Big Doors

[alarmo]

Hi all -
after years of planning and plotting, and a lot of work, what used to be a 20' x 20' detached stone-walled garage in my backyard is now a rehearsal/small home project studio space. Overall, I'm really happy with how it's turned out - a bigger post with pictures will be coming! - with one catch: the building does a really good job of keeping sound in, except for the big opening in the stone shell where the garage door used to be.

Currently, that big opening has big "barn-door" style wooden doors (which I drywalled the inside of for more mass) that swing outward, and an inner pair of MDF panels/"doors" that swing inward, separated by a few inches. This combination is "pretty good" but I'm pretty sure it can be done better. That total opening is about 7 feet tall and 13 feet wide.

Windows aren't a problem - I've split the garage with a hefty multi-layer wall between the big "loud room" and the skinny section on the side that's used to store gear, which is where the only windows are - so the only opening in the loud-side shell is those doors.

Predictably, it's mostly just bass that gets out, once I added enough weatherstripping to seal those doors. I know that with bass it can be hard to tell where a leak is, but from walking around the building it's decidedly louder in front of those doors, so I'm pretty sure they're the biggest culprit.

I'm ordering a copy of Rod Gervais' book now - but what have other people here done for big doors that they're happy with, and would recommend looking into?

thanks!

[JWL]

Sounds like you are on the right track, and Rod's book will get you there even if you aren't.

Soundproofing, esp. at bass frequencies, requires mass, airtightness, and good construction techniques.

Without seeing more of the door assemblies it's tough to comment further.

[alarmo]

Thanks, JWL. I can post pics of the actual doors when I'm near them with a camera. Here's a quick not-to-scale plan of the room - all outer walls are stone exterior over a wood shell over insulated studs over a multilayer drywall sandwich:


The current outer doors are a layer of plywood on rectangular frame of 2x4s, with soundboard inside that frame and drywall on the other side. The current inner doors are 3/4"MDF on 2x4 frames. The doorframe in the wall itself is a 6" deep opening, so the inner/outer doors are hinged on either side of it, much as you'd picture from how they open in the diagram.

My first thought is to get those big doors re-done with as much mass as possible - a couple of inches of plywood and/or MDF for both, possibly. But that's the point where I'm fishing for what's worked for other people... and will be checking to see what The Book has to say when it arrives!

thanks!

[Snarl 12/8]

I'm no expert, but it seems like the best AND cheapest solution would be to brick up that opening down to a normal door size and then put in a sound proof door in the new, smaller opening. Am I high?

[MoreSpaceEcho]

probably. but that's still a good idea.

[Waltz Mastering]

I'm by no means an acoustic/sound proof expert...

Adding mass to the doors will definitely help. The weakest link for sound escaping will most likely be where the doors seal.

The door jam will be important to make air tight...and as mentioned the doors you have have a large surface area so area of the seal will be greater.

I've seen a technique used where there is a slight angle or bevel cut in the door and jam, so the door and jam pinch more when they close.

As mentioned, it might be a good idea to fix on of the doors so that it is semi permanently closed and air tight, so that you just have to deal with one of the doors, and less surface. 2 cents.

[JWL]

These are all good ideas. Rod's book is on the way, and the answers you need are there.

Mass and airtightness.... mass and airtightness. Those are the main 2 for doors. Flanking noise is good to think about if you have the luxury.

[alarmo]

Thanks for the feedback everyone! I do like the idea of keeping the big doors if possible - loading big stuff in and out is really, really convenient that way, and it also means at some unforeseeable point in the future it could potentially still be used as a garage.

I'm still thinking that the double-layer doors (separate swing-in and swing-out) are a good idea, but rebuilt with more mass. Rod's book should arrive today, so I'm sure I'll get some more input from there, too.

I'll update with what I wind up doing and how it works out...

[norton]

Tom's right on the money about the door seals.

"Most" of the time... any decent solid core door can be effective, with a proper door stop that allows the door to seal nice and tight around the entire perimeter of the door.... floor included.

In your case, ready made off the shelf options will be pretty impossible to find. Which is actually a good thing for you.... Those options are extremely expensive and rarely ever offer more than you can easily fabricate for yourself.

Your center seam will prove to be the trickiest and possibly the most crucial. Is there an overlap of one door to the other? Is the outer door offset from the inner?

If you're going to beef up the doors themselves use green glue between the layers... If you can have one of the inner doors overlap on the outer-most layer that'll help out a TON.

It sounds to me like you're already way more than half way there.

good luck on squeezing that last little bit of silence out of the assembly!

[alarmo]

So after talking to some studio people I know here in town, and spending last night poring through Rod's book, I think I understand what's going on with my current "pretty good but not as good as I hoped" doors: the main outer pair of doors has a fair amount of mass but nowhere near what a design like Rod's recommends for standalone doors, and my inner layer is a little lightweight and way too close to the outer layer to make much difference.

So when I'm talking to the contractor I've used before, I think my plan will be to see if the frame will support a wood-lead-wood sandwich like Rod recommends (which'll be several times heavier than the doors I have now, with an expected increase in isolation), and if that's not feasible, then plan B is to extend the doorframe to get at least a foot between the inner and outer doors (the outer doors are currently inset into the stone exterior, since that's where the original doors were before I started remodeling).

Thanks everyone for the pointers and advice! It may be several weeks before this is finished, but I'll update with the results.

[alarmo]

Oh, and as for pictures - these are of the inside, when it was being finished (so various items like corner bass traps and the drum riser aren't shown, since I hadn't built them yet. Also the ceiling is still taped from painting!). The roof gets a little low at the sides, so rather than rebuild the roof during the remodel, I had the ceiling slope to make the room feel bigger (and get more air space); it's about 10 feet at the highest point.



And here are the doors we've been talking about!

[JWL]

Nice space there, man.... looks great. Though I'm obligated to point out that I don't see any bass traps in there....

Sounds like you're well on your way with the door....

[alarmo]

Though I'm obligated to point out that I don't see any bass traps in there....

That's because there weren't at the time those pictures were taken, last fall. I've got some trapping in the vertical corners now, and while it could use some more, that seemed to cover the basics (no obvious bass nulls or booming spots)...

[JWL]

Perfect! LOL