Soundproof a Room With Caulk By Reducing Airflow

Man using caulking gun, close-up
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Perhaps it’s the dog or new baby in the other room. Or maybe your partner likes to watch TV in the other room while you’re trying to sleep. Whatever it is, sound is bothering you and you need to soundproof your room.

While soundproofing involves a battery of several tactics—some of them quite involved—there is one surprisingly easy and inexpensive way to cut down sound: filling in cracks. For the cost of a couple of cups of coffee at Starbucks, you can reduce outside sound by as much as 15%.

Reduce the Airflow, Reduce the Sound

Professional soundproofing is highly expensive. It involves adding insulating materials and extra drywall—or replacing existing wall materials with new and more expensive materials. It often involves other people and special tools: contractors and consultants and decibel meters. All of that means more expense.

But one trick that is used to cut down on the transmission of sound is to reduce airflow. Physics tells us that sound is borne by air, since sound is vibrations traveling through the air. Wind promotes the transmission of sound even more.

Think of the room that you want quieter as having air flowing into it from the outside. How is the air escaping into your room? The gaps between outlet boxes and drywall are one area. Another area: gaps under doors. If the sound is coming from outside, airflow coming through or around windows is another place to look.

It doesn’t seem like it should, but even these pencil-thin seeps of air carry sound. Remember, sound is caused by vibrations traveling through the air, right?

The type of thinking that is used to detect cold air coming into your house is the same type of thinking needed to detect sound carried by airflow.

Imagine an incredibly thick, apparently soundproof wall. If that wall had a crack running through it, even it would transmit sound to the other side.

How to Block Sound Carried by Air Seepage

Caulk, weatherstripping, and insulation are used. Suggestions:

  • Caulk around outlet boxes for a tight seal.
  • Install weatherstripping along the leading edge of windows.
  • Place weatherstrip under doors.
  • Fill cracks in drywall with caulking (or better, drywall compound, and then painting over it).
  • Fill in cracks in floorboards.
  • Put up storm windows.

Recommend: White Painters' Caulk. You'll most likely want to use what is called white painter's caulk. There is a big difference between this and the silicone kitchen/bath caulking. It's easier to work with and can be painted over.

How Much Sound Can You Block?

Sound Transmission Class (or STC) is used by sound consultants to measure sound levels. STC is not the same thing as decibels. STC is just a general range, not a precise measurement.

In the 30-35 STC range, the person in the next room who is talking loudly can be heard in the intended quiet room. By merely caulking, you can reduce that STC rating by about 15%. So, the loud voice is mitigated, but not stopped.

It is worth caulking to reduce the sound transmission, and you will probably be surprised at the results.