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Does anyone know what the code is (UBC or BOCA) on what size concrete cylinder foundation base that a 6″x6″ treated post can be place on for a small deck. I’m building a small 16’x 22′ Cedar deck in MN. Our frost line is 42″, so I placed a 6″ thick, 12″ dia. footing to the frost line. Then I place a (same pour with a sona tube) 8″ concrete cylinder to 2″ above grade with a J-bolt in the center for anchorage.
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Should be just fine.
*we would go all the way to your footing with our post and eliminate the intermediate sono-tube..that gives our posts some lateral strength too..the only question is the bearing strength of your soil.... but 12 inch dia. should hold up most uniformly distributed deck loads..
*I usually use at least a 12" thich bearing surface. The diameter is determined by the deck load, tributary area and the soil bearing pressure. (Here, the local building department specifies a maximum pressure, anything higher and they require a soils engineer report.)To come up with the load, you determine the tributary area. This is the portion of the deck which will contribute to the post. Typoically it is a rectangle drawn with each side halfway to the neighboring post/wall. Take this area and multiply it by the dead and live loads. This number will be the number of pounds on the post.Then take the area of the footing (12" is 113 sq in) multiple by the soil bearing pressure (XXX lb/sqin) Your load had better be less than the footing will bear.(Apologies if this is too rudimentry or not on point)I'm not sure if your 6" thich pad would be a problem, perhaps an engineer would comment? (The difference between the 12" footing and the 8" sonotube is only 2 " around the perimeter, so probably none practically speaking) I'd also put in a piece of rebar or two on such a long column.(Don't ya just love the after-the-fact advice.) :)
*We would use an 8" sono tube with an abe66 Simpson standoff post base , so you can bolt your post to your footing, and yess use rebar between your footing and sono tube. Good luck, Bob
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Does anyone know what the code is (UBC or BOCA) on what size concrete cylinder foundation base that a 6"x6" treated post can be place on for a small deck. I'm building a small 16'x 22' Cedar deck in MN. Our frost line is 42", so I placed a 6" thick, 12" dia. footing to the frost line. Then I place a (same pour with a sona tube) 8" concrete cylinder to 2" above grade with a J-bolt in the center for anchorage.