Waterproofing fence posts

More on my fence building subject. I live in Oregon, Lebanon, near Salem. Rains all year. Lots and lots of rain. I'm using pressure treated ground contact rated 4x4x8' posts. I plan on setting them 2 feet deep in concrete. Would it be worthwhile to apply any additional waterproofing coating to the posts before setting them in concrete? What kind of life expentancy can I expect from these posts set in concrete? Assuming I take reasonable care to taper the concrete, cap the top, and keep it painted. If they rot out in 5 years, I'll be stuck with rotted posts in concrete that will need to be dug up, and I'll have several dozen big chunks of concrete that I won't know what to do with.
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On Tue, 11 Jul 2006 12:23:57 -0700, "Matthew Reed" <nospam at zootal dot com nospam> wrote:

Sure. And pile it on thick at the very bottom especially up to about 4 inches from the surface. (Ugly when it shows).
I've dug up lots of those concrete bottoms with broken posts in them and it is always VERY hard work, so you are right to do what you can when planting them.
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"Matthew Reed" <nospam at zootal dot com nospam> wrote in message

It has always seemed to me that those metal post holders that you set in concrete would be a better bet. The end of the post will be able to breath some, so it should last way longer. Plus, replacement would be way easier.
Bob
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I'm not sure I've seen these before, but I think I know what you are talking apart. Do they hold the post securely enough to take the load of wood, gates, etc. ?
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According to Matthew Reed <nospam at zootal dot com nospam>:

No. They need side support if they're of any height or significant side load. Same for "post spikes". Not suitable for fences or freestanding decks (unless very short).
The trick with concreted fence posts is to bed the bottom end of the post in several inches of gravel before pouring concrete. Any moisture entering the post can leave out the bottom, and the bottom isn't held in direct contact with moisture. PT posts will last a very long time when done properly.
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Depending of course on the water table. They'd be in the water all winter where I am.
Bob
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It rains all fall, winter, and spring, but the water table stays down 6-8 feet or so. I think I'd be safe with a 30 inch hole with 6 inches of gravel at the bottom. Maybe less gravel.
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With all the success everyone has had, I hear that your using PT posts. Did you also add water repellent to those post? I live in Seattle and get lots of rain. I am installing the PT posts as reccomended (gravel at the bottom and in concrete) but am conteplating the time/cost/effort of applying the water repellent to them first.
Thanks! Tim
Matthew Reed wrote:

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I'm not that far south from you, maybe 90 minutes south of Portland. Do you have any more info on water repellent treatment? I'm using PT posts rated for ground contact (very important - they can't be just PT, they have to be rated for ground contact). I don't want to have to dig up 3 tons of concrete 10 years from now when the posts rot out.

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With all the success everyone has had, I hear that your using PT posts. Did you also add water repellent to those post? I live in Seattle and get lots of rain. I am installing the PT posts as reccomended (gravel at the bottom and in concrete) but am conteplating the time/cost/effort of applying the water repellent to them first.
Thanks! Tim
Matthew Reed wrote:

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Matthew Reed wrote:

Any particular reason you're not using metal posts? Smaller holes, less concrete, won't rot, easier to attach rails (they make clamp-like things for that purpose), easier to replace when something goes wrong (hit by car?).
I don't think you want to PAINT pressure-treated posts.
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Never done it that way, and I already have a bunch of wood posts. Need to research it, I don't think I've ever seen a wood panel fence with metal posts.
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On Tue, 11 Jul 2006 19:20:45 -0700, with neither quill nor qualm, "Matthew Reed" <nospam at zootal dot com nospam> quickly quoth:

I have, but those were there to support broken wooden posts. <g>
Black locust wood posts with charred ends seem to last forever. The suggestions to plant the PT post in gravel, then add mounded concrete on top is a good one.
LJ in Grants Pass, OR south of you guys but still in the PNW.
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Matthew Reed wrote:

Just make sure you use enough gravel and keep the posts clean from debri. I put PT posts in my house near Portland 20 years ago and there is no sign of rot at all, except for one post near a fir tree that was always covered at the base with pin needles and rotted out after about 15 years. If you install them so they can dry out after getting wet, the'll last a lot longer than 20 years.
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20 years is pretty good! Did you set yours in concrete? Where near Portland? I used to live in Vancouver before moving to Lebanon. Still working in portland, on 82nd about a mile north of Glisan.
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Matthew Reed wrote:

In Hillsboro. I did set them in concrete and sloped the concrete to drain the water away. The whole key is to keep the base of the post clear and use enough gravel for drainage. My neighbor put a fence up the same time as me and used Cedar, his fence is still their, but he is noticing some rot just now. I wouldn't worry about rot using PT lumber at all. Just install them right.
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I've just pulled out about 6 posts that I put in almost 25 years ago. Set them 2' deep, no concrete and a standard 1x6 'dog ear' 6' tall fence. I was pleasantly surprised to see that there was NO rot on the posts at all. I'd never intended to leave the fence up that long once the kids grew, but never got around to removing it. We're in the centeral Ohio USA area, maybe not generally as rainy as Portland, but it was very damp where the fence was located - often got a couple inches of standing water after a good rain due to poor drainage.
Of course 25 yrs ago we used the 'good old' arsnic preserved wood, not the stuff they havce today.
"Matthew Reed" <nospam at zootal dot com nospam> wrote in message

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My drainage is very good, but in fall/winter/spring it is not unusual to go for weeks and weeks without a non-rainy day. Anyone know how good the new posts are? Maybe I need some creosote :)

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