Commercial reroofing often requires temporary removal or elevation of rooftop HVAC units, commonly called rooftop units (RTUs). These units can be large, heavy, and connected to multiple systems, so disconnecting and resetting them is not simply a matter of moving the equipment out of the way. Proper coordination between the roofing contractor and qualified HVAC and electrical professionals is essential to protect the equipment, maintain building operations, and preserve the integrity of the new roof system.
What Happens Before an RTU Is Disconnected?
Before work begins, the existing rooftop unit should be inspected and its operating condition documented. This establishes a baseline so any problems discovered after the reroof can be distinguished from pre-existing issues. Commercial roofing specifications commonly require testing equipment before disconnecting electrical or mechanical connections.
The project team also determines whether the unit needs to be completely removed, temporarily lifted, or reset higher on its existing curb. This decision depends on the roofing assembly, insulation thickness, curb height, equipment weight, and the finished elevation required for proper flashing.
How Is a Rooftop Unit Disconnected?
RTU disconnection should be performed by appropriately qualified HVAC and electrical professionals. The unit is shut down, electrical power is isolated, and applicable lockout/tagout procedures are followed before connections are disturbed.
Depending on the equipment, several services may need to be disconnected, including:
- Electrical power and control wiring
- Refrigerant lines
- Gas piping for gas-fired equipment
- Supply and return ductwork
- Condensate connections
- Equipment anchorage and curb connections
If refrigerant lines must be opened, refrigerant is recovered using appropriate procedures and the lines are protected from contamination. Gas connections are shut off and safely capped, while electrical and control wiring is labeled and protected for reconnection. A typical commercial roof specification describes this process as disconnecting ductwork, control wiring, gas piping, refrigerant lines, and equipment anchorage before the unit is lifted.
How Is the Unit Moved During Reroofing?
Once the unit is safely disconnected, the RTU may be lifted from the curb using a crane or another engineered lifting method. Crane requirements depend on the unit’s weight, building height, distance from the building edge, and crane location.
For some reroofing projects, the unit can remain nearby while the roofing contractor removes the existing roof system and installs the new membrane and insulation. In other situations, the unit may need to be temporarily removed from the roof entirely.
The roofing contractor then completes the roof work around the curb or prepares the curb for the required finished roof elevation.
How Is the Rooftop Unit Reset?
After the new roofing system is installed, the RTU is carefully positioned back onto the curb or its new support configuration. The unit must be securely anchored, and the roofing contractor must ensure that flashing and membrane details create a watertight transition around the curb.
The HVAC contractor then reconnects the previously disconnected systems. Ductwork, electrical and control wiring, refrigerant piping, gas lines, and other connections are restored as required. Depending on the work performed, refrigerant may need to be recharged and gas systems may require testing.
The unit is then started and tested. Technicians verify electrical operation, airflow, controls, refrigeration performance, heating operation where applicable, and other manufacturer-specific requirements.
Why Professional Coordination Matters
An RTU reset is a coordinated roofing, mechanical, electrical, and sometimes structural operation. Incorrectly disconnecting a line, damaging equipment during lifting, or improperly flashing the curb can result in equipment failure or roof leaks.
At Shieldline Roofing, commercial reroofing projects involving rooftop equipment should be planned around the equipment and the finished roofing system—not treated as an afterthought. Proper scheduling and coordination with qualified HVAC professionals help ensure rooftop units are safely disconnected, temporarily moved when necessary, and correctly reset after the new roof is installed.
For Florida commercial properties, this coordination is particularly important because rooftop equipment and roof penetrations must withstand demanding weather conditions. A properly reset RTU should be secure, operational, and integrated with a watertight roofing system designed to provide long-term protection.
Related Questions
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- What is a curb adapter and when is one used?
- How do vibrations from HVAC units affect the roof?
- How do you sequence roofing around a building automation system upgrade?
- What crane pick considerations apply to rooftop equipment replacement?
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