How to Build a River Rock Wall With Mortar

A river rock wall adds character to any landscape and will help define property lines. Constructing a wall is backbreaking work, but the results will be a structure that will for last for generations. Dry stone walls are methodically stacked rock structures that can be damaged by people, animals and weather. Slightly more work to build, a mortared rock wall will stand for decades or even centuries.

Stream in forest
credit: Ingram Publishing/Ingram Publishing/Getty Images
Attractive rocks for a stone wall can be found in creeks.

Step 1

Dig the area for the foundation of your rock wall with your shovel. The trench should be deeper than the frost line and at least 2 feet wider than the wall will be. Rake the bottom of the foundation hole until it's smooth. Use the plate compactor to tamp the soil until firm.

Step 2

Line the trench with landscape fabric taking care to overlap the fabric at the seams. Place a 6-inch layer of small rocks on top of the fabric and tamp it with the plate compactor. Add more rock and until the footing layer is 6 inches below the grade level.

Step 3

Mix the mortar in a wheelbarrow, combining 3 parts sand and 1 part portland cement. You'll use 5 to 6 quarts of water with a 50-pound bag of portland cement, and you want to be careful to not use too much water. Pour water in the wheelbarrow and combine it with the cement and sand mixture. Stir the mixture and add water slowly until the mortar is a pliable thick paste -- you want it to stick to the trowel when you turn it upside down, not drip off. Air temperatures and humidity can influence the thickness of the mix. The mortar package instructions will give you an approximate amount of water to use, but you'll have to be careful to find the right consistency as you stir in water.

Step 4

Pour the mortar over the rock foundation and let it harden for at least one day.

Step 5

Place a stake at each end of the foundation's trench and run a mason's line between them. Select the largest stones for the wall base. Place your first stone at one end just barely touching the mason's line. Place your next stone snugly beside the first stone and continue until the wall's base line is laid.

Step 6

Wet the rocks before applying mortar allowing the mortar to stick better. Trowel mortar between the base rocks. Use wet rags wipe off any excess mortar.

Step 7

Add additional stones one at a time with the flattest side facing up. Trowel at least a half-inch of mortar on top of each rock. Use a mallet to tap the rocks deep into the wet mortar. Remove, chisel and reapply any rocks that can't fit easily.

Step 8

Select flat rocks that are flat on one side to be top stones. Place the top stones as the last layer of rock, taking care to make the top of the wall as flat as possible. Apply mortar to seal in the top stones. Wipe any excess mortar from the rocks.

Step 9

Clean your tools thoroughly with water before the mortar can harden.

Tom Nari

Tom Nari has been writing professionally since 1998 and has written extensively for a variety of websites. He has coached competitive swimmers and triathletes and holds an additional degree in Kinesiology Theory, specializing in nutrition and resistance training. Nari holds a Master of Arts in creative writing from Loyola Marymount University.