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…
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!
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.
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.
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.
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!
Green glue = 50 year chalk
Green glue = ex$pen$ive / 50 year chalk = ¢heap
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!
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.
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.
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.