Fence post installation? Concrete vs packed gravel

[summit151]

Hello everyone,

I am building a wooden privacy fence in northern Alberta. Our soil is a few inches of top soil and then clay. I have been researching and reading a lot of different ways to set the posts. I am planning to go 4 feet down and the fence to be 6ft tall.

Sounds like the concrete actually retains water when then wood shrinks and can rot the 6x6 out. It is also prone to frost heaving. Gravel let’s the water drain away and makes replacing fence post down the road easy.

I do plan on adding 2x 8 foot gates to make one large gate for a RV. The other end of each gate will be supported by a trailer jack with a large wheel. But I am worried gravel around a post won’t support the gate posts and corner posts

I am looking for some advice on which route I should go. I like to think projects through and utilize the best technique to not have to re do them down the road.

Spoke with a few local fencing guys and they seem to all have different ways. One company suggested only 3’ deep and 2 bags of concrete per post? Frost line is 4ft


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[summit151]

It is also interesting that the power companies around here use crushed gravel on there large power poles?

Picture of a example fence


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[Bigwoodsman]

Try Sika Pro Select Fix. It’s an expanding foam for setting fence posts. Works well for the fence runs. If your gates are large and heavy you can cement those.

BW

[Pathfinder76]

Gravel. I’m in the windiest place in the world it seems and I built a 6’ fence in the backyard 15 years ago. I used pea gravel around the posts to set them. Dozens of people told me I was a fool for not using concrete. That fence is still there and has not moved. How many 10’ slab snow fences in southern Alberta have been built with concrete? I’m guessing zero.

[Big Sky]

If you're drilling into clay and filling with gravel, will any water that seeps in ever dry out? This year might be an exception due to dry conditions.

[Pathfinder76]

Yes. Put gravel in the bottom of the hole. But clay doesn’t hold water indefinitely.

[Pathfinder76]

Also, water in the ground isn’t as big of an issue as water pooled on the surface. I just pulled a fence post out of the ground that has been there for over 20 years. It was put in wet ground and is wet every year between thaw and freeze. It was a handmade aspen post treated in bluestone. It was as good as they day it was put there.

[Trochu]

I had 6"x6" posts, similar conditions. Went with 10' posts, 4' hole, about 1' of concrete at the bottom then 3' of clay. Worked quite well.

[pikergolf]

For the price difference I would use steel posts. A regular yard it might add 200 bucks to the project.

[summit151]

Originally Posted by Trochu

I had 6"x6" posts, similar conditions. Went with 10' posts, 4' hole, about 1' of concrete at the bottom then 3' of clay. Worked quite well.

How tall was your fence? I thought about 10ft posts but they would be flush with my 6ft fence Boards


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[Trochu]

Originally Posted by summit151

How tall was your fence? I thought about 10ft posts but they would be flush with my 6ft fence Boards

It was 6' tall.

[Dick284]

Most people get wooden post installation wrong IMO.

Start with about 3-4” of pea to 3/4 gravel(not crush) at the hole bottom(you’ll have to auger a bit deeper depth) set your post, and square it up. Then dump 1/2 of a bag of dry ready mix, then pack in the clay(mechanical tamped) till 3/4-7/8 of the way full then add the other 1/2 of the ready mix. Top what’s left with more clay or top soil.

Resist the urge to use wet cement with posts. That’s what degrades the wood.

Dry ready mix draws moisture out of the soil/earth and sets up like a honey comb type structure.

[lannie]

I auger and dig lots of post holes. I would not be using concrete. Use gravel and compact it with what ever you have.

[Tungsten,]

I see more and more horizontal boards,sure looks nice when done right.

wheels on the gate is good,hinges that are adjustable would be a good choice.

[summit151]

Originally Posted by Trochu

It was 6' tall.

So the posts where flush with your fence boards?


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[Tungsten,]

Post flush with fence board. I think the idea here is to cover the end grain of post.

[Trochu]

Originally Posted by summit151

So the posts where flush with your fence boards?

I did it exactly like the picture you posted. So maybe the posts stuck up 6' 2" then the fence portion was 6'.

I also said concrete at the bottom of my posts, I meant cement.

[nimrod]

I have a Jiffy Ice Auger, also a earth auger, can dig a 4x4 hole in no time in Earth, i could possibly lend you the earth auger if you do need one, Camrose area

[W921]

If you use round eight foot sharpened treated fence posts from UFA. Rent there post pounder. If you pound them in three feet they will be tight.
Problem with gravel or especially concrete is if you have to replace them in future

[mooseknuckle]

Sorry to hi jack your thread, I need 80ft of fence along the back yard in west edmonton. Getting old and thinking I'll just hire someone. If anyone has a recommendation I'd appreciate a contact. 6 x 6 posts, 1x6 boards with an overlap for privacy.

Anyone with a recommendation please pass along.

[pikeman06]

Just built myself a huge fence project...10 ft 6x6 posts 4 ft down, 12 inch hole, with 4 inches of crushed gravel tamped with post into bottom of hole. Leveled and braced posts in position, added 3 bags of quick Crete (60lb bags) per hole, added water into hole according to directions mixed in the hole with track shovel and an old shovel handle, left me with roughly a ft of space to fill used gravel and clay mix and tamped it in. Those posts are rock solid. Didnt use the tube forms as I'm in good sticky clay. Not cheap, the posts were 50 bucks the concrete was 8 dollars a bag, the holes were augered with a skid steer I rented, so you can imagine what 40 holes cost a guy but sure happy with the end result. That fence will be there long after I'm dead and gone. I would go with the concrete if I was you for a Residencial fence. Just my two cents.

[Trochu]

Pike, in Alberta, it's not necessarily about making the fence super solid, unless you plan on running into with a car, as the load on the posts is next to nothing. It's all about trying to reduce frost jacking. Depending on a variety of situations, which varies from site to site, there is a decent possibility posts with concrete in the frost zone will move. That why some guys use gravel, it's not a frost active material.

[ram crazy]

I used steel post. Brother works for an oil company and they had bunch of heavy wall tubing they were getting rid of so I took enough to do 300' of fence around my place. Cemented the posts 4 1/2' into the ground (a friend drilled all post holes with his Bobcat) with a 12" x 8" foundation wall then run 1" x 2" tubing as stringers (had a friend weld all the stringers together and weld them to the posts). Then screwed 6' x 4' tin sheets and a capping on top of the tin. I won't live long enough to ever have to look at the fence again and it's been up for 15 yrs. now

[roper1]

The posts will actually last a lot longer with gravel. Concrete will rot them at ground level much faster.

[crazy_davey]

Originally Posted by roper1

The posts will actually last a lot longer with gravel. Concrete will rot them at ground level much faster.

100% true.

[pikeman06]

Originally Posted by Trochu

Pike, in Alberta, it's not necessarily about making the fence super solid, unless you plan on running into with a car, as the load on the posts is next to nothing. It's all about trying to reduce frost jacking. Depending on a variety of situations, which varies from site to site, there is a decent possibility posts with concrete in the frost zone will move. That why some guys use gravel, it's not a frost active material.

I just wanted it solid. The fence is north south and the wind howls through the area from west to east real bad at times. My clay I augered out was super lumpy and wouldn't have tamped in worth a darn. Consulted with lots of local before I went with concrete and they all agreed that was the way to go in our area as I said the concrete is down a foot or maybe a bit less from surface as I was aware of surface concrete rotting posts. It was a big project for one man and lots of locals stopped by and 95 percent agreed with my procedure. Tamping 40 6x6 posts in 12 inch holes, by hand, I would still be out there and my blown out rotator cuffs would have parted ways with my skeleton for sure!!!

[CBintheNorth]

4x6 PT post, 8" hole, 2" of rock at the bottom, concrete all the way up.
Make sure your concrete is at least 1 inch above final grade, and sloped away from the post in all directions. My fence is 15 years old and the posts are as solid as the day I put them in.

[sirmike68]

I just helped my dad put up a new fence. We pulled the original 40 year old posts he put in way back when with a jack-all. The portion of the post that was in the ground looked new while the exposed post was starting to rot. He had them in 3 ft deep and tamped in......no concrete. I couldn't believe it. The new posts were slid right back down the originl holes and retamped. Good for another 40 years.

[Dewey Cox]

I've only ever built 1 residential fence, and I had a guy set the posts for me as he was there doing the neighbour's.

He explained that he put gravel in the bottom of the hole for drainage, put the post in, and tipped it up with cement.
He said if the bottom of the post was encased in concrete the water had nowhere to go and would rot it out. With the tip touching the gravel the water that ran down the post would drain away.

Made sense to me, and as far as I know that fence is still up.

[ruffy71]

I need to replace the gate at our acreage, currently 9 foot farm gates, but increasing to 16 footers. The ground has sig frost heave, so given the size of the gates, I have two 10 foot metal posts and thinking to go a full 4 feet in the ground in concrete.

I am planning to put each pole in concrete, but just wondering if they need to be treated with anything? I read in this thread to slope the surface concrete so no water pools, sounds like a good idea.

Any other ideas?