one direction 45 degrees, then the next layer in the other direction). No hardware needed (except staples to hold the ply together until set up). Or, use thinner CDX ply running fore-aft. The slight bend on the ply greatly increases rigidity. The resulting structure will be extremely light weight and very, very rigid and strong. It can be built up/bolted to a concrete footing.

Another option, if you don't want to build it yourself, is to purchase corregated metal arches (bolted together) which are tipped up one at a time. The corregation in the metal provides great rigidity. Quick, easy and relatively painless.

JEH

PS How do you like your TC40? Just bought one a few months ago (only 100 hrs so far) myself and it works nice for me. Have you have many probs with it?

buckeye · Jun 27, 2003

grimreaper:

Thanks for your comments. I am not really set on any one type as of yet, but I am leaning towards the pole barn. No matter what it will be, it will be something I put together myself along with my Dad and some friends.

As for the TC-40, it has been great for us. I would buy it again, no questions asked. The only problem I have encountered to this point is with my 16-LA loader. I just wasn't attaching and detaching it correctly and slightly bent the metal that allows the support leg to pivot on. Thanks to Jinman, I have downloaded a series of pictures that shows a better way to do things and I should not have any more problems. Just to be sure, Dad and I are going to weld a support behind the metal this fall when it gets cool and we have time for shop work.

Gatorboy · Jun 27, 2003

I am probably repeating what is already said, but what I have found to be the benefits of laminated posts are:

1. Lower cost -- no need to have PT all the way up, just the portion that is in the ground.

2. Better treated wood -- 2x6's are going to be treated more uniformly than a 6x6 would. Not sure how much of the treatment of a 6x6 would make it to the middle of the beam.

3. Weight - Untreated wood for the upper portion of the pole will be far lighter.

4. Ease of use - Setting your posts in the ground should be far easier with a shorter lower section of laminated PT than trying to set a 12'-16' PT post.

Morton Buildings use the build-up method for making posts. I am sure if there were problems with using them, they would have stopped years ago.

I started making some posts for building my own Pole Barn -- I made them with one 2x6x8 and one 2x6x12. The 8' piece is in the middle, and I cut the 12' piece into a 6'8" piece and a 5'4" piece.

Darren · Jun 27, 2003

What I meant was I didn't know for what application the .8 treatment was intended. If you order the material from the treatment plant you can also specify the grade of lumber. Because of the process, vacuum first to extract moisture then pressure to force the CCA into the wood over a period of time, there should be no problem with treating the "stick" all the way through at least for the marine grade stuff. The stuff comes out with a dark green almost black coloring.

FWIW, if you're going to use a glue consider resorcinal. It's a structural glue meaning that if you try to break a resorcinal glued joint the wood fibers will tear before the glue will release. Resorcinal is also insect proof and waterproof. Not water resistant, waterproof. It may be the two part glue others have mentioned.

For the amount of labor involved in gluing stuff up, I'd find a local lumber yard that buys their treated lumber straight from the treatment plant and order the marine grade. A Home Depot or Lowes will not be able to do that. Another plus is that carpenter bees won't bore holes in your posts if they're treated from top to bottom and the structure will still be standing long after something built with lesser treatment has rotted.

The .4 stuff buried in the ground is eventually going to rot. The heavier the treatment the longer the life. Do you want your structure supported by .4 or .8 treated posts or 2.4?

SteveBenson · Jun 27, 2003

>The .4 stuff buried in the ground is eventually going to rot. The heavier the treatment the longer the life. Do you want your structure supported by .4 or .8 treated posts or 2.4?

You are right about marine grade, I was wrong. .8 is not marine grade. Someone told me that once and it stuck I guess. I did a little research:

Termite protection: .25 pcf
Ground or fresh water contact: .4 - .8 pcf
Saltwater contact: 2.5 pcf

Anonymous Poster · Jun 27, 2003

Termite protection: .25 pcf
Ground or fresh water contact: .4 - .8 pcf
Saltwater contact: 2.5 pcf


Wow! That is a great jump up to the salt water rating.

Anyone know the reason for this? Not sure why, but I would have expected less problem with salt water vs fresh water, rather than greater rot potential.

Anonymous Poster · Jun 27, 2003

From what I've heard there's a few reasons for the jump.

1. Salt water is heavier than fresh and therefore seeps into the grain easier it takes more density to keep it out.

2. Some of the critters that grow in salt water attack the wood more voraciously.

3. The chemical makeup of salt water is such that it will corrode or rot almost anything.

I'm sure there are others who know more than I about this.

knucklehead · Jun 28, 2003

Jim - I haven't been around the PC for a couple days. Looks like you got enough answers, huh? I searched Google on "built up posts", then "laminated beams", then "laminated posts", and in amongst the thousands of hits, I found a manufacturer's page that gave a few specs. There are a lot of engineering sites, as you may imagine, but I was trying for a cookbook solution that could be used to go right into building design/construction without reading extensive research and digging out the old books. In my opinion, you'll find pretty much what you need right here!

Back in '01, Chuck52 started the Pole barn thread. It's got pictures by Bill_In_MI of the built up posts Morton uses, about halfway down the first page of posts. Following the pictures, there's more talk about built up posts that you might find interesting.

HuntsEndFarm · Jun 29, 2003

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. 

 I'm not sure I agree that the continuity is important provided that the building is braced adequately. I am currently in the middle of a pole barn project (I'll post pictures soon). I designed the construction according to an adjacent Bonanza horse barn (I think Morton bought them out). I am using 3-2x6 CCA to 1' min above grade with staggered heights. I will then extend these with 2x6 SPF forming a pocket at the top to drop my 2x12 rafter into. 2x6 T&G sheathing will be installed around the perimeter of the building, extending above the post joints. My Bonanza barn, with the same construction, has stood for 20 years with no problems. Now I will say that if I wasn't using the T&G sides (which add alot of stability) I would install diagonal metal bracing all the way across each and every wall.

Keep in mind though, that if you have any freestanding exposed columns that these should be 6x6. For instance, some horse barns have an overhang where the horses can stand under. These outer posts will take a lot of side impact (esp. if you have an itchy horse) and no laminated pole would be adequate.

Advantages:
Knowing I would be doing this project by myself, I felt it easier to move and attach everything in smaller pieces. The posts are much less prone to warping and twisting and the tops provide a nice slot for the rafters without getting into tricky cuts.

Another great advantage....When the gravel truck backs over one of your posts, its an easy fix. Try fixing a cracked 6x6x16. /forums/images/graemlins/frown.gif