One thing you see posted a lot in this forum is the importance of a good door in improving sound isolation for a theater room. I thought I would post my thoughts since last night I finally mounted the door on my theater room, which just has carpet and trim left to go.

The room has double walls, double drywall with GG, DC04 clips on the walls/soffits, RSIC-1 clips on the ceiling, and only caulk-filled penetrations for romex (outlets and lights are surface-mounted or in columns). For ventilation, I built two baffle boxes where the air makes 12 90° turns along a path lined with 1” Linacoustic. So I think I went to as much sound reduction effort as I could.

Last night I hooked up some speakers in the room (no sub) and cranked some music at a volume higher than I would normally listen (90-95 dB average volume). I was impressed with how well the construction did. Putting my ear to the baffle box, I can only hear the music faintly (unreadable on my RS SPL meter), even though the speaker is only sitting 3 feet away. It is hard to hear much of anything in the bedroom, which is not quite directly above the theater, but is only offset by a few feet.

What you do still hear is a lot of sound through the door, and that sound makes it upstairs to the family room pretty easily (no door to the basement). My door is a solid-core 1.75” thick wood door with a bottom threshold and a neoprene seal. However, I have not yet put weather-stripping on the door stop and I have a small gap under the threshold of the door (concrete slab has a ¼” slope) that I will fill with acoustic caulk. I have also not yet installed the second, communicating door yet.

So, hopefully things get better when sealing up the first door better and installing a second door. I’m very pleased with the rest of the construction.

Hi Kevin,

Your exploration of this issue will be interesting to everyone. Thanks for taking the time. Doors are such a large surface area and pale in performance comparison to the walls usually. So having you assess the improvements is intriguing.

I took TWO MDF solid doors and GG them, screwed them, and finished them last week. Put an exterior/compressable weather striping around the entire door jam. We are going to tweak the door and put a beefier threshold in sometime this week, but I can tell you right now that 98% of the sound is gone. With a loud test stereo in the room you can only hear muffled sound in the halway on the other side of the door.

Twist,

You were able to hang these doors OK? That's not a simple task!

That's impressive, twizted - I'm glad it worked out for you.

I thought I'd update this thread since I got the secondary door installed and the primary door sealed up. For easy measurements, I put on some Godsmack (fairly constant volume with a lot of base) and adjusted the sound to 100 dB at the listening position.

In the family room, standing directly above the speakers, I measured 70 dB and in the bedroom (above and offset ~10 feet from the speakers) I measured 60 dB.

Bass obviously penetrates far more than treble - I repeated the experiment with Beethoven's 7th at 100 dB and the readings upstairs were about 10 dB lower.

All in all, I remain happy with the isolation. Once I had a subwoofer in the room, bass containment will get worse, but I don't think it will be objectionable. You can easilly tell that something is going on downstairs, but it's not hard to hold a conversation over it.