Axiom Home Page Forums General Discussion Home Theater Lets plan a theater space

My thread is polluted with broken links. The horror. Lol.

Welcome back Aaron. I've been working on my own "best for less" solution for sound isolation. I'm going with,in order, 5\8 drywall on resilient channel and roxul safe and sound on all sides. My common wall will be a 2x6 plate with staggered studs and roxul woven into it. The ceiling will have 1" spray foam on bottom of upper floor and then roxul with channel and drywall. 3 of my four walls are backing onto foundation so that's a plus.

Spray foam was the way to go for me as the subfloor is 3\4 tongue and groove. Too much work to seal with caulking gun. Each plate and header will be spaced with foam\neoprene to help reduce transmission of vibration. You can of course do much more... But this plan is already adding roughly 1.5K to the cost of my build over standard building strategies ie. a bedroom.

You are more than welcome to share this thread. Many questions you may have will likely benefit us both being answered. I put this up to help and get others involved anyway.

Wow that's a of good stuff thanks. I will take a look at the roxul. Looks pretty inexpensive which is great. What do you think of the acoustic mass loaded vinyl sheeting? From what I read if you put it between the drywall and studs it basically reduces the amount of bass vibrations that travel up the studs and into other areas of the house. Also is there any benefit to doubling up on the drywall?

One suggestion for the walls is to use 6 inch upper and lower plates, then use staggered 2x4's so that each one only touches one wall instead of both. Maximum reduction of vibration this way.

Is it too late to suggest something other than square (18x18) for the room dimensions ? IIRC the room would be large enough that the dominant room mode would be down at 30 Hz but it would still help a bit if you could get length and width to be different...

The only way for me to adjust the length or width would be to build out one of the walls. Would that really be that much of a benefit and worth losing the space in the room?

Too late to edit: Also fill the wall cavity with insulation.

There is always a way to deal with problems if you are willing to learn(spend) and treat the space for anomalies. I say keep the square footage (literally square) even though it is the acoustically worst scenario. Room modes will reign supreme!

My room is a from scratch design. No accidents. Few comprimises. If you have the same latitude, you should take advantage.

Aaron, your pictures don't show up because they are locked down by security on Facebook.

Some notes on the room size...
A "square" is an acoustical nightmare. 1 Foot difference in length or width will make a difference (pun intended) in the acoustical performance.

Staggered Stud Wall is what Catbrat is mentioning with the 2x6 top and bottom plates. I did this. You will need to be a little creative with a door, but this will help with a lot of the sound proofing. You will still need to do something with your ceiling (search Whisper Clips and Hat Channel). Floors are REALLY tough to do.

Do NOT "fill" the wall cavities with insulation. Fill 1/2 of the walls with regular pink/fluffy normal insulation, but leave the other side with an air gap. You want sound isolation, and stuffing the wall cavities recouples the inside and outside of the room.

Here are some pages with GREAT information (and pictures) on the subject. Look at the first link and note that it talks about filling in just some (most) of the air gap between the two walls with insulation in point #2

4 Elements of Soundproofing

Here is the one graphic that I like. Think of the "his side" as the theater side. This has 2 layers of drywall on both the inside and outside of the staggered stud wall, with green glue applied between the layers. Now, I opted NOT to do the 2nd layer on the outside of the theater because the performance improvement really goes down at that point, but if you can swing it, do it.




Better yet, just go here and read all of the links within the link below. If you have questions, give Ted or John a call. They will give you sound advice without trying to "up sell" you on things that you don't need. You can certainly get products like Green Glue and the Whisper Clips elsewhere, but their prices are good, and they really helped me out.

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Soundproofing 101

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Lots of good stuff right there...

Or you can ask me. I've gone through so much of their material and others. Their website and Ted and John both give real and true assistance and are considered one of the best and most helpful soundproofing companies out there.

One thing that surprised me recently was that low frequency waves didn't seem to care much for my spindly little internal walls, and only the solid external walls really seemed to contribute to standing wave formation. That might turn out to be good in your case, although I imagine that doing a good job on soundproofing would make your walls have a greater effect on standing waves.

Any chance you could post a floorplan pic ? Not just the room, but the entire floor including exterior walls. I have this crazy idea that you should soundproof three of the walls and leave one untreated so your room *acts* rectangular even if it's actually square.

Without naming names, there are some frequent posters here with square rooms who might be able to offer more useful advice than me.