How to Set Fence Posts in Concrete and Gravel
Setting Fence Posts
Whether you're building a fence to corral livestock or to add definition to your yard, make sure that your fence is fully functional by setting the fence posts correctly. Before you dig a post hole, decide what material you are going to use to set the posts, and lay the proper groundwork for a straight line for your fence and for stability. The way you set the posts depends partially on personal taste and partially on soil type.
Setting the Line
Before digging the holes for concrete or gravel footing, set the line. Put stakes in the ground where the corner posts will go. Run a taut string between the two stakes for each side of the fence. Use a measuring tape to measure regular intervals where the fence posts will go. The length between posts depends on the type of fencing material you're using. If you're using preset panels, take that into consideration when marking for the holes. Use marking paint to mark the post hole locations.
Setting Fence Posts in Concrete
Set fence posts in fast-setting concrete if you're planning to leave the fence in place for a long time or if you have very loose, sandy soil. First dig the holes using an auger or a post-hole digger. Plan to set at least one-fourth to one-third of the fence post underground, and dig the hole accordingly. Then set the fence post in the hole. Once you set the next post, you'll need to measure to make sure the same length of post is above ground for all posts. Pour 6 in. of gravel around the fence post and then top with concrete. If the concrete is too loose, use braces to keep the post upright. Check that the post is flush with the string line and plumb. It's best to let the concrete cure for three or four days before attaching fence rails, fence panels, or chain link. Make sure the concrete is hard before attaching anything that puts weight on the posts.
Setting Fence Posts in Gravel
Gravel is less messy than concrete, but it can be less durable. 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. When setting fence posts in gravel, you should bury at least one-third of the fence post. Use crushed gravel to set the posts. Pour 5 in. of gravel in the hole around the posts and tamp it down. Add another 5 in. and tamp again. Continue until you've reached the top of the pole. If you want to grow grass around the fence post, leave 2 in. of space between the top of the gravel and the soil line around it. Top the gravel with soil. Unlike concrete, gravel doesn't need to set. You can immediately install fence rails, panels, or chain link.
Setting fence posts right the first time is the best way to ensure that your fence is sturdy and wind- or animal-resistant.