Zero International

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Automatic Door Bottoms

Engineered for easy installation and superior sealing performance.

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From ease of installation to hassle-free performance, the patented technology in ZERO automatic door bottoms deliver superior results.

They ensure an efficient seal with an adjustable plunger that is compressed against the frame as the door is closed, activating a concealed flat spring mechanism. This mechanism drops the seal smoothly from the housing in a scissor-like motion. The seal compresses on either even or uneven surfaces and retracts automatically when the door is opened.

Automatic Door Bottoms serve many important functions, including blocking penetration by:

  • Sound
  • Air
  • Smoke
  • Flames

A variety of types of automatic door bottoms are available to accommodate the specific needs of your application. Our special-purpose door bottoms give optimal results to help meet the biggest challenges in sealing door perimeters:

  • High-level sound control achieved with unique, patented design features
  • Blocking fire, smoke and toxic gases with integral intumescent material
  • Minimizing door-opening force with "Light Spring" action to meet ADA access requirements

ZERO automatic door bottoms meet the highest standards in the industry for reliability and performance. See the catalog for specific certification by model number. They include certifications for:

  • Fire Rating
  • Smoke and Draft Control
  • Air Infiltration
  • Sound

See catalog for dimensions, drawings, available options and certifications for each part number.

Heavy duty automatic door bottoms: For high use and abuse applications, primarily in institutional and commercial markets requiring the best acoustical performance.     

Regular duty automatic door bottoms: For standard applications, primarily in commercial markets.

Light duty automatic door bottoms: For applications with lower abuse and traffic applications, primarily for use in multifamily markets or projects where cost is a concern.

Special purpose automatic door bottoms: Unique solutions including intumescent fire protection and applications with sliding doors.

ZERO automatic door bottoms are available in the following finishes:

AA Clear anodized aluminum

Clear Anodized Aluminum Finish

BK Aluminum black anodized

Aluminum Black Anodized



D Aluminum dark bronze anodized

Aluminum Dark Bronze Anodized

G Aluminum gold anodized

Aluminum Gold Anodized

Door bottoms are available in specialized versions for a variety of applications, including:

  • Light spring (LS)
    This feature can be useful for reducing opening and closing force for use with ADA-compatible doors
  • Air flow/sound block (FLO)
    This option uses sound-dampening silicone seals or nylon brush which are notched and overlapped in staggered rows for applications requiring air flow while blocking sound
  • Z49 End cap (Z49)
    Easy-access end caps for mortised door bottoms provide easy access for cleaning, well suited for health care applications


Full Line Zero International Catalog

Installation Instructions

Zero Automatic Door Bottoms Model 355 Installation Instructions

Zero Automatic Door Bottoms Models 320, 350, 7350, 351, 352, 360, 361, 362, 364, 365, 366, 367, 368 & 369 Installation Instructions


Zero Product Solutions E-Brochure

Additional Resources

Intro to Thresholds and Gasketing White Board Video

iDigHardware.com – answers to your door, hardware and code questions from Allegion’s Lori Greene

LEED Certification – Recycled Content ZERO International

CAD Drawings and Cut Sheets

Find CAD Drawings and Data Sheets (Cut Sheets) in the Document Library


In accordance with California PROP65 - WARNING WARNING: Cancer & Reproductive Harm P65Warnings.ca.gov

Need Replacement Parts?

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Get answers to your door, hardware and code questions from Allegion's iDigHardware team.