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Reducing Sound Transmission

The location of a building has a very large influence on noise levels. Those in high sound areas near airports, freeways, transit systems, and high wind patterns are most easily affected. Airports are huge contributors to environmental and noise issues, and although progress has been made in regulating airport noise, it remains a major factor for site selection and the need for noise reduction measures for both residential and non-residential structures.

In some cases noise can be reduced or muffled with earth-berm barriers for lower levels before it reaches a building, but in most cases it is the building materials and sound attenuating windows and doors that help reduce the amount of unwanted noise penetrating all levels of a building.

Acoustical Properties of Glass Types

This chart shows various levels of sound attenuation for different types of window and door glass. The higher the STC rating, the better the capability of the glass type to provide insulation against sound.

A modern double-pane, weather-stripped window or door offering 3-mil, double-strength glass, has a 28-to-32 STC rating. By comparison a 2-foot-by-4-foot wall with a single layer of 5/8-inch drywall with an empty cavity has an STC rating of 33. The same wall filled with insulation has an STC rating of 39 and a solid wood door can have an STC ranging from 35 to 45. To push the STC past the mid 40s, requires combining several techniques and conditions including: creating air space between panes, layering and laminating the glass, checking the method and quality of weather stripping, evaluating framing and storm panels and verifying installation methods.

Improving the STC rating of a window or door depends on the structure, its location, and factors such as the difference between flexible and solid installation, air gaps, and the addition of weather stripping. Specifications for airport locations, and other noisy areas, for example, often require STC ratings between 35 and 45. If an exterior background sound level is 75 dB or slightly higher than the general noise produced in an office environment, (experts recommend) an interior partition with an STC rating of 40 should be specified to provide the proper sound control. However, the most critical step is to determine the degree of tolerable noise within the structure as well as the needs of the owner and occupants at the outset of a project.

In determining specific STC ratings of glass and a window or door assembly performance to certain ASTM standards should be required including:

ASTM E 90–90, Sound Transmission Class, is a laboratory test method for measuring airborne sound transmission loss of building partitions such as walls of all kinds, operable partitions, floor-ceiling assemblies, doors, windows, roofs, panels, and other space-dividing elements.

ASTM E 413–04, Classification for Rating Sound Insulation, covers methods of calculating single-number acoustical ratings for laboratory and field measurements of sound attenuation obtained in one-third octave bands.

About Marvin Windows and Doors Marvin Windows and Doors is a premier manufacturer of made-to-order wood and clad wood windows and doors. The company’s Made for you® philosophy enables Marvin to offer the industry’s most extensive selection of shapes, styles, sizes and options. With each product made to a customer’s exact specifications, there are no stockpiles of standard sizes, nor warehouses of finished product.