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I'm needing to replace a blown down fence, and have been seeking advice and quotes from fencing contractors. There seem to be two conflicting schools of thought.

One contractor advises that using pressure treated timber posts concreted into the ground, along with a continuous strip of feather-boarded fence (again using pressure treated timber) will result in a longer lasting fence. He specifically said that pressure treated timber will last longer than concrete posts, which are likely to crack over time due to frost. He also said that using pressure treated timber boards will mean the fence doesn't need to be treated in any way after installation.

Another contractor pooh-poohed that, and said concrete posts with gravel board and feather-board panels is the way to go. He said that pressure treated timber is a gimmick for applications where the timber is not in direct contact with the ground, and that it would need to be treated periodically.

To summarise: both options involve concreting thee posts into the ground, but the first option uses timber posts, and the second concrete.

Which route should I take for a long-lasting, low-maintenance fence? Looks are not especially important, and security is not really an issue. I'm prepared to pay more if it will last well.

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Pressure treated lumber loses it's pressure treatedness over time, and should be retreated periodically. –  Tester101 May 3 '12 at 11:45
    
It depends a lot on your climate. If you have a lot of wind, make fence that lets air through will last longer. If you have a heavy frosts, that will be the source of trouble. –  Jay Bazuzi May 3 '12 at 20:52
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Remember also that you can pay a lot for a long-lasting fence, and then your needs change and you want to change it long before its life is done. It happens. –  Jay Bazuzi May 3 '12 at 20:52
    
After much research, I went with an aluminum fence. Not an option if privacy is desired. With wood, tamp gravel around the posts instead of concrete or earth. It will keep it dry more than any other method. –  Evil Elf Sep 23 '13 at 14:14

7 Answers 7

up vote 4 down vote accepted

A concrete post/form in the ground with some sort of above ground post or embedded post in the concrete is the way to go. Depending on what you want from your fence, ie: privacy, security, looks, etc. will effect what kind of materials to use for the actual visible fence. There are many choices of composite materials and vinyl products out there that are low or no maintenance and will outlast any wooden materials. The first serious structure to fail is usually where a wood post meets the ground. You need to pay special attention to this area, keep wet dirt, leaves etc from building up around the wood posts. The concrete should be sloped away from the post so water drains away and no water stands around your posts. Use good hardware, galvanized at minimum, stainless steel screws are best, but a little pricey.

I'm not sure if either contractor has really given you good advise. Tell us a bit more of what you what your fence to do and look like and we can help you more.

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Yes, where the wood meets the concrete is the point of decay. After the wood posts dry, you can caulk where it meets the concrete. Also, you can wrap the post in tar paper right there. –  Jay Bazuzi May 3 '12 at 20:51

It really depends on your surroundings and climatic conditions.I think the pressure treated timber posts concreted into the ground are good to go.You just have to follow these simple steps while installation:

Remember the 1/3 rule while installing the post: that is 1/3 of the post length should be buried.

STEP 1 Dig the hole widening out at the bottom. A 10-10.5" flare at the bottom is considered ideal.

STEP 2 Dig the hole about 6" deeper than needed for the post. Set rubble, a rock or gravel in the bottom of the hole first and then set the post on top.

STEP 3 Align posts to guide string and fill the hole half-way with the dirt removed. Pack the dirt well around the post until it can support the post. Keep adding/packing dirt until the dirt is about 2/3 up the post or 8" below ground level.

STEP 4 Brace posts in 2 directions with fence rails; usually 2 - 2x4's. Plumb posts, keeping them aligned to the guide string. Stake the base of the braces to prevent any shifting or movements.

STEP 5 Pour concrete. This should rise 2" above ground level. Taper the concrete collar so that when it dries, rain water will run down the concrete collar and away from the post hole.

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+1 for the good advice. For any links back to your company, register your account and then put the links in your profile. –  BMitch Sep 18 '12 at 11:36

The quick answer is both/neither. You want pressure treated for any lumber that is exposed to the elements, especially moisture from rain or the ground. And you want the fence posts in concrete. The rule of thumb is 2/3 above ground, 1/3 below, so a 6' fence should be at least 3' in the ground. For the concrete, flair out the bottom of the hole to prevent frost heaving. For the best protection from moisture, bring the concrete slightly above ground level and slope it away from the post.

For the continuous strip of feather board vs panels between the posts, I don't think it makes much of a difference in how long the fence will last, but panels make maintenance easier. A repair is usually limited to the space between the posts. And if it's screwed in with brackets, you can often lift out a panel should you ever need to move something large in/out of the fence line.

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+++ vote on the flair or mushroom at the bottom of the concrete sauna tube. A must so frost won't raise it. –  shirlock homes May 3 '12 at 12:47

A lot depends on why you want the fence and how much room you have. Driving around Southern Ontario, I can easily see cedar rail fences that are over 100 years old, unmaintained, and have not fallen down. They don't even have posts! Cedar just won't rot, and they were constructed to be stable, let the wind and snow through, and endure. They take up a ton of room though, and don't hold back anything smaller than a cow or a snowmobile.

So, are you just marking your property line so snowmobilers and hikers stay out? Confining your dog, excluding the neighbour's dog (or cows which have been a bigger problem for us over the years), excluding deer, reminding your kids where your land ends, preventing neighbour children from visiting your pool and drowning, providing shade, providing privacy, cutting the wind, building something to hold up trees and vines, ... ?

I just had to replace my mailbox. A pressure treated post was put in the ground (no concrete) over 20 years ago. It's still solid, I just had to move the mailbox to somewhere else. The stresses on a fence are higher, but don't get too worked up about "making it last" from a contractor point of view. Design the fence so that if one post does happen to fail (perhaps water pools there) you can disconnect the boards, replace the post, and put the boards back. That will be your most maintainable and longest-lasting fence.

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I'll tell you what I did, following the boys on "Ask This Old House":

Pressure treated posts, 10' Hole dug with power awl to 4' plus a few inches Pea gravel in the hole bottom Set post on pea gravel and adjust height with more pea gravel Begin filling around post with pea gravel, tamping down frequently with big steel stick Fill with pea gravel to within a few inches of ground level, and finish with dirt.

Concrete is just a substitute for sinking the post deep. Go the 1 below:2 above ratio and you don't need concrete - and if it does break/rot, you'll be able to replace it more easily.

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Concrete does not react well to vibration so I certainly wouldn't rely on concrete. Concrete is also porous and will deteriorate over time, like concrete tile roofs. I prefer powder coated aluminium, it's a versatile and long lasting product that requires only a wash down every year. You can get modern slats or lazer cut privacy screens. Reproduction iron lace and fret work, columns and posts. Matching lattice. Wrought Iron is making a come back and what's best about metals is they can be recycled, unlike poisoned timber and crumbling concrete. Good luck :-)

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All you need is hedge posts if you want a fence posts to last 50 plus years

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Your answer would add more value if you explained 1) what hedge posts are and 2) why they will last 50 + years. –  The Evil Greebo Oct 23 '13 at 12:54

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