How To Install a Commercial ADA Door Threshold on a Hollow Metal Door (Concrete Slab Install)

1/2" Tall ADA Compliant Saddle Threshold - UL Listed Options for Fire-Rated Openings

Hey, this is Gary with Door Closers USA. In this guide, I’m showing you how to install a commercial ADA door threshold on a hollow metal door installed over a concrete slab. This threshold is 1/2" tall, which makes it ADA compliant and suitable for many commercial and fire-rated openings.

Tools & Materials Needed

• Commercial ADA threshold (1/2" tall recommended for barrier-free transitions)
• Tape measure + pencil/marker
• Hacksaw or miter saw (metal cutting blade) to trim ends
• Rotary hammer / rotary drill with concrete bit
• Plastic concrete anchors (if not included)
• Fasteners (screws appropriate for concrete anchors)
• Exterior-grade caulk / sealant
• Vacuum or brush to clean dust from drilled holes

4-Step Installation (Concrete Slab)

Step 1 - Measure the Door Opening (Jamb-to-Jamb + Stop-to-Stop)

First, measure the width of the openingjamb to jamb, and also stop to stop. This tells you exactly where the threshold needs to be trimmed so it fits clean around the door jambs and stops.

Step 2 - Trim the Ends & Dry Fit

Once you’ve got your measurements, trim the ends of the threshold and dry fit it in the opening. Make sure everything lines up and sits flat before drilling anything.

Step 3 - Drill Pilot Holes & Add Anchors

Because this is a concrete slab, use a rotary drill/rotary hammer with a concrete bit. With the threshold in place, drill pilot holes through the pre-drilled holes in the threshold and into the concrete.

After drilling, insert plastic concrete anchors into the slab. These anchors help lock the threshold down securely once the screws are installed.

Step 4 - Apply Caulk & Secure Threshold to Floor

Before fastening the threshold, this step is critical: caulking.Apply caulk under the full length of the threshold legs and also at both ends of the threshold. This helps create a proper seal and helps prevent moisture from getting under the door—especially important on slab installations.

Set the threshold back in place and secure it to the concrete using the supplied screws, tightening everything evenly.You want it snug and flat, but not overtightened.

Final Checks

• Close the door and confirm a smooth transition across the threshold
• Verify proper clearance and that the door doesn’t bind
• Confirm the install maintains ADA compliance for accessibility
• Inspect caulk coverage at ends and underneath for a consistent seal

Watch Installation Video

Download PDF Installation Instructions

📄Commercial Door Threshold Installation PDF

Related Hollow Metal Door Resources

🔩 Hollow Metal Door Hub (Doors, Frames, Parts & Guides)

🚪 Shop Hollow Metal Door Packages (IBC / ADA / UL / NFPA / ANSI/BHMA)

🧰 Shop Hollow Metal Door Parts

This is Gary with Door Closers USA - thanks for watching.