I have a concrete pad patio, 12x40 feet. It is covered by a heavy tile-roof
overhang from the main house.
The roof overhang (12') is supported by three 8x8 wooden posts.
When they poured the slab, 25 years ago, they embedded the wooden posts
about 4 inches deep into the concrete slab (I can tell from the screws).
Therefore, the bottom of the posts are imbedded 4" into the slab and get wet
whenever it rains: A perfect setup for dry rot in the posts.
Is there anything I can or should do about this in order to prevent dry rot?
Anything to seal the joint between the slab and the wooden posts that are
inserted 4" in the slab? Inject something into the posts?
As you've already pointed out; direct wood/concrete contact is a no-no
unless you've got treated wood. Embedding wood in concrete is also a
Depending on the framing design, you might need the moment resistance
that the embed gives you (at least until rot sets in)
Do you actually have rot or is this just a preventive measure?
I suggest something lke this:
unfortunately they don't make an EPB for an 8x8
which they do make for an 8x8 but this product shows installl with the
plate at the concrete surface.......better but not great. I like to
have an inch or two standoff from the concrete to the post end. This
way the post less likely to get wet or stay wet.
Another possiblity is that you could wait for the weather to get really
hot & dry then drill some hole into the post 45deg down & inject some
wood perservative into the post. But the only way to ensure good
saturation is letting the end of the post soak in tray of the stuff.
Or maybe you could build a little dam around the post base & flood it
with the wood perservative.
The outside of the posts is solid, but nobody knows what's going on inside
or underneath. In that respect I am looking at it from a preventative
Maybe I should probe the inside/bottom of the posts with a long 1/4" drill.
That would also enable me to infiltrate some fungicide.
It would also provide a convenient starting point for
the kind of cracking and rotting you're trying to prevent.
If the posts are far enough under cover so that they're
not getting direct weather, and you don't get standing
water on the patio, I'd say leave well enough alone.
With 8x8 posts, you might have to replace them once
in your lifetime.
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