Wood Rot At Post Base
A situation like this is never a good
idea. As a matter of fact, I don't even think that you're allowed to
build things like this anymore. If you look close enough, you will
notice that a 1 x 6 piece of wood is actually positioned at the edge of
a concrete patio slab.
The structural wood post sits on top of the 1 x 6 which sits on top of the concrete and believe it or not is directly in front of some plants that get watered regularly.
The homeowner looks like they have maintained the wood post and the 1 x 6 that sitting under it for quite some time.
If you look close enough, you will notice that the soil is darker in color and this would give me a pretty good idea that the soil is moist and moist soil will eventually create problems for any wood that is this close to it.
Here's what happens, the moisture from the soil absorbs into the concrete like a sponge soaking up water. I would be willing to bet that the bottom of the 1 x 6 that's directly under the wood post has some sort of damage and probably was never painted.
The wood rot at the post base doesn't look that bad, until you stick something sharp like a pointed screwdriver into these areas. In this case, you could probably poke a nail into the bottom of the wood rot about an inch and a half, before it would stop.
Home Repair Tip: Replace the 1 x 6 with some type of composite material and then replace the post. This type of construction isn't as common as it used to be, because of the problems they have had with wood in direct contact with concrete.