Seal Every Gap.
Preserve Privacy.
Regardless of door type, sound isolation is only as effective as the seal. Even small gaps at the perimeter, head, or sill can significantly compromise acoustic performance, allowing sound to bypass the door leaf entirely and reducing the effective STC of the overall assembly. This is true for both standard doors and high-performance acoustic doors; without proper sealing, the door’s rated performance cannot be realized.
Door Seal Systems and Thresholds address these vulnerabilities with engineered gasketing and automatic sealing solutions that close critical air paths. Designed for both new construction and retrofit applications, these systems provide consistent compression, long-term durability, and verifiable acoustic performance when tested in accordance with ASTM E90 and ASTM E413 standards.
Door Seal Systems and Thresholds address these vulnerabilities with engineered gasketing and automatic sealing solutions that close critical air paths. Designed for both new construction and retrofit applications, these systems provide consistent compression, long-term durability, and verifiable acoustic performance when tested in accordance with ASTM E90 and ASTM E413 standards.
Common applications:
- Education environments such as classrooms, lecture halls, and music rooms
- Hospitality and multifamily buildings seeking noise reduction between rooms
- Government and secure facilities where confidentiality is essential
- Healthcare and research facilities requiring acoustic and infection-control integrity
- Corporate offices and conference rooms where speech privacy is critical
Product Overview
DOOR SEAL SYSTEMS & THRESHOLDS
Automatic Door Bottoms (Drop-Down Seals)
Automatic door bottoms, also called drop-down seals, use a spring-loaded mechanism that seals the threshold as the door closes, preventing drag and ensuring a consistent compression seal along uneven floors. The gasket activates from the hinge side first, closing gaps efficiently without resistance.
Performance & Design Highlights:
- Tested to 5 million cycles for durability
- Surface-mounted, semi-mortised, or fully mortised options
- “Light Spring (LS)” models available for ADA-compliant doors
- Airflow/sound-blocking “FLO” versions balance ventilation and isolation
- Part of tested seal systems rated STC 49 to 53
- UL10C Fire-rated | ADA accessible | Tested assemblies to ASTM E90
DOOR SEAL SYSTEMS & THRESHOLDS
Perimeter Gasketing (Head and Jamb Seals)
Engineered perimeter gaskets that line the head and jambs of the door frame provide compression or magnetic sealing around the entire door perimeter. Options include adjustable gaskets, ligature-resistant seals (ZAG), and double-sealing EBF profiles for maximum acoustic performance.
Performance & Design Highlights:
- Adjustable gaskets for misaligned or warped doors
- Double bulb and magnetic seals for improved STC ratings
- Ligature-resistant (ZAG) configurations for behavioral health and detention environments
- Available in aluminum, bronze, or stainless finishes
- Part of tested seal systems rated STC 49 to 53
- Fire-rated and UL listed components
- Finishes:Clear anodized, dark bronze, black, gold, or oil-rubbed bronze
DOOR SEAL SYSTEMS & THRESHOLDS
Acoustic Thresholds
Acoustic thresholds form the foundation of a complete door seal system, bridging the gap between the door and floor surface. Aluminum and stainless steel thresholds incorporate resilient gaskets for sound, air, and smoke control while maintaining ADA accessibility.
Performance & Design Highlights:
- Compatible with all automatic door bottom models
- Low-profile and ramped options for barrier-free entry
- Available with neoprene, vinyl, or brush inserts for tailored performance
- Heavy-duty saddle and half-saddle profiles available
- EBF (extruded bulb/finger) options ensure tight contact on uneven flooring
DOOR SEAL SYSTEMS & THRESHOLDS
Sound-Tested Door Seal Systems
A door’s STC rating is measured on the door leaf alone. Once the door is hung, the gaps at the head, jambs and sill decide the real result. Zero International SOUND TRAP® systems are complete seal kits (head and jamb seal, automatic door bottom and threshold) tested together by independent laboratories on STC 55 metal doors.
Tested systems, with an STC 55 door:
- STC 1: single swinging metal door, tested at STC 53
- STC 2: single metal door in a frame without a stop (cased opening), with an adjustable head and jamb seal, tested at STC 52
- STC 3 and STC 4: single swinging metal door, tested at STC 51
- STC 5: single swinging metal door, tested at STC 49
- STC 6: single metal door in a frame with a stop, tested at STC 49
- JD6S (pairs): pairs of metal doors with astragals at the meeting edge, tested at STC 41 with STC 52 or higher doors
The manufacturer describes STC 49 as the level where loud speech is heard only faintly and cannot be understood on the other side. That suits schools, multifamily buildings, doctors’ offices, counseling centers and churches.
We match the system to your door, frame and swing. A lighter or older door leaf sets a lower ceiling no matter which seals are used.
DOOR SEAL SYSTEMS & THRESHOLDS
Double Doors, Vision Lites and Louvers
Double doors. Pairs of doors leak more sound than single doors because of the gap where the two leaves meet. Astragal seals close that gap. The tested pairs system reaches STC 41 with STC 52 or higher doors.
Vision lites. A window in a sound-rated door needs its own sealed frame. Sound-rated vision lite systems are rated STC 45 for 1 3/4 inch doors and up to STC 44 for thicker doors. Glass is supplied separately. For sound-rated glass walls and windows, see Acoustic Glazing Systems.
Louvers. A standard louver leaves a door with almost no sound rating. In tested assemblies, a door with a standard louver rated STC 0. An acoustical louver raised it to STC 9, and adding the matching adaptor raised it to STC 16. If a door has to pass air, plan for that loss early.
DOOR SEAL SYSTEMS & THRESHOLDS
Performance & Design Highlights
Our engineering team ensures every system is properly specified, installed, and verified for optimum results.
- Engineered Acoustic Control: Designed to maintain sound isolation performance up to STC 53 when paired with STC 55 rated doors
- Complete Perimeter Sealing: Systems integrate automatic door bottoms, perimeter gaskets, and thresholds to seal gaps along all four edges of the opening
- Advanced Automatic Mechanisms: Spring-loaded drop seals activate from the hinge side first, creating uniform contact even on uneven flooring
- Multi-Function Performance: Provides sound, smoke, draft, and light blocking in a single assembly, with optional heat-activated components for fire-rated openings
- Durable Construction: Extruded aluminum, stainless steel, and bronze housings with replaceable silicone or neoprene inserts ensure long-term reliability under high-traffic use
DOOR SEAL SYSTEMS & THRESHOLDS
Installation & Integration
Memtech Acoustics provides design coordination with architects, contractors, and door manufacturers to ensure that seals, thresholds, and frames integrate seamlessly with door construction and acoustic requirements.
Our approach includes:
- Pre-Installation Prep: Verify frame alignment and door clearances to ensure proper compression along the full perimeter.
- Mounting Options: Choose from surface-mounted or concealed hardware depending on door type and application.
- Threshold Compatibility: Match threshold height and profile with automatic door bottom models for a continuous seal.
- Adjustment: Use built-in adjustment screws on perimeter gaskets to maintain uniform pressure as doors settle or flooring conditions change.
- Seamless Integration: Systems can be paired with acoustic, smoke, or fire-rated doors for complete performance assemblies.
DOOR SEAL SYSTEMS & THRESHOLDS
How to Specify Sound-Rated Door Seals
- Start with the door. The systems above were tested on STC 55 doors. The door leaf limits what any seal can achieve.
- Check the frame. Frames with a stop and cased frames without a stop take different head and jamb seals.
- Match the threshold to the door bottom so the drop seal lands on a continuous surface.
- Confirm the gaps. Perimeter gaskets are made for gaps up to 1/8 inch. Automatic door bottoms drop up to 9/16 inch.
- Confirm fire and smoke labels. Automatic door bottoms are UL listed and 10C classified. Perimeter gaskets are UL 10B classified up to 90 minutes and UL 1784 listed for smoke.
- Plan for glass and louvers using the ratings above.
- Specify the tested system, not loose parts, so the assembly carries a lab-tested STC.
The Memtech Acoustics Advantage.
We go beyond simply supplying components. We engineer complete, door sealing solutions that ensure every opening meets its acoustic, fire, and accessibility standards.
Data-Driven Design
We size the seal system to the door’s tested rating and the frame you have, so the opening performs like the lab assembly.
System Integration Expertise
Seals, thresholds and door bottoms are matched to frame type, door thickness and swing so the set works as one system.
Long-Term Reliability
Automatic door bottoms are tested to 5 million openings and closings, with replaceable neoprene and silicone inserts.
Material Specification & Procurement
Direct access to a full range of door kits, thresholds, and mounting hardware for simplified purchasing
Local Turnkey Implementation
Installation coordinated in select regions, with clear instructions for crews everywhere else.
Performance Verification
Optional field measurement and acoustic performance verification
Technical Highlights
Engineered sealing systems built for acoustic, fire, and accessibility performance.
Construction
Extruded aluminum or stainless steel housings with replaceable neoprene, silicone, or magnetic inserts.
Operation
Compression-fit or automatic drop-seal mechanisms for consistent, gap-free sealing.
Integration
Compatible with perimeter gaskets, thresholds, and full Sound Trap® acoustic door kits.
Fire Rating
UL listed and 10C classified door bottoms; UL 10B (up to 90 minutes) and UL 1784 smoke-listed gaskets
Compliance
Meets ASTM E90 / E413, UL10C, and ADA 404.2.5 standards.
Acoustic Performance (STC)
Achieves up to STC 53 when integrated with rated door assemblies.
Support Beyond the Product
Installation coordinated in select regions
Engineering consultation to ensure proper material selection
Custom sizing and integration with other Memtech Acoustics systems
Replacement parts available for future reconfiguration
Frequently Asked Questions (FAQs)
What makes Zero International door seals different?
Zero automatic door bottoms activate on the hinge side first, so the seal does not drag along the floor or threshold while the door closes. Every model is rated for 5 million cycles.
Are door seals compatible with existing frames?
Yes. Surface-mounted gaskets and automatic door bottoms can retrofit existing frames without major modifications.
Do these seals also block smoke and fire?
Yes. Intumescent and smoke-rated inserts are available for fire-rated openings.
What STC ratings can be achieved?
Tested seal systems reach STC 49 to 53 on single doors and STC 41 on pairs, fitted to sound-rated doors (the tests used STC 55 doors).
Can seals be field-adjusted?
Yes. Adjustable gaskets (e.g., Model 770) can be fine-tuned with a screwdriver to restore pressure as doors settle or shift over time.
Are these products ADA compliant?
Yes. Automatic bottoms with low-force “light spring” mechanisms and ADA thresholds maintain accessibility.
Do you provide turnkey services?
Yes. Memtech Acoustics handles measurement, engineering, material supply and post-installation validation, and coordinates installation in select regions.
What’s the typical lead time for material supply?
Most standard door kits are stocked and delivered within 1–2 weeks.
Can I add acoustic seals to an existing interior door?
Yes. Surface-mounted gaskets and automatic door bottoms retrofit most frames without major work. The door leaf still sets the limit. A hollow or lightweight door will not reach the ratings of a solid, sound-rated door.
How do I reduce sound through door gaps in a hospital corridor?
Seal all four edges: head and jamb gaskets, an automatic door bottom and a matching threshold. Fire- and smoke-rated versions suit corridor doors, and ligature-resistant gaskets are available for behavioral health areas. This keeps conversations in exam and consult rooms private.
Do double doors seal as well as single doors?
Not quite. The meeting edge between the two leaves leaks more sound. The tested pairs system reaches STC 41, compared with STC 49 to 53 for single-door systems.
Can a door with a window still be sound rated?
Yes. A sealed vision lite system keeps the window from becoming the weak point. Tested systems are rated up to STC 45.
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