Commercial door thresholds and seals

Thresholds and seals for existing openings

A door threshold is the strip across the floor of the opening; with a sweep or door bottom on the door and gasketing on the frame, it seals the gaps around a closed door.

Thresholds, gasketing, door bottoms, sweeps and astragals that close the gaps around a commercial door against drafts, water, light, sound or smoke.

How it is specified

• Width and profile. Thresholds are cut to the opening width.
• Height on an accessible route. Under the 2010 ADA Standards, a threshold at a doorway may be no more than 1/2 inch high (section 404.2.5).
• Door bottoms and sweeps. A sweep mounts on the door face; an automatic door bottom drops a seal as the door closes.
• Gasketing. Perimeter gasketing seals the frame stop against drafts, light, sound or smoke.

ADA threshold height, door bottoms, seals and astragals

What usually fails

Sweeps and gaskets wear out and go hard, and light under the door is the sign. A threshold that has lifted is a trip hazard and a water problem at once. A door bottom that no longer drops has usually lost its plunger adjustment.

On an accessible route, the threshold is one of several door rules in the 2010 ADA Standards. Our ADA door clearance guide sets out the threshold height, clear width and floor space each side, section by section.

Measure the opening width and the gap under the closed door, and tell us whether the door is exterior and whether it carries a fire or smoke label.