Replacing or Repairing Rotting Deck Support Posts
Post rotting at base
One of the three main deck support posts supporting my deck is rotting just above the ground. The other 2 may be starting to rot just below the ground. The house is about ten years old, but we've had a kiddie pool on the deck and I think the splash water from that may have contributed to early rot of pressure treated wood (6x6). The supports are sitting on top of concrete a foot down I think. I got two estimates to fix it
1) Jack deck up and replace 6x6's and put rubber sleeve on them.
2) Summary: Concrete three 6x6 support posts under deck, Concrete above ground and a 10 " diameter around existing 6x6 posts.
Detail (for #2)
Jack up the deck and brace it.
Dig down 20 to 24 inches into the ground.
And sleeve that hole approx 6 inches above the ground so there is no chance it will ever rot again.
The wood that is there will be into the concrete six inches or more and will be protected above and or below the ground .
Is it ok to concrete in supports that are rotted? Will the rot travel higher up the board once they are concreted?
Is there a better solution?
The first option is more of quick and dirty short term solution. This is because posts can often continue to rot once they get going. So this notion of putting in a new post and wrapping it in a sleeve is a good solution if you plan on resting the post on the footing and burying the post in the ground.
In fact, this technique is used by a lot of pole barn builders. There is a fellow in Pennsylvania who specializes in this exact technique and you should read his article.
The solution he came up with is called the Post Protector. I think this would be a very good solution if you go with the first type of solution proposed by your builder. They have a 30" sleeve but you could cut that down to the length you need. You can check it out at PostProtector.com
The second option seems more like a long term solution except that setting wood posts into concrete is always second best to resting the post on a standoff on top of the concrete pier above ground. Concrete is porous so water will always be able to wick up into it and then into the post. I would consider removing the post and separating it from the concrete with some kind of standoff base. You might be able to avoid replacing the post entirely and the work that entails if the rot is localized and you can easily cut off the rotted portion. You would then have to fill the void with a filler block of the same dimension and you would have to scab 6x6's along the side of the post to stabilize the block with the existing post.
So there is work to be done in either case.