Specifications
- Width: 2" to 48"
- Height: 2" to 48"
- Materials: Galvanized Steel, Aluminum, Stainless Steel
- Gauges: 26, 24, 22, 20
- Connection: Raw, Slip, Drive, TDC, Flanged
Standard Duct End Cap Sizes & Pricing
| Width | Height | Material | Gauge | Connection | Price | Order |
|---|---|---|---|---|---|---|
| 4" | 4" | Galvanized | 26 ga | Slip | $14.33 | |
| 6" | 6" | Galvanized | 26 ga | Slip | $16.00 | |
| 8" | 6" | Galvanized | 26 ga | Slip | $17.00 | |
| 8" | 8" | Galvanized | 26 ga | Slip | $18.33 / $15.50 | |
| 10" | 8" | Galvanized | 26 ga | Slip | $19.67 / $17.50 | |
| 10" | 10" | Galvanized | 26 ga | Slip | $21.33 | |
| 12" | 8" | Galvanized | 26 ga | Slip | $21.00 / $18.50 | |
| 12" | 10" | Galvanized | 26 ga | Slip | $23.00 | |
| 12" | 12" | Galvanized | 26 ga | Slip | $25.00 | |
| 14" | 10" | Galvanized | 26 ga | Slip | $24.67 | |
| 14" | 12" | Galvanized | 26 ga | Drive | $28.00 | |
| 16" | 10" | Galvanized | 26 ga | Drive | $27.33 | |
| 16" | 12" | Galvanized | 24 ga | Drive | $37.20 | |
| 18" | 12" | Galvanized | 24 ga | TDC | $41.60 | |
| 20" | 12" | Galvanized | 24 ga | TDC | $44.00 | |
| 20" | 14" | Galvanized | 22 ga | TDC | $61.00 | |
| 24" | 12" | Galvanized | 22 ga | TDC | $62.00 | |
| 24" | 18" | Galvanized | 22 ga | TDC | $80.00 | |
| 24" | 24" | Galvanized | 20 ga | Flanged | $134.00 | |
| 30" | 18" | Galvanized | 20 ga | Flanged | $128.00 | |
| 36" | 24" | Galvanized | 20 ga | Flanged | $182.00 | |
| 48" | 24" | Galvanized | 20 ga | Flanged | $230.00 | |
| 12" | 12" | Aluminum | 26 ga | Slip | $33.25 | |
| 12" | 12" | Stainless | 26 ga | Slip | $55.00 |
Custom Duct End Caps — Seal Unused Openings
Duct end caps are flat closures that seal the open end of a rectangular duct section. Every terminated duct run, unused tee branch, or capped plenum opening needs a properly fitted end cap to prevent conditioned air from leaking into unconditioned spaces. Our end caps are fabricated to your exact dimensions with your choice of connection type, providing a tight, rattle-free seal.
Why End Caps Matter for Efficiency
A single uncapped duct opening can leak 50-100 CFM of conditioned air, costing hundreds of dollars per year in wasted energy. Field-fabricated end caps made from scrap metal and tape degrade quickly and often fail within a year. Our precision-cut end caps with formed connection edges provide a permanent seal that maintains system efficiency for the life of the installation.
Connection Types for End Caps
Slip end caps slide over the outside of the duct for a clean finish. Drive end caps use drive cleats for a mechanical connection without screws. TDC end caps mate with TDC flanged duct sections using corner clips and gaskets. Flanged end caps bolt to the mating flange for a pressure-tight seal on high-pressure systems. Raw end caps are flat panels for field attachment with screws and sealant.
Applications Beyond Termination
End caps are also used as access panels for duct cleaning, as temporary closures during construction, and as backing plates for inline dampers. For duct cleaning access, specify a flanged end cap with gasket for easy removal and resealing. Large end caps (20"+ in either dimension) should use 22 or 20 gauge material to prevent oil-canning and drumming noise.
Frequently Asked Questions
When do I need an end cap?
Use an end cap to seal the end of a duct run, close unused trunk openings, or terminate dead-end branches during phased construction.
Can end caps be removed later?
Yes. Slip-fit or drive-cleat end caps can be removed for future expansion. Flanged end caps can be unbolted.