wood rot

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Old 05-17-15, 04:06 PM
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wood rot

will untreated wood last longer in sand or soil..?? or are both the same??
 
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Old 05-17-15, 04:30 PM
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Sounds like a trick question, so here goes. Untreated wood isn't degraded by the sand, nor the soil, but by the moisture/water contained therein. I'd do whatever you are doing right and use treated wood approved for ground contact.
 
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Old 05-17-15, 06:10 PM
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I would say sand because it drains better.

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Now, why doesn't wood rot when it's constantly wet? Venice, Amsterdam and the Taj Mahal are all supported on millions of wood piles. Many of them centuries old and still going strong.
 
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Old 05-17-15, 06:17 PM
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Oxygen and the micro-organisms that cause actual wood rot aren't present when the wood is completely underwater I would imagine. Plus no critters to chew on it. And there's a difference in the type of old growth wood used in the past to what is commonly available now.
 
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Old 05-17-15, 06:24 PM
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Depends on the wood. Pine certainly is low on the totem pole, so to speak. I have black locust posts for grape arbors that have been in the ground probably 15 years and show no signs of rotting out.
 
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Old 05-18-15, 04:45 AM
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I posted photos a few months ago of 15+ yo cedar posts on a concrete pad (no soil contact) that had rotted out. The ones that were covered by plywood sheathing at the base had rotted at base.The ones at ends that were partly covered rotted only on the side that was covered. The ones that were not covered hadn't rotted. The PT footer (covered) had started rotting in places. I don't have an explanation for all this but it seems pertinent!
 
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Old 05-18-15, 04:49 AM
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It's all about moisture! The longer it takes wood to dry out, the more likely it is to receive damage. Both dirt and wood nailed to the posts make it harder for the posts to dry out. Also concrete will retain moisture and if the post isn't elevated slightly above the slab it can wick up moisture.
 
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Old 05-18-15, 05:29 AM
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The decay zone is usually within the first 6"-12" from the grade line. Micro-organisms can thrive in that wet/dry alternating zone. The sand would be better than soil unless you can pack clay around the buried portion of the post which tends to limit oxygen availability for growth.

Borate rods also can help prevent decay. I have also wrapped the upper portion of posts (just below grade) with light gauge copper which also is a natural biocide.
 
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Old 05-20-15, 05:42 AM
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Semi-related question: I was planning on wrapping the new PT 4x4 porch columns in PT 1x to make em look more substantial. Bad idea?
 
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Old 05-20-15, 05:55 AM
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I've painted a lot of porches that had 1xs wrap around the bottom portion to give it more style. If the tops are caulked to prevent moisture getting between the 2 there won't be any issues, the problem is caulks will fail and if moisture stays for any length of time under the wood it will fail. Using PT wood does slow that process down.
 
 

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