Should I use Sonotube or Not for my fence post ?

[SpykeYs]

Hello,

I am about to start building my wooden fence. I will use 4x4 pressure treated post.

I plan to dig 4ft x 8'' and use concrete. I am currently debating to see if I should use Sonotube or not.

Half are saying it's the best, the other half are saying the sonotube will mess up my post in the future because it is paperboard.

Any help would be appreciated.

Thanks!

[Anonymouse]

Depending on the soil you're working with, you may not need concrete, especially if you're willing to go down 4 feet. Just put 6 inches of gravel in the hole, then 6 inches of dirt, compact firmly and repeat.

I have a 6 foot fence plus 2 foot trellis built with this technique that's perfectly vertical after 10 years.

[AudiDude]

If you use sonotube, it can lessen the amount of concrete you use. If you do not make the post holes perfectly straight, the sonotube will limit your adjustability because of the angle it will be on. I did sonotube once, probably will not bother the next time because of the adjustability issue. Either that or use larger tubes, but that just means more digging.

[YeemJeem]

Depending on the soil you're working with, you may not need concrete, especially if you're willing to go down 4 feet. Just put 6 inches of gravel in the hole, then 6 inches of dirt, compact firmly and repeat.

I have a 6 foot fence plus 2 foot trellis built with this technique that's perfectly vertical after 10 years.

From what my fence contractor told me, concrete does more than "anchor" the post in place. It also acts as a coating to slow down rotting, water damage and warping to the wood.

[Anonymouse]

I have a different theory - I think the concrete will hold the water against the post and cause it to rot. If you're committed to concrete, the thing to do is set a post holder in the concrete such that you bolt the wood into a purpose-built bracket above ground. The wood never touches the ground. If the post rots, you simply unbolt it and replace it.

Most people who use concrete don't realize the amount of swearing you do when you try to dig all the plugs out within 10 years after the posts rot!

[arisk]

I have a different theory - I think the concrete will hold the water against the post and cause it to rot. If you're committed to concrete, the thing to do is set a post holder in the concrete such that you bolt the wood into a purpose-built bracket above ground. The wood never touches the ground. If the post rots, you simply unbolt it and replace it.


I agree, if the situation allows it.
I have a related opinion regarding encasing below grade posts in concrete.

Some would encase the lower end in the concrete, including the bottom end.
This creates a dish of water that the post sits in.

I believe the post should sit on gravel and be surrounded by a doughnut of concrete.

[leonkaz]

sonotube - extra expense and hassle, so I say no
concrete - I plan to use limestone screening or something similar,
it can be mixed with water and poured into the hole. compact with 2x4

[3weddings]

lol...just had a contractor over to quote our fence repair (it blew over this weekend) and he indicated he would use the sonotube with 12' posts. His quote was substantially higher than the local guy who was using 10' posts with no sonotube.

We are in clay and I have a cheap neighbour, so guess which way we will end up :D

[mork]

From what my fence contractor told me, concrete does more than "anchor" the post in place. It also acts as a coating to slow down rotting, water damage and warping to the wood.

As other have said, this is simply not true. Encasing the post in concrete will accelerate rotting.

I'm in a new area and everyone has been happily building their fences here and I couldn't find a single person using concrete.. seems to be a thing of the past here now.

I bult my new fence just like my previous one (about 5 years old and still tanding strong) - I put a couple of inches of gravel under the post, then surround it with gravel and pack/tamp tight. I use base gravel and it packs pretty much as solid as concrete but drains better (so theoretically, it will slow down rotting).

[attitude21]

What about putting the post into a post anchor in the sonotube, does that decrease the rotting?

BTW, 10% off fencing this weekend @ Home Depot.

[tallAJ]

what about covering it in 6mil poly like interior supports?

[TrevorK]

I bult my new fence just like my previous one (about 5 years old and still tanding strong) - I put a couple of inches of gravel under the post, then surround it with gravel and pack/tamp tight. I use base gravel and it packs pretty much as solid as concrete but drains better (so theoretically, it will slow down rotting).

I'm getting ready to start my fence, and am looking to go the no-concrete route.

With your method, am I understanding correctly in that you surround the post with gravel rather than the dirt you dug out of the hole? And the post is secure (as in it doesn't move when you push on it)?

[TrevorK]

What about putting the post into a post anchor in the sonotube, does that decrease the rotting?

The post will not be in direct contact with moisture (except in winter) so it's rotting will be decreased.

The problem with fence posts is that when in the ground they are always in contact with moisture, and from what I've read, it's just a matter of time before the moisture seeps through the layer of wood that's pressure treated to the part that is not.

Many believe that the rotting is further accelerated when concrete surrounds the post because concrete does not allow water to wick away (since it'll pool on the concrete) and concrete actually draws in moisture from the ground.

[leonkaz]

what about covering it in 6mil poly like interior supports?
moisture will be trapped between the poly and the wood = rot