Quick Answer
For a root cellar, top natural insulation materials include straw bales, wood fibers, and recycled denim insulation, providing thermal mass, moisture control, and eco-friendly performance.
Straw Bale Insulation
Straw bales are an excellent choice for root cellar insulation due to their high thermal mass and ability to regulate humidity. A 3- to 4-inch thick straw bale wall can provide R-30 insulation, while also helping to maintain a stable temperature. Apply a natural, breathable barrier like lime plaster or clay plaster to the straw bales for added protection from moisture.
Recycled Denim Insulation
Recycled denim insulation, also known as “recycled denim fiber,” is made from post-consumer denim jeans and is a highly effective natural insulation material. With an R-value of R-3.8 per inch, this eco-friendly insulation can be applied at 2- to 3-inch thickness for adequate root cellar insulation. This material is also resistant to moisture and pests, making it an excellent choice for a root cellar.
Wood Fiber Insulation
Wood fiber insulation is another natural option for root cellar insulation, providing an R-value of R-4 per inch. A 4- to 6-inch thick wood fiber insulation can maintain a stable temperature, while also helping to regulate humidity. Wood fiber insulation can be applied in various configurations, including batts, blankets, or loose-fill, depending on the root cellar design and local building codes.
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