Commercial kitchen exhaust fans and grease ducts require special attention during a reroof because they are not ordinary roof penetrations. They are part of a high-temperature exhaust system that removes grease-laden air from cooking areas. During a commercial reroof, the roofing contractor must protect the exhaust equipment, maintain required clearances, and properly restore the roof around the duct and fan curb.
For Florida commercial buildings, this work should also be coordinated with applicable Florida Building Code requirements and the requirements governing commercial kitchen exhaust systems. The Florida Building Commission identifies specific requirements for grease duct enclosures, exhaust equipment, penetrations, and related systems.
What Happens to the Exhaust Fan During a Reroof?
The rooftop kitchen exhaust fan is normally temporarily disconnected, lifted, or removed as necessary to allow the roofing contractor to install the new roofing system correctly around its curb or support.
The exact procedure depends on the fan design, curb configuration, roofing system, and project requirements. A qualified roofing contractor should coordinate with the mechanical contractor or kitchen-exhaust specialist before moving the equipment.
The goal is not simply to work around the fan. The roof assembly must be properly installed and watertight underneath and around the equipment. Once the new membrane, flashing, or coating is installed, the fan is securely reinstalled and checked for proper operation.
Rooftop grease exhaust fans also need to remain accessible for cleaning and maintenance. Commercial kitchen exhaust systems can accumulate grease, making proper fan access, drainage, and roof protection especially important.
How Are Grease Ducts Protected?
Grease ducts are treated differently from ordinary HVAC ducts because they carry grease-laden exhaust and operate under demanding conditions. The roofing contractor must avoid damaging the duct, its supports, insulation or enclosure while removing the existing roof and installing the new system.
Where the grease duct penetrates the roof, the roofing work must create a durable weatherproof transition around the penetration. The duct itself should not be altered simply to make the roofing installation easier.
Florida requirements address grease duct construction and enclosure conditions, including fire-resistance and penetration protection in applicable situations. The specific requirements depend on the building assembly and the type of exhaust system.
How Is the Roof Sealed Around the Grease Duct?
The roof penetration is one of the most important parts of the reroof. Existing flashing and roofing materials around the duct are removed as needed, damaged components are repaired, and new flashing or membrane details are installed according to the roofing manufacturer’s requirements.
The finished detail must prevent rainwater from entering the building while accommodating the movement and operating conditions of the exhaust system.
For commercial buildings using TPO, PVC, EPDM, modified bitumen, or other roofing systems, the exact flashing method will vary. The roofing contractor should use a compatible, manufacturer-approved detail rather than relying on generic caulking as the primary waterproofing method.
What About the Exhaust Fan Curb?
The fan curb is another critical component. If the existing curb is damaged, deteriorated, improperly flashed, or no longer compatible with the new roof system, it may need repair or replacement.
The curb must remain structurally secure and properly integrated with the new roofing assembly. Grease exhaust systems also have specific requirements concerning equipment mounting, ductwork, clearances, and exhaust-fan installation.
Does the Kitchen Have to Stop Operating?
Usually, yes, at least temporarily, if the reroof directly affects the exhaust system or requires the fan to be disconnected. The shutdown period should be coordinated between the building owner, restaurant operator, roofing contractor, and mechanical contractor.
Planning the work around kitchen operating hours can reduce disruption and help ensure the exhaust system is safely returned to service.
Why Professional Coordination Matters
Kitchen exhaust penetrations are among the more complicated areas of a commercial roof. Improperly handled fans, grease ducts, curbs, or flashing can result in roof leaks, equipment damage, unsafe conditions, or problems with code compliance.
A professional commercial roofing contractor should inspect the exhaust system before beginning the reroof, coordinate equipment removal or temporary relocation, protect the grease duct, properly flash the penetration, and verify that the completed roof is watertight.
Bottom Line
During a commercial reroof, kitchen exhaust fans and grease ducts are not simply roof penetrations to work around. They require coordinated handling between roofing and mechanical professionals. The fan may need to be temporarily removed or lifted, the grease duct must be protected, the curb and penetration must be properly integrated with the new roofing system, and all applicable fire, mechanical, and manufacturer requirements must be maintained.
For Florida restaurants, commercial kitchens, and other buildings with rooftop exhaust equipment, careful planning before the reroof can prevent leaks, equipment problems, operational interruptions, and expensive repairs later.
Related Questions
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- How does Florida’s humidity affect grease buildup and roof degradation?
- Are there specific codes for restaurant roofing materials?
- How are rooftop units disconnected and reset during a reroof?
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Commercial Roof Replacement / Re-Roofing
