Building your own walk-in cooler room only takes careful attention to the insulation you add and the corresponding refrigeration equipment installed by the professionals. Handling the insulation part of the task yourself can save you thousands of dollars, but only if you do it correctly to avoid cooling losses due to gaps and drafts. Use these five tips to get the wall, ceiling, and floor insulation you need for a restaurant or farm walk-in cooler.
Go by R-Value
Many restaurant and business owners share advice with their peers based on the number of inches of foam found in their coolers. However, it's not necessarily the depth of the insulation that is important, but rather its total insulation power. This is measured on the R-value scale, with higher numbers offering more insulation. Walk-in coolers tend to require at least a total of R-25 insulation on the walls and ceilings.
Sometimes this isn't enough because this is estimated for around an average of an eight-foot-tall ceiling and only occasional opening of the door. If your crew goes in and out constantly or if you need to build a taller room, you'll need to compensate with a higher R-value to reduce wear and tear on the refrigeration equipment. Each material you can use has its own R-value per inch, so you could end up with thick or thin walls depending on what you choose.
Stick with Closed Cells
Most walk-in coolers rely on some kind of foam insulation, either sprayed in or mounted as rigid boards, because the foam offers a high R-value per inch. Foams have a reputation for being resistant to moisture. However, open cell foam has tiny open pockets that can trap moisture, lower the R-value due to freezing water in the insulation, and create a mold problem inside the walls of your walk-in cooler. Regardless of what form of foam you decide to use in your cooler, make sure it is closed cell foam only. The closed cells keep out dust and moisture, resist mold and mildew, and also offer a higher insulation value. Don't be tempted by the lower price of open cell foam since it's not appropriate for a damp environment like a refrigerated cooler.
Cover the Studs
When you're insulating a home's walls or attic, the insulation material is usually cut to fit or sprayed into the cavities between two framing studs. This may work reasonably well for a home, but walk-in coolers can't handle the potential for gaps to form when insulation only spreads from stud to stud. Both foam boards and spray applications tend to shrink slightly after installation, causing it to pull away from the studs and let air through to waste your refrigeration energy. For a more airtight installation, try making sure that insulation reaches from the top of each stud to the next instead. Overlap the seams of your insulation as well to make sure you have as few drafts as possible due to gaps.
Consider Pre-Assembled Panels
Don't want to deal with sticky sprays or the hassle of applying a protective skin to the foam once you're done? Pre-formed foam panels are available that come complete with an outer finish that is resistant to moisture and easy to clean. Mounting these panels goes faster than just using rigid boards as well, especially since they tend to contain all the layers needed to reach the designated R-value.
Avoid Fluffy Batting
Finally, resist the temptation to use inexpensive fiberglass or cellulose batting for your cooler. While you'll save a little money upfront, these materials are too likely to compress and are very likely to absorb moisture. You'll need to replace it within a few years, making it a poor investment when you compare that to the longevity of foam insulation. Spun rock and mineral wool panels are just fine to use because they're naturally hydrophobic.
For additional advice, contact a commercial refrigeration installation expert in your area.