Fence post confusion

[Justin M Rovang]

Ok, I've searched and searched, and searched some more and I've come to a meltdown of what I'm supposed to -really- do for a fence that won't turn into one of those buckled/shifted looking nightmares.

Which is the best for my scenario:
6' PT privacy fence, 4x4 posts planned.
- Minnesota winters
- Very clay soil,
- It can get pretty windy on the hill where I live.

1. The standard seems to be to set your fence in concrete, making sure it all slopes away from the center. However, I've read that it's a nightmare if something goes wrong and you need to repair, or flat out replace.

2. Alternatively, I've read to pack the posts with angular gravel to lock in the posts and allow for outside pressure and great drainage.

3. I've also read all are a wash and you can straight out pack with the native soil, as long as you pack it good enough.

I've got ~330ft of fence to put up and I want to do it myself, and I want to do it the smartest, most stable way - I want her to be as straight as the day I put her up. I understand there might be some follow up tampering/leveling for a few months as things settle.

What are your thoughts / experiences on this? Is concrete just a no-brainer and I'm over-analyzing?

P.S.: If this is in the wrong spot please let me know and I'll have it moved/removed.

[Glen Butler]

What is the fence material?

[Justin M Rovang]

What is the fence material?

PT pine, stick built is the plan.

[Glen Butler]

Sorry not experienced with pine fences. I will pass on this one.

[Justin M Rovang]

Well I'm sure any suggestions you may have would be helpful under the umbrella of 'made out of wood' :) I understand PT vs. Cedar vs. Redwood have their differences in rot resistance and expansion.

[Glen Butler]

Ok, What I do know is the main cause for a buckling shifting fence is that the peices fit together too tightly and there is no room for expansion and contraction. Whether the posts are mounted in concrete or gravel, is a less serious concern than allowing for expansion in the fence itself.

I am experienced with PVC fencing and I have seen some buckle and not buckle, whether surrounded by a concrete mow strip, or concrete post holes or gravel post holes. It's mostly about expansion.

This advice is worth what you paid for it :)

More info: You can pour a concrete mow strip and put sleeves in the concrete which you can later slide the posts into if concrete suits your fancy.

[Ray Schwalb]

I built a similar PT fence last year and set the posts in concrete. With 6' sticking out of the ground, my experience is that most of the movement happens above the ground, the posts twisting or bending as they dry. Next time I might spring for cedar posts so things stay straighter- at least a the gates.

[Dan Hintz]

If you're worried about replacement and concrete being semi-permanent, can you sink metal supports into the concrete and screw into the posts? If any of them need replacement, it's the removal of a few screws rather than digging up a concrete anchor...

[Mark Patoka]

Can't help you on setting the posts but make sure your PT has dried or seasoned a little before putting it up. My next door neighbor put in a 6' PT fence (his friend got him a really good deal on the lumber) but it was still very wet wood when they installed it. Six months later the boards were warped all over the place as it dried out and the fence looked horrible. Neighbor wasn't too happy about that good deal he got.

[Tom Scott]

Almost all new fences in my area of Texas are done with galvanized steel posts set in concrete. No worries about rot or twisting. There are standard connectors to attach the wood 2X horizontals to the posts, and then normal picket installation. You may replace the wood in 15 years, but the posts will still be there.

[Rick Pettit]

I have put up alot of 6ft dog ear privacy fence in my life. I have always set the post in concrete and have never had to replace a post. My first fence is still standing after 20+years. Are some of the boards twisted or warped? Yeah, it's wood, exposed to the elements 24-7. Buy your lumber, sticker it in the dry for a month and then start building. I try to use 4x6 posts now because of the quality of lumber. They will warp less. Drill or dig your holes set the posts in and leave them a little long. Set them, pull a string at 6ft and start nailing. Personally I like to hang the runners on the center of the posts using a metal hanger but that is only for looks. I have even went so far as mortising the posts to catch the runners. Nothing fancy just the same size as the 2x4. When you're done get the chainsaw out and saw the long posts off or use a sawzall.

[Ken Fitzgerald]

My neighbor had a great privacy fence and it lasted well over 25 years before we removed it to put in a driveway so he could back his 5th wheel trailer into the new shop he built in his backyard.

He used metal posts set in concrete about 3 1/2' deep. Then the wood crossmembers were attached to the posts and the upright boards were nailed to the wooden crossmembers. Allow room for expansion between the uprights. Keep the paint in good condition.... don't wait for it to go bad.

[Chris Padilla]

My neighbor and I recently rebuild the fence between our houses.

We went ALL OUT:

(0) Removed ALL of the original fence and concrete footings...that was fun.
(1) 6x6 (not 4x4) PT posts (ours are red in color...not green)
(2) We poured a concrete "curb" between our houses and set in galvanized Simpson post ties into the concrete.
(3) We bolted the 6x6s to these Simpson post ties. They have a small metal plate that the 6x6 rests on and it raises the 6x6 a 1/2" from the concrete so no wood touches the concrete.

It was spendy doing all this and mucho time consuming but this fence should outlast our children. :)

[scott vroom]

I'd avoid using wet set anchors in a high wind environment; they don't offer the strength to combat high winds broadsiding a 6' fence. IMO the best way to set fence posts is to dig a hole deeper than the frost line, fill the bottom with several inches of gravel and set the post in concrete, making sure to slope the top of the concrete away from the post. If you use pressure treated fir with this method the fence will last many years.

Or use galvanized steel fence post set in 'crete as one poster suggested. Probably more expensive than wood posts but would probably outlive you.

[Justin M Rovang]

See I've read the frost line thing about a fence - my understanding is that's more applicable to load-bearing construction, I hope! The frost line here is 6 feet.

The post ties seem like an interesting proposition, do you use a 'setup post' attached to the tie to make sure the tie stays level while the concrete sets?

[Lee Schierer]

If you decide to use concrete be sure your post holes and the bottom of the concrete are below your frost line. Frost line in your area should be 42-48". You also want straight sided holes tapered holes where the top is wider than the bottom and no place where the concrete on top is wider than that under it. Both can lift a fence post right out of the ground with frost heave.

[Chris Padilla]

The post ties seem like an interesting proposition, do you use a 'setup post' attached to the tie to make sure the tie stays level while the concrete sets?

Pull strings to keep things lined up and a bubble vial ensures the ties stay coplanar as the concrete sets. Keep in mind we only had about 15-20 posts to deal with. It is all in your prep work before the concrete truck shows up.

[Josiah Bartlett]

Whatever method you use to set the post, stick about 2" of pea or drainage gravel in the bottom of the hole and set the post on top of that before filling and tamping the rest of the hole. The post needs to breathe at the ends to allow water to exit. The problem most people have with concrete is that it traps water at the base of the post, which will rot even PT lumber. Allowing water to get out of the bottom of the post greatly extends the lifetime.

[Jon van der Linden]

One basic thing about posts is that thicker is better, 6x6 has more than double the material of 4x4. Assuming an inch of decay on all sides a 6x6 leaves you with a 4x4, a 4x4 leaves you with a 2x2 and a broken fence.

A helpful guide to installing posts from a site that makes custom fences is here: http://www.prowellwoodworks.com/gate/postholes.htm
The guide addresses most of the questions in this thread.

[Willard Foster]

I did mine just as Rick Petit did.

Our fence has survived 10 Minnesota winters with no problem.

Bill