Soundproofing a Door - The impact of Air Flow on Sound Transmission We get calls and emails all the time regarding how to block sound through walls, ceilings, floors, and windows, yet it surprises me how often doors tend to get overlooked. Soundproofing a door with door seals is an important aspect to soundproofing a room.

You can add all the layers of mass-loaded vinyl and gypsum to your wall that you want. However, if you have even a 1% gap opening when the door is closed, you are losing a substantial amount of the sound-blocking capability. Yes, that’s right, a 1% gap opening can reduce door soundproofing effectiveness by 50%. Below are some proven methods for soundproofing a door assembly using door seals.

As the picture illustrates, different size openings are a factor when it comes to airflow versus sound transmission.  As you can see, a smaller opening reduces the amount of airflow.  However, it does not reduce the amount of sound transmission. So, how do we seal the door and defeat the 1% Rule?  Read on…

Door Seal Kits

Acoustic Door Seal Kit

Acoustic Door Seal Kit

Door seals kits can be a very effective means of stopping sound from getting through a door. For a standard door, there are basically three parts that are needed. The door must be sealed on all four sides. A kit includes automatic door bottoms and neoprene door jamb and a threshold to engage the door bottom..

For standard-sized (3’0″ x 7’0″) doors we make a door seal kit that gives you all the necessary parts above that are pre-cut and ready to install. In addition to the parts referenced above, Astragal Seals can be used in the case of a double-door setup where you need to seal up the area where the two doors meet in the middle.  These seals are available for double doors with two active leafs or one active leaf.  One type of door that cannot be sealed well is a pocket door.  Because of the way this type of door operates, it is next to impossible to seal efficiently. A pocket door is not recommended for an application where sound transmission is a priority.

Automatic Door Bottoms

Our automatic door bottom / door sweeps utilize a concealed flat spring mechanism. This activates when the door is closed, lowering a neoprene seal insert against the floor or saddle. An Automatic Door Bottom can be attached to the bottom of the door to seal off the bottom edge. The advantage of an automatic door bottom over the typical door sweep that you can purchase from a building supply store is that the automatic door bottom is mechanical. Closing the door engages the plunger mechanism on the side which drops the seal to the floor. This gives you a nice tight seal whenever the door is closed.  Door sweeps do not seal as well and can allow for small gap openings like those mentioned at the beginning of this post. Automatic door bottoms are available in surface-mount, semi-mortised, and fully mortised versions. Choose the look that best matches your application.

Door Jamb Seals

This acoustical seal features our unique compress-o-matic design with a sound absorbing neoprene rubber gasket that compresses to form a tight seal as the door is closed. the Jamb seals attach to the sides and top of the door jamb. These are available in versions that either attach to existing door jambs or door frame.

Meeting Stiles for Double Doors

Acoustical door astragals are designed to effectively seal off the air gaps that create sound leaks where the doors meet.

Door Thresholds and Saddles

These acoustical door thresholds, commonly called saddles, feature a neoprene bulb fitted with a protruding rubber finger. This helps to correct any misalignment in the door as it is closed. In most cases you will want to use a good quality Threshold in conjunction with the automatic door bottom.  

This way the door bottom has a solid surface to seal onto. If the area the door bottom is sealing to is a hard surface like concrete or tile, you may be able to get by without one.  If it is carpet you are definitely going to want a threshold and even in the case of hard flooring substrates mentioned previously, a threshold is still recommended for the best results. Like the door bottoms, thresholds can be made in a number of different ways; some are simple and flat while others can be taller and have seals of their own to create a double seal when used in conjunction with the automatic door bottom.  The former are typically used in high traffic areas or when ADA certification is needed, while the latter are typically used in applications involving high noise levels like recording studios, server rooms, or industrial applications.

Cam Lift Door Hinges

The can lifting action greatly improves the sealing characteristics along the door perimeter, lifting and lowering the door with the swing.

Click below to see videos about door seals.