Could anyone tell me the proper procedure for planting posts for fences, decks, and pole buildings? I know they need to be excavated below the frost line, but this is where I have conflicting stories. Do they bear on concrete or well draining material(gravel)? Are they encased in concrete, or backfilled with gravel, or tamped dirt. If encased in concrete should the hole be formed with sonotube or just fill the hole. I’m so confused, who’s right?
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Prescriptive codes don't address the connection at less common angles, so base the connection off more typical ones using bolts, structural screws, blocking, and steel tension ties.
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In my not so humble opinion the fastest way to get a psot to rot is to set it into concrete. Water seeps in far enough to keep the top six inches wet all the time and that's where it falls apart after about four or five years.
If you dig a post hole and fill it with concrete the edges of your cured concrete are rough so it is easy for frost lens to get a good grip on it and heave it up out of the ground. The edges must be smooth as in sonotube forms.
Here's what I do: dig at least a foot below frost level. Land a bag of sakrete mix in the bottom of the hole. Native moisture in the ground will harden it without all that mixing. If your hole was dug by a backhoe you have plnty of room to just lay it down and set the post on it.
Backfill needs to be extremely well tamped gravelly soil for drainage. Soil that doesn't hold moisture against the post won't cause it to rot out as fast. It also is less prone to frost damage because for the soil to expand in freezes, it must be wet. The more water it traps, the more heaving is likely.
I never built a pole building, but when building decks, I pretty much do it the way piffin described....set a concrete "punch pad" in the hole first, then set the pole in place, and later backfill with soil.
However, I prefer to mix the concrete in a wheel barrow first and then pour a 12 inch thick pad into the hole. I let the concrete pad set up for at least a full day before coming back and placing the posts in the hole.
A trick that was taught to me is NOT TO BACKFILL THE HOLE UNTIL after most of the deck framing is in place....this way, if a corner is slightly out of square, or a post slightly out of alignment with the others, that post can be physically nudged into the correct position with a long prybar. Only after everything is in alignment, should you then go ahead and backfill the posts with soil and sand mixture.
You can't make those kinds of corrections if your posts are buried in concrete. And, remenber to buy posts rated for long term ground contact (treated lumber @ 60% I believe) and also use stringlines to aid in positioning your posts.
LOL.
Davo
Fence posts don't need any concrete, according to me. Where I live, the frost line is about 3", so maybe this doesn't work up North. But my daddy taught me to plant fence posts by digging a hole as deep as you can to leave enough post sticking out to hook the fence to it. I'll dig till the post hole digger handles don't let me go any further. If you have some gravel, put a shovelfull in there. Put the post in, and then add dirt back about one or two shovelfulls at a time. Tamp it more than you think you have to with the shovel handle or, better yet, an iron bar. They sell 'em just for that. I've used a sledge hammer with good results. Hold onto the head and pound with the handle, if you have the kind of sledge hammer that doesn't come apart if you do that. Go one or two shovel fulls at a time like that. Check for level with each addition of dirt. They have neat little post levels at HD that you put on your post with a rubberband so you can see both directions at the same time. You should be able to fit all the dirt back in there, despite having added a post. It should take about as long to fill it back up as it did to dig it or you aren't doing it right.
What those guys said about deck posts is right about hooking them together to get it all square before you fill up the hole. I like to assemble the ribbon joists to the corners, square it and brace it, then fill up the holes. But I disagree on the bottom of the hole thing. Here in the south, I put gravel under the post for drainage. (And I am SURE the end in the ground is treated, and not cut or anything.) Then I use dry Quickrete and tamp it just like a fence post, adding just a trickle of water to make it pack. Again, the moisture in the soil will set it up. And if you pack it good, it should be sturdy enough to work on in the meantime. I use maybe one or two bags of Quickrete per post, and finish with dirt at the top. This is for frou-frou reasons as much as anything because I like to plant vines and flowers right up to my deck posts.
I feel this method works extremely well, but there is a big catch. Some building inspectors are convinced that you have to have a concrete footing with the post attached to it above ground and they won't stand for anything else. (Which bugs me to no end, because then it only holds things UP and you waste all that strength of a big post to resist lateral motion and you have to put braces all over.) If you want to risk burying a post, be sure the stamp that shows the ground contact rating is visible, and have the applicable codes highlighted to show you can do that. I have found the codes here in GA that say it's OK, and I consulted Geotechnical and Structural PEs regarding my method, and they both gave it a thumbs up. Still, engineering is no match for bureaucracy.