Premature Failure of Pressure Treated (Ground Contact) wood
#12
Those of you in California can ignore the following discussion of wood fences. Yours are concrete.
 
Regarding wood treatment criteria, the similarities in deterioration are identical with Sleepy's failure. I was in the design business when the requirements switched from arsenic to various concoctions. The changeover happened in the early 2000's. We were all leery of durability since the new process 'borrowed' materials used earlier that weren't very good. [Designers were leery, not the industry.] At the time I think government relinquished some authority to private control, which is never ever a good path to travel. 

There is some comment on post burial techniques, which I won't get into. This topic revolves around treatment process. 

I have specified miles, and *miles* of wood fencing in my career and mostly all of it was not to the best design. Professional design in the USA follows the tenets of herd philosophy--rather than good design--because careers are made for 'good-ol-boys'. Meaning: "the cheapest construction methods drive engineering", or find a new career. Add to that standard the “logic of short-term memory”, so 10 years actual is as good as 30, 40, or even 90-year guarantees. Which year sounds better? Plus, there is a lot of crap to control besides weak wood, useless and poorly applied chemicals, or bottom feeders propping up sticks in order to get their retainer at the end of construction.

 

With posts, shear loads or strength of material to protect against blowdown and structural failure, and environmental protection of the material are the basic properties to include in design. Concrete, slopes, and gravel or concrete under a post plus, voodoo incantations plays the cheap game.

 

Natural durability depends on ancient trees having natural chemicals, not 30-year slash; and there are no more old-growth forests. Nix cedar. So, using pioneer species (fast rotting) for durability requires potent chemical changes in all of the material; that’s the only protection. Traditional methods include applied chemicals soaked onto or pressed into the surface wood to kill and repel nasty destroyers. And, none of the chemicals penetrate more than an inch below the wood surface. Years ago, an outdoor play toy company augured out the centers of their round posts and treated the interior surface as well to achieve thorough chemical coverage. Also, to reach some protection depth structural integrity is destroyed to whatever depth punching knives penetrate.

 
Yikes! Lose an inch to shredded wood when doing structural engineering. And, don’t forget, strength of material is significantly altered by age and growth rate.

BTW, I did a construction go-by rebuild of my deck on this forum a couple years ago and used the same Camo deck attachment system as Sleepy H mentioned. It sure is a definite improvement in esthetics and maintenance process. The tool had an advantage in the install technique that was easier than I anticipated. 
Heirlooms are self-important fiction so build what you like. Someone may find it useful.
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