Greenhouses, Sheds and Sun Rooms - How deep do my shed support beams need to be underground?
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tlhfirelion
02-09-09, 12:39 PM
I am in the extreme northwest of Arkansas (right near Missouri) and I am building a small shed in the corner of my yard. It will be a small 7 X 8 shed with 5 4X4 support posts since it is on a slope. How deep should I go with the concrete to make sure I don't get any shed movement? I was going to use the cardboard concrete tubes and quickcrete. Thanks.
lefty
02-10-09, 08:56 AM
tlhfirelion,
Since frost isn't an issue, the bottom of each footing should be about 15" below grade, about 12" thick and 15" to 18" square. Sonotube up from that so that your post or colmn bases are about 4" to 6" above the dirt.
I question the use of 4X4's for anything other than the posts. You are essentially building a deck (the floor of the shed) and putting the walls on that. 4X4's would work for the beams if you put 3 footings under each one. But using a 4X6 or dbl 2X6's for the beams would eliminate the need for the center row of footings.
Since frost isn't an issue, the bottom of each footing should be about 15" below grade, about 12" thick and 15" to 18" square. Sonotube up from that so that your post or colmn bases are about 4" to 6" above the dirt.
I question the use of 4X4's for anything other than the posts. You are essentially building a deck (the floor of the shed) and putting the walls on that. 4X4's would work for the beams if you put 3 footings under each one. But using a 4X6 or dbl 2X6's for the beams would eliminate the need for the center row of footings.