Mortared Stone Wall

There are several methods for creating stone walls. Some stone features are dry-stacked, or laid in place without mortar. Others appear dry-stacked but in fact have mortar hidden behind the stones (figure A). And still others are clearly mortared.

Each technique has its own advantages and disadvantages in terms of degree of difficulty and durability. Dry-stacking is arguably the simplest method, although the stones can shift over time. The dry-stacked look using mortar is beautiful, but it's tricky to pull off. So all things considered, a conventional approach using mortared stones is perhaps the best for most garden projects.

Here's a simple project that demonstrates how to mortar stones. The wall to be built is along the border of a garden bed and is just eight or so inches tall and wide and roughly 25 feet long.

Establish the wall's footing

While digging, allow for changes in the grade so that the wall is the same height from beginning to end, cutting deeper into the soil where the grade is highest.

Use a level to verify that you've dug enough at the high end, but on such a short run you can, like James, "eyeball it." "

I can use more or less mortar when I put the first layer of stones down to correct for any grade changes," he says.

Next, lay the foundation stones in place just to make sure the footing is wide enough. Here you can use a cheap builder’s limestone or some other large-sized, cheaper rock since they won't be visible. Save the best-looking stone for the top layer because it'll be highly visible. Once the stones are in place, remove and lay them on the edge of the border.

Set up a level

Once the footing is complete and level, verify that the border is level as you continue to build. One easy method uses a string and two sticks. The length of the sticks depends on the ultimate height of the wall you are building, so you'll want sticks that are as long as the wall is tall (and string as long as the wall is long). Tap the sticks into the ground at both ends of the wall. Tie one end of the string to one stick, stretch it tight, and tie the other end loosely to the other stick (figure F). Then set a level at the center of the string, and adjust the loosely-tied string up or down until the level is level, and tie the string tightly. As you add additional layers of stone (figure G), you can raise the height of the string and recheck to make sure it's level.

Add the subsequent layers

Stop every now and then to check for leveling and to admire your work. Occasionally you may have to stop to mix more mortar, but in no time at all you'll be back at work, adjusting the string level and getting ready for the third layer of stones. It's a good idea to check how quickly the mortar already in place is drying because you don't want it to dry so fast that you don't have a chance to do a little clean-up work.

Just how much mortar you put down depends on the look you're going for. You certainly want enough to bind the stones together, but you don't want as much that it oozes out all over the place. There aren't any hard and fast rules to this, but you'll get a sense of how much you need in no time.

Apply the finishing touches

After the top layer is done, it's time for the finishing touches. The back portion of the stone border is pretty messy, but that doesn't matter because you'll backfill the bed with soil up to the top layer of stone so nobody will see it.

The front of the border is a different story. It obviously needs to be cleaned up a bit, and that involves dressing up the joints. You can use any number of different tools for this--including your finger or a stick--but the idea is to create a clean, relatively smooth joint by removing any excess mortar. So you'll want to do this while the mortar is still somewhat wet but clearly beginning to dry.

Take a wire brush and scour the rough edges. You can even use a handheld whisk broom to create a brushed effect on the mortar.

There, you have a finished stone border.