How is my plan to join an old post's concrete footer with a new one?


Old 09-01-16, 04:33 AM
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How is my plan to join an old post's concrete footer with a new one?

So I am replacing my carport posts this weekend because of rotting 4x4 posts. It seems as though the posts are buried directly in the ground but likely on top of concrete footers that are about 2 feet underground. I was able to stick a metal probe about two feet down where I then hit something solid.

My local building code requires an 8" diameter pier 6" above grade for the 4x4 posts. So if I find there is already a footer down there can I join the old footer and new pier together by epoxying in 3 to 4 pieces of rebar to the existing footer? My plan would be to drill about 3 or 4 holes about 4" down to hold 1/2" rebar that I would epoxy in. I would run the rebar a few inches up from the top of the pier. After the epoxy dries I would join with fresh concrete in a sono tube.

Does this sound like a reasonable plan?

Note if I see the footer down there is in poor condition or too small I could jack hammer it out and put in the pier to a depth of 48".
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Old 09-01-16, 04:41 AM
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It will be determined by the size of the original footer, as the building code would require. Drilling, epoxying rebar in the original footer would be a good plan. Over digging and placing a sonotube in the hole will give you the opportunity to make the above grade pour.
Old 09-01-16, 06:30 AM
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First there is the consideration whether or not replacing the posts is normal maintenance and does not require a permit. But, it would be better in the long run to bring the concrete above grade to keep the posts out of the damp ground.

My inspectors would not allow adding onto an existing footer without you or an Engineer proving that those footers meet the modern code requirement. In most cases that means it would be cheaper and easier to start from scratch when installing the new footers.
Old 09-01-16, 07:07 AM
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I think it's highly likely that your existing footing is inadequate... 2' is not very deep, it would need to be 2 ft thick to get to frost if that is @ 48" deep in your area. Its possible that they just threw down a thin concrete disk to help prevent the post from settling.

Dig a post hole on each side of your "footing" to determine it's depth. If it's not below frost that would definitely determine the route you take. I agree that pulling them out (excavating and jackhammering) then starting over is the best option.
Old 09-01-16, 07:17 AM
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I think the footer starts 2 feet down but goes down deeper, but I will dig to find out. The carport has been standing now for 20+ years without any sinking, but I would like to take it up to code.

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