When designing an isolation plan, it is vital to not compromise the integrity of an isolating partition by having leaks in the wall. HVAC grilles, outlets, conduit runs, windows, or doors are common weak points. When properly selecting and implementing a door to ensure that a wall’s isolation properties are not compromised, it is important to choose a door that has similar Sound Transmission Class (STC) and Transmission Loss (TL) values to the rest of the wall’s components.
Selecting the Door
We always prefer to analyze a door’s TL data rather than only it’s STC value. For this reason, we typically work with manufacturers who provide TL data for their products. Below are a few different manufacturers we often work with for isolation doors:
Sealing the Door
When isolating a room, it is important to seal the room from any potential leaks – if you imagine filling a room with water, anywhere that water may leak out is also where sound will leak out. With this in mind, selecting the door is only half the battle. Properly installing and sealing the door is key to ensuring the door retains its isolation properties. Below are a few components and products commonly used in the door system to create an airtight seal:
A common technique when isolating a space is utilizing a double-studded wall design, meaning that the wall will have two distinct sets of studs, separated by an air gap. This type of design greatly increases the isolation properties and helps reduce mechanical vibrations transmitting through the wall. A common short in this type of system is the entrance into the room. If a single door is utilized, this door becomes a point for mechanical vibrations to transfer, and it is difficult to find a single door that matches the isolation properties of a massive wall system like a double wall. A common way to remedy this issue is to implement a communicating door system, which utilizes two doors in a single entranceway into a room. This allows you to maintain the air gap and keep the wall systems truly separate. When implementing this type of door system, it is helpful to utilize two different types of isolation doors, as having two doors with different acoustical performances will help cover various frequencies more effectively. We also recommend having the doors open in opposite directions so that the door handles are on opposite sides of the frame, thus not causing an issue with the door handles touching. See below for a diagram showing this type of door system.
Testing The Door
There are certainly standardized testing methods to measure the sound leakage through a door system, but subjectively, you can play loud music inside of your room and then shut the door and listen for potential weak spots around the perimeter of the door. It is also helpful to use a bright work light inside of the room and search for areas around the perimeter of the door where light is shining through. This will diagnose spots where the seals will need to be adjusted.