Diameter of footings for deck

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Old 08-05-10, 09:43 AM
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Diameter of footings for deck

What size (diameter) should the footings be for a deck?

The existing deck (that I'm extending) has the posts buried in concrete, but I'm planning to use footings instead, so I can't go by what's there. I'm going to use 4x4 posts and embed some post braces down in the wet concrete. I was planning to use 8" tubes - is this large enough?

The deck is about 3' off the ground.
 
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Old 08-05-10, 11:19 AM
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You could probably call the local codes inspector...they may have requirements. My local office back in VA had a handout they gave out at the permit desk that outlined all the requirements. The ladies that worked our permit desk were always very helpful and most knew the answers to the basic questions. Even if you aren't getting the permit..it would be best to build to those specs.

That said...its best to dig an upside down mushroom shaped hole below your frostline (again..check with your inspectors office), brace the tube about 4" or so off the bottom, then do your filling. They even make forms like that...kinda looks like an upside down Y.

An 8" would prob work for 4X4 posts....but 10" would be better.
 
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Old 08-05-10, 12:17 PM
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I'm also wondering what the best thing is to use when anchoring the post to the footing. The Simpson brackets look to be around $20 or more per bracket (Yikes!).
 
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Old 08-05-10, 12:19 PM
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Yep...that they are....

They make slightly cheaper versions that might work...but you lose the standoff feature and adjustability.
 
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Old 08-05-10, 07:08 PM
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4x4.......... http://www.lancova.com/deckinfo.pdf

Be safe, Gary
 
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Old 08-11-10, 08:54 AM
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This info seems similar to the one on decks.com. So I'm using a 16' unsupported joist span and 6' unsupported beam span. so I need a 20' x 3' pier (3' is my frost depth)? heck I could support my whole house on that lol. That seems like a bit overkill. Why so large?
 
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