How can you block outside noise from entering a room or building?
There are three components to any plan for managing exterior sound: understanding the source-path-receiver model, selecting the right acoustic insulation for continuous exterior assemblies, and following general tips to soundproof from environmental noise pollution.
Part 1: Understanding the source-path-receiver model
When it comes to managing exterior sound, the source-path-receiver model continues to be useful. Looking at a commercial building, industrial facility, or even a residential home, the principle remains the same: start by looking at all the possible sources of noise and then look at all the possible entry points, or pathways, for the sound to travel. That list includes the roof, windows and doors, and wall assemblies.
Do you know which of these are the weakest sections of the building envelope when it comes to blocking external sound? You wouldn’t be alone if you assumed it was the exterior wall and roof systems. But you’d be wrong. Windows and doors are the most common culprit for allowing exterior sound to negatively affect the indoor environment.
That being said, building and design professionals are always encouraged to design exterior wall and roof insulation systems to help block as much of that environmental noise as possible. The overall mass of the wall and roof systems is what blocks most of the noise, but concrete alone isn’t usually sufficient, as it’s a poor medium for controlling other interior conditions, e.g. temperature. In addition, insulating exterior wall and roof systems means interior designers might even gain some freedom – needing fewer wall assemblies or other materials to block and absorb sound because the external noise is minimized by the building envelope.
Part 2: Selecting the right acoustic insulation for continuous exterior assemblies
Construction practices from architects and builders are important in reducing noise and sound transmission. Pay close attention to material selection for insulation. When it comes to acoustic insulation, noise sources near the building will have a major effect on what type of building envelope material should be used.
The strategy behind noise control with insulation? You can improve the indoor acoustics and reduce stressors by limiting structure and airborne transmission from external sources by integrating sound reduction measures into the basic planning and layout of your home or building.
Consider the following checklist when evaluating the insulation to use in your CI applications, which as outlined above, is now a required practice under most building code legislation.
- Raw materials used in manufacturing the insulation
- Manufacturing processes
- Operational performance
- Combustibility of the insulation
- Moisture mitigation properties
- Overall durability
- Impact on acoustic performance (OITC / STC)
While building codes and material costs should be a component of your selection process, the desired performance factors for your commercial office, healthcare facility, educational institution or other structure, are most important when evaluating and specifying products to deliver CI.
Stone wool insulation is well suited to deliver sound reduction benefits and control unwanted noise in occupied spaces. When properly installed in today’s building enclosures on the outside face of the building substrate behind the building facade, stone wool, as part of your CI system, supports thermal performance and provides additional acoustic comfort.
When the building enclosure is wrapped in stone wool insulation, it provides exterior wall OITC rating results that improve productivity, health, and wellbeing for those within the space. Block environmental noise pollution from neighbors, traffic, airplanes, construction sites and more by planning a good acoustics approach from the beginning with your choice of acoustic insulation.
Common assembly combinations and the resulting OITC:
|Gypsum||Studs||Insulation||Sheathing||Vapor Barrier||Continuous Exterior Insulation||Outdoor-Indoor Transmission Class (OITC)|
|1 layer, 5/8" Type X USG||25 Gauge Steel – 3-5/8”||3.5" COMFORTBATT||1 layer, 5/8" GP Densglass||Tyvek Home Wrap|
2" COMFORTBOARD 110
|1 layer, 5/8" Type X USG||25 Gauge Steel – 3-5/8”||3.5" COMFORTBATT||1 layer, 5/8" GP Densglass||Tyvek Home Wrap||2" CAVITYROCK||32|
|1 layer, 5/8" Type X USG||25 Gauge Steel – 3-5/8”||3.5" COMFORTBATT||1 layer, 5/8" GP Densglass||Tyvek Home Wrap||1" COMFORTBOARD 110||32|
|1 layer, 5/8" Type X USG||25 Gauge Steel – 3-5/8”||N/A||1 layer, 5/8" GP Densglass||Tyvek Home Wrap||1" COMFORTBOARD 110||30|
|1 layer, 5/8" Type X USG||Wood - 2" x 6"||6" COMFORTBATT||1 layer, 1/2" CDX Plywood||Tyvek Home Wrap||1.5" COMFORTBOARD 80||29|
|1 layer, 5/8" Type X USG||Wood - 2" x 6"||6" COMFORTBATT||1 layer, 1/2" CDX Plywood||Tyvek Home Wrap||N/A||27|
Part 3: Tips for soundproofing from environmental noise pollution
To soundproof your building from environmental noise pollution, consider the acoustical performance of every assembly on the building envelope. Noise travels through the weakest sections of the building envelope, meaning the effectiveness of a high-performing wall or roof system may be reduced when the rest of the building is not equally designed.
In many cases, unwanted noise can enter the building under a door, through a window, your roof, or a connected exterior wall. This type of noise is called flanking noise. The assembly and its connecting features should be tested during the planning stage of a project to minimize flanking through the building envelope, especially the parts of the enclosure that are known deficits in a wall or roofing design (e.g. windows and doors).
Review and consider all of the following applications during the planning process of your next project:
- Roofing: Stone or mineral wool insulation has superior sound abatement properties, which is essential when designing today’s roof system. High-performing systems using stone wool insulation can add mass layers to assist with improving the sound attenuation properties of the assembly. Research has shown dense acoustic roof insulation, including stone wool flute fillers, are an effective solution to reducing sound transmission through a roof.
- Connecting assemblies: Areas of deficiency for façade sound transmission paths can be things such as roof soffits, vents, fans, air sealing details and probably many others depending on the type of façade system being constructed.
- Exterior wall systems: How can you reduce exterior noise coming in through walls? For starters, the addition of better acoustic performance in your exterior wall assemblies comes down to the type of construction and the building materials being used. All insulation for exterior walls should be designed to meet or exceed energy code. Soundproof your exterior walls using the right materials that offer improved acoustic performance (like stone wool) while still meeting the other demands of your assembly to create cost-effective solutions and more livable spaces. For example, foam plastic insulation with multiple layers of gypsum could be optimized with stone wool insulation and a single layer of gypsum.
- Windows and doors: Windows are one of the largest deficits in building wall design for acoustical control and heat loss. Pay careful attention when designing the windows and their connections to the wall elements for a high-performance wall system. Consider the type of window (we recommend double- or triple -pane for best soundproofing), the pane thickness and how it will be installed.
The higher the likelihood of exterior noise (i.e. traffic noise or aircraft) the more assemblies including the roof-ceiling and exterior walls should be focused on sound isolation. All exterior penetrations and joints between components should be sealed as required for thermal performance which will also improve the building acoustics.
The common thread throughout these tips for soundproofing from environmental noise pollution is using stone wool which provides a high-density acoustic insulation solution. This makes the insulation resistant to airflow and excellent at noise reduction and sound absorption. This means that even the loudest infrastructure will sound quieter for occupants living, working or learning inside the structure. See below for an overview of three assemblies focused on the exterior walls and roof systems of the building and demonstrating which combination of construction and materials provide the highest levels of STC, OITC, and R-Value.
1. An acoustic baseline for wall assemblies
2. High-performance enclosures: stone wool insulation wall systems
3. High-performance enclosures: stone wool hybrid roof systems