Guide
Setting fence posts without concrete
Tamped crushed stone holds a line post well and drains the base.
Short answer
Yes, for line posts on a fence up to about 6 ft. Fill the hole with crushed stone that has fines in it, tamping every few inches: a 4x4 in a 9 in hole 30 in deep takes about 0.89 cu ft, roughly 2 bags of 50 lb. Keep concrete for corner, end and gate posts.
How to set a post in gravel
- Dig the hole to full depth, about three times the post’s width across.
- Put 3 to 4 in of stone in the bottom and tamp it, so the post stands on a firm, draining base.
- Stand the post, brace it plumb in both directions, and add stone 3 to 4 in at a time.
- Tamp each layer hard with a tamping bar before adding the next. The tamping, not the stone, is what holds it.
- Finish the top with soil sloped away from the post so rain runs off rather than down it.
Use crushed stone with fines, sold as 3/4 in minus, road base or crusher run. Round pea gravel rolls instead of locking together and never gets firm.
Stone per hole
| Post and hole | Fill | 50 lb bags |
|---|---|---|
| 4x4 in a 9 in hole | 0.89 cu ft | 2 |
| 6x6 in a 12 in hole | 1.44 cu ft | 3 |
For more than a few posts, buy the stone loose by the ton or the yard; it is a fraction of the bagged price.
Gravel or concrete?
Gravel drains, so the base of a wooden post dries out between rains instead of sitting in a cup of wet concrete, which is where most set posts rot. A post in gravel can also be pulled and replaced without breaking out a lump of concrete. What gravel gives up is stiffness: corner, end and gate posts, anything on a fence over 6 ft, and any post in loose or sandy soil should go in concrete. Many builders mix the two: concrete for the posts that take load, stone for the line posts between them.
Other ways to set a post without concrete
- Tamped soil: the original method, and sound in firm clay loam. Tamp in thin layers.
- Expanding foam post setters: quick and light, and fine for light fences; less proven than stone for tall or heavy panels.
- Metal spike anchors: for mailbox posts and low decorative fences, not for a privacy fence.