Soundproofing a door comes down 2 things:
- The materials in the door
- Filling space around the door
Let’s start with the first:
How The Door Is Made
Size matters when it comes to sound deadening. A thicker door will reduce the amount of sound that comes through.
Interior doors are typically hollow and have a STC rating less than 20. Recessed decorative patterns make the door even thinner.
Get a door with a solid core interior. You can use exterior, back-door style doors for your interior doors.
If you need additional soundproofing, apply mass loaded vinyl (MLV) to one or both sides of the door.
Filling Gaps Around The Door
Soundproof Below Your Door
The gap at the bottom is typically the largest. Get a door sweep designed for soundproofing. Make sure it lightly touches the floor. You can attach a small piece of wood to the bottom to “extend” your door before adding the door sweep if it is sitting too high.
Soundproof The Door Frame
The door frame is another weak point for sound.
Remove the molding and apply soundproofing rubber strips in any gaps between the door frame and wall frame.
Follow up with acoustical caulk (Green Glue) to fill in any remaining holes and reinstall the molding.
Where the door meets the door frame is another spot that usually needs a little help. There are 2 ways to accomplish this:
Closed-Cell Foam Tape
This is the cheaper option, but depending on use, the tape will compress and wear down over time.
Apply closed-cell foam tape to the side of the door frame that the door closes into. This works well but won’t last as long as a more permanent solution:
Adjustable Door Gaskets
These are pricier but will last much longer and provide better soundproofing. Because doors can shift over time, using adjustable door gaskets allows you to easily adjust them if the gap widens.