The roofing system on a cold storage facility will be very different from that of a traditional building. Whether the building stores refrigerated foods, frozen foods, plants, flowers, life-saving medications, or something else entirely, the roofing system plays an important role in keeping cold air inside the building.
Here's how a properly installed roofing system helps keep facilities cool.
In cold storage situations, the interface between the roof and the walls are key to the building's performance. They must come together to form an airtight and vapor-tight system.
GAF Technical Manager of Specialty Installations Kristin Westover explains why those details matter: "You're generally not going to have air leakage in the main field of the roof. Air leakage usually comes from an area where you have an opening or a penetration or where you have an interface between the materials."
Westover says these interfaces require extra attention to detail; she uses the example of a traditional building with a metal deck and insulated metal wall panels.
"When you look at the interface between the steel deck and an insulated metal wall panel, you have to make sure that you are sealing that intersection," she says. "In a typical building, you would just lay down the insulation and call it a day. In a cold storage facility, closed cell spray foam should be installed along the deck to wall interface as well as at penetration perimeters. We want to make sure that all details are sealed to prevent air leakage."
GAF Director of Building and Roofing Science Jennifer Keegan says that ensuring the roofing system is sealed can help contribute to energy efficiency-preventing the transfer of heat and energy from the outside to the inside. Beyond ensuring the penetrations and transition points between conditioned spaces are airtight, the effects of expansion and contraction must also be considered.
"If I've got the freezer section next to the loading dock, next to the office, or freezers that are being drawn up and down at different temperatures, that's going to put a lot of stress on the details," says Keegan. "So, we need to consider the details and attachments to be sure they will allow for that level of movement."
Air and Vapor Transfer Risks
Building owners and property managers should understand the risks that come with air and vapor transfer in the cold facility. In traditional buildings with conditioned interior spaces, hot air typically tries to escape to the outside. In a cold storage situation, the opposite is true: the warmer outside air will attempt to enter the building anywhere it can.
"We know that condensation occurs when warm humid air meets a cold surface, that's when it forms water on a surface," says Westover. "When that happens in a cold storage facility, it is detrimental because that water will likely turn to ice. Ice may form at the underside of the roof deck, within the roof assembly, or on floor surfaces."
In addition to protecting the goods stored inside, precautions may be needed to help ensure a safe environment for workers in the building. Ice forming not only leads to potential property damage, but it can put workers at risk of slips and falls. When a building experiences excessive air leakage, the mechanical system has to strain to keep the interior at the proper temperatures, which may increase cooling costs.
Maintenance and Prevention Considerations
Just as with traditional roofing systems, these cold buildings require regular maintenance to stay in good shape.
Westover advises cleaning your membrane each spring and fall, inspecting it after storms or harsh weather, and regularly clearing debris from the roof. If contractors access the roof, be sure they use walkway pads and have not dropped any tools that might cause a puncture. Consider creating a rooftop access log to keep a record of traffic and activity on your roof.
What to Do If You Suspect You Have a Problem
If you see ice forming inside the building or notice that the mechanical system isn't operating as efficiently as it should, have your roofing system inspected by a qualified specialty roofing consultant or contractor. Not all roofing contractors have the experience and knowledge required to fully understand the challenges and unique needs of a cold storage facility.
You can always turn to the experts at GAF for assistance. Find the information you need on the GAF cold storage page or take advantage of the opportunity to meet virtually with a GAF building science professional during their recently launched office hours. Owners, contractors, and designers can schedule a meeting for help and advice with any roofing challenge or new installation project.