Hi all, I have a sign with two 6" treated posts The posts are 16' long. The sign is on private property so I won't need to deal with a permit, etc.
What diameter do you recommend I make the hole and how deep do you think I should go? Now can you tell me how much concrete I need if I use 60lb bags?
Thanks in advance!
Posted by Chris Lovelady (Member # 2540) on :
we do these all the times...something that big..3' in the ground 12" diameter...we usually rent an awger with a 12" bit. generally we use around 3 80lb bags per hole. also we started using round concrete forms to raise up the concrete around 3-4" so the weed eaters don't eat up the bottom of the posts!
Lovelady
Posted by Dana Stanley (Member # 6786) on :
The question isn't how big the posts are, it is how big is the sign, how heavy is the sign, and how high up from the ground is the sign?
Think of the sign as a sail and the concrete as an anchor! If you use a big enough footing the post will snap before the footing lets the unit bend over. But if you have a small enough sign, you don't need as much of a footing.
Posted by Jeff Wisdom (Member # 6193) on :
Thanks you two! I will definitely use the forms, I like the idea of coming up a few inches above ground. So 12" holes are wide enough? GREAT. The sign is 4' x 6' double sided HDU with aluminum frame system so it is pretty small and not too heavy. I do have two horizontal cross pieces of the 6" x 6". Posts are 16' total length. So if I sink them in 3' like Chris said then 13' up in the air. I am thinking of going 3.5 - 4' down. I am going to see if the farm where the sign is going has an auger.
Posted by Dave Sherby (Member # 698) on :
You also need to consider the frost line in your area. In Georgia, Chris can get away with 3' holes. That would never fly here in Michigan. If you don't go below the frost line, (at least 4' in my area) the frost will push up the poles no matter how much concrete you put in.
If you are using 6x6 poles, and you use the rule of thumb of 1/3 underground, 2/3 above ground, as long as that 1/3 is below the frost line, and you don't have loose or wet soil, you don't even need concrete. Many use it with those shallow 3' holes because of the need for more ballast.
Posted by Rusty Bradley (Member # 6938) on :
Jeff...here is one of the diagrams I have sent in the past...I do all the entrance signs for a company that has over 100 locations in the Southeast...I send a diagram ahead and their maintenance people have it ready for me when I arrive...I know alot of people dig deep...but I've never had a problem in our part of the country going just a couple of feet down...I will use 3 bags of sacrete per hole...25 years...never a problem.
[ June 07, 2010, 12:29 AM: Message edited by: Rusty Bradley ]
Posted by Jon Butterworth (Member # 227) on :
The 1/3rd rule of thumb depth works for over the years.
Also applies to the amount of concrete you put in the holes.!
An engineer told me to pour 1/3rd of the concrete in ... the 1/3rd packed soil then top up with concrete.
It not only saves money on materials but is actually a STRONGER foundation. Works like a screw rather than a nail!
[ June 07, 2010, 02:11 AM: Message edited by: Jon Butterworth ]
Posted by Dave Sherby (Member # 698) on :
Jon, that is a cool idea for when I have to use concrete, although I seldom do.
Rusty, what works in Tennessee won't work here. We've put in hundreds of poles for golf tee signs. We don't worry about depth as much with them when we can't get down deep because of rock, because wind load is a non factor. All of the poles that are 3' or less end up being pushed up by frost, sometimes as much as over a foot in just a few years. The key is your location's depth of frost in the ground, which in Tennessee is probably no more than 12 to 18 inches. Here in Upper Michigan it's 42 inches. If you don't get a pole bottom below the frost line, it WILL push, shift, and move all over the place. And no amount of bracing or concrete will prevent it unless the concrete is below the frost line.
[ June 07, 2010, 11:22 AM: Message edited by: Dave Sherby ]
Posted by Rusty Bradley (Member # 6938) on :
Dave...true...our frost line is not that deep here...got to do whatever it takes where you live...if I lived up north I'm sure I would invest in some sort of auger being that the holes have to be so deep and digging is not my favorite past time.
