Concrete footings - mess up

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Old 05-22-18, 12:06 PM
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Angry Concrete footings - mess up

Hi there - I'm really hoping someone here can provide some assistance. This weekend, as I was building our deck, I dug holes etc. but filled them up too high (oversight, ground slopes towards house) to the point that I don't have enough space for beam. I only noticed this morning when concrete is dry.

I already have post holders in there. Can I dig about 6+" that I need and reconcrete? Will the old and new concrete bond together or I'll have issues in the future? What are my options now?
 
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Old 05-22-18, 12:26 PM
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Im not sure I understand. If youre removing concrete, why would you have to pour more?

Also, can you bear your beams directly on the footing? If you do away with the post then maybe youd have enough room.
 
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Old 05-22-18, 12:29 PM
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I was thinking, I'll have to fill more so that I can set the post holder in them?

I've thought about resting the beam on concrete footing but being in Canada means snow = rot?
 
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Old 05-22-18, 12:30 PM
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No, you can't knock the tops off what you have then just pour new on top. There will be poor bonding between the old and new concrete. Why don't you cut them off to the height you need. Then install a new bracket using a concrete anchor, the kind you drill a hole and install in cured concrete.
 
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Old 05-22-18, 12:54 PM
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Thanks - for 18x14 deck (14 against the house), I've got 3ft deep footings at 2ft, 9ft, 17ft (3 in total). Questions:
- Is that enough?
- If I chop off 6" to 12" at the edge (footing @ 17ft), that'll reduce that footing. Will this be able to bear the weight etc?
 
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Old 05-22-18, 01:49 PM
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My question is, is 3 feet deep enough for the frost line? Here in Southern Maryland its 20" and we don't get near as cold as you guys. If you're building a ground level deck then you just have to go to undisturbed earth, which may be at 3' for you, I'm not sure. It's not so much the thickness of the concrete that determines the weight bearing capacity, it's the diameter/footprint. In reality, you only need a 6 inch thick footing that's 3x post diameter at the base of the hole, and the rest can be backfilled with dirt but that will lead to post-to-ground contact which leads to rot, so most people opt for a post on top of the concrete, which is clear of the soil. A footing with 4 square feet of ground contact but only 6" thick will bear much more weight than a footing with only 1 square foot of ground contact that extends to the moon. As long as you aren't reducing the footprint, and you're at the minimum depth, then you can cut 30" of concrete out if you wanted, but that sounds like a ton of work. As Pilot Dane said, get a post base that only needs to sit on top of the concrete and drill a hole into the existing concrete and anchor it with a 1/2" diameter wedge anchor (Redhead, etc.). If you remove more concrete, just make your posts longer. But what did you mean by "chop of 6" to 12" at the edge"?

in regards to whether or not you have enough footings, it all depends on beam type/thickness. I can also only assume that you have multiple rows of 3 footings each? It sounds like it's free standing and you're cantilevering it 2 feet to the house? If that's the case, you'd need 9 footings at least, with one row of 3 at 2 feet from the house, the next row at 9 feet from the house and the furthest row of 3 at 17 feet from the house, and each footing in a row should be spaced on 6 foot centers with one foot of cantilever on each end. Are your beams running parallel to the house, meaning they're 14' or do they run perpendicular making them 18'?
 
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Old 05-22-18, 01:54 PM
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Another option is to just break up and remove the whole footing and pour another one. How big around are the footings?
 
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