Can You Hear Me?

Party walls. Fire walls. Area Separation walls. Shaft walls. Demising walls. These terms are often used interchangeably when discussing the walls constructed between townhomes in residential construction. Their primary and most important function is to provide fire-rated protection between dwelling units, and there is a myriad of options to achieve the required fire ratings, including widely-available products like Type X gypsum board and unique board products that utilize proprietary coatings.

When weighing the options, builders often consider cost, ease of construction, overall wall thickness, and durability against the elements. However, one important consideration that is often overlooked that should be a priority is “how resistant to sound transfer is the party wall?” Frankly, this is the #1 thing that homebuyers will notice once they move into their new home. You can be sure that they will have an expectation that they will not hear their adjoining neighbors’ conversations, music, etc. And if you don’t do this right the first time, this is something that is difficult to improve post construction.

So, when weighing the various options for party wall construction, be sure to analyze the Sound Transmission Class (STC) rating of given assemblies. The STC rating scale (where a higher number correlates to greater resistance to sound transmission), gives builders insight into what their homeowners are likely to experience in their homes. When the rating is considered, a threshold of 50 is the most common answer I hear, but, as seen in the chart below, loud television and music are still audible at this level. This could lead to having some very unhappy homeowners.

So, a small step “up,” –  choosing assemblies with a rating of 60 or above – will result in a better performing wall from a sound perspective, and can provide a marketing opportunity for your next townhome project, as no one wants to hear the loud party next door!