Bill,
Thanks. Those are very informative. It is clear that for a given duration of treatment, a 2x6 will be more thoroughly saturated with preservative than will a 6x6. I don't have the physics or engineering background to know how a 6x6 built up of 2x6's compares in strength to a solid 6x6, but in general composites, like plywood, often exhibit superior qualities. I suppose the splice might represent a weak point toward flex in at least one direction, but "weak" is a relative term at best. I've been looking at lots of 6x6, 4x6 and 2x6 lumber in the last few days. One thing I have noted is that it is easier to find really good looking 2x6's than 6x6's. Many of the 6x6 poles appear to be squared-off single trees, while the end grain of the 2x6's gives the impression they were cut from larger diameter logs. The quality of 6x6 lumber may vary sigificantly around the country. Here in mid-Missery they look to be mostly southern pine. The prices for longer pieces of lumber can also be dramatically higher, which makes sense, and the difference is greater for the larger cuts. While a 2x4x16 may be about the same price as two 2x4x8's, a 6x6x16 costs quite a bit more than two 6x6x8's.
This has been an entertaining project so far, and I've not yet driven a single nail. I'll bet most farm boys could slap together a decent pole barn/shed like I plan with very little brain strain. I on the other hand, have only a little building experience, and none with pole-type construction, so I started by trying to get plans. Payless Cashways ran me off a plan and materials list for the 16 by 32 foot shed I at first thought I would build, but then they went bankrupt....I thought their prices were a bit high anyway, and that might be related to their demise. I also got a similar plan from Lowes, this time for the 24 by 32 foot structure I now want to build. Neither of these plans gives enough detail to even show how the roof trusses are supported. However, in both plans, the horizontal below the trusses are 2x12's and are identified is "truss supports", which implies that the trusses are set beside the poles but are supported by these horizontal "beams". I suspect that this is done because it allows the builder lots of leeway about setting the poles. That is, if the site is uneven or the poles are set at different depths, it is no problem. The Payless plan even calls for 6x6x14's even though the walls are to be 9 feet. Slap the poles up. Nail on the beams and set the trusses on them. Then cut off the excess pole. This is probably OK for a relatively light metal roof, but clearly direct bearing vertical members would be superior. In the plans I got from the site Beenthere gave me, the trusses are set on the poles. Though I'm just building a 24x32 open sided barn/shed, with 9 foot walls, I think I'll make laminated poles, using screws or nails and construction cement, and set the trusses in a slot on top, ala Morton. My beams will probably be all treated lumber, with no splice, because that will be easier for me. My site is not perfectly level, and I doubt I'll do precision pole setting, so I may have to get creative. I'm thinking I'll leave the nails or screws out of the top foot or two of my laminated poles, and after I fix the horizontal members at the 9 foot mark, I'll cut off the excess pole a few inches up, then take out the center piece with my chainsaw to make the slot for the truss. Then I can add the fasteners to the poles. Sounds like fun. I ordered the trusses yesterday and they'll take more than two weeks to show up, so I have time to contemplate.
Chuck
