Fences are a great way to protect your privacy and define your property while also adding something aesthetically pleasing. However, if you’re going the DIY route, you need to be precise. And finding the ideal size gravel for fence posts is critical long-term durability.
The ideal size gravel for fence posts is roughly three-eighths of an inch in size. You should find a happy medium between finer gravel, which provides good support, and larger-sized gravel that will provide good drainage and prevent the wood from rotting (or metal from rusting).
It is also vital that you dig the holes for your fence posts the right size and, if you’re using concrete, that you set your posts correctly – because, if you don’t, you’ll be creating a lot of trouble for yourself in the future. Your fence won’t last very long and will be susceptible to frost heaves. And, it just won’t look very good.
Why Is Gravel Size Important?
The size of the gravel you’re using, whether you’re using gravel as a base layer for your fence setting or all the way to ground level, is essential for two reasons. Drainage is important because, whether you’re using steel fence posts or wooden fence posts, your fence will be exposed to bad weather conditions, particularly over the winter: wood rots, metal rusts. And post support is vital for obvious reasons. You can use large gravel sizes and have perfect drainage, but if your fence post isn’t stable, it’s not much of a fence, is it?
Picking The Right Size Gravel
When your post hole has been dug, it creates a place for water to collect. This means that the bottom of your fence post will be consistently exposed to water if you don’t get enough drainage. Because large gravel leaves big gaps when packed together, water can run through it efficiently. Smaller, sand-like gravel absorbs water but provides better support.
So, it depends on the soil that you’re digging into. Heavy, clay-like soil needs less support. Sometimes, if it’s exceptionally stable and doesn’t shift around easily, people often opt to use gravel up to ground level without any addition of finer gravel or concrete. But you’re more likely going to need to use a base layer of gravel no matter what. The lighter your yard’s soil is, the further up you should pack large gravel. Most people will opt to add concrete once the fence post is ready to be set.
How To Set Your Fence Post With The Right Size Gravel
Now that you’ve figured out the correct gravel size, we can take you through the process of digging a hole for your fence post and how to set it:
- Safety is rule number one. So, before you do anything, put on a pair of protective gloves and get hold of your local municipality or utilities provider to make sure that you aren’t digging into any pipes or wiring.
- Dig the hole for your fence with a post-hole digger. The depth of the hole should be one-third of the total height of the fence. So if I’m building a six-foot-high fence, I should have a nine-foot post and set it three feet deep into the ground. The diameter of your hole should be double the diameter of your fence post. Dig the hole so that it’s at its widest at the bottom, and you can create a conical shape.
- Now that the hole has been dug place three to five inches of gravel at the bottom of the hole, flatten it, and set the post in the center of the hole.
- Add another six inches of gravel around the post, creating a conical shape underground so that you can prevent frost heave. Pack the additional gravel taut with a tamp. Repeat this process up to ground level, mixing your gravel sizes up to provide extra stability closer to the top.
- Once you’ve got your gravel packed taut from top to bottom, add some quick-set concrete to fill in the gaps, add water and save some of the mix to create an additional concrete slope at the bottom of your fence post to keep water from seeping into any wood above ground.
- Allow the fence post to set overnight before adding any rails, chainlinks, or panels.
To help you visualize what you need to do when setting your fence posts and putting your gravel and concrete in the correct place, here’s a diagram that may help:
What Are The Variables?
Many factors that determine the ideal size of gravel for fence posts have to do with the soil and fence structure. If you’re using a lightweight fence, you can skip the concrete altogether. But you still have to use gravel for proper drainage. Concrete is added merely to provide stability. If you have to use concrete, you can prevent water by grading it away from the wood as you go further into the ground.
When confronted with the variables, just try to stick to the same logic and adjust appropriately. Do whatever it takes to make all of your posts are level and consistent. And remember that you can’t rush this and want something that has long-term durability, so you need to be methodical. You can never do too much research. I recommend that you order a copy of The Fence Bible to have a comprehensive guide to fence building and handle any unpredicted issues that may arise.
Building A Fence That Lasts
The key consideration when it comes to building your fence is that this is a structure that you want to stay in shape for decades. That means that you have to make it right, and you have to maintain it. A big part of building a durable fence that won’t be affected by the elements and pests is to make sure (if you’re using wood) that your wood is appropriately treated, painted, and sealed.
A problem that will likely arise with your gravel/concrete set fence posts is that you may see a seam at the bottom of them where the wood meat the concrete. A helpful tip for long-term durability is to apply Caulk over that seam – if left unchecked, it is an entry point for water and could create the rot that you’ve worked so hard to avoid.
Over the months and years, you will need to re-apply this chaulk if you see any more seams, and you need to sand and retreat your wood in the summer regularly. So don’t think for a second that, once that beautiful fence is up and your yard is looking great, the job is finished.
Finding the ideal gravel size for your fence posts is essential. If you mess up the drainage, you’re going to have to dig up all of that concrete, replace the posts and do it all over again! You need to consider so many things, but if you get it right, your fence will last for a very, very long time.
Your new project to construct a fence will be far easier if you find the ideal gravel size to fit both your fence posts and your soil type. Your fence will make it through many more winters if you get it right. Get it wrong, and either you’re stuck with an eyesore in your yard, or you’ll have to reconstruct the entire thing by next year.
Sources
What Size Gravel to Backfill Fence Posts? | Garden Guides
How to Set Fence Posts in Concrete and Gravel | Life Out Here
How to Set Fence Posts Using Pea Gravel | SF Gate
Should I set fence posts in dirt, gravel, crushed rock, or concrete? | Stack Exchange
The Dos and Don’ts of Setting a Fence Post | Bob Vila
Hole Sizes for Fence Posts and Other Types of Posts | The DIY Doctor