How to Set a Post in Pea Gravel
Using gravel to set fence posts is a popular option used by many homeowners. Unlike concrete, gravel is easily permeable and drains well. Posts set in gravel are less likely to shift if the ground freezes and are much simpler to remove, should you decide to. Pea gravel has a greater tendency to shift and settle than sharper-edged varieties of gravel, however, shifting and settling can be prevented by combining the gravel with soil. The addition of soil helps to fill the spaces between the gravel pieces, forming a rigid base for your fence post.
Calculate the necessary depth of the post hole by adding six inches to the length of the buried portion of the post. Measure the width of the post. Calculate the diameter of the post hole by multiplying the diameter of the post by three. Note the calculated depth and diameter of the post hole.
Dig the post hole, using a post-hole digger, to the calculated dimensions. Shovel about three inches of gravel into the hole. Add two shovelfuls of soil to the top of the gravel. Add water until the water is just above the top of the gravel and soil. Tamp the wet soil and gravel with a piece of scrap lumber. Allow time for the water to settle. Add more gravel, soil and water, then tamp. Continue until the depth of the hole is equal to the buried length of the post. The foundation for your post will be nearly solid and semipermeable.
Position the post vertically in the center of the hole. Ask an assistant to hold the post upright as you shovel five or six inches of gravel around the base of the post. Lay a carpenter's level along one side of the post. Lean or reposition the post so it is plumb. Repeat to check and plumb an adjacent side of the post. Your assistant will hold the post vertically as you reinforce its foundation with gravel and soil.
Distribute a couple of shovelfuls of soil around the gravel in the hole and add water. Tamp to settle the soil between the gravel particles. Repeat until the post hole is back-filled to ground level.
Things You Will Need
- Measuring tape
- Post-hole digger
- Spade or shovel
- Pea gravel
- Scrap 2-by-4
- Carpenter's level
- When installing fence posts, a minimum of one-fourth of the overall length of the post should be buried in the ground. To calculate the overall length of the fence post, multiply the aboveground height of the post by 1.33.
- For gate posts one-third of the length of the post should be buried underground. To calculate the overall length of the fence post, multiply the aboveground height of the post by 1.50.
- Pea gravel, with rounded surfaces, does not compact as tightly as sharp-edged varieties of gravel such as crushed granite.