Covering up useless doors

[inasilentway]

Forgive me if these are obvious questions, this is my first foray into this forum and DIY room treatment.

I just moved into a great new apartment (cheap, comfy and close to work), and would like to continue my long history of bedroom recording. The problem is that, besides the door actually I go in and out of, there are two doors that each lead to one of the two adjacent bedrooms (a relic from the past, I guess? you can pass through all 4 of the bedrooms in this apartment without using the hallway via these doors). They are in fact completely useless, since we have no need to go directly into each others rooms, and all they do is leak sound.

Compounding the problem is the fact that these other roommates are guitarists, and I can hear both of them practicing/listening to records/snoring/etc, and they can hear me working on tracks (obviously quite annoying if I'm trying to nail a part!). I've switched to headphones but their general existience noises bleed into open mics, and any sort of late-night DI hollowbody electric guitar or Wurlitzer playing is out of the question since the clacking of those instruments passes through these paper-thin doors (to give you an idea, if I'm not listening to music I can hear one of them strumming his Strat unplugged, and I can hear whenever either of them are typing out something on their Mac keyboards).

The walls are pretty solid, and the doors are definitely the cause of an overwhelming majority of the bleed. Here is my question: Can I just build two huge panels out of 703 to cover these doors up, so that I can remove the panels when I move? My plan would be to build a plywood frame, cover it in fabric, and hang it so that it completely covers the doors (the doorknob on one would probably have to be removed due to way the frame is), and then make a third, much smaller one for the door I actually use to keep the sound from bleeding into the hall. Would these panels be effective? Is there some other method that would be better?

I'm not looking for treatment inside the room (though that would be a nice bonus, but the room sounds pretty good as-is since it's fully carpeted, has non-parallel walls, and I've arranged bookshelves as diffusors), I'm more looking for broadband two-way soundproofing so that we don't drive each other nuts. I really like this apartment but as it is I have no peace and quiet for practicing or recording. Any help at all would be greatly appreciated!!

[kslight]

Sounds like typical apartment/roommate problem...not sure that you'll ever find a solution that's effective and you're totally happy with (besides moving into your own home). There is NO privacy in most shared apartments, and as the rumours go even people in different units and floors than you are probably heard in their daily "activities"...unavoidable.While the doors are certainly part of the problem the walls and ventilation system and proximity to your roommates is also a factor, which cannot be practically solved in a rented space...the most effective solution is to schedule your practice times or work out alternate forms of recording (DI).

[jnTracks]

kslight is probably right but if you really want to try something anyway, it's going to take more than fiberglass. absorption is important but if you want to stop sound transmission you need dense mass.

for example, heavy exterior doors stop a lot more sound than hollow core doors (probably the kind in your apartment)

you may find that it's a ton of work and material to get a %30 change in sound.

[inasilentway]

kslight is probably right but if you really want to try something anyway, it's going to take more than fiberglass. absorption is important but if you want to stop sound transmission you need dense mass.

It's certainly not my first time in an apartment, I've been renting places both excellent and crappy in this city for 6 years and happily recorded the whole time. I can put up with a certain amount of sound leakage for sure. But this bleed is scary detailed like I've never experienced, as in keyboard typing in the next room bleeding into a condenser, and it's definitely localized to these doors (problem diminishes when I hunker down in an opposite corner, but I'd really rather not have to if I can treat it somehow). I definitely have experimented with moving mics around, and am trying to record as much stuff DI as I can, but without some kind of treatment I'm going to lose my mind.

What kind of material would give me mass while still being non-permanent?

[Snarl 12/8]

If it was me, I'd try creating an airtight plug using multiple layers of sheetrock. Like, green glue together 3 layers of 3/4" sheetrock that practically friction fits into the door frame. I don't know what I'd put around them to make it hermetic. Multiple courses of weather stripping, I'd imagine.

Have you made sure to seal off the gaps under the doors? Sound can get through the tiniest crack. Are you in a cold climate? They make these long skinny sandbad type things that are designed to be thrown against that crack to seal out the wind. Or you could make your own out of something.

[500Norsepower]

You might be able to seal the air space around the unused doors with' backer rod' (tubular foam 'rope') found at home improvement stores for a few dollars per 20 feet of material. You could do all those doors for about $10 (US). Its used to shove in cracks when caulking to reduce the amount of caulking used and to improve seal around doors and windows. Its cheap and comes on 1/4 inch and 5/8 inch diameters. May help somewhat and would be a cheap first start; definitely cheaper than replacing the door. Worth a shot.

[Rod Gervais]

You might be able to seal the air space around the unused doors with' backer rod' (tubular foam 'rope') found at home improvement stores for a few dollars per 20 feet of material. You could do all those doors for about $10 (US). Its used to shove in cracks when caulking to reduce the amount of caulking used and to improve seal around doors and windows. Its cheap and comes on 1/4 inch and 5/8 inch diameters. May help somewhat and would be a cheap first start; definitely cheaper than replacing the door. Worth a shot.

Won't help.

The seal for windows/doors is thermal in nature - designed to minimize drafts - backer rod with caulk (form an acoustic point of view) is a seal used for cracks that are created at the edge of large mass assemblies - even backer rod and caulk will not (perceptional)) help with light mass assemblies - it takes mass to isolate sound to any degree.

BTW - just for the record - backer rod is NOT used to reduce the amount of caulk used - it is used because caulk will (lengthwise in the joint) is there is a 3 sided joint, this due to movement that takes place in structures.

Only a 2 edged joint caulk has a high probability of success - 3 sided joints (joints without backer rod) will fail in the long run.........

Rod