Newbie question regarding placing wooden posts

[Barrdwing]

Okay, got a real construction-n00b type of question here. Our chickens run in a very large yard fenced for horses--woven wire attached to 5-inch-diameter posts set in concrete, with toprails. I want to fence off a corner of this yard, an area about 30 feet long and 10 wide, attaching the new fence (only the wire portion) to the existing fence. Because we'd like to have some support for the welded-wire walls, I had planned to set four eight-foot 4X4 treated posts into the ground at approx. 7 foot intervals, then attach top rails and bottom rails to create a sturdy long wall and staple the wire to all of it. I'd run lengths of welded wire fencing from this wall back to the existing fence to create the side wall and partitions. The post holes are to be 30 inches deep.

My question is this: While the posts are of treated wood, will they hold up for any length of time if they are just set in the ground without concrete? Also, can a structure like this support its own weight without concrete around the bases of the posts? While we aren't going to have any large animals pushing against this new pen, we do sometimes get high winds. The site is partly sheltered by the house, but not entirely. I would hate to have the wall begin to sag just because I didn't provide the base enough support. The rails are also not going to connect it to the existing fence, so this long wall will be free-standing.

Also, we're on clay, and we get a fair amount of rain in the winter. I believe I remember hearing that treated wood will still rot in damp ground, just not as quickly as untreated wood. But we're trying to do this on a bit of a shoestring and these pens are semi-temporary, so if this will last five years or so without the concrete, that would be long enough for our needs.

What do you more experienced fence-builders think of all this?

 

[Judy]

I've gotten more than 5 yeas out of treated 4x4's with no concrete. It is pretty wet here and lots of clay.

 

[Huskeriowa]

Hi,

I don't know what part of the country you are in but 30" is above the frost line of many areas. If you do get frost in the ground you will want to find out what that depth is and place them below that. If you don't, the post may heave Also you stated that 'I believe I remember hearing that treated wood will still rot in damp ground, just not as quickly as untreated wood.' Actually its just the opposite especially if the posts are rated for ground contact. The treated posts will rot but they will last for a few years.

You can set them in clay if you wish. I would personally set them in kwik crete but thats just me.

All that being said, many privacy fences are set above frost-line with no concrete and they last years.

People that put a fence in that would be a freestanding line would sink the further most posts deeper and secure them with concrete to give the rest of the fence more of a base.

Good luck

 

[teach1rusl]

Not a chicken run, but our board horse fence is in the ground with no concrete, and it's extremely sturdy...been up for 4 years so far with no problems. We have a lot of clay...

 

[NanaLantana]

I'm in Florida, lots of sand, sand, sand. When you dig postholes here, the sand falls back in by itself! Well, I've set tons of posts, and I do a good job. I don't use concrete, either. But the trick is to TAMP the dirt down around the post a little at a time. Tamp hard, all around the post, then add some more dirt, over and over until you've gotten to the ground level. Now, I mean, tamp HARD - use some energy! Then when you've got your post in, give it a shake - it will barely move at all. Another way to pack it good is to use water as you add dirt, but I don't personally think it comes out as sturdy.

That's how I do it!

 

[patandchickens]

Quote:
Setting the posts entirely in concrete does not really make them last any longer, indeed often it makes them rot out *faster* (as soon as the wood shrinks back from the concrete that it's embedded in, a little, water pools there I guess and starts rotting -- anyhow, empirically I've dealt with any number of concrete-set p/t 4x4s that have rotted off at the top of the concrete)

And you certainly don't need the concrete just to withstand the weight of the fence itself, not even if you are in super squishy wet clay.

Nor will it contribute nearly as much to withstanding wind load as just setting the posts DEEPLY and having a good number of them.

If you do set them in concrete, if you live somewhere that gets frostheave I strongly recommend either using sonotube or stopping the concrete below frostline (this means a pretty deep hole). Otherwise it accentuates frostheave, IME.

I would unhesitatingly skip the concrete, myself. On wet clay, good p/t 4x4s set directly in the soil with the earth crowned up arond them a bit should last at least 10 years before weakening significantly, most likely closer to 15-20. You're not really going to get any much better lifespan from anything else anyhow.

However, if there is any possibility of EVER having horses in the horse paddock again (or other large livestock) you might want to seriously consider using 5" fenceposts like the rest of your horse fencing. Horses leaning on 4x4s is usually a very quick decision in favor of horse

JMHO, good luck, have fun,

Pat

 

[Barrdwing]

Wow, thank you all for your input! I am feeling much better about omitting the concrete. We live in an area that rarely if ever gets snow, and don't have to worry about the ground freezing, so no frost heave (although if we ever move someplace with more serious winters, I will have to keep that in mind!). And I will also keep the horse element in mind, patandchickens. Although I sure don't see us getting horses anytime soon--the chickies keep me busy enough!

Thanks for the pointers, too! When we eventually get around to putting in a new barn and chicken yard, I'll have a better idea of how to build that fence to last. For now, though, these little pens will do. I just need to wait for the rainwater to dry out of these holes!

 

[patandchickens]

Quote:
For a chicken run it may be fine, so I'm not tellin' you you *have* to go out and dig new ones... but just to file away in your head for future reference, esp. for posts that need to have some real structural robustness to them, it is a really bad idea to dig the hole before you are ready to put the post in. Firstly because it will slump and fill back in and you will have more digging to do *anyhow* when it comes time to set the post; but secondly and much more important, because it tends to result in a less tightly set post. I am not 100% sure why, but IME it does. At least on clayey soil (I have not spent much time on other kinds LOL). So, what you've got is probably fine now, just a heads-up for next time

If you ever HAVE TO sink a post when the groundwater level is so high that the hole fills back up, btw, THAT is sometimes a good time for a sack of Quikrete or fast-setting post mix. Dig hole, bail out as much water as possible, put post in, dump sack of premix in (wear goggles and dust mask), squoosh it around as well as possible with a long stick, then refill on top of it with dirt, figuring you'll have to go back and re-tamp real hard once things are drier (wet clay cannot really be tamped down very well). I've done this in emergency situations, twice, when I just HAD to insert a post no matter what the water level was; and they've ended up reasonably solid despite the circumstances. Whereas otherwise in those conditions you end up with intractably loose wibbly posts.

Good luck, have fun,

Pat

 

[Moabite]

Indians in the southwest, would use cedar logs and char the ends in fire. Many are still standing today. On my wood shed, I used untreated natural cedar logs set on smooth, flat river rocks with a piece of asphalt shingle between the two (smaller in diameter then the log). It hasn't blown away yet and is showing no signs of rot. Also, you could pack dry sand or dry concrete in the post hole. The concrete would slowly cure using ground moisture without bubbles. The sand, packed in there, would hold tight and reduce moisture some. Just food for thought.

 

[Barrdwing]

I've been keeping an eye on these holes. So far they aren't showing any signs of filling in, and the walls are solid. The clay I've been digging in is as dense as anything. It was dried out and hard as iron, actually; I had to run water into the holes just to soften it enough to dig. And I was feeling pretty cocky about how I'd managed to hoist all of the water back out, in the form of mud . . . until this ever-helpful storm came along, and put several inches of water back in them! (I really should be careful about what I wish for out loud.)

We're on a hillside, and the groundwater is a good 75 feet down, so at least once the storm passes I can try to bail the holes out and they shouldn't seep. But you're absolutely right, patandchickens, if we were on a lighter, wetter soil I would have been tearing my hair out over the delay--I've dug in that stuff, and had it fill in on me; I've also seen how the walls of the hole weaken and fall and what that does to the post stability. I'm just crossing my fingers that I can get these holes dried out and my posts set fairly soon: I don't think there's any chance of the holes collapsing, but if we got a really heavy rain I might be very, very sad. And swearing a lot. And heading down to the hardware store for some Quikrete.

Moabite, I like the technique you've described! I've been thinking that it's daft for me to be digging when the ground is hard, and that I should try doing this kind of thing in winter when the ground is soaked. Your method sounds like a great way for me to deal with the "too much water" issue then!