Proper Insulation and Humidity for a Wine Cellar

I cannot begin to count how many times I have been asked to build a wine cellar for a client that either had little or no vapor barrier or it was done wrong. Most of the time the client,builder, or GC had no idea what a vapor barrier is. I will try to explain the importance of proper insulation,vapor barrier, and of course humidity.

A poorly constructed wine cellar may require much more moisture during the same time period (not to mention mold issues and your cooling system having to work overtime). In my humble opinion the best insulation for a wine cellar is Closed Cell spray foam which is also referred to as 2 pound or medium density. This foam expands 20 to 30 times its liquid size, and seldom requires trimming with little to no waste. Closed Cell foam cures rigid and the millions of microscopic bubbles which form during the expansion reaction remain closed and intact. This traps the reaction gases, and as such the R-Value of Closed Cell foam is close to that of the reaction gas, around 7 per inch. With an R-value of about 7 per inch this takes your cellar comfortably above R-30 on average. The Closed Cell structure is very strong; increasing shear and racking strength by 300%. Closed Cell foam is a Code Approved Vapor Barrier with a permeability rating of under 45 ng, as well as a Code Approved Air Barrier and Thermal Insulation. Closed Cell foam is spray applied as a liquid to create an air-tight seal as it expands as a foam to stop air leakage. But unlike Open Cell foam, Closed Cell foam stops both convection through and within the wall cavity. So the closed cell insulates and is the vapor barrier in one. Besides closed cell other types are rigid foam, and 6 mil plastic sheeting.Please make sure your wine cellar has a vapor barrier,mold resistant sheet rock(green or purple board) and proper insulation.

The proper humidity level for a wine cellar is 55-75%. The importance of humidity can not be overlooked in your wine cellar. Humidity in a wine cellar also keeps wine bottle corks from drying out, preventing them from losing their sealing capacity. Humidity refers to the concentration of water vapor in the air. Through a perpetual natural cycle, moisture is evaporated from the earth and then returned as precipitation. Relative Humidity (RH) is the percentage of water vapor the air is holding at a given temperature. In your wine cellar, the RH can fluctuate above and below the optimal range of 60 to 65% required for proper wine storage. The ability to maintain proper RH is crucial to providing the proper wine room environment and ensuring quality wine storage. A properly insulated wine room with vapor barriers in the walls and the ceiling might mean that your wine cellar will require less moisture to maintain the required levels of humidity, as well as your cooling system lasting longer.

By following these easy steps one will be able to maintain the proper temperature, and humidity levels for your wine cellar.

For more than 25 years, The California Wine Club founders Bruce and Pam Boring have explored all corners of California’s wine country to find award-winning, handcrafted wine to share with the world. Each month, the club features a different small family winery and hand selects two of their best wines for members.

Curtis Dahl is the President of Global Sales for Joseph & Curtis, an industry leader in custom wine cellars and wine racks. He is a regular contributor to IntoWine.com.