How the Reglet-and-Counterflashing System Works
The reglet-and-counterflashing system is a two-piece assembly:
- Reglet — a formed channel or groove installed in or on the wall that provides a receiver slot for the counterflashing insertion leg. Reglets are available as surface-mounted extruded aluminum profiles fastened to the wall face, or as saw-cut grooves cut directly into masonry.
- Counterflashing — a sheet metal profile with an insertion leg that locks into the reglet and an exposed face leg that laps the base flashing below. The counterflashing hangs in the reglet mechanically, not just with sealant.
The system's key advantage is the independent movement it allows. The base flashing is attached to the roof structure; the reglet is attached to the wall. As the building moves — thermally, structurally, and under live load — the reglet and base flashing move independently without tearing the weathering lap. Caulked-in-place single-piece counterflashing doesn't accommodate this movement and fails within a few years.
Surface-Mount Reglet vs. Saw-Cut Reglet
Surface-Mount Reglet
A formed aluminum extrusion fastened directly to the wall face. The extrusion includes a hooded slot that faces downward, receiving the counterflashing from below. Surface-mount reglets are used on new construction, on concrete walls, and on any wall where cutting into the wall material is not desirable. Fastening pattern is typically at 12"–18" on center; the top of the slot is sealed with sealant after installation.
Saw-Cut Reglet
A horizontal groove cut into existing masonry using a diamond-blade saw. Used when retrofitting counterflashing into an existing building where no surface-mount reglet was provided at initial construction. The groove is typically ¾"–1" deep and just wide enough for the counterflashing insertion leg. After installation, the top of the groove is packed with a backer rod and sealed with urethane sealant.
Counterflashing Profile for Reglet Systems
The counterflashing in a reglet system has a specific insertion leg geometry — a hooked tip that engages the back edge of the reglet slot. Trimgy draws this as a two- or three-leg profile with the insertion leg width matching the reglet slot depth (typically ¾"–1"). The exposed face leg hangs down and laps the base flashing by at least 4".
Materials
| Component | Material | Application |
|---|---|---|
| Surface-mount reglet | Aluminum extrusion | New construction, concrete, standard commercial |
| Counterflashing | .040" aluminum | Standard commercial |
| Counterflashing | 16 oz. copper | High-end commercial, historical restoration |
| Counterflashing | .050" aluminum | Heavy commercial, wide face legs |
How Trimgy Handles Reglet Counterflashing
On Trimgy, you order the counterflashing component (the sheet metal piece that inserts into the reglet). Surface-mount reglet extrusions are typically ordered separately from a sheet metal supplier. The counterflashing profile on Trimgy is drawn with the insertion leg matching the reglet slot depth, and the face leg length set to the required weather lap over the base flashing.
For roofing contractors who regularly do parapet and chimney re-flashing work, having the standard counterflashing profile saved in Trimgy means ordering takes seconds — just update the footage and reorder.
Draw Your Counterflashing for Reglet System
Insertion leg depth to match your reglet, face leg for required weather lap. Aluminum or copper. Instant price with freight.
Start Drawing Free →Frequently Asked Questions
What is a reglet?
A groove or slot in a wall that receives and mechanically retains counterflashing. Either surface-mounted (aluminum extrusion fastened to wall face) or saw-cut (groove cut into existing masonry).
What is the benefit of a reglet vs caulked counterflashing?
Mechanical retention — not just sealant. Reglet-mounted counterflashing stays engaged through thermal cycling and building movement. Sealant-only counterflashing fails within a few years as movement cracks the sealant.
What is the difference between surface-mount and saw-cut reglets?
Surface-mount is an aluminum extrusion fastened to the wall face — used on new construction. Saw-cut is a groove cut into existing masonry — used when retrofitting without a pre-formed receiver.
How does the counterflashing lock into the reglet?
The insertion leg has a hook at the tip that engages the back edge of the reglet slot. Weight and hook geometry maintain position without face fasteners. Top of slot is caulked as a secondary seal.
What is the typical price for a reglet and counterflashing system?
Aluminum reglet: $3–$6/LF. .040" aluminum counterflashing: $4–$7/LF. Combined system: $7–$13/LF. Copper counterflashing system: $12–$20/LF.