.040″ Aluminum Inside Corner Flashing is a precision-fabricated 90° corner flashing designed to create a clean, weather-resistant junction in wall systems. It’s built from .040-inch aluminum (approx. 0.040″ thick), with 1/2″ closed hems on each side to reinforce the edges and reduce sharpness. The profile is painted on one side (interior or visible side) and comes in multiple finish options: Mill Finish, Black Onyx, Bone White, Silver, and Mill (unpainted).

This flashing is configured to ship in standard lengths: 10′ sections (freight) or 7′-8″ lengths (UPS-friendly). It’s available in multiple inside-corner sizes:

• 1.0″ × 2.0″
• 1.5″ × 2.0″
• 2.0″ × 2.0″
• 2.5″ × 2.0″
• 3.0″ × 2.0″

Key Features & Benefits

• .040″ aluminum construction — durable but formable

• 1/2″ closed hems on both legs — adds strength, hides raw edges

• Painted on one side — provides the finished look where it shows

• Multiple color/finish options — for aesthetic match and performance

• Two length options — 10′ (freight) or 7′-8″ (parcel)

• Ideal for inside corners of siding, cladding, or wall assemblies

Typical Applications & Use

This inside-corner flashing is used in exterior wall systems where two surfaces meet inside a corner (e.g. inside corners of window wells, recessed walls, or inside returns). The flashing manages moisture and provides a crisp visual termination, while the closed hems reinforce edges and protect against damage or deformation.

Because it’s painted on one side, you’ll want to orient it so the painted face is toward the visible, exposed side. The hemmed edges provide a safer, cleaner line and help reduce oil-canning or warping in thin aluminum.

When installing, fasten through the non-finished (back) face into the substrate, ensuring that sealants or overlapping membranes are properly lapped to maintain waterproofing.