Add gravel into the hole for improved drainage. Stomp it down with a stick or tamping bar. Place your post in the hole so that it's straight and level with the other posts in the fence or structure. Get an assistant to hold it steady or secure it with stakes and screws to keep it in place.
Put some gravel into the bottom of the hole and tamp it down well with the post. The place the post and add a bit more gravel around. That will keep the open grain end from being in direct contact with soil and reduce moisture wicking/trapping.
One of the simplest methods is simply attaching something to the bottom of the post before putting it in the ground. One method is to nail a piece of wood to the bottom of the post. This device is often called a deadman and is shown in Figure 1.
Installing a wooden fence post to prevent rot involves setting it in gravel or crushed stone at least one-third of the post's length, allowing for drainage. Tamp the base firmly and slope the top away from the post to shed water. Apply a wood preservative to the post below ground level and cover with soil.
Treat the Post With Preservatives
Prior to installation, soak the bottom of the posts in a wood preservative containing copper napthanate, such as Cuprinol. Note: Available at some paint stores and home centers, this wood treatment is specifically designed for in-ground applications.
A pressure treated fence post can generally last 10 to 25 years.
Add gravel into the hole for improved drainage. Stomp it down with a stick or tamping bar. Place your post in the hole so that it's straight and level with the other posts in the fence or structure. Get an assistant to hold it steady or secure it with stakes and screws to keep it in place.
Backfilling with Gravel and Soil. Fill the first few inches of the hole with gravel. This aids in drainage, keeping wood posts dry and preventing rot. After the gravel, backfill the hole with the dug-up soil, tamping down every few inches to eliminate air pockets and ensure soil compaction.
Fast-setting concrete is ideal for setting posts because there's no mixing—you simply pour the dry concrete from the bag right into the hole, then add water.
Fill the first three inches up with gravel so the end of the post doesn't come into contact with the dirt. Gravel allows water to drain quickly away from the post and into the soil. Be sure to place the post in the center of the hole. Finally, fill the entire hole up with cement to the top.
You can use a post hole digger or post driver to help create the hole. Add about 10-15 cm of gravel to the base of the hole to increase the drainage ability. Position the post in the hole and drop two stakes into the soil next to the pole. Nail or screw two pieces of wood between the stakes and the pole.
Method 1 Fix your Fence Post with Concrete
Re-level the fence post and add a support beam to hold it in place. With the post supported, fill the hole with the concrete compound to about an inch below ground level. Work the air out of it with your shovel to ensure that it fills the hole completely.
The bad stuff seeps downward right into the “Hot Zone”. Mix in some oxygen, the moisture from below, the fact that concrete holds a constant temperature and moisture, and those wood posts are going to prematurely rot. No exceptions.
Gravel is best for fencing in heavier (more clayey) soils, and won't work well if you have loose, sandy soil. Gravel also allows water drainage around the fence posts, making the posts less susceptible to frost heaves. Dig the holes the same way as you would to set posts in concrete.
While expanding foam can secure posts for lightweight fences, such as vinyl or wire mesh, it's better to go with concrete for structural posts, such as posts for porches, decks, or large and heavy gates. Expanding foam is not as strong as concrete when supporting load-bearing posts.
To set a post in gravel or soil, tamp down a 2-3 inch (5-8 cm) layer of gravel and insert the post. Then, add and tamp gravel or soil into the hole until it's filled. To set a post in concrete, tamp down a 4-6 inch (10-15 cm) layer of gravel and insert the post. Brace it with stakes, then shovel concrete into the hole.
Stabilize Your Fence Post
You'll first want to dig a few inches of soil out from around the post's perimeter. From there, you can fill the hole with gravel and top the gravel with a rapid-set cement mix. Finally, pound the fence post back into place using a mallet.
For a standard 4x4 post you want the diameter for the hole to be around 12 inches, while the depth should still be around a third of the post, but with an added 6 inches for gravel.
You are right in your assumption that you should not pour around the post. Concrete experiences fractures quite often, especially microfractures around points of varying stress (i.e. at the edge of a post). Additionally, any moisture/water that may enter your basement will probably get into the post.
The general rule of thumb when setting a post is that the depth of the post's hole needs to be one-third to one-half of the actual above-ground height of the post.