Alot of pole barn builders (ala Morton) use laminated 2X6 treated lumber instead of whole 6X6 posts for thier vertical members, and then "finger joint" regular construction grade 2X6's for the above-grade portion. Advantages seem to be better pressure treatment as you're more likely to get chemical into the center of the laminated post than into the whole 6X6, the thicker stock these days tends to be crooked or split, so you're more likely to get a straight post with lamination.
I believe you could duplicate the technique for deck posts by using PL400 and stainless steel nails, and then extend up with structural 2X6's for the railing posts and/or vertical posts that could support a screened porch roof over the deck.
Anyone tried this method?
Edited 3/30/2006 11:04 am ET by johnnyd