Wording footers. Am I wrong?

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Old 06-08-16, 08:50 AM
J
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Wording footers. Am I wrong?

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Size:  14.4 KBCan anyone help if I'm reading this correct? I've attached a picture of what's required. If I'm using 6x6 posts. How big of concrete tubes do I need? 16 inch diameter at 30 inches deep right? It says that the footers most be 8 inches larger then the post I'm using. (6+8=14) but they don't make 14 inch. So i need 16 inch tubes. Right? The contractor worded the footings like this " All in ground posts to be 6x6 #2 grade, Arsenic free pressure treated wood All in ground posts to be set on 8? thick footer in 30? deep hole " Shouldn't the thickness be 30 inches? Or am I totally wrong....


Picture of city wording is attached.
 
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Old 06-08-16, 01:32 PM
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Local codes supersede any other suggestions or best practices. If the city says they must be a certain size, then the contractor would be negligent in doing otherwise. Is there a reason for 6x8 posts? He is stating 6x6. We use a minimum of 12" sonotubes at the prescribed depth according to the frost line, using 6x6 posts with proper metal stand off post bases properly secured to the concrete base.
 
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Old 06-08-16, 03:03 PM
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It sounds like contractor is proposing digging a 30" deep hole, pouring an 8" thick footing at the bottom, and then having 22" of the post buried in the ground. While this meets the letter of the specification you provided, generally it's preferred to pour concrete the full depth and use a post anchor, as Larry mentioned, to attach the post. Usually the concrete is poured an inch or two above grade to keep water away from the anchor and post.

If the post is buried, then it needs to be pressure treated wood that is rated for ground contact. The common PT lumber is not rated for ground contact and has less of the preservative chemical. If the full depth concrete is used with a post anchor, "regular" pressure treated wood can be used for the post.

Your calculation of the footing diameter seems correct.
 
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Old 06-08-16, 03:32 PM
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Your contractor has the right math, it can be confusing to a first timer.

But notice all replies here, including mine, are asking why not stand-off post bases? The bases raise the posts off the footings ~1". Less chance of rot, especially when the footing is 6" above grade. Posts rotting out can cause some serious structural issues.

Maybe they are not allowed in your area, but that's hard to imagine.
 
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Old 06-09-16, 12:05 AM
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Thanks I think he is doing that to save money.....
He is significantly cheaper then all the other estimates I've gotten.

Thanks
 
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Old 06-09-16, 04:50 AM
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As far as I know all PT 4x4s and 6x6s are rated for ground contact but it's still not a good idea to embed them in concrete! The posts will last longer if kept an inch or three above ground. I suspect it is cheaper/easier to embed the posts but I wouldn't want a deck built that way.
 
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Old 06-12-16, 01:57 AM
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There are usually good reasons for a contractor being considerably cheaper than his/her competition--and very few of them are good.
 
 

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