I have a steel square pole that is 11 feet height, 11cm depth and 11 wide. The post is for a wooden heavy gate which is 4 foot high and a bird house at 7 foot high from the ground. If I float the 11 foot steel pole in the concrete at 3 foot with bolts coming out of the steel pole at the bottem, would that work ? or would I need to put in steel bars in the ground with the concrete ? Also will be putting back top soil and there is lot of big rocks under the ground where I am digging the hole (there is an old building foundations in the ground where the hole will be. Thank for reading
You need to dig down at least 20ft. Reinforce the base with steel work. Steel beams and pour in the toughest concrete you can buy, flown in from Russia.
Wants to be in ground 450mm minimum & up to 600mm depending weight of gate. No need for rebar in hole, just a few bolts on post is enough.
Don't think 18" deep is anywhere near enough for a steel 4x4 out the ground by 9½ feet, never mind the weight of the gate. If he has[11ft post] 8ft above ground, 3ft below, and 18" concrete at the bottom of the hole, I would think that minimum. Mr. HandyAndy - Really