Howdy, folks~ if you’re a DIY enthusiast looking to set up your fence and wanna do it right the first time, then you know it’s gonna feel a heck of a lot more complex than it seems. In particular, you’re gonna need precise calculations for things like how much spacing you need between fence posts, which we’ve covered already, but also, once you’ve figured that out, you need to work out the right volume of concrete to put inside every post of your fence. Today, we’re gonna focus on that, so without further ado, let’s get right to it~
Why It’s Important To Get The Amount Of Concrete For Fence Posts Right?
Now, if you’re wondering what’s the big deal if you mess up the amount of concrete for your fence posts, here’s the short answer: if it’s less than the right amount, chances are your fence posts will not be affixed properly and might get uprooted, on the other hand, if you use too much concrete than the necessary amount, there’s a chance the post itself will break due to the rigidity of concrete holding the bottom half of the fence tightly, plus all the issues with drainage and frost lines will clog up and damage your fence. So, yeah, you need to calculate the precise amount of concrete to pour for fence posts to make your fence stable.
What Is the Right Amount Of Concrete On Fence Posts?
Alright, so the long and short of it is that if you wanna know the correct amount of concrete for your fence posts, you have to work out the specific math for it. Here’s how it works:
- Diameter of the standard hole where you’ll plant your fence posts.
- Depth of the hole where you’ll plant your fence posts.
- Diameter of the post of the fence you’ll plant in the hole.
- Height of the post you’ll plant in the hole.
The general rule of thumb here is the diameter of the hole of the fence should be exactly or very close to three times the diameter of the fence post. Also, the hole depth of the fence should be one-third (⅓) or half (½ )in some cases, of the total post length.
For example, 4-inch diameter posts require 12-inch diameter holes, and if the height of the post is six foot tall, then the depth of the hole should be two or three feet. (This is without factoring in the frost line and gravel room).
What’s Next?
After you do all the above, you can calculate the specific amount of concrete by finding the volume portion of the post inside the hole and the volume of the post hole itself by using these formulas:
For a rectangular-shaped post and its corresponding post hole, the volume is determined by multiplying the length by width and depth. Volume (in cubic inches )= length x width x depth
Whereas for a cylindrical-shaped post, you need to find the radius which is done by dividing the diameter of the post by 2, then multiplying with ℼ (3.14), and the depth of the fence. Use this formula: Volume (in cubic inches) = radius² x ℼ x depth
The next part’s easy, you less the volume of the post within the hole from the volume of the hole. In short: Concrete amount= hole volume – post volume
Voila~ you’ve got an accurate assessment, then you can convert the volume from cubic inches to cubic feet by dividing your volume in cubic inches by 1728.
