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July 23, 2008
Soundproofing Question
I'm thinking about adding some soundproofing to a common wall (represented by the red line above) using a layer of drywall and some Green Glue. Considering that the neighbor's front door shares a small chunk of hallway off the main stairs with mine, and the doors don't do much to keep out noise, would this have any effect at all?
Thanks!
Comments
I did this once to dampen the sound from the adjacent room in the next building. I used caulk on the back of the drywall to create a cushion and some air space between the plaster wall and the new sheetrock. It was definitely an improvement, although the noise was still more than a light sleeper would desire.
Posted by: cornetor at July 23, 2008 1:23 PM
Green glue seems to work. Use plenty of it and 2 layers of 5/8 drywall. Use acoustic caulk at corners and openings, this is important as the smallest openings can transmit a lot of sound.
If this is bad, you might consider building an additional wall spaced off by 1-2" from the commmon (not touching it). This can be 3" wood (better than metal) studs with 5/8 drywall, insulation stuffed, which will be 5" in all.
If you then add outdoor weatherstripping to the door (bottom sweep, side & top flex) it would probably do the trick.
Posted by: cmu at July 23, 2008 1:24 PM
If you go cmu's first route, make sure the seams on each layer don't line up with each other.
Posted by: slopefarm at July 23, 2008 2:30 PM
http://www.supressproducts.com/products/ - sound reduction drywall.
Posted by: guest at July 23, 2008 2:45 PM
There is also an expensive, but effective, product on the market called "Quietrock". If you google the product, you will also find links to forums discussing home versions of the produc and other other noise- and vibration-reduction solutions.
Posted by: guest at July 23, 2008 3:22 PM
You want to have a balanced soundproofing solution. You achieve this by strengthening the weakest points. If for example you leave your door open, it makes no difference how much soundproofing you put up on the wall, the sound in the room will be the same because the door is open and the sound finds the weakest point.
So i recommend turning your nieghbors tv or radio on, then closing the doors and walk around your room and listen carefully to see if the wall is a problem or if its the doors that let in the sound or both. Then you will be able to make the best decision whether one thing has to be upgraded or both.
I recently asked my contractor to replace the "hollow core" doors here with "solid core" doors because doors can let a lot of sound in, but made the mistake of ordering "panel doors" which when they arrive the panels are recessed with further recessed beveled edges making the door almost paper thin in some areas (the panels look nice though). If you already have solid core doors the other thing you can do is seal the doors, closing up the gaps around the door can help alot, with my doors the floor is uneven so there is a 1+1/2 gap on one side of the door and almost no gap on the other. The contractor said because it is uneven like this there was nothing he could do.
I had wanted green glue (contractor never heard of it) solid core doors, sealed doors, etc. etc. and none of it worked out, so i fell back on my backup plans and have fans in each room for white noise. When winter comes i have white noise machines for the rooms. Good luck.
Posted by: 11211 at July 23, 2008 3:37 PM
Structurally-born noise is very difficult to isolate because it radiates through the building shell. That's why recording studios typically have a box-within-box architecture (floating walls, floor, ceiling). I've built a couple of studios. It can be a real challenge.
If you're going to hang drywall, look into vibration isolating furring channel. These are made from extruded aluminum and are mounted on the existing wall. The drywall is screwed into that. You can get it through places like Kamco.
Just be aware that all you have to do is drive a single screw or nail through the new wall into the old one to negate much of the acoustic gains of the new wall.
Posted by: Steve at July 23, 2008 3:37 PM
Thanks everyone! Lots to think about now... Luckily the unit next door is the model, and still unoccupied, so experiments can be done.
And nice to still see some guests!
Posted by: deadnancy at July 23, 2008 4:55 PM
Green glue = 50 year chalk
Green glue = ex$pen$ive / 50 year chalk = ¢heap
Posted by: guest at July 23, 2008 6:52 PM
The channels Steve mentioned can work really well, or they can make matters worse if you install incorrectly.
Soundproofing is hard. The concepts are counterintuitive, it really pays to be meticulous. As Steve says, you can do a lot of really good work and foul it with one misstep.
Good luck!
Posted by: vanburenproud at July 23, 2008 8:55 PM
When you're beefing up just one wall, you run the distinct risk that sound will find another route around that one wall (or ceiling). This is called flanking.
Flanking varies on a case by case basis based on construction. Sometimes treating one surface works well, and other times if there's too many flanking pathways it just doesn't.
Your situation looks way too open, and I would think treating that one wall would not work as well as you hope.
Regarding some of the other thoughts posted:
Quiet Rock and Supress are tremendously expensive relative to performance.
Green Glue is much less expensive relative to performance. "Guest" has posted that it is 50 year caulk, which is a foolish assertion. Green Glue is in the same family of visco-elastic materials as whant is inside Quiet Rock and Supress Board.
You want to avoid introducing a small air cavity in your efforts. Installing clips and channel as Steve suggested works if applied directly to the stud or joist. If you apply these to the existing dywall surface, you'll trap a small pocket of air that will act as an amplifier. These channels are generally 20,22 or 25 ga, steel. And Steve is right on about the misplaced screw negating much of the benefit.
Posted by: JamesW at July 24, 2008 8:56 AM
The air cavity is to decouple one wall from another. The air space works like a shock absorber. The conversion of acoustic energy from structural to airborne and back to structural is one of the things that helps burn its energy. It's the same principle behind a double wall or a recording studio's double/triple glass (as opposed to double glazed) windows.
The inner wall should be relatively heavy because the more mass the energy has to move the more it depletes its energy -- at least one layer of Type X although I've mostly used two layers laminated with construction adhesive.
In any event, it's an impractical solution for an apartment, especially if there's wiring in the existing wall.
Posted by: Steve at July 24, 2008 1:37 PM
The NRC in Canada did a lot of great research into many odd areas. One great study involved looking at airspaces. The net of the study was that a small airspace introduced made things a lot worse at some frequencies. If you're going to introduce an airspace, make it big or do none at all.
Posted by: JamesW at July 24, 2008 8:11 PM
That's why I suggested stuffing with insulation, not for mass but to reduce the airborne transmission of sound.
As far as massing is considered, I wonder whether 2 layers cement board which is cheap and heavy would be as good as the more expensive proprietary boards. Of course you want structural integrity too, or the entire heavy wall will act as a diaphragm.
Posted by: cmu at July 25, 2008 11:06 AM
Some studios line the walls with lead sheets made for the radiology industry. I dunno what the building codes are for that would be though.
Posted by: Steve at July 25, 2008 12:46 PM
The insulation in the small airspace does not remove the liability. Lab tests confirm this. If you can't have a gap bigger than 2", leave no gap.
Good question about the cement board. In this case, mass is mass, so generally the cheapest source is most practical. That's why 5/8" drywall is so effective. Cheap, easy to use and heavy.
The "proprietary" boards like quiet rock and supress use a damping compound inside two sheets of standard 1/4" drywall or cement board. Build your own with green glue, save the $$ and have a heavier, more thoroughly damped wall as a result.
Posted by: JamesW at July 26, 2008 10:36 AM
In other words, your contention is that no inner wall works as well as one with only a 2" air gap?
Posted by: Steve at July 27, 2008 5:13 PM
What is an inner wall?
What the data says is that the introduction of a small air cavity is a liability. See their exhaustive study "Control of Sound Transmission through Gypsum Board Walls." It's online and a good read. http://irc.nrc-cnrc.gc.ca/pubs/ctus/1_e.html
Also here: http://irc.nrc-cnrc.gc.ca/pubs/bsi/85-3_e.html
Some of these findings are perhaps counter-intuitive.
Posted by: JamesW at July 28, 2008 10:08 AM
I have a terraced house in London. On one side I have a party wall that joins next door's hall and kitchen.
When they were talking in the kitchen I could hear every word they were saying and when they used pots and banged things down it was as if it was in my house-it was that loud and clear.
The walls are nine inch brick with plaster on top.
I stuck plasterboard with green glue directly onto the wall.
I then stuck another layer of green glue and plastboard onto that.
I then used resilient bars and put another two sheets of plasterboard with green glue between them on top of that.
Now I can hardly hear anything at all except when they bang things down in the kitchen I can hear the impact noise, although it is somewhat muffled.
The green glue took several months to cure-it fact it still seems to be improving over a year later, possibly because the number of layers I've used has stopped it from drying.
Posted by: Herbert Smith at August 18, 2008 4:00 PM
Herbert,
It looks to me that you built a triple leaf wall and that is why you think that the Green Glue is taking a year to cure. It probably cured within the first 30 days, but when you added the resilient channel over the first layers and then put more layers on top of that you created a small air pocket and that is why you can still hear some of those sounds. If you could open up your wall and take out those "resilient bars" you would have a better performing wall.
Posted by: SPC at October 21, 2008 3:51 PM
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