A reglet is a narrow groove, slot, or recessed channel formed into a wall or other vertical surface to receive and secure the upper edge of a roofing or flashing component. In commercial roofing, reglets are commonly associated with counterflashing, particularly where a low-slope roof meets a parapet wall, masonry wall, concrete wall, curb, or other vertical surface.
Reglets are important because roof-to-wall transitions are vulnerable areas for water intrusion. Commercial roofing systems require properly detailed flashing wherever the roof meets a vertical wall or parapet.
How Does a Reglet Work?
A typical reglet is installed or formed several inches above the roof surface. The counterflashing is inserted into the groove and secured, often with fasteners or appropriate wedges, depending on the system. Sealant may also be used to protect the opening and help prevent water from entering behind the flashing.
The purpose is to create a more secure termination for counterflashing than simply fastening metal to the face of a wall. For example, GAF commercial roofing details show reglet-based counterflashing as one option for terminating wall flashing systems.
However, a reglet should not be viewed as a complete waterproofing solution by itself. Proper roof-to-wall flashing must be integrated with the building’s overall water-management system. Building Science Corporation notes that simply cutting a notch into masonry and inserting counterflashing does not necessarily address water entering behind the exterior masonry.
Common Types of Reglets Used in Commercial Roofing
1. Metal Reglet
A metal reglet is a manufactured metal receiver or channel designed to accept counterflashing. It can be incorporated into certain wall or roof details and is commonly used when a defined termination point is required.
Metal reglets can provide a consistent installation detail and may be particularly useful during new construction or major roof replacement projects.
2. Surface-Mounted Reglet or Receiver
Some commercial roofing systems use a surface-mounted termination or receiver instead of cutting a groove directly into masonry. The component is installed against the wall and provides a location for securing the flashing or membrane.
This approach can be useful when cutting into an existing wall is undesirable or impractical. GAF details, for example, identify surface-mounted counterflashing as an alternative to a reglet in certain commercial roofing assemblies.
3. Preformed Reglet
A preformed reglet is manufactured as part of a flashing or termination system rather than being created entirely in the field. Preformed components can help provide a predictable geometry and simplify installation when they are compatible with the specified roofing assembly.
4. Saw-Cut or Field-Cut Reglet
A field-cut reglet is created by cutting a groove into an existing masonry or concrete surface. Counterflashing is then inserted into the groove and secured.
This method can be encountered during commercial roof repairs or replacement projects, but it must be designed and installed carefully. Cutting into masonry does not automatically create a watertight roof-to-wall assembly; the flashing still needs to connect properly with the roof and wall drainage systems.
Why Are Reglets Important on Commercial Roofs?
Reglets can help create a durable termination for counterflashing at critical roof-to-wall transitions. A properly designed flashing assembly helps direct water away from vulnerable joints instead of allowing it to enter the roofing system or wall assembly.
This is particularly important on commercial buildings with parapet walls, rooftop equipment curbs, masonry walls, penthouses, and other vertical transitions. Flashing is a critical part of protecting these interfaces from water intrusion.
Reglet vs. Counterflashing: What’s the Difference?
The terms are sometimes confused. A reglet is the groove, channel, or receiver used to accept flashing, while counterflashing is the metal or other flashing component installed at the wall to protect the underlying base flashing.
In a properly designed assembly, the reglet and counterflashing work together as part of the overall roof-to-wall flashing detail.
Final Takeaway
A reglet is a small but important component in many commercial roofing assemblies. It provides a termination point for counterflashing and can help protect roof-to-wall transitions from water intrusion. Common approaches include metal reglets, surface-mounted receivers, preformed reglets, and field-cut reglets.
Because commercial roof systems differ in membrane type, wall construction, movement, and flashing requirements, the correct reglet detail should always follow the roofing manufacturer’s specifications and project requirements. Proper installation is especially important when repairing or replacing flashing on an existing commercial building.
Related Questions
- What is a cant strip and why is it required at wall and curb transitions?
- How do I detail a roof at a masonry parapet with through-wall flashing?
- What is a termination bar and how is it sealed?
- What flashing plies are required at walls and curbs?
- How do tilt-wall buildings affect roof-to-wall detailing?
- What is the difference between a wet flash and a dry flash?
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