This is a professionally applied polyurethane product that can turn leaky barns or sheds into well-insulated walk-in coolers in a short amount of time. There are two types of spray foam, for a refrigerator use closed cell spray foam. R Value and cost can vary drastically. Depending on your location, this may be a practical solution for you; check with your local installer for costs. Four full inches are necessary to keep your cooler below 40°F (4.4°C). Spray foam is generally more expensive than rigid foam options, but can also be easier to install.