posted October 01, 2015 09:40 AM
I am currently working on a 4 X 4 sign made of Poly Panel (Alupanel). This is going to be free standing outside subject to Iowa extreme climate changes and wind. My question is does anyone know of a formula to figure how deep the holes should be to hold the sign and not blow over. I know I can consult and engineer but that is pretty expensive for their services.
-------------------- Rob Lenz Lenz Signs 402 Elm St. Osage, Iowa 50461 Posts: 134 | From: Osage, Iowa | Registered: May 2002
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posted October 01, 2015 09:55 AM
A 4 x 4 should suffice with a couple of 4x4 posts 2 feet in the ground.
Signweb.com has a download excell spreadsheet used in conjunction with engineering sign structures. It can be a little confusing by itself.
If you can't find it, I can look it up this afternoon when I get back into the shop
-------------------- Mark Kottwitz Kottwitz Graphics Ridgely, MD www.SeeMySignWork.com -------------------------- Imagination is more important than knowledge. -- Albert Einstein Posts: 746 | From: Ridgely, MD | Registered: Oct 2000
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posted October 01, 2015 10:57 AM
I generally go 3'. Check with someone you know in the area who does dirt work. Find out what the frost line in your area is.
-------------------- Chris Welker Wildfire Signs Indiana, Pa Posts: 4254 | From: Indiana, PA | Registered: Mar 2001
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posted October 01, 2015 12:20 PM
Good advice, Rob; but also remember to frame in that sign all around, or in some way make sure it's securely fastened to the posts....and supported all around.
Those aluminum panels are not very structurally strong, and will bend pretty easily in the wind.
-------------------- Dale Feicke Grafix 714 East St. Mendenhall, MS 39114
"I can do all things through Christ, who strengthens me." Posts: 2963 | From: Mendenhall, MS | Registered: Apr 1999
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posted October 01, 2015 12:56 PM
Soil conditions can be a significant factor, so when I do smaller signs that do not require engineering, I use the 1/3 underground, 2/3 above ground rule. Of course in my northern area, we have frost that can go 4' or more below the surface. You definitely want the bottom of the posts just below your maximum frost depth. Other considerations are the overall height of the sign. Think about leverage and you'll realize that a 4'x 4' sign with the top of the sign being 8 feet off the ground will experience much more wind load than the same sign with an overall height of 6 feet. The 2 to 1 ratio will usually take care of a higher sign.
-------------------- Dave Sherby "Sandman" SherWood Sign & Graphic Design Crystal Falls, MI 49920 906-875-6201 sherwoodsign@sbcglobal.net Posts: 5396 | From: Crystal Falls, MI USA | Registered: Apr 1999
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posted October 01, 2015 10:30 PM
Don't forget to put some gravel in the bottom of the hole...
-------------------- Bruce Bowers
DrCAS Custom Lettering and Design Saint Cloud, Minnesota
"Things work out best for the people who make the best of the way things work out." - Art Linkletter Posts: 6451 | From: Saint Cloud, Minnesota | Registered: Jun 1999
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