I’d make sure you can actually modify that door before attaching anything to it. Doing so may be throwing your security deposit away and aggrevating your landlord.

Good point, Steve. If Ricardo isn't permitted to make even semi-permanent changes to the door, here's a somewhat crazy idea. Build a freestanding temporary sound lock behind it!

This would be a complete U or L shaped enclosure standing behind the door, maybe 3-4' square, with its own soundproofed door on the inside.

Using screws for easy teardown later, assemble it from 2x4 lumber, drywall, and a solid prehung door. Don't anchor it to the building structure, just let it sit on the floor and butt up against the wall and ceiling, with rubber seals for soundproofing at each contact point.

You could then soundproof THAT door as much as you wish. But you might not even need to.

If necessary, you could even use double drywall (hung with screws and not taped) for better sound deadening. I wouldn't use green glue between the layers as you might in permanent construction, though. That would make the drywall too difficult to remove when it was time to leave the apartment.

Mad, I know, but it just might work.

@Steve J @DavidR

I own the place, so it is not an issue. The only issue would be if I modify the outside of the door.

I've heard a lot about using drywall, but my concern is the weight, my door is heavy, but with a sheet of drywall it would become way too heavy in my opinion. Just as FYI, for the 2010 earthquake, the door jammed, imagine if it were to weigh twice as much!

I was thinking for of a foam, and what kind of framing could support the hinges.

I will upload some pictures once I'm back from a business trip.

Cheers.

Foam won't block noise. You need mass to block noise. Before the introduction of MLV, lead was commonly used.

Start by installing the rubber gasket and threshold seal. If that doesn't give you enough relief, then go to MLV or other dense material attached to the inside of the door.

Double door sound locks are another common isolation method used in studios. So, if mass is a problem for your present door, then maybe you should consider trying something like my "plan B" above. Be sure to gasket both doors.

Since you own the place, you could install it permanently. If it's to be a permanent part of the building, I'd recommend contracting with an acoustic engineer to design it, so that it complies with code requirements.

In my opinion maybe you should try with sound blankets or noise curtains. It could help you to optimise space by providing control over the sound. They can be of different sizes, as well as different materials. Unlike other sound absorption solutions, their level of performance can be adjusted according to noise level. They represent a great solution, regardless of whether it's about separation, isolating or preventing noise.

For example, some of soundproofing stuff can be seen here: Sound Absorbing Blankets & Sound Curtains.

nykmark is on the right track .... the downside is that they are aesthetically "fascinating". Here

Interesting. Nykmark has only 2 comments on Gardenweb. Both of them reopened old threads to post what's hard to interpret as anything but spam for a Chinese manufacturer of soundproofing material.

I may have missed something, but at a glance, the links posted don't appear to be of much use to an end user or homeowner. I wouldn't try it, but maybe you're OK with direct-ordering hundreds or thousands of dollars' worth of goods of unknown utility and quality from a Chinese company of unknown reputation.

Ricardo, if you're still monitoring this thread 3-1/2 weeks later, I suggest that you talk to a local sound control service. If you can't find one on the web or in the phone book (remember those?), you might call up the audio tech person at a nearby home theatre dealer, recording studio, or radio station, and see if you can get a reference.

If you'd rather go the DIY route and order sound control material online, I really don't recommend trying to direct-import it. A web search should turn up several legitimate and experienced national dealers who can supply proven products.

I can't vouch for the dealer Joe links to, but it sure looks safer to me than some anonymous Chinese operation. You may think otherwise.

Either way, good luck.

I was not endorsing the product linked by nykmark except that in my own search, I found these door blankets and they were unique but pricey so I can't even vouch for the one I posted. It was a random find on the Internet and an option that the OP might explore. Please, do your research.

I apologize if it came across as an endorsement for a specific product, that was not my intention.

You could go to a lot of trouble trying all the above and find out it does not work or the sound is just coming through the walls. Get some rolls of foam weatherstripping with adhesive on one side and line the door frame. Get one of those movable cushion things (like a bean bag) that blocks air for the bottom of the door. See how that does and go from there.

Foam weatherstripping and a draft stopper might help a little, and maybe give you a hint of what's possible, but they're not really dense enough to do the job well. You need a real sound blocking gasket and threshold sealer. You can get them in a door soundproofing kit.

I spent over 4 decades working in studios behind doors soundproofed this way. It does the job.

The door itself also has to be suitably solid, heavy, and dense to begin with. See above for some ideas of how to improve an ordinary solid core door.

Here is one example of a door soundproofing kit. Also look here to see how a proper door gasket differs from simple foam weatherstripping, and here for a threshold sealer.

NOTE: the links are for information only. No endorsement is intended. To find other vendors, search for "door soundproofing kit."

Well if you really want to get it soundproofed and with an endorsement of a product, hang some Insulquilt over the door.

https://www.insulquilt.com/