There are two main things to look out for when soundproofing any type of door. Density - the door should be dense enough to block airborne noise. Sealed perimeter - the perimeter of the door should be well sealed and should not allow sound to escape through openings or gaps between the door and the wall. For soundproofing a hollow core door to get truly good resutls, here are the steps you should follow:

1. Replace your door with a solid core door
2. Seal the perimeter of the door with a door seal kit

Hollow core doors lack both of these key soundproofing qualities. So, if you want to improve the soundproofing performance of your door, you will either need to replace the door entirely or make some significant additions to the door. There multiple different approaches to soundproofing a solid core door we recommend. Here are the steps you should take for soundproofing a hollow core dore:

Step 1: Replace the Door!

We highly recommend that you chuck out the hollow core door and install a solid core one instead. We know this may not be the answer you were hoping for, but simply installing a more dense solid core door will give you 10 more STC points right off the bat. If you care about how soundproof the door is, replacing the hollow core door is absolutely essential! Once you have a solid coor door, you can take steps to have an even better soundproof solid core door as well!

Step 2: Seal Around the Edges

If replacing the door entirely is not an option, your next best bet is to seal any gaps around the edges of the door. Sealing the gaps on a hollow core door will NOT soundproof your door, noise is still going to pass through the door itself because it is not dense enough. But you can expect to reduce noise by a few decibels. We wouldn’t recommend one of our professional door seal kits, because frankly… it’s overkill and not worth the effort on a hollow core door. We recommend our gasket tape or our Sound Lock Gasket Kit for cost-effective results. This will help reduce some sound, but typically only by about 2-3 decibels.

Alternative: Use BlocknZorbe on a Hollow Core Door

BlocknZorbe is another material that can be used on a hollow core door. BlocknZorbe is a much more lightweight material than mass loaded vinyl, so it is much easier to install and will not compromise the functionality of the door. Mass loaded vinyl has a much higher STC rating than BlocknZorbe, but BlocknZorbe will still add 8-10 STC points to the door. As with other treatments, you’ll still want to seal the bottom of the door.

Here are a few alternative methods:

Attaching Mass Loaded Vinyl onto a Hollow Core Door

One thing some homeowners will do to add density to their hollow core door is installing mass loaded vinyl onto the door. Although MLV will help block noise and reduce the amount of sound heard on the other side of the door, we don’t generally recommend this method for a few different reasons.

• Mass loaded vinyl is very heavy, so the MLV can fall off the door unless securely fastened. The extra weight on the door also can cause issues with opening and closing the door.
• It is a pretty labor-intensive project to install mass loaded vinyl on the door
• The sound reduction you get from this isn’t as good as upgrading to a solid core door

That being said, mass loaded vinyl can be added to a hollow core door as an alternative soundproofing solution. This method combined with an affordable door sweep will modestly improve the STC rating of your door.

Sealing Off the Entire Doorway Using Mass Loaded Vinyl or Soundproof Blankets

You can also use mass loaded vinyl or a soundproof blanket like our Quiet Quilt Indoor Soundproof Blankets to seal off the doorway entirely. If you do not plan to use the door at all, this is a decent option and will actually soundproof the door well. Get a roll of mass loaded vinyl or a Quiet Quilt soundproof blanket and install it over the door with an airtight seal. This will create an effective soundproof barrier at the door opening. Keep in mind that if you do this, the door will no longer be useable, because you are essentially turning the hollow core door into a wall. We most commonly see this method when a door is not needed, such as with an in-law suite or Airbnb rental space. See this video for an example of mass loaded vinyl used to completely seal off the door using industrial strength magnets.

Not every door is made with soundproofing in mind. Before you begin soundproofing a door like your interior door, it is important to distinguish what kind of door you have. You will either be dealing with a hollow core door or a solid core door.

Hollow Core Door

Hollow core doors are made of thin wood and have a hollow interior, so they are generally very lightweight. Hollow core doors lack density and are notoriously bad at blocking sound. Hollow core doors are common in residential homes, because they’re the most cost effective way to construct a door. You’ll know if you have a hollow core door based on the weight. To check your door, tap on it, pick it up, or swing it back and forth. A hollow core door will have an STC rating in the low 20s.

Solid Core Door

Solid core doors are more dense, and do not have a hollow interior. The center of the door is filled with wood or wood composite. Solid core doors are noticeably heavier when compared with hollow core doors. Even without additional soundproofing materials, solid core doors are MUCH better at blocking noise. They are not entirely soundproof by themselves because they still have gaps at the bottom and around the perimeter. But with an STC rating closer to 30, they perform well when compared to hollow core doors.

For an entirely soundproof door, you’ll need to add a Sound Lock door seal kit or upgrade to our Sound Lock Soundproof Door, which has an STC rating of up to 56!

If you are serious about soundproofing your hollow core door, the only real option is to replace it with a solid core door one. There is no other way to make a significant difference in the amount of sound traveling through your door without also compromising the door’s ability to be a door. If you are interested in the cost of soundproofing a door, check out our article on the topic. While we walked through some ways to slightly improve the soundproofing abilities of your hollow core door, remember… these methods will only make a small difference.

If you have any more questions on door soundproofing or any other soundproofing topics, feel free to reach out to us!