Curtain Slat

A curtain slat is one of the formed or extruded metal sections that link together to make up the curtain of a rolling steel door. Each slat hooks into the one above and below it at a curved interlocking edge. The assembled curtain is flexible enough to coil around the barrel assembly at the head of the opening but rigid enough to resist forced entry and wind pressure when the door is down.

Common slat profiles:

• Flat slat: A straight, planar section used on lighter-duty service doors and interior applications.
• Corrugated or curved slat: A slightly bowed cross-section that adds stiffness without adding gauge thickness. This is the most common profile on commercial service doors.
• Heavy-duty slat: A deeper corrugation or thicker gauge (18 gauge or heavier) specified for high-security or high-wind applications.

Slat material is almost always galvanized steel, though aluminum slats are available where corrosion resistance is the priority over dent resistance. Slat width (the dimension from top to bottom when the door is closed) is typically 2 inches to 3 inches. Taller slats make a stiffer curtain with fewer interlocks to maintain; shorter slats produce a more flexible, tighter coil.

At set intervals along the curtain, windlocks are attached to the slat ends. The windlocks engage the vertical guides and prevent the curtain from bowing out or pulling free under lateral wind load.

The bottom of the curtain terminates at the bottom bar, a reinforced steel member that carries any sensing edge or astragal seal. The top of the curtain attaches to the barrel. When the door rises, the barrel rotates and the slats coil around it inside the hood. A correctly specified curtain coils without binding and uncoils to hang plumb in the guides.

Slat replacement is done section by section: the curtain is uncoiled enough to reach the damaged slat, which is then swapped out by releasing the interlocking edges. Slats that are dented but still interlock do not require immediate replacement; slats that are kinked enough to jam the coil or prevent the guide edges from engaging should be replaced promptly.