Setting fence posts in gravel rather than concrete and other fence tips and tricks?

[IHDiesel73L]

I'm putting up a 6' dog ear privacy fence around my backyard-about 400 linear feet total. We will likely sell our house in the next 10-12 years so what I would like to do is put up and largely leave it alone aside from washing/painting it every so often. I'd also like it to still look good when we go to sell so that it's a selling point rather than something that is seen as needing to be updated/replaced eventually. I'm not so concerned about the panels themselves-I'm building them myself and spraying all of the components twice-once before they go up to coat all sides, and once after they go up to seal the whole panel. I'm using three 5/4x3x8 rails per section and stainless steel nails-everything will be pressure treated of course.

My biggest concern is the posts-my neighbor has an old stockade fence that was up before he bought the place and the infamous "landscape timbers" (the ones with the rounded sides that Lowes tries to pass off as pressure treated on sale sometimes :laughing were used instead of pressure treated 4x4s. They're twisted, they lean in spots, etc...which I'm trying to avoid. They're also concreted in. I've heard a lot about ways to make fence posts last a long time so I wanted to go through and list some of the things I've heard here so that other members can comment on what worked (or didn't work) for them.

- Setting posts in gravel - I've been hearing this one a lot. I get that gravel promotes drainage which prolongs post life, but what kind of gravel? How small? How deep should the posts be sunk? I was going to go 2', but in my mind I'm imagining that a 4x4x8 sticking 6' out of the ground wouldn't be all that sturdy set in two feet of pea gravel. I should also add that we have very heavy clay soil here if that makes a difference.

- A footing for the post - Much like with pole barns I've heard of people using a "footing" at the bottom of the hole (like a cheap concrete paver), but others say use gravel at the bottom of the hole to ensure that moisture doesn't sit at the bottom end of the post where it will wick its way up.

- Treating the buried portion of the post - First off I planned on treating the entire post with a water sealer prior to setting it anyway, but I've heard of dipping the buried portion of posts in driveway sealing tar to further water proof them. Still others say you should paint the tar on and leave the bottom uncoated so that moisture can escape through the bottom if need be.

- Sealing the tops - This is a no-brainer. I'm going to buy the little copper "hats" for the tops of the posts because they will weather nicely.

If you've got any other tips for making a wood fence last 20 years, lay 'em on me!

 

[beenthere]

You have a good plan, to avoid the concrete. Use backfill that can be tamped to set the post. Limestone gravel with fines can be tamped, but I find just tamping the soil back around the post is just as good. Avoid gravel that cannot be tamped tight.

Remember that there are different quality wood preservative treatments. Get the highest treatment you can and select good quality wood in the posts. Any decay will be at the ground line, not at the bottom of the post so I wouldn't drop any pads in the bottom (unless this is a post with construction it is supporting like a deck).
An additional brush-on preservative at the ground line will help some with longevity. Twenty years with your plan should be easy to do, especially if you avoid the use of landscape material (heartwood doesn't treat with preservative so the wood is vulnerable to decay).

 

[mustangsallysdad]

I would add from experience...mix up a solution of bleach and water and liberally spray any wood that you are using...sometimes the mold or mildew isn't obvious and will rear it's ugly head after you have primed and painted or stained and have literally sealed it in...it will be an ever recurring problem then.

 

[IHDiesel73L]

You have a good plan, to avoid the concrete. Use backfill that can be tamped to set the post. Limestone gravel with fines can be tamped, but I find just tamping the soil back around the post is just as good. Avoid gravel that cannot be tamped tight.

What about "quarry dust?" I think this is the same stuff people refer to as "crusher run."

Rutgers Landscape And Nursery Services, NJ Nurseries, Hunterdon Garden Center, New Jersey Landscapers,

They also offer the same stuff blended with 3/4 clean which I'm actually planning to use for a driveway-it's the same price per yard ($25.00)-would that be better? My project calls for just over two yards of concrete (90 80lb bags) which works out to about $380-two yards of quarry dust or blend is only $50!

 

[CurlyDave]

Crusher run, or what is called 3/4" minus, out here, is what I would recommend for tamping. It should pack nice and tight.

For driveways, we use the same material. Looking at your link I think the "quarry dust" is finer than 3/4" minus, more like 3/8" minus. I think your plan sounds fine.

For the fence, I have seen a lot of fences put up with only rails on the panels, and frequently these sag over time. You need what is called a kick board at the bottom to prevent this. You are willing to put a lot of effort into this fence, and a kick board is something that will preserve its looks for a long time.

 

[MarkV]

How deep you set the post will often depend on where you live. Up north frost heave can be a problem. 5/4x3" is kind of light for an 8' span in my opinion.

MarkV

 

[dieselscout80]

I like to put some washed gravel at bottom of the hole and even a 4" up from the bottom of the post for drainage, then add dirt and tamp tight.

I do add concrete on the posts that have gates hanging from them (two 80lb bags).

 

[ustmd]

Two critical questions are:

1. What part of the country are you in?

2. What type of soil are you on (clay, loam, sand, rocky)?

I am in Central Texas on the Blackland Prarrie, so I don't have to worry about frost heaving, but since the soil has a very high clay content, it has a very high elasticity rating--meaning it moves alot depending on the moisture content. During the summer months it is not uncommon for the soil to drop 2-3 inches and to develop cracks 3-4 inches across (and going down "miles"). For us, it is required to dig the hole for the post with a flair or bell shape at the bottom and to set the posts in concrete.

Also, you need to use pressure treated wood from one fo the big box stores or a lumber yard. Treating the posts with a spray will not last if the wood is in contact with the soil or concrete. For the wood that is above grade, you need to be prepared to retreat the wood every few years depending on its location and sun exposure.

 

[The Dougster]

I highly recommend using a fine sand instead of gravel.. a little sand, gently washed down followed by a little more. Works almost as well as concrete without the moisture/rot.

 

[Obed]

Don't buy your posts from one of the big box stores. Their pressure treated posts tend to be substandard. Often they are not rated for below ground use. Get the pressure treated posts from a lumber yard. Gravel under the posts is a good idea.


I installed these posts for my outdoor electrical service panel pedestal. I expect them to outlast me. The holes were 3 feet deep. We have red clay soil. I put gravel below the posts. I tamped in QuickCrete around the bottom half of the posts and poured some water over the tamped QuickCrete. I did this in 6" increments. I then filled the top half of the holes with clay.

Here's the rationale. Like you mentioned, the gravel under the post will keep the posts from sitting in water at the bottom of the posts. The QuickCrete provides a solid base for structural integrity. The clay mounded up on the surface around the post will help cause surface water to drain away from the posts instead of drain down the posts. Getting the water to drain away from the post is the most critical piece of the whole process. Clay mounded up and tamped around the point where the post meets the ground is an excellent method of preventing the water from running down the post. Posts that are installed with concrete around the post will rot if the concrete is higher than the surrounding dirt because water will collect on the concrete and run between the concrete and the post.

Good luck with your project. It sounds like you are going to build a fence that you will be proud of.

Obed