laminated post for pole barn

[Steve_M]

I am ready to build a new saw shed and would like to use as much of my own material as I can.  I would like use green red oak 2x6 to make laminated post 13' long that will be placed on concrete piers 12"
above ground.

I am looking at at least a 40 x80 shed so I will need a lot of these post.  I have a good supply of short low grade red oak logs that  I would like to use.

Is this a mistake???  Will I have problems with mold/rot by nailing the wet lumber together?  Any other concerns?


Steve

[mike_van]

Unless they are air dried for a few weeks to get the surface moisture dry, they will get moldy between the boards. Will this affect the future strength? I don't know.  After a long spell of dry weather, they will shrink up enough that the three boards will no longer be tight. you might need to renail.  Why not saw 6x6's ?   The shrinkage won't matter, nor the mold problem.

[Steve_M]

Mike,

I would like to to that but all my logs are in the 7'-11' range and was hoping to be able to utilize them.  I am just looking to get the roof on before winter so maybe I could cut and sticker the 2x6 and let them air dry for a month or 2.

steve

[IL Bull]

That sounds like a good idea.  I would bolt the boards together with carriage bolts so that you can come back and tighten then up in a year.  You won't believe how much they will tighten. :P
Joe

[mike_van]

That will work Steve, anything to get that moisture off the outsides. Bulls tip is good too, I bolted up 2x12's [oak] for my headers, after the summer, every bolt was loose & got retightened.

[Steve_M]

How close would you guys suggest putting the bolts?

Steve

[Gary_C]

Where you have a joint on the outside board, you should put a steel plate over that joint. The plate does not have to be all that thick, something like a truss plate. Just screw or nail it good on both sides. When they make the commercial laminated beams, they finger joint the splices. If you did not have too many, you could dovetail the joint.

A box store that makes laminated beams uses all stainless fasteners. Actually they use SS nails machine driven and clenched on the back. Course they are using kiln dried dimension lumber, except for treated wood for the ground contact pieces.

I would both bolt and glue the layers together. It certainly would be better for the glue if the wood is somewhat dry.

[beenthere]

If I was sandwiching green oak together I'd add a liberal layer of Borax between the boards. That will offer some protection against mold while they dry out over time.

Years ago we use to laminate with bolts and use split-ring connectors. I think they are still around, and offer a lot of additional strength (not needed as much in a post, but would be great in a laminated bolted-beam.  There was a tool to make the circular slot around the bolt hole that the split-ring would drop into.  Used them a lot when we made our own trusses.

[mike_van]

Steve, I think a bolt every 2 ft would be enough,  but where you have a joint, should probably be on either side of it, a few inches away.  If you know any utility co. guys,  they're a good source for bolts, many don't re-use them, their scrap metal dumpsters a full of them.  Be worth a try.

[Don P]

I looked up bolted built up colums in the manual the building codes use;
Trying to simplify the wording here's the basics of it I think.

All laminations are at least 1.5" thick and are all the same face width.

If all laminations are not full length then the weakest cross section is used.

A metal washer is provided under the bolt head and nut.

Nuts are tightened to insure that faces of adjacent laminations are in contact.

For softwoods end distance should be 7-8.4 bolt diameters.
For hardwoods bolts should be from 5-6 diameters from the ends.

Bolts in a row should be no closer than 4 diameters, no further than 6 lamination thicknesses apart. (for a 2x they show 8" apart in the row)

Use 2 rows of bolts when the width of the face is greater than 3 times the thickness of one lamination. (~2x8's and wider need 2 rows)

Spacing between rows of bolts should be from 1.5-10 diameters.

Rows of bolts should be the same from the edge. No closer than 1.5 diameters but not further than 10 diameters from the edge.

The example shows a 4 ply post made of 2x8's. 2 rows of 1/2" bolts are spaced 4" from the ends 8" between bolts in the 2 rows, and each row is 2" away from an edge.

Hopefully all that greek will be of some use  .

[Camp Run Farm]

There are some books at either Borders or Barnes and Noble that have good information, also the USDA website has information.  The USDA also has information on roof trusses.  I built my own trusses last year for a storage shop building I built.  I used the USDA spec's for the trusses, they make allowances for different areas of the country for snow load.  I beefed them up using larger gussets that I made from plywood, glued everything along with screws.  The roof is very solid.  I also made up laminated posts for a deck, I would not use 6x6 or 4x6 post again as the laminated worked so much nicer.  I was told they would hold up better than solid posts since the preservative treatment on a smaller piece of lumber is better than on a larger piece, better penetration?????  Who knows it will probably outlast me by a mile and then who cares..