Guidelines for Laying Stone Walls
Master the basics and gravity will do the rest.
Synopsis: A practiced stone mason explains the proper method for building dry-laid stone walls. He covers the use of story poles and string lines for layout, cutting stone and how to fit pieces together so the wall stays put.
When I assess the quality of a stone wall, I look not at the stones, but at the spaces between them. That’s where the knowledge and the craftsmanship of the mason is revealed. By reading the joints, I can tell how tightly the wall is tied together and how well the stones fit.
Dry-laid stone is perhaps the oldest form of building. Fieldstones stacked and shimmed together created rough walls long before recorded history. But because there is no mortar in drylaid work, it has the disadvantage of being permeable by air and moisture. That’s why its use is usually limited to retaining walls, where the passage of water is necessary, or to simple foundations where ventilation is desirable.
Dry-stack construction is nearly as old as dry-laid work. Mortar is used in dry-stack work, but it isn’t visible. The mortar is troweled in behind the stones, filling the voids between them. Dry-stack walls are laid stone-on-stone, like dry-laid walls. But because, they’re less permeable by air and moisture, they’re the better choice for house walls and chimneys.
In my area, dry-stack chimneys built stone-on-stone and backed with clay mortar have stood for over two-hundred years. Although it’s arguable that today’s stronger portland-cement mortars make this meticulous fitting unnecessary, I prefer to build the old way. To Steve Magers, the mason who taught me stone, the only law of masonry is gravity. Gravity always prevails, so it’s best to learn how to cooperate with it. Whether you’re building a dry-laid or a dry-stacked wall, a garden wall or a chimney, the same basic guidelines apply.
Though it isn’t always possible, my helpers and I like to provide a footing under every stone wall or chimney we build. A lot of the repairs we’ve done would have been unnecessary had there been footings in the first place. Footings distribute the weight of the stone and provide protection against frost heave. The footing must sit on solid, compacted earth below the frost line. It should be at least twice as wide as the wall it is going to carry. In most cases, local building codes spell out the depth and dimensions of the footings.
Sometimes, dry-laid stone footings are used for retaining walls instead of concrete. They should have broad, flat stones at the base to spread the weight evenly. In this type of footing, we usually lay 1 in. to 2 in. of crushed stone under the first course and below the frost line to help it drain.
String lines and story poles
When the footing is complete, the use of string lines or story poles will help keep the stone courses straight. For walls, two methods are commonly used. Batter boards are the preferred method for foundations and low walls. A line strung between them is used to indicate both the face of the wall and its top edge. By sighting between the line and a chalk line snapped directly on the footing (or the first course), you can keep the walls plumb without the constant use of a level.
For more photos and guidelines for laying stone walls, click the View PDF button below.