What size earth auger bit do you use for a 4x4 fence post?

[nyone]

2 3/8" used oilfield pipe is the way to go. One every hundred feet with t-posts in between every ten to twelve feet. I will never put another wooden post in the ground again after the wildfire of 2011 taught me a painful lesson.

I wish we had acess to that stuff here.

 

[Username Taken]

You surely do not want concrete on fence posts. It will trap moisture and either rot the post, freeze and split the concrete, or both.

I don't know. I've had to bust up concrete that's been down for 50+ years and the wire/rebar in it looked as good as the stuff we'd had delivered the day before.

You could be right, but water doesn't necessarily cause damage/rust/oxidation to metal -- or even wood. Oxygen AND water does. If you cut off the oxygen supply, you prolong the life of materials. Look at some of the shipwrecks that have been in water for -- A really long time. And driftwood.

The guys in Michigan back fill the post holes with gravel or the cheap stuff like re-cycled, busted up concrete or asphalt. Maybe because of what you're saying

I'm looking at this, too. Thanks for the input

 

[nyone]

ack fill the post holes with gravel or the cheap stuff like re-cycled, busted up concrete or asphalt. Maybe because of what you're saying

If you do that in clay you have basically made a underground pool for your post to sit in.

 

[Wolfy]

Certainly the ground conditions you have makes a big difference. Im thinking any sort of stone, or crushed concrete would be a free flowing water drain and your posts would benefit.

 

[nyone]

Certainly the ground conditions you have makes a big difference. Im thinking any sort of stone, or crushed concrete would be a free flowing water drain and your posts would benefit.

Clay dosnt drain. In clay your better off putting the clay back in and mounding it up a bit so it sheds surface water away.

 

[sdef]

I'm a compacted soil or mixed concrete into the hole kind of guy. If I'm going to do the work, I will do it once NOT many times.

Amended response. When using wood post. I coat pressure and non pressure treated wood with "roofing cement" for the entire length that the wood will be exposed to earth plus extra 3ish inches above ground level. Posts don't rot off at ground level because water and bacteria can't get at the wood to rot it.

+1. Exactly what I do. I only have the time and money to perform things one time and not every few years due to issues. I call it, "Once and Done". No saggy gates, doors, fencing around my place.

 

[Bushbunnie]

I had a campground that needed fence , lighting and sign posts. I did it all with an 8". I never used cement or foam. Packed the soil with a tamper (2 x4) and they are all still standing 28 years later

 

[Gord Baker]

I've seen 3x the size online but nobody seems to do that in real life. What size bit would you use for a 4x4 post? I will use either concrete or the foam stuff, probably the foam, so maybe the hole should be smaller diameter?

10" or 12"

 

[Paul McILwain]

I've seen 3x the size online but nobody seems to do that in real life. What size bit would you use for a 4x4 post? I will use either concrete or the foam stuff, probably the foam, so maybe the hole should be smaller diameter?

Don’t use an auger just sharpen posts and rent a post pounder

 

[aircommuter]

There are two considerations, first is enough thickness over the corners, second is soil softness in the winter since surface area is what supports the fence from side pressures, like animals leaning or scratching themselves. Square posts are not as good as round ones for that same reason. Minimum would be 3” thickness and then soil considerations.