Sealing off bedroom windows acoustically

I've got to seal off a couple of bedroom windows acoustically. The problem is, *nothing* can show from outside the house. I need to leave the 2" wood blinds on the windows. I recognize that I'm dealing with a bad situation - just trying to do what I can. What I'd like your opinion on is my crazy plan to reduce leakage in/out the windows. I'm thinking of taking a sheet of 1" thick plywood, putting 4 2x4 strips of lumber on their side in a big square at the edges of the plywood, then sealing everything tight. If you lay this on its front, it would be like an open box. Then I'd put rubber gasketing on the edges of the 2x4s, and 1" insulation inside the box. I'd then put the whole thing over the top of both the windows and the blinds and screw it to the wall with some brackets. From the outside, it would just look like a normal window with closed blinds. Does this sound like I'd get some kind of attenuation this way, or am I way off base? Thanks, -lee-

If you want to keep the outside look that's about all you can do, but I bet steve has other ideas ;) - make sure you paint the plywood black so it doesn't show through the blinds. cheers john

Lee, SCREW THE PLYWOOD (not TO anything, just SCREW it :=) Seriously (I CAN occasionally do SERIOUS, really I can...) plywood is more expensive and less effective than either gypsum board (sheet rock) or MDF/particle board. The only thing plywood is better at, is bend/flex strength and lighter weight for things you need to carry. Here is a link that may help with your problem - http://www.johnlsayers.com/phpBB2/viewtopic.php?t=239 If you have any more questions, fire away - sometimes when I go back and read my explanations even I have questions ??!?*$*#?? If that wasn't what you were trying to do, then don't read the previous comments, and don't click on that link ...

I've got a problem situation -- my son has severe asthma/chemical sensitivities and my wife read an article saying MDF outgasses formaldehyde which is bad for his condition -- so thats not possible in my strange situation. The room I'm finally actually getting is full of compromises, not the least of which is the two windows I need to try to block acoustically, but cannot have anything show from the outside -- in other words, I can't even get rid of the blasted window blinds. I appreciate your knowledge regarding plywood versus MDF versus gypsum board. I'll admit it puzzles me a bit - I would thing 3/4" plywood would be heavier than gypsum wallboard and I would think mass is good for sound - but you're the man. :D I'm also a RANK beginner at construction techniques. Would it be better to use wallboard instead of plywood over the frame? In other words, still make a box of 2x4s put on end, but cover that with wallboard, stuff in some insulation, put gaskets on the end of the 2x4s, and screw it up to the wall. I'm not expecting a *great* sound barrier - more like a sound attenuator. I'm just trying to figure out what I can do that is removable and would give some improvement. I wish I could put things on both sides, like the other link, but that's just not possible in my case. So, should I replace the plywood with wallboard? How many layers? Thanks much, -lee-

Lee, you're right about the aldehydes in MDF and particle board outgassing - I'm not sure if you could stop that with a heavy coat of Urethane varnish or not. In your case, it sounds like wallboard would be better - the reason I drew that plug using particle board was mainly for durability. As near as I'm aware, an equivalent amount of weight SHOULD perform at the same or similar level, so the 1" plywood should be approximately equal to maybe 5/8" particle board - For your particular situation, especially where you can't put a layer next to the window surface, I would make a sandwich using 5/8 sheet rock (on the frame) then a layer of 1/2" soundboard, then the heavy plywood - if you can find Rockwool locally, try and put a layer of that inside the "box", to help absorb outside sound coming thru the window glass. Keep the wide "shoulder" around the inside of the window molding, and use as wide a gasket around the inner window molding as you can. You'll definitely want the whole thing so you can tighten it into the window as you mentioned, so you can compress the (closed cell foam) gasket by at least enough for a tight seal. If these plugs are going to be removed from time to time, I'd be sure to get some of those heavy Stanley Barn door handles - if you can, mount them with long screws that penetrate into the frame by at least 1", and drill small enough pilot holes so the threads get a good grip. The handles will work best, especially for something this heavy, if you can mount them at a height so that, with your hands gripping the handles and your elbows bent until your elbows touch the face of the panel below the handles, your fore-arms should be angled down and away from your body at about 15 degrees or so - this will let you use your elbows against the panel while having enough lifting power to raise the panel slightly, controlling the angle of the panel with hands and elbows while you install or remove it. That was a pretty crappy explanation - if you don't get what I meant, say so and I'll draw a picture next time... Steve

I had a band I was working with cut some heavy ply wood just smaller than my kitchen window surround / sill, then using a butter knife I pushed socks (clean) lenthwise into all the gaps, this held the board in place and blocked the sound out pretty well. I was able to do punk rock vocals in my apartment and one of the bands got signed to Virgin Records UK and the tracks were released....

So my original window covers have really worked out well. They knock down the sound wonderfully. But now..... <grin> I'm looking at a different space. (I've got this one pretty much finished, time to kill myself again!) This space has several windows, and I don't want to give up the light. In another thread, I believe it was mentioned that glass actually has pretty good properties -- more density than wallboard. I wonder about making a window cover, like the others, but with a glass window inset. I'd angle the glass a bit so I didn't have two equal panes of glass. I'm also thinking about making it have a number of smaller panes with wood in between so that each piece is smaller and stiffer. Around the edges inside, I'd put rigid fiberglass wrapped in cloth. I guess what I'm thinking of building is sorta kinda like making a control room window out of normal outside facing windows. Thoughts? -lee-

I do it all the time Lee. :wink: Here's a pic of the booth in Left Bank - it's an outside window treated like a control room window. cheers john

OK, Lee, now if you tell us you also want this window to OPEN and still have as good isolation, we WILL hafta kill ya... :twisted: Steve

Opening.....now that sounds cool! :twisted: :twisted: :twisted: So - is it better to have one big window, or a set of smaller panes? I would *think* smaller panes because they would be more rigid, but sometimes acoustics get counter-inuitive. -lee-

use 1/2" or 5/8" glass and you'll be OK with one sheet. :) cheers john

If the Insulco "freebie" calc is right, smaller panes but everything else the same= same STC but better TL at lower freqs by several dB. I think though, that to accomplish that you would just have to use a smaller window unless you planned on building frames as stiff as your walls - Never seen a studio with "french windows"... :?

Hey guys, I tried to check out the plans/drawings, but it appears this link is broken. Any updated link? As a fellow rank beginner, I need all the help I can get. Also, any idea of what the attenuation of this box is? I probably would build it with MDF (or whatever the most isolative material would be). Thanks! -Will

Sorry, Will - we changed servers a while back and I've still not caught enough time to fix all the links - here's yours - http://www.johnlsayers.com/phpBB2/viewtopic.php?t=239 If you find any more, call it to our attention - if you're desperate, just replace this http://www.homer.com.au/phpBB2/ with this http://www.johnlsayers.com/phpBB2/ then paste in the rest of the old link behind the end slash, and it should work... Steve (I fixed that link if you don't want to cut and paste...)

awesome--thanks, knightfly! :D

knightfly wrote:

OK, Lee, now if you tell us you also want this window to OPEN and still have as good isolation, we WILL hafta kill ya... :twisted: Steve

I know I've been quiet around here lately - been putting a new studio together. This one has seperate rooms and is turning out nicely. Its not very far from a moderately busy road, so I had some road noise to deal with, but I still wanted windows to the outside because I had a nice view of a park on one side, and a view of the city skyline and ocean on the other. I ended up using Milgard Quietline windows. They even open! <grin> http://www.acousticalsolutions.com/prod ... etline.htm They were expensive, but work wonderfully. Mine have a STC rating of 47, which isn't shabby. (They came with a sticker on them with the individual rating) -lee-

So keep us in suspense just a bit longer, Lee - :cry: Do those windows make the road noise completely inaudible, or just "quiet enough"? How 'bout a more elaborate description??!? Steve

knightfly wrote:

So keep us in suspense just a bit longer, Lee - :cry: Do those windows make the road noise completely inaudible, or just "quiet enough"? How 'bout a more elaborate description??!? Steve

What do you want, bro? Suspense or info? :wink: The windows work VERY VERY well. There's still a little bit of very low frequency coming in, but I believe its actually more through the ceiling and walls than the window. Its hard for me to judge well with low frequencies, however. Its definitely below 80 Hz - engaging the high pass filter on any of the mic channels cuts it right out. There's only a few sources that I work with where that makes a difference. Kick is loud enough that its not a problem, and often as not I'm running the bass direct in. At its worst, its down about 50+ dB from any reasonable signal source. If I end up recording any operatic basses, I'll have them go into the 2nd room where there's no real interference at all. The windows are *thick* -- about 6-8" thick overall. They have a non-moving center section, and then two openable sections, one on each side. To open a section, you have to slide back two seperate sliders. After you slide the first one, you start hearing the traffic quietly, sliding the second one, the traffic seems deafeningly loud -- because the room is nice and quiet. The windows were easy for the contractor to install. They first mounted in the plastic frame into a hole just the right size, and caulked it solidly. The various sliders and windows for the overall window just tilt in. -lee-

That's pretty impressive Lee; just curious - saw this comment - "Features a primary, external insulated glass unit and a secondary internal acoustical lite." - this sounds like at least a triple leaf construction, can you tell if the inner "acoustical lite" is also double glass? If so, this might explain high STC numbers with lesser performance in the low end - as you add leaves to a barrier, midrange values improve while bass gets worse. It would be interesting to see a full TL chart on these, but there wasn't one in evidence on their site. Still, bottom line is they work for you - all that and fresh :? air too, wow... Steve

The middle fixed section appears to be triple leaf. I can't really tell what the layers are like. Someday (about a year from now?) I'll have to pull it apart for cleaning - I can check now. The side openings appear to be identical, with 2 panes in each slider, for 4 panes of glass on each side. -lee-

you're replying to a 6 year old thread... :blah:

Hi guys, Im looking to seal off a window and door totally and with the best possible sound reduction. I can't find a link anywhere on here apart from this one and its for a removable option. Has this been discussed previously? Im starting a full studio build and am gathering all the info together and my plans to ask the forum, but first I need to seal off these damn windows :/ You're help is much appreciated All the best, Sam

Hi Sam, and welcome! :) It would be best to start your own thread about your build, with all your questions, designs, and construction details in there, instead of asking things on several different threads at once.

Im starting a full studio build and am gathering all the info together and my plans to ask the forum, but first I need to seal off these damn windows

Actually, you don't! :) The first thing you need to do is to design the entire studio, which will include the plan for sealing off the windows. You can't seal them off yet, because you don't yet know how the studio will be built, so you don't yet know how to seal them off, what materials to use, what method to use, what level of isolation to aim for, whether or not the window plug will create a dreaded 3-leaf system, if so what to do about that, etc, etc, etc. Put another way, you are saying "I'm going to buy a new car, but first I really have to pump some air in the wheels!". Obviously, you cannot pump air into the wheels of a car that you don't have yet! And you also cannot plug the windows of a studio that you didn't design yet. Plugging them now would be a mistake, as it could have unexpected repercussions down the line. - Stuart -

Hi Stuart, Thank you for you're reply! In that case I will get all the relevant information together and start a thread of my own. My main worry was creating a 3-leaf, I guess I was thinking I need to find a way to start with all 4 walls the same before starting the build inside. I've downloaded the Sketch up that everyone is using on here and drew something that looks like a star drawn by a 4year old! I will take some photos and do some hand drawings and explain a little more where I'm at. Thanks again, Sam

I've downloaded the Sketch up that everyone is using on here and drew something that looks like a star drawn by a 4year old!

:) There are several very good tutorials for beginners on YouTube. SketchUp has some strange way of doing things, but once you get the hang of it, it's a fantastic tool.

I will take some photos

Photos would be VERY useful! - Stuart -