A Local Construction Method for the Flint Hills // AJ Henry
Construction methods today tend to preference low cost and quick implementation, rather than defining value by the lifespan of a project. Low cost and limited time are the reasons why some construction methods, such as dry stack limestone, have taken a back seat to newer construction methods. Sometimes these newer methods are not the answer architects are looking for to solve their problems, as they encounter issues of addressing climate, traditional architecture of the area, and implementation. Our Design+Make studio faced this dilemma for our project in the Flint Hills; to build a natural dry stack stone retaining wall or to pour a concrete retaining wall with an attached stone veneer.
In the Flint Hills of Kansas, dry stack stone walls have been around for centuries, in forms of stone fence and retaining walls. The reason these walls are so prevalent in the area is due to the amount of readily available, suitable limestone, and the ability of these types of walls to flex with the dramatic freezing and thawing cycles that the ground undergoes throughout the year. There are a few problems with the dry stack stone wall. First, there are few structural engineers interested in understanding how dry stack performs relative to contemporary building codes. Second, there are few craftsmen who can construct them.
Many engineers will not work with architects on the design of a dry stack limestone retaining wall due to the inability to calculate what the wall is able to withstand. With a concrete wall there are charts, testing standards, and psi numbers that can be used to calculate how thick a wall needs to be to hold back a certain amount of force. Finding an interested engineer is difficult; finding a capable mason is more challenging. Anybody can stack stone, but it takes someone with substantial skill to build a retaining wall that is nine feet tall. This is the task the Design+Make studio is dealing with now, learning a highly articulated method of construction from an extraordinary stone mason in a short period of time.
Dry stack stone fence located at the Tallgrass Prairie National Reserve
Photo courtesy of Dry Stone Conservancy
Dry stack stone retaining wall created by Luke Koch
The dry stack stone has many benefits over the concrete retaining wall. One of those is that the site where the wall is located is plentiful with usable limestone. Hauling in a material to do the work that the onsite limestone can do makes little sense. Another benefit is that a dry stack stone wall is able to allow moisture to flow through it freely. This eliminates the need for drainage tiles which would disrupt the flow of the natural watershed. The complex, unpredictable movement of water through the ground in the Flint Hills is one of the major challenges for construction in this geological condition.
Sometimes architects need to consider non-traditional methods of construction and materials. Ironically, for this year’s Design+Make Studio project, this meant studying and embracing a traditional, underemployed dry stack approach to creating a substantial retaining wall. The studio is pushing the limits of time and budget to create not only a great wall, but a significant piece of architecture.
The Design+Make stone workshop taught by stone mason Luke Koch
Written by AJ Henry