soundproofing walls

Soundproofing a wall

The most common type of wall to soundproof is drywall.

sheets of drywall

Drywall is made of gypsum and paper, basically chalk and paper. The STC rating of drywall is actually very low. The STC value of two sheets of drywall, fastened on studs is approximately 33.

what is drywall made of

Below is a table that outlines the STC rating of different materials

STC values

Below is a table of the STC values of construction Materials.

STC values of construction material

Based on the information above, a simple interior drywall wall does not impede the sound of voices travelling through it, even with insulation in the wall. What is required is dense material designed to stop the sound waves or sound vibrations. By using a thin dense material with the same STC value such as mass loaded vinyl, inside the wall, the STC of the wall, has increased significantly.

This is preferred method of soundproofing, as opposed to using a double layer of drywall, because it doesn't change the physical footprint of the room, and there is no impact to room sizes, fixtures and finishings.

See video below for using Acoustiblok soundproofing material, an alternative to the generic mass loaded vinyl.

The application and installation of the soundproofing products are just as important as the products themselves. Installing the products improperly may reduce their effectiveness. For example, sound blocking material should be decoupled from the surface, to inhibit the transmission of sound to the adjacent surface.

The use of resilient channel and sound absorbing rubber products are commonly used in the decoupling surfaces.

When you think of soundproofing a wall consider all the ways that sound may be travelling. Sound also travels under the wall, through receptacles, around doors, through doors, through hvac, through ceiling tiles, through the window, along a common radiator etc.

Determine which part of the wall the sound is travelling through the most, and address that first. For instance doors usually have a gap of 1/8" to 1/4" between the frame and the door, seal that off.

Determine if sound is travelling along the hvac ducts, they are tin and conducive to transmitting sound. Wrap those pipes with soundproofing material.

If sound is travelling under the wall, you would have to take the wall down to correct that problem.

Determine if sound is coming through the receptacles in the room, you can buy sound putty to correct this.

It may appear that sound is travelling through a wall, when in fact it may be coming through the ceiling tiles installed in the ceiling.

Don't assume sound is bleeding into the room from the walls. When investigating where the source of the sound is, there is no substitute for the human ear. Simply get out a ladder, get on your hands and knees and get close to the different parts of the wall and listen.

To find soundproofing products for your house, office, commercial or industrial space, call Jim at

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