When it comes to building a wooden fence it is good to have solid fence posts to ensure the most stable installation possible. Fence posts are the main component that are responsible for keeping your enclosure upright and straight. Installing wooden fence posts can be tricky but with the right knowledge and tools, you can get the job done correctly.
For starters, make sure you buy the right kind of wooden posts. It is recommended you stick with pressure treated wood that is rated for ground contact. Also be sure to check the posts for straightness – obviously the straighter, the better and be sure you acquire posts that are long enough to bury about 1 -2 feet of them in the ground. The proper wood will minimize rot so be sure to ask your lumber professional for advice or contact Fence Specialists for professional assistance.
Next, make sure you measure out the distance between each post and mark the approximate location of the posts will be set. Typical spacing is right around 8 feet between each post however different circumstances may call for different measurements and it is not uncommon to have spacing between posts reach up to 10 feet. Once you have a rough idea of your post layout start by digging your first hole.
Digging fence post holes is backbreaking work so make sure you have the right tool to make it easier. A basic post hole digger (clam shell digger) should make things much easier for you and a pry bar can help when you encounter large rocks that need to be knocked loose. If you have access to one, you can also use a power auger and you can check with your local hardware store to see if they rent them. Dig the hole to be a little bit bigger than the fence post. If you are going to surround the post in concrete or gravel leave a little extra room to fill it in. Concrete usually requires a larger hole roughly 12 inches wide for a 4×4 post while gravel can be roughly 8 inches wide for a 4×4 post.
Next, take your fence post and stick it in the hole. Make sure it is the right height and adjust accordingly by continuing to dig or filling in the hole. For a sturdy post you should try and make your hole at least 2 feet deep. Once you get the height correct, it is time line your post up properly.
Lining up your post correctly is pretty easy to do as long as you have a few extra pieces of wood and a level. Use the 
level to make sure your post is straight (plumb) and take the pieces of wood and lightly nail them to the post and push them into the ground to act as a temporary holder. Make sure to leave some of the nail head sticking up as we will be removing these boards once the post has been set. Here is a nice visual image of how this is done courtesy of how stuff works.
Once you get your first post lined up and secure you can move onto the next hole. Waiting until after your first post is installed to dig the next hole will help you ensure you get the spacing right. We also suggest waiting until all your posts are temporarily set before you pour any concrete or dirt back in the hole. This way you can ensure everything is lined up correctly and minimize your mess to just one day if you are pouring concrete.
To line up your next post there is a nice trick that involves using a piece of string and running it from the first post to the next. You can also use this trick to help you line up your holes. Finish digging your holes and repeat the steps above to ensure each post is plumb, etc.
Once all posts are temporarily set you can proceed to mix any concrete you are going to use or fill in the holes with dirt or gravel. When it comes to concrete there are several different options you can choose from. For a very sturdy fence you can pour concrete in every hole. This is also recommended for areas with soft or wet soil as it will help slow down the rate of post rot. Another approach is to use concrete on every other post and each corner post. This will also offer a sturdy option however is not as sturdy as using concrete on every fence post. Finally, you can opt to strictly fill the holes with just dirt or a mix of dirt and gravel. This option will offer the weakest fence posts and your fence will most likely not last as long. Furthermore, you increase the speed that your post will rot but not encasing it in concrete.
A good practice when pouring concrete is to scrape the concrete up against the fence post so it create a sort of cone above the dirt about and inch or two. The idea is to seal off the wood so when water is running around the fence post it will not make contact with the wood and rot it out. Concrete tends to be porous so there will already be a good amount of moisture in contact with the post set in the concrete but this technique aims to reduce the amount of moisture as much as possible.
Once your posts are set allow the concrete to dry and soil to settle before moving on. You can check your work with a level and by making sure your string is setup in straight line. And that’s it, you have now set your fence posts and are ready to start laying your boards!
Need more help? Give Fence Specialists a call at (253)531-5452 or check out this video: