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Old 02-16-2013, 01:36 PM   #1
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24" x 24" x 12" footing rebar question


How do I arrange the rebar in the footing? What size square should I make? How do you figure out what depth to put the rebar at? Do I need 1 layer or two layers?


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Old 02-16-2013, 01:43 PM   #2
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24" x 24" x 12" footing rebar question


I would imagine it depends on what your engineer spec'd. I just poured the same size footing a few weeks ago, and the engineer had spec'd that rebar was no going to benefit me, so I didn't put any in. His basic explanation was that for a hole that size it wasn't going to add any strength.

Hope that helps.

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Old 02-16-2013, 03:14 PM   #3
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24" x 24" x 12" footing rebar question


I need to put in a couple of verticals just to tie in a column afterwards, so I have to put in a couple of pieces at least. If it doesn't matter, then it sounds like this will be an easy one.
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Old 02-16-2013, 04:47 PM   #4
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24" x 24" x 12" footing rebar question


You have provided minimal information. You don't say what load you are supporting. You don't mention the type of soil your footing rests on. You don't mention what type of column you have. You don't mention if you are in a seismic zone. You don't mention if you designed this footing yourself, or if an engineer told you that you need steel in the footing.

The design of the steel reinforcing is driven by the loads the footing needs to carry, the type of framing and columns, the soil conditions, and any seismic issues.
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Old 02-17-2013, 01:34 AM   #5
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24" x 24" x 12" footing rebar question


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Originally Posted by Daniel Holzman View Post
You have provided minimal information. You don't say what load you are supporting. You don't mention the type of soil your footing rests on. You don't mention what type of column you have. You don't mention if you are in a seismic zone. You don't mention if you designed this footing yourself, or if an engineer told you that you need steel in the footing.

The design of the steel reinforcing is driven by the loads the footing needs to carry, the type of framing and columns, the soil conditions, and any seismic issues.
Thanks Daniel.

I do realize i'm missing a lot of information here. I probably don't really have the right answers, but here goes.

The floor system of the 1st floor of the house is post and beam.

The footing I am replacing is supporting a 4x10 beam(species unknown, but i'd guess DF) that is supporting the load bearing wall that carries the center of the floor joists on the 2nd floor.

The original footing appears to be 4-5 bags of concrete in a hand dug hole (the bottom of the hole was not even flat) set on fill dirt with a pier block plopped into it after the concrete was dumped into the hole. The whole thing is probably about 12 - 14" round, and it was sinking into the dirt.

I've since dug down to undisturbed soil (no idea what type of soil really) approximately 18" below grade, levelled the area as best I can with a claw hammer and a small garden trowel. I figure going onto a more soild surface, with a bigger footing should keep it from sinking again. At least in my lifetime anyway.

I don't know if I need steel in the footing or not. I figure that it can't really hurt anything for it to be in there, can it? I guess I was looking more or less for a general guideline as far as where to put the steel.
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Old 02-17-2013, 09:44 AM   #6
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24" x 24" x 12" footing rebar question


"The footing I am replacing is supporting a 4x10 beam(species unknown, but i'd guess DF) that is supporting the load bearing wall that carries the center of the floor joists on the 2nd floor."

I assume that the word beam refers to a major horizontal structural element, so I am guessing you mean that the footing supports a column which in turn supports the beam. What type of column are you planning to install to replace the existing column?

You are correct that installation of steel in the footing will not hurt anything, although it may not be necessary. You should really check with your local building inspector, they probably have minimum requirements for any footing to support a column, and they may be willing to explain how you determine the vertical load on the column, and how you place steel. Regardless, if you install a standard lally column, either hollow steel or concrete filled, you will probably be fine, unless you have exceptional loads on the column. Every manufacturer of legitimate lally columns has a table listing vertical capacity of each of their columns, you simply need to verify that the specific column you install meets required minimum safety factor for your location, your building inspector will tell you what that is.

As for the footing, many lally column manufacturers have instructions on minimum footing size and required steel reinforcing, if they do not, check with the building inspector.
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Old 02-17-2013, 10:48 AM   #7
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24" x 24" x 12" footing rebar question


Sorry, i missed that point in my last post.


What was there before was approximately a 10" long piece of 4x6 as the vertical column. it appeared to only be toenailed to the beam, not to the pier block.


I'm talking about pouring an 8x8 x 12 tall concrete column just tall enough to bring the wood connection above the dirt, and setting a post bracket in the column to keep the wood off of the concrete. This isn't going to be any substantial column (of course in my mind it seems simple, but you aren't here to see it, so i can see where your concern would come in)

This is why I want rebar in the footing so I can tie a couple of vertical pieces into the column to ensure that they are locked together.
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Old 02-17-2013, 03:30 PM   #8
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24" x 24" x 12" footing rebar question


a smaller central type support column would need more of a re bar enforcement as apposed to a wide support column that lands on more surface of the footing thereby spreading more of the load (weight) evenly onto the footing
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Old 02-17-2013, 04:12 PM   #9
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24" x 24" x 12" footing rebar question


Certainly you can pour a concrete column, but why go to that effort? For residential work, a 6x6 PT post should be perfectly adequate, easy to cut to size, easy to fix on both ends using Simpson brackets. You still need the footer, but if you install the proper galvanized bracket you can easily support the column on the bracket. Just verify the vertical support capability of the bracket, and make sure it is greater than the imposed load by at least a factor of two.
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Old 02-17-2013, 04:25 PM   #10
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24" x 24" x 12" footing rebar question


The only real reason is to keep the wood connection out of the dirt that would be 6" below if I didn't put up a column.

Kind of a pain to drag wet concrete under the house, but it seems to make more sense to me to have the wood elevated.


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Old 02-17-2013, 04:32 PM   #11
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24" x 24" x 12" footing rebar question


Yes you want the wood elevated, but you stated you would be placing a footing, which presumably will have the top of footing level with or slightly above the dirt. The bracket you need would be a standoff bracket that would give you at least an extra half inch or so of clearance, so the post would never be in direct contact with soil. You can always set the top of footing a couple of inches higher than soil for extra security.
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Old 02-17-2013, 06:40 PM   #12
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24" x 24" x 12" footing rebar question


Well the bottom of my footing is 18" below grade.... i figured rather than pouring a 20" thick footing a column on top of the footing would be easier and perhaps a little less work than towing a toboggan full of concrete from one end of the house to the other.

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