Step 1: Verify the Louver and Door Compatibility
Before cutting into the door, confirm that the louver assembly matches the project specifications.
• Louver size. Verify the louver dimensions match the size specified on the door schedule or hardware schedule.
• Fire rating. If the door is in a fire-rated opening, confirm the louver carries a fire label matching or exceeding the door’s rating (20, 45, 60, 90, or 180 minutes). A non-rated louver installed in a fire-rated door voids the assembly’s fire label.
• Fusible link. Fire-rated louvers must include a fusible link. Verify the link is present and confirm the activation temperature matches project specifications (165°F is standard for most applications).
• Door thickness. The louver frame depth must match the door thickness. Commercial hollow metal doors are 1-3/4” thick.
CDF Distributors factory-installs louvers into doors during fabrication when louvers are included in the ProBuilder assembly configuration. Factory installation eliminates field cutting and ensures the louver cutout, placement, and fire-rating compliance are verified before the assembly ships.
Step 2: Lay Out the Louver Cutout
If the door requires field installation of a louver, begin by marking the cutout location on the door face.
• Position the door on a flat, stable surface (sawhorses or a door cart) with the face side up.
• Measure 12 inches up from the bottom of the door and mark a horizontal line. This establishes the bottom edge of the louver cutout. The 12-inch dimension is the standard louver prep height used by CDF Distributors.
• Calculate the horizontal center of the door. For a 36” door, the center is at 18”. Measure half the louver width to each side of center and mark vertical lines.
• Mark the top edge of the cutout by measuring the louver height up from the bottom mark.
• Verify the rectangle is square by measuring both diagonals. Equal diagonals confirm a square cutout.
Step 3: Cut the Louver Opening
With the layout marked, cut the rectangular opening in the door face.
• Drill a starter hole at each corner of the marked rectangle using a drill bit large enough to accept the reciprocating saw or jigsaw blade.
• Insert the saw blade into one corner hole and cut along the marked line to the next corner. Repeat for all four sides.
• Remove the cutout piece from the door.
• File all cut edges to remove burrs and sharp metal. Deburring prevents injury during louver insertion and ensures a flush fit between the louver frame and the door face.
• Apply touch-up paint to exposed metal at the cut edges. Unpainted cut edges will corrode over time, particularly in humid environments.
Hollow metal doors are composed of two steel skins over an internal core (honeycomb, polystyrene, or mineral core for fire-rated doors). Cutting through both skins is required. Exercise care to cut cleanly without deforming the surrounding door face.
Step 4: Test-Fit the Louver
Before final fastening, insert the louver into the cutout to verify fit.
• Slide the louver assembly into the cutout from the face side of the door.
• Verify that the louver frame sits flush against the door face on all four sides. Gaps between the louver frame and the door face indicate an oversized cutout or a misaligned cut.
• Confirm the louver is oriented correctly. Inverted-Y blades should angle downward toward the corridor side to prevent water entry and limit visibility.
• Check that the louver frame depth matches the door thickness. The frame should not protrude beyond the door face on either side.
Step 5: Secure the Louver
Fasten the louver permanently using the manufacturer-supplied attachment hardware.
• With the louver seated in the cutout, attach the clip angles or mounting brackets from the reverse side of the door. Clip angles are L-shaped metal brackets that grip the louver frame and the inside edge of the cutout.
• Tighten all fasteners evenly. Do not overtighten, as excessive force can deform the louver frame or the door skin.
• If through-bolts are specified instead of clip angles, drill bolt holes through the louver frame flange and the door face, then install bolts with nuts on the reverse side.
• Verify the louver is secure by applying light pressure. The louver should not shift or rattle within the cutout.
Step 6: Verify Fire-Rated Louver Operation (If Applicable)
For fire-rated louvers, an additional verification step is required after installation.
• Confirm the fusible link is properly connected and positioned within the louver assembly. The fusible link is a heat-sensitive element that holds the louver blades in the open position during normal operation.
• Visually inspect that the louver blades move freely. If the blades are manually deflected and released, they should return to their normal open position.
• Verify the fire label is visible and legible. Fire-rated louvers must display a label from a recognized testing laboratory (such as UL or Intertek/WHI) showing the rating and listing information.
• Do not paint over or obscure the fire label. Do not remove, replace, or modify the fusible link. Altering any component of a fire-rated louver voids the assembly’s fire rating and constitutes a code violation.
NFPA 80 requires annual inspection of fire-rated door assemblies, including louvers and fusible links. Facility maintenance teams should include louver inspection in their fire door inspection program.
Step 7: Final Inspection
After installation, perform a final check before the door is hung or returned to service.
• Louver is centered horizontally on the door face.
• Bottom of louver cutout is 12 inches from the bottom of the door.
• Louver frame is flush with the door face on both sides.
• All fasteners are secure and not protruding beyond the door surface.
• Cut edges are deburred and touched up with paint.
• Blade orientation is correct (inverted-Y blades angled toward corridor side).
• Fire label is visible and legible (fire-rated louvers only).
• Fusible link is connected and blades move freely (fire-rated louvers only).
