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Adding concrete to footings

joenorm | Posted in General Questions on

I hand poured a few footings for a small deck with a covered porch. I am now worried I may have undersized them a bit. Furthermore having looking back at my construction photos I may have not put them at a depth that was truly undisturbed soil.

I am wondering if there is a good method for adding to the footing? or should I just dig new ones next to the existing? I still have good access all around.


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  1. Expert Member
    PETER G ENGLE PE | | #1

    As with much of this, it depends. If your soil is naturally good and hard, with a decent mix of gravel, sand and some clay, I wouldn't worry about undersize footings for a deck. If your soil has a lot of organic matter in it (the soil is very black), a lot of clay and/or a lot of water in your area, undersized footings might settle a bit over time. Adding to a footing like this is not easy and probably not worth the time if you are still under construction. One option is just to add more footings and columns to support the deck. That would reduce the loads on the undersized footings.

  2. JZohio | | #2

    Hi Joe,

    Details of your climate will effect this result. If your anywhere it freezes the ground, 36-40" is enough depth to get pass freezing concerns. I've learned by experience that when your constructing, now is the time to correct errors and ensure a long lasting product. It may take a few days to correct something that will last many years.

  3. 1869farmhouse | | #3

    I’ve dug out ancient footings and added concrete to make them deeper - but it’s a massive pain and I’d much sooner pour a sistered footing alongside if that was an option.

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