Zero International 355A Semi ...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$101.97
Zero 355A Semi Mortised Automatic Door Bottom with Neoprene Seal

Zero International 355A Semi Mortised Automatic Door Bottom with Neoprene Seal

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Model: 355A-36

In Stock (leaves warehouse same day if ordered before 3pm ET)

$101.97
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Zero 355A Semi Mortised Automatic Door Bottom with Neoprene Seal

The patented automatic door bottom technology from Zero ensures an efficient seal against the floor or saddle. As the door is closed, the adjustable plunger is compressed against the door frame, activating a concealed flat spring mechanism. Zero door bottoms are designed to block penetration by air, sound, smoke, and flames.

  • Semi-mortised, 1/2″ drop
  • AA = Anodized aluminum
  • For use with hollow metal doors
  • Supplied without end caps
  • Supplied with solid neoprene extrusion
  • Air Infiltration and sound tested
  • Fire-rated UL10C

Product Specs

Commercial/Residential:
Commercial
Product Group:
Door Trim and Accessories
Product Subgroup:
Door Bottom Sweeps and Door Shoes
Product Type:
Door Bottom
Department:
Door Hardware

Zero International 355A-36 – Frequently Asked Questions

1) How much floor clearance does a Zero 355A need under the door?
The drop is 1/2 inch. Measure the gap from the door bottom to the finished floor or saddle with the door in the closed position: anything up to 1/2 inch gets sealed, anything more and the neoprene will not reach. On an undercut door over a thick carpet or a raised threshold, check the gap at both ends, not just the center, since a door that has settled will show more gap on the lock side.
2) Can I cut a Zero 355A door bottom down to fit my door?
Order by door width rather than planning to trim it. The 355A comes in 12, 32, and 36 inch lengths, so pick the length that matches the door and mortise pocket you are cutting. Note it ships without end caps, so if your detail calls for finished ends you are specifying those separately.
3) Is the Zero 355A fire rated for a labeled opening?
Fire rated, and UL10C listed. That is the positive pressure fire test standard, which is what an inspector on a labeled hollow metal opening will be looking for on the smoke and flame seal.
4) How does the Zero 355A automatic door bottom actually operate?
There is no motor or power involved. A plunger sticks out of the hinge end of the unit, and when the door swings closed the plunger hits the frame stop, compressing a concealed flat spring that pushes the neoprene seal straight down onto the floor. Open the door and the spring retracts the seal so it clears the floor. The plunger is adjustable, so you tune how far the seal drops and how firmly it contacts.
5) What is the difference between a semi-mortised automatic door bottom like the Zero 355A and a surface mounted one?
A surface mounted automatic door bottom screws to the face of the door with no routing, so it is the retrofit choice on a door already hung. The 355A is semi-mortised: you rout a pocket in the bottom edge, and the housing sits partly recessed, which keeps it tighter to the door and less exposed to being kicked. It is more work at install and it means machining the door, so it suits new hollow metal doors or a door you can take down and prep. If you cannot mortise the door, you want a surface applied unit instead.
6) Will a Zero 355A stop sound and drafts from coming under the door?
It is tested for both air infiltration and sound, and the seal is a solid neoprene extrusion rather than a hollow bulb or a brush, so it makes continuous contact across the door width. Zero rates the design to block air, sound, smoke, and flame. For it to perform, the rest of the opening has to be sealed too. A door bottom only closes the gap at the floor, so if the perimeter has no gasketing on the head and jambs you will still get transmission around the sides.
7) What finish does the Zero 355A come in?
Anodized aluminum, designated AA. Since the unit is semi-mortised into the door bottom edge, most of it is out of sight anyway, so the finish matters mainly where it meets a visible door edge or where you are matching other Zero gasketing on the same opening.
8) Is the Zero 355A rated for commercial traffic or is it a residential part?
Commercial. It is a commercial door hardware item, matched to hollow metal doors and labeled openings, which is where automatic door bottoms earn their keep: schools, hospitals, corridors, and stair doors where a fixed sweep would drag on the floor every cycle.
How fast can I get the Zero International 355A-36 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Zero International 355A-36 come with a warranty?
Absolutely. The Zero International 355A-36 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Zero International 355A-36?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Zero International 355A-36 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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