Replies

1. 
   calvin | Jan 13, 2011 06:28pm | #1

   wanna

   Do I understand this right: fence posts (6 foot fences) do not get cemented in the ground and generally (in Chicago) are dug no deeper than 24 inches and secured with gravel and dirt.

   Don't know the procedure in Chicago, but here in NW Oh a 2' depth of a fence post would be the absolute minimum, most likely 30-36 inches depending on whether a privacy or split rail.  Many would pour concrete around (dry-add water) the post, not much if any stone at the bottom or sides of the hole.  Bad procedure as the concrete sleeve would hold water tite to the post and cause premature decay (even in pressure treated).  Better to fill with stone.  I toss a pc of busted concrete block in first, set the post on it and plumb, fill the remaider with tamped 3/4" (57's) stone.  Another problem with a concrete sleeve-pushes the post up during frost in the ground.

   And if that's true is it only deck posts that are dug 12 inches deeper than the frost line (36 plus 12 equal 48 inches) and cemented with a little gravel at the bottom?

   No, while the depth might be right, there's a footing in the bottom of that hole-size and thickness depending on the load of the deck.  Backfill with stone for the same reason as above.

2. 
   DanH | Jan 13, 2011 10:03pm | #2

   Best practice in most parts of the country for wood fence posts is to bury them about 2.5 feet down and backfill with crushed rock (not river gravel).  Generally the post should be set on compacted gravel or a smal chunk of concrete (or concrete can be poured into the hole and allowed to set).

   Practices will differ from the above if metal posts are used, or the soil is particularly unstable (eg, very sandy).

   Deck posts (except perhaps posts for low, free-standing decks, depending on local code) should go on a footing that reaches the local code-required footing depth.  The interface between the post and the footing need not reach below the frostline.

3. 
   wannaknow | Jan 14, 2011 02:27pm | #3

   Good info but I would like more. What if fence posts are metal? By footing underneath you mean either concrete of gravel? Six inches deep  and below post? And what about sandy soil? Also how important are gravel differences: compact, river, crushed, etc? Thanks for second effort. I'm really looking for a "complete" understanding of good post-in-the-ground management whether it's deck or fence.

   And really, thanks again. I think this forum is the best and it's the reason I subscribe. I like the direct contact and yes I buy books and refer to past articles. But some questions aren't answered and I know the answers are out there.

1. 
   calvin | Jan 14, 2011 05:44pm | #4

   j

   Who's your reply to?  It has your name replying to your name.  Did you click on the reply button on the original post, or the one below the reply by someone to you?

   This has happened alot and I'm not sure why, you could clear it up with an answer.

   thanks.

   Difference-a deck needs a footing, a fence post does not.

2. 
   DanH | Jan 14, 2011 08:33pm | #7

   The problem with metal fenceposts is that they have so little cross-section to resist sideways force.  For this reason, depending on the soil conditions and the nature of the fence, they may need to be set in concrete.  Otherwise (as stated by someone else), the best way to install them is to drive them, so that no soil is disturbed.

   With regard to gravel (around/under wood posts), you want something resembling "crushed rock" rather than "river rock" or "pea gravel"  The "crushed rock" has angular faces that will interlock, and, with proper compaction, resist movement by the post.  "River rock" or "pea gravel", on the other hand, is rounded and the pieces will easily move relative to each other, allowing the post to move.  The size of the gravel depends in part on what's available, and on soil conditions, but you want pieces that will easily drop down the hole, but not be so small as to be more like sand.  You'll get varying opinions as to whether the "fines" (rock powder and small pieces) should be left in or screened out.  They help the rock pack tighter in some conditions, but also retain more moisture and might somewhat accelerate rot of the post.

   In terms of a footing, you don't really need a footing per-se under a common fence post, but it's wise to put in some gravel or a chunk of concrete or some such to provide a little bit of bearing surface and keep the post end away from direct contact with the soil.

   For deck footings and the like, the diameter of the footing (and hence the diameter of the hole) will be speced as a part of the deck design, based on the weight bearing on the post and the PSI rating of the soil.  In that hole there needs to be a footing.  For reasonably small diameters (roughly a foot or less) this can be several inches of concrete or some clean crushed rock of roughly 1.5" size, poured in and well-compacted to be about as deep as the hole is wide.

   Setting posts in sandy or peaty soil is a problem.  The soils can be too easily compressed or deformed to hold posts well, and something like large-diameter concrete surrounds may be needed to provide enough sideways bearing surface.

3. 
   Piffin | Jan 15, 2011 05:31pm | #8

   Whale now
   I set fence posts four feet deep, but i have never done a steel fence post.

   Most questions that go un-answered are because of poor information provided by the OP. For instance,I really don't understand what you are asking about deck posts.

   This forum is free, and those of us who are left answering questions are doing it for the fun of it, and the satisfaction gained either from helping a fellow human, or from our personal egomaniacal needs. If you are paying Taunton any money to use this forum, I feel for yah.

4. 
   renosteinke | Jan 14, 2011 06:33pm | #5

   Whoever told you that is either nuckin futz, or is deliberately seting you up to fail. I'll bet they also told you that snow tires were over-rated, and that you'ld never need snow tires.

   I was raised outside Chicago, and put in many fences. Even the 4-ft ones got set 30" down, then cemented in place- and these were uninspected DIY jobs.  6-ft. tall? I'd go 36" down. 

5. 
   Clewless1 | Jan 14, 2011 08:15pm | #6

   24 inches sounds shallow. I agree 30-36", no concrete, set on gravel, then tamped in layers w/ appropriate backfill (mixed of gravel/earth).

   But ... you say metal, but you don't say what. Steel fencing posts (e.g. barbed wire) are driven into the ground, done. Steel/hollow pipe? What diam? You might be able to drive them into the ground, too. W/ steel, you may have good options of concrete vs. earth backfill. What type of fencing material are we talking about?

   You want more thorough answers, you need more detail in your description. Thanks.

1. 
   wannaknow | Jan 16, 2011 03:50pm | #9

   ask better questions

   You opened my eyes. I wasn't even thinking about different metal fences. In my ignorance I lumped them all together. Now I've got something more to think about, but my thoughts and questions will be more nuanced.

1. 
   calvin | Jan 16, 2011 04:17pm | #10

   And answer this one...........

   J, look up a ways in my reply to you at this message:  http://forums.finehomebuilding.com/breaktime/construction-techniques/fence-posts-3#comment-2176926

   Hopefully that'll take you up to the one I'm talking about.  The software here on this board drives me a just a few others crazy-it's not very user friendly.  If all that gobblygook means what I hope it does...............please respond to the question up in that post.

   thanks.

   This is like trying to deliver a pizza at night on a dark street with no house numbers and it's raining and your wipers are bogus.

1. 
   Piffin | Jan 16, 2011 04:52pm | #11

   whale now Cal,

   if he would ask the Q over at BT classic, You could answer it over there and everyone would be happier!

   ;)

1. 
   calvin | Jan 16, 2011 05:47pm | #12

   He most certainly could ask over there.

   But then again, he's here and asking.  Now let me ask you this................how many answers can be given for this particular question?   Perhaps a couple............till we mix in regional differences.  And even just street differences around here for example.

   To make the point.......

   A young friend wanted to put on a small horseshoe tourney in Bowling Green.  I learned a little topography or geography or whatever deals with rock.

   I brought over shoes and stakes for 4 pairs of pits.  Most of my stakes are 36" long-I've got a pair of 48's in case of sand, of which there's some ridges around here-all sand.  But mostly there's clay.

   Except in his yard-the site of an olllllllllllllllllllllld limestone quarry nearby.  Now, they managed to put a house on his lot and maybe there's a footing-never hope to know.  But I'll tell you this-back in his spacious backyard............if we could get stakes in the ground 40 ft from each other, we surely couldn't get them down more than maybe a foot.  No one ever said that day that they were short staked from a ringer.

   Post over there?  no need, that's where the whole gang is-plenty of answers, anymore would just confuse old j.

6. 
   MarkH | Jan 16, 2011 07:11pm | #13

   The oft quoted rule found on various Internet sites is 1/3 of the post is in the ground, sometimes with the additional requirement of "plus six inches".  Which is an OK rule, but the frost depth also is a consideration not usually mentioned.  I would want the posts below the frost depth to reduce upheaval.  But we are talking fences, sometimes getting below the frost depth is impractical, and the 1/3 rule or (1/3 +6") is generally OK, except if the winds are high or the soil is weak. 

   In short, I recommend that YOU plant your posts below the frost depth if it is greater than the 1/3 +6" rule, while I will continue to take chances with somewhat less depth.

   No warranty is implied or granted for this opinion.