Seashell driveways are something of a tradition in coastal areas of New England. When one homeowner decided his gravel driveway wouldn’t cut it anymore, he called the team at Ask This Old House for help installing a shell driveway of his own. Landscape contractor Lee Gilliam answered the call, helping the homeowner expand his old parking space and install a new one made from beautiful shells.
Things to Know About Seashell Driveways
Shell driveways are quintessentially classic coastal New England. They look great once they bleach in the sun, have a distinct crunch sound, and drain as well as any gravel base. But, they do have drawbacks to consider. For one, they can be difficult to shovel, plow, or snowblow. Also, they can be very uncomfortable for bare feet. Finally, as vehicles drive over the shells and they break down, low spots may form, and you’ll need more shell to fill the depressions.
Installing a Seashell Driveway
- Layout the new driveway design with marking paint.
- Measure the driveway to determine how much material you’ll need to buy. You’ll need the Length, Width, and Depth. Most landscape supply companies can do the math for you if you give them these dimensions, but you can also calculate it yourself.
A general rule of thumb for Depth is:
New driveway = 3 inches
Refreshing an existing seashell driveway = 1 inch is usually enough
Step-by-step calculation:
Multiply Length x Width x Depth (in feet) = total cubic feet
To turn inches into feet, divide by 12
3 inches ÷ 12 = 0.25 feet
Total cubic feet ÷ 27 = cubic yards
Since 1 cubic yard = 27 cubic feet.
The result is the number of cubic yards you’ll need to order.
- If there’s an existing gravel driveway, remove the stone with a power broom or rake. Make piles and scoop the stone into a wheelbarrow with a shovel. Leave the bottom layer, known as a “hardpack” for stability.
- Remove any border or edging stones that may exist. Use a pickaxe to get under the stones and pry them up out of the ground. Save them for reuse if they fit your design plans still.
- If you’re expanding the driveway into the yard, use a sod cutter to cut under the topsoil and make the grass easier to remove. Remove the loose grass and dirt so it’s roughly even with the hardpack layer.
- Dig a trench 3 to 4 inches deeper than the surface and install a string line from corner to corner to serve as a guide.
- Fill the trench with ¾-inch crushed stone. Tamp the stone down by hand. the perimeter of the driveway layout for edging.
- Install new edging stones (or reinstall the edging stone you removed) by placing it on the gravel border and setting it in place with a rubber mallet.
- With the border installed, cast shovelfuls of seashell out across the driveway. The goal should be to create a shell base about 3 inches in thickness.
- Use a plate compactor or tamper to compact the shell into place to create a smooth, flat driveway.
- Keep some extra shell on hand to fill any low spots that may form over time.
Materials
Tools
You can rent a sod cutter and a plate compactor.
