Replies

1. 
   gfretwell | Mar 16, 2010 10:46pm | #1

   Concrete tends to destroy wood posts, PT or not. If you have sandy soil you can usually make them very solid just by tamping in the back fill as you fill up the hole in 4-5" lifts.

   My mailbox was put in that way id it was impossible to pull out after it rained a few times.

2. 
   KFC | Mar 23, 2010 11:02pm | #2

   A lot of guys insist on gravel, and say concrete will cause posts to rot out.  There's some logic to that, in that it allows for drainage, but at the same time, it creates a low pressure sump that will accept water from the surrounding soil, so I have my questions too.  In any case, I've re-visited posts I've set more than 15 years ago in concrete, and they are solid.

   I always set the bottom of the post in 3-4" of gravel and pour the concrete above that, so there is really only a concrete "collar".  I would not set the bottom of the post in concrete like a cup.  I do bring the concrete up above grade and slope the top to shed water.  Works for me.  The gravel at the bottom of the hole kind of holds the posts temporarily while you get them all lined up and plumb, too.

   k

3. 
   KFC | Mar 23, 2010 11:11pm | #3

   Good point about the frost heave.  Not something I think about.

   k

4. 
   MGMaxwell | Mar 24, 2010 10:53am | #4

   Well, there you have it. You asked which of three ways was the best to set fence posts and you got three answers promoting each one of them. That's pretty funny. I live in Florida and I use sand..............that's all I've got for soil. Unless I want to go buy gravel to put in the holes............I don't think so!  Besides, in my neighborhood if I dig down 18 inches I'm in water so it doesn't make a lot of difference

5. 
   Scott | Mar 24, 2010 03:06pm | #5

   Around here, as long as the posts are PT, we just set them in the ground. The only issue I'm aware of is that the posts driven with a tractor-mounted ram don't last as long because they sometimes get split or gouged by rocks when driven. A two-man auger might be slower and more work, but the posts last much longer.

   Otherwise, there are plenty of 30 to 40 year old posts that are doing fine.

6. 
   rdesigns | Mar 24, 2010 05:53pm | #6

   Posts on this forum are usually set in BS.

   Edit: (Broken Schist, fancy name for crushed gravel.)

7. 
   Clewless1 | Mar 27, 2010 10:53am | #7

   Thought I responded on this ... it's either me or this new forum structure.

   I'm the old school ... set posts in soil and backfill and tamp in lifts. I've seen many a post last a LONG time doing it this way. The west is full of these along hundreds of miles of fence lines. Concrete doesn't necessarily guarantee much ... it can move w/ the post if the surrounding soil is soft. Concrete is a lot of work and hassle that IMO is often not really worth it.

1. 
   DanH | Mar 27, 2010 02:11pm | #8

   Of course, those old posts were likely to be slow-growth, and from a rot-resistant species.  The new posts -- who knows?  Certainly not slow-growth.

1. 
   Clewless1 | Mar 28, 2010 01:45pm | #9

   Old posts? Out here in the 'West', not too much 'slow growth', I don't think. But certainly may have 'rot resistant species' (e.g. cedar). New wood? Pressure treated is likely, so there shouldn't be too many issues. I built a full basement house w/ PT wood foundation walls.

1. 
   DanH | Mar 28, 2010 01:55pm | #10

   I've seen "pressure treated"

   I've seen "pressure treated" lumber rot out in under ten years.

1. 
   Clewless1 | Apr 06, 2010 08:57am | #11

   Yeah I've seen some of the same. Not sure what conditions that would occur. I built a full finished basement wall out of PT products and the house still stands today ... that was 30 years ago.