Replies

1. 
   RobertLee | Feb 19, 2005 04:24am | #1

   6' high fence should have posts 3' into the ground.

2. 
   DanH | Feb 19, 2005 04:28am | #2

   Two and a half feet minimum for any post. Three is probably what you want here.

3. 
   msm | Feb 19, 2005 04:50am | #3

   darn. they come 8' and 10' and they're always out of 10'.
   not deep enough is why the previous home owners did such a cheesy job and the fence is falling all over the place, i'm sure. i haven't checked yet to see just how deep they did sink them.

   ps- do i need to set them in concrete or is plain dirt okay?
   could i drill a hole in the bottom and stick in a rebar "extension" in lieu of the longer post?

   thanks

   
   

   ---

   Edited 2/18/2005 8:55 pm ET by MSM

1. 
   DanH | Feb 19, 2005 05:05am | #6

   It varies some with soil type, but generally the best way to set the posts is with a backfill of crushed limestone. Also put a little in the hole (and tamp well) before placing the post.

1. 
   msm | Feb 19, 2005 05:14am | #7

   sorry to be so dense- but is the limestone for drainage too?
   just curious as to why; i would have thought pouring in concrete was best...

2. 
   Luka | Feb 19, 2005 05:29am | #8

   Order the tens and wait on them.Yer wasting yer time, otherwise. Unless, of course, you WANT the same thing happen ?; )The rebar would do no good at all. Just promote faster rotting of the wood.Dig hole. Drop some gravel in. Set pole on gravel. Bounce a time or three to compact the gravel below it. Fill remainder of hole with gravel. (Not dirt.) Tamp the gravel solid in layers as you fill.

   The person you offend today, may have been your best friend tomorrow

4. 
   SteveInCleveland | Feb 19, 2005 04:51am | #4

   Basic rule of thumb I go by is 1/3 of the post length; so for six exposed feet, you would want three feet in the ground.

    

1. 
   Sphere | Feb 19, 2005 04:57am | #5

   What he said..1/3 in, 2/3 up..been there. 

   Spheramid Enterprises Architectural Woodworks

   Restoring, Remodeling, Reclaiming The Quality..

5. 
   SantaCruzBluz | Feb 19, 2005 06:25am | #9

   It wouldn't bother me a bit to use 8 footers for a 6 foot privacy fence. I've built many that way. You'll wind up with a little more than 2 feet in the ground if you work it right. I always used P.T. pine 4 X 4's when I lived in Georgia, and poured Sacrete around them. Unless the winds get really high that fence ain't goin' nowhere.

   Allen in Santa Cruz
   Thank you God for Life, Love, and Music
1. 
   jimbotoo | Feb 19, 2005 06:33am | #10

   I have built scores of fences with steel posts and one with 4 x 4's.  I will never use 4 x 4 PT for fence posts again.  No matter how long you let them dry out before installation, they will bend like a boomerang while they dry out.  Your perfectly straight fencelines then look like the Tacoma Narrows Bridge.  Steel posts look and work better, IMHO.

   /your mileage may vary.

6. 
   TOOLS1 | Feb 19, 2005 06:37am | #11

   If the soil is sandy (Like here in SC where I live) set the post with cocreate. If its hard clay use gravel.
   Kipherr

7. 
   Lawrence | Feb 19, 2005 07:06am | #12

   Not going to explain our footings further here until FH asks for the info for an article...but it is all based on common sense logic and we have never had a callback or a single post heave out of the ground. It's so simple it is stupid.

   Posts in 3.5-4', don't care if it is florida or alaska. Bottom half of the hole... concrete, top half screenings. We warranty them for 5 years.

   Too many principles to get into here... but this is how our contractors do it.

   L

    

   GardenStructure.com~Build for the Art of it!

8. 
   Yogi | Feb 19, 2005 07:26am | #13

   Treated posts, three feet in the ground, square posts for corners, tamp in or pour cement (drive a few nails halfway in where they'll be submerged in the cement)-  Actually, you can just pour in the ready-mix stuff dry and damp it as it goes in- 

9. 
   RichColumbus | Feb 19, 2005 09:24am | #14

   2/3 - 1/3...  and be sure you are below the frost line if heaving is even a remote possibility.

   If you use red bag Quikrete (http://www.quikrete.com/catalog/FastSettingConcreteMix.html ), you can just set the fence posts, pour the crete mix in.. then add water.  Slick as snot.  Plus... it sets up fast.

1. 
   msm | Feb 19, 2005 06:18pm | #15

   darn it, but thanks for talking me into the 10'.it's so humid here, i don't imagine that these things would ever dry out so fast they'd bow.
   no corners.
   no real danger of upheaval.but now i need a tie-breaking opinion on the sacrete vs. packed gravel. (and why limestone specifically?)what are the pros and cons of each?

1. 
   TOOLS1 | Feb 19, 2005 08:08pm | #16

   Limestone because it has irregular shapes and does not move around like round gravel. Its like the difference between a box of blocks and a box of balls.
   As for using cocreate or limestone. It depends on drainage and how stable your soil is.
   Kipherr

1. 
   msm | Feb 19, 2005 11:47pm | #19

   thanks for all that excellent information.
   information is so much more helpful than just advice/opinion.getting 10' posts
   will use alternating limestone/sackrete (have some sackrete to use up)
   thanks again!

1. 
   Piffin | Feb 20, 2005 01:01am | #21

   I can't believe nobody asked where you are before offering all that advice. Since posts ahe to be below frost line, anything less than four feet deep would heave right back uop and out of the ground in a lot of places.In West Texas, they would need a minimal third of the length to avoid being blown down in the windConcrete surronding them can promote rot and/or frost heaving.so where in the world are you? 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   msm | Feb 20, 2005 03:15am | #22

   thuh mississippi dayultah

3. 
   Piffin | Feb 20, 2005 04:15am | #23

   In that case, definitely use the stone backfill and set them 3' deep, or until your shovel hits a gator skull or the hole fills with water and crawdads 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

4. 
   coonass | Feb 20, 2005 06:25am | #24

   piffin,
   I'm in the delta also. Since we don't have frost heaves and the soil is a heavey clay, setting untreated post in gravel invites rot. It just traps the water. Much better to backfill with plain clay or concrete. We set the cypress, cedar, ect. in a bucket of Woodlife or equal for a day to water proof first. Treated post, .50 get set in concrete.KK

5. 
   Piffin | Feb 20, 2005 07:22am | #25

   concrete traps the water too. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   TJK1141 | Feb 19, 2005 08:13pm | #17

   If you ever need to remove/replace a post, the gravel option will make perfect sense to you...

3. 
   UncleDunc | Feb 19, 2005 08:38pm | #18

   Advantages of gravel:
   * Promotes drainage.
   * May resist lateral load better than the native soil when properly tamped. As a previous message noted, crushed rock will do this better than round rock.
   * Probably cheaper than concrete.
   * Easier to remove and replace post than concrete.
   * Self tightening.Disadvantages of gravel:
   * May not resist lateral load as well as concrete.
   * Takes more effort to tamp thoroughly.Advantages of concrete:
   * Increases the lateral area of the post, which increases resistance to lateral force.
   * If placed wet, easier to consolidate than tamping dry gravel.Disadvantages of concrete:
   * If you don't provide for drainage at the bottom, that is if you install the post in a concrete cup rather than a concrete sleeve, it can trap water and hold it against the wood, which is not a good thing even for pressure treated posts.
   * Probably costs more than gravel.
   * Hassle to mix, unless you place it dry.Advantages of backfilling with what you dug out of the hole:
   * Cheaper than dirt. Or anything else you would have to haul in.
   * May tamp easier than crushed rock.Disadvantages of backfilling with what you dug out of the hole:
   * May not resist lateral force adequately.Edited to include data from other messages.

   Edited 2/19/2005 5:44 pm ET by Uncle Dunc

1. 
   DanH | Feb 20, 2005 12:05am | #20

   One other point in favor of crushed rock: It is self-tightening. If the post works loose for some reason, the rock will settle and again lock it in. Soil backfill will just remain loose, and concrete is apt to either crack in half an "rattle" or develop looseness around the margins of the concrete.