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Soundproof Hollow Doors: Cost-Saving Materials & Methods On Filtering Outside Noise

hand holding a knob of white door

Last Updated: May 10, 2024

We can't do without hollow core doors.


They are cheaper to install as interior doors, and they serve the purpose.

Their only downside, and the reason you want to know how to soundproof a hollow door, is the empty cardboard space inside that makes them transmit sound.

Before you think about replacing a hollow door with a solid core one, try soundproofing it.

So here’s to it! 

How To Make A Hollow Door Soundproof In 7 Ways

When you compare the cost of getting a new door, plus the cost of taking down the first one, it's better to soundproof what you have.

So, here’s how:

1. Fix A Door Sweep

wood door sweep for wood door

The gap at the bottom of your hollow door is enough to let sounds through and disturb the peace. Block that space with a plastic or rubber strip. There are many types of door sweeps.

The strip door sweep is the easiest to install because you can get a design to stick on the door frame with adhesive.

If you're worried about scratching the floor as you open and close the door, you can install a bristle door sweep instead.

Just like the name suggests, it has brush-like bristles, unlike the strip design we've mentioned earlier.

The third type in the market is the under-door sweep, which is the best if you're soundproofing a hollow door for privacy. It seals the space under the door completely.

For instance, it's the kind you'd install on the master bedroom door. Even a nursery may need such soundproofing if the noises in the rest of the home disturb a baby's sleeping pattern.

Note: Installing a door sweep will also prevent bugs and dust, so there's more to reap from this process.

2. Sealing Gaps And Cracks

For old doors, the answer might be sealing cracks and gaps. Before you apply a sealant, pinpoint the door cracks.

First, switch on the lights in the hallway. Next, enter the room with a hollow door, close the door and the curtains. You'll see the cracks on the door to know the amount of sealant needed. If there are many cracks, getting a new door might be the best solution.

Why? After applying soundproofing sealant on all the door cracks, it'll be an eyesore, so you'll have to paint the whole door.

If sealant doesn't solve the noise problem...

3. Soundproof Hollow Doors With Weatherstrips

man putting strips for door

Yes, they don't work on windows only as you can seal your door with weatherstrips. These self-adhesive strips make the process easy on how to soundproof a room from outside noise.

Nonetheless, the surface preparation process is tasking because you must clean the door thoroughly before laying the strip. Let the surface dry, then peel off the strip as you stick it on the door.

Start with the top as you move down, covering a small part of the perimeter where the door meets the frame. It is an effective way of how to keep a door from slamming.

Onto another simple solution that doesn't need sealants and adhesive strips...

4. Soundproof Curtains

It's an affordable option, one that is also aesthetically appealing. The only drawback of soundproof curtains is the gap they leave between the door and the door frame.

You'll have to be creative to seal this gap, or you'll still hear the noises you're trying to drown.

One way of doing that is using double thickness by installing two curtains instead of one.

Or install a...

5. Soundproof Blanket

man holding a black soundproofing blanket

The fiberglass fiber inside absorbs sound. It's not aesthetically pleasing like curtains, more so when using it on one of the high-traffic interior doors.

It's one of the best ways to insulate a hollow door like the entrance to a recording studio.

When you get a soundproof blanket with grommets, you don't need velcro. An alternative to the soundproof blanket is a moving blanket because it's cheaper and available easily.

Let's look at a few more solutions:

6. Use Sound Absorbing Furnishings

The two best ways to block sounds are to absorb or dampen them. Maybe your room needs more furniture and area rugs to drown the noise.

It's worth a thought because the door is part of the whole structure, so if the room can take in the echoes, the door and walls will do the rest.

Start by adding an area rug to absorb the echo or use an entryway rug on either side to soundproof apartment door.

Onto one technical solution...

7. Soundproof Hollow Doors With Foam Insulation

By doing this, it'll no longer be a hollow-core door because you'll fill the cardboard interior with foam insulation.

It's an affordable way to soundproof a  door, so don't worry so much about changing the interior design of the door.

To get the foam into the door, drill holes on the bottom edge of the door to fit the straws of the spray foam can. You may have to remove the door lock to view the filling process to avoid leaving gaps. After filling the hollow, seal the holes you made.

Here's a guide on how to do it on doors or windows:

FAQs On How To Make A Hollow Door Soundproof 

Is Soundproofing A Hollow-Core Door With Cellulose Possible?

Yes, cellulose is better than other insulation materials because of its high density. It raises no health concerns, and it fills the hollow sufficiently.

Does Soundproofing A Hollow Metal Door Have The Same Process As Wooden?

Yes, some of the solutions you'd use on a wooden door, mentioned in the section above, can also work on a metal door. For instance, you can drape soundproof curtains or a soundproof blanket over a metal door. 

You can also drill some holes to fill the hollow with vermiculite, a lightweight loose-fill insulation material. There might also be cracks to fill on the door casing, where you can use neoprene rubber strips, rock wool, or fiberglass.

One solution that you'll probably use more on metal than wooden doors is installing door gaskets. They are expensive, but they have a firm grip.

Now you have ideas on how to soundproof a hollow door. In conclusion:

Final Thoughts

If you soundproof the door and forget the space beneath, you'll still hear noises. Hence, a door sweep at the bottom of the door is necessary.

Another area you must remember is the space between the door and the door frame. Therefore, when soundproofing with a soundproof blanket or curtains, you must extend these materials slightly to seal that space.

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