2

I'm looking to redo part of this deck and found that the 4x4 post supporting the overhang has started rotting at the base. The frost line here is 48'', and after digging about 10'' I haven't hit any concrete, though I suspect it's embedded closer to the bottom and mostly backfilled with dirt. The rotted area is soft in some places but not disintegrated. Is there any chance to save this post and stop continued damage? I was thinking of spraying around the base with liquid rubber and adding post mending plates? I wanted to dig it out and replace it with a sonotube and 6x6 on top, but with it being attached to the roof I do have some fear of it frost heaving. Is this a valid concern with say a 10'' or 12'' tube place 48''+ below grade? I don't believe it's bearing a lot of weight as it's only the ends of 3-4 trusses spanning the entire width of the house with most of it supported above the sliding door header.

Post

Overhang

2
  • 1
    Bad form from whoever put that up. Fortunately the post is likely mostly ornamental, not load bearing. I’d put up a temporary support, dig the post out, and pour a footing to support a post at/above grade.
    – Jon Custer
    Commented Jun 1, 2022 at 13:49
  • Can support the (unrotted part of) the same post above grade, if I understand correctly where it's rotted as being at/below grade. Poor quality pressure treatment...
    – Ecnerwal
    Commented Jun 1, 2022 at 14:21

1 Answer 1

4

Your best bet is to replace the post with a proper install, what should have been installed there in the first place. 4x4 is probably plenty, and you can use any diameter of concrete footer between 8-12" with a 4x4 post.

Is there any chance to save this post and stop continued damage?

Not where it has already rotted. You could cut the post above the damage (after supporting the roof temporarily) and build a new base from concrete to the level of the cut.

I was thinking of spraying around the base with liquid rubber and adding post mending plates?

Spraying/sealing the exterior might help by preventing new water intrusion and sealing the existing rot away from oxygen, but it will continue to deteriorate inside - slower, maybe.

I wanted to dig it out and replace it with a sonotube and 6x6 on top, but with it being attached to the roof I do have some fear of it frost heaving. Is this a valid concern with say a 10'' or 12'' tube place 48''+ below grade?

The reason to dig below the frost line to place footers deeper is to avoid frost heave. You will have frost heave issues in colder climates if your concrete footer is not below the frost line (the depth to which the ground freezes in winter). If your area's frost line is above 48" and you dig to 48", you will be fine. You can look up your frost line but here is a general indication:

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.