I'm planning to build a fence that's about 6 feet tall, and I've already dug post holes that are 36 inches deep to accommodate the frost line in my area. I even made a "bell" shape at the bottom to help with frost heave. There's a common guideline suggesting that at least one-third of the post length should be below ground and filled with concrete. However, I'm having trouble finding 9-foot cedar posts, and they tend to be more expensive. If I use an 8-foot post and bury 2 feet of it in concrete, will that be sufficient? Do I really need to ensure that 3 feet of the post is underground if it's secured in concrete?
3 Answers
You could actually consider using 10-foot posts and just cut them down to the desired height. That could save you some hassle in the long run. Just remember that having a solid anchor below the frost line is important to keep the fence stable, especially with strong winds.
The one-third rule is there to help prevent wind damage. While the frost line ensures your fence won't shift due to freezing, having it 36 inches deep is crucial for stability. If you only have 8-foot posts, consider some creative anchoring or just bite the bullet and get the 10-foot posts, they'll give you that extra peace of mind.
Yeah, I think going a bit deeper is safer, especially in winter months when frost hits hard. You could always fill in with some extra concrete to be extra sure!
Have you thought about using an elevated post base? It can help with costs and still give you the structural support you need. Plus, using a secured steel bit instead of just concrete can help prevent fractures. Just a thought, but it doesn't sound too crazy cost-wise if you're filling multiple holes.
That's an interesting alternative! If it's only a bit more per post, it could work out better in the long run for fewer issues.
I get your point, but it seems like the price jumps quite a bit for those extra two feet of cedar around here. The concrete adds minimal cost compared to the posts.