Soundproof Door Grades, Materials, Types, and Applications

1. STC 35: Residential Environments and Door Retrofitting Craftsmanship

STC 35 belongs to the foundational soundproofing level, capable of blocking environmental noise and conversational sounds. Untreated hollow wooden doors typically have an STC value between 20 and 25. Upgrading the door to STC 35 can meet residential demands for privacy and quiet spaces.

Retrofitting Craftsmanship and Material Application

Without replacing the existing door, a wooden door can achieve an STC 35 rating through material superposition and structural modification. The retrofitting process involves three steps:

1. Filling the Core Structure (Ribs): The interior of most wooden doors consists of a hollow structure (ribs) made of honeycomb paper or wooden strips. The retrofitting procedure requires injecting sound-absorbing materials into the hollow sections to reduce the resonance effect within the door panel.
2. Underlay with ENA NE-200 Soundproof Felt: Attach ENA NE-200 damping soundproof felt to the surface of the door panel. This material possesses high surface density, increasing the door's weight according to the Mass Law to block airborne sound.
3. Surface Finish with ENA NE-100 Acoustic Panel: The outermost layer is covered with ENA NE-100 acoustic panels. This porous material absorbs the reflection energy generated when sound waves contact the door surface, reducing reverberation time.

Combined with the installation of airtight rubber seals around the door frame to block gaps, this craftsmanship enables the transmission loss of the wooden door to reach the STC 35 testing standard.

2. STC 45: Material Structure and Attenuation Data

Soundproof doors with an STC 45 rating adopt a solid wood composite structure or metal materials. The interior of the door is filled with acoustic cotton and soundproof panels, and multi-layer sealing rubber strips are configured around the door frame to prevent sound from diffracting through gaps.

Its acoustic attenuation capability can block human conversations, TV sounds, and corridor footsteps. Based on attenuation data, when outdoor noise reaches 80 decibels, the sound transmitted indoors through an STC 45 door can be reduced to a background volume of around 35 decibels.

3. STC 45: Applications in Commercial Spaces and Hotel Guest Rooms

STC 45 doors support wood finishes and diverse exterior designs, capable of complementing different interior decor styles. They are mainly applied in the following scenarios:

• Hotel Guest Rooms: Ensuring guests are not disturbed by noise from the corridor or other rooms, maintaining indoor tranquility.
• Academic and Educational Institutions: University lecture halls, conference rooms, and libraries, blocking external student activity noise.
• Commercial Office Areas: Boardroom meeting rooms and administrative offices, preventing internal speech from leaking out.

4. STC 55 and 58: Metal Structures and Airtight Design

Soundproof doors with STC 55 and 58 ratings are products designed to handle high-decibel environments. Doors of these levels adopt double-layer or multi-layer steel plate structures, filled internally with rock wool, damping felt, and acoustic cotton. To counter sound wave leakage between the door and the floor, these types of soundproof doors are equipped with magnetic airtight rubber strips and an Automatic Door Bottom, ensuring the gaps between the door frame and the floor are completely sealed.

5. STC 55 and 58: Applications in Specific Facilities and High-Decibel Environments

Designs at these levels are used to isolate high-decibel low-frequency and high-frequency noise, and are mainly applied in building facilities with strict standards for sound control:

• Machine Rooms and Heavy Machinery Operating Areas: Such as electrical and mechanical rooms in airport terminals, blocking engine and machinery operating noise from transmitting into public areas.
• Government Departments and Specific Facilities: Such as detention rooms or interrogation rooms, ensuring that sound does not leak out.
• Acoustic Spaces: Recording studios, broadcasting rooms, and cinemas.