Should I use concrete for my root cellar walls?

Concrete Limitations in Root Cellars

Concrete walls can be detrimental to root cellar performance. Concrete has a high thermal mass, which means it absorbs and releases heat slowly. This can cause the cellar’s temperature to fluctuate significantly, especially in colder climates. For example, if the outside temperature is 32°F (0°C), the concrete walls can remain at this temperature for several hours after the sun sets. This temperature swing can lead to the growth of mold, rot, and other issues that can compromise the cellar’s contents.

Alternative Materials for Root Cellars

A more suitable choice for root cellar walls is materials with lower thermal mass, such as earthbags, straw bales, or even rammed earth. These materials can help maintain a more stable temperature, reducing the risk of temperature fluctuations and the associated problems. Earthbags, in particular, can be an excellent option, as they provide excellent insulation and are relatively easy to work with. A common earthbag technique involves creating a 2-inch (5 cm) thick wall with 2-foot (60 cm) long bags, which can be stacked to achieve the desired height.

Designing a Root Cellar with Concrete

If you still want to use concrete for your root cellar, consider designing it with a few key features in mind. For example, you can use a concrete foundation and then line the cellar with a different material, such as plywood or OSB, to break the thermal connection between the concrete and the cellar’s contents. You can also install insulation, such as foam board or fiberglass, between the concrete and the lining to reduce heat transfer. Additionally, consider using a concrete with high thermal mass, such as insulated concrete forms (ICFs), which can help to mitigate temperature fluctuations.