Traditional Masonry Archives

Building Dry Stone Walls
Who needs mortar? Dry stone walls can last for hundreds of years, and they only become stronger as they settle. Here's how to put up a dry stone wall that will stand with the best of them.
by Alan Ash

Top of page: After. Above: Before stone wall.

Traditional dry stone walls have many benefits. These 100 percent recyclable walls become stronger as they settle, are earthquake-resistant, and can last for hundreds of years if built correctly. Because dry stone walls are free-draining compared to mortar walls that require weep holes and a drainage system, they don’t need the elaborate foundation of poured concrete. You can build in any weather — you don’t have to worry about your mortar setting. Finally, stone is unmatched for beauty.

Except for New England, Kentucky and Kansas, retaining walls seem to be more popular than free-standing walls in the United States. But one rule reigns over all no matter which one you choose to build: It takes gravity, friction of the stones and the skill of the mason to build a good wall.

1
First, dig to where the ground is solid. In the Pacific Northwest climate, you don’t have to go below the frost line. In colder climates, there is controversy as to whether you should dig down and put in a gravel fill or build right on the ground. People should check in their local area and find out what professionals are doing and what works.

2
Once you have a good base, set up string lines to outline your wall and put down your foundation stones. Use the largest stones you have. The basic rule for dry stonework is that the length of the stone has to go inwards, into the wall, which helps distribute the weight. Laying it along the wall, called tracing, takes four times less rock, but the wall won’t last and could fall down at any time.

3
Once you lay a stone, pack it with little pieces of stone, called hearting or packing. Fill in the gaps. When you put hearting in, don’t throw it in; hand-place it. And never hammer on the wall. It may be convenient, but it shakes everything and can move your hearting out of place. Follow these techniques for the entire wall.

Also, don’t use dirt or gravel, only rock. Make sure that you are packing on the inside and not from the ends, which is called end-pinning or face-pinning. Packing from the front, or end, is a common way to disguise poor workmanship. The rocks will fall out over a short period of time.

4
You want your foundation to be really stable, so walk across your foundation stones and make sure there is no movement. After the foundation is finished, you will want to put up your batter boards and stretch a cord or string from one to the other, which will help to ensure your wall ends up about the same height all the way across.

5
Once you do this, you can start your first course. Keeping the stones level (depending on the type of stone because every site and stone is different), lay the stones going lengthwise into the wall, using a two-over-one, one over-two technique.

That is, you have to break the joints, but don’t let the joints remain unbroken course to course, called “running joints.” You need the weight of one rock on top distributed onto two rocks below, which ties it all together.

6
Lay five stones and stand back and look at what you have done. When you are on top of a wall, it is easy to make mistakes, such as not following your lines or not breaking your joints.

When you move on to the next row, follow the 6-1 rule when building a traditional stone wall. For every six inches you go up on the wall, you go in an inch. If you are working on an unstable slope, you may go 5-1 for added stability.

If you have some through stones that are only a few inches longer in length than the wall, you can allow them to stick further out. This helps distribute the weight better and can actually add about 75 years to the lifespan of a wall because the wall can settle that much more before it falls apart. Just make sure the wall isn’t next to a sidewalk or somewhere else where this could create a hazard.

7
About midway up the wall, after you are past the foundation, you put in through stones, which tie the different courses together. If you don’t have a long stone, you can use what is called a “galf stone,” a stone that is three fourths of the way “through.” Two galf stones are laid on different courses with their tail ends overlapping. Friction between the two helps them substitute for full-length through stones.

8
Once the through stones are done, run the course again, and repeat these steps until you are nearing the top of the wall. The next to last layer is the cover course. In the Northwest, the cover course is usually the last layer, but some walls require a last layer as well. It is laid with stones in the upright position wedged tightly together. Called “coping,” it brings the whole wall together.

Width is about one third to one half the height of the wall, depending on the stone. Here in the United States, a retaining wall usually cannot go above four feet without being engineered, but a free-standing wall can often go up to six feet because it is considered a fence. This is something you should check locally.

Build to your lines, not above. If you follow the rules, you are going to have a good wall that is going to last generations. But if you skip any of the rules, the wall is going to fail prematurely.

When you’re done, none of the stones in the wall should move as you run your hands along the wall. www.thestonemason.com

TM