Notes I took while researching how houses are constructed and wiring placed, etc.

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Do the screw backwards a bit until you hear a click, then go forward. This ensures you don't strip. 

Any amount of air in the wall, even just holes in the metal, allows sound to travel. So you really need everything fully sealed for a good sound seal. 

Drafts in a house are caused just by the plastic covering the insulation/the insulation itself having a gap. You just have air blowing through the wall basically. 

Electrical things need to be a certain distance from water sources to be compliant. 

You usually have to staple electric wires to the stud every couple of feet to prevent it from hanging. You don't want a situation where a wire is pressed between a stud and drywall for instance, or if it's kinked, that could cause a fire. 

Ceiling lights only have like 5 feet of light on the floor, and only 2 feet at your eye level, so you need to have them close enough that when you walk around you're not going between light and dark areas. 

Studs are typically spaced out every 16 inches (could be up to 24), that's actually why there are red marks on tape measures every 16 inches! 

Drywall is surprisingly easy to repair. You just cut out a hole, then buy some more drywall, then cut it to fit around that size, then tape it down then fill on top with putty and then do a couple of layers. California patch is a great way to patch a big hole you made. Super easy. 

Lots of instances for mounting where you are too far from a stud and so you might want to take a two by four and then attach it to the stud using screws to extend things a bit so you can mount whatever you need. 

2 by 4s aren't actually that size anymore. It's smaller, like 1.5 by 3.5 or something. The length is variable, 2 by 4 is just the thickness and the width. 

Some doors are hallow, which will be much more permeable to sound. 

Basic structure of most houses is: structure is put up (studs with 16 inch spacing) then you put in a bunch of electrical stuff (wires all around), you mount the outlets and such to the studs (seems like it's usually on the right side of the studs, but it could just be because the electricians are right handed), around this time you fill all the exterior walls with isolation (like fiber glass kinda stuffing stuff) and then you cover that area with plastic all of which is to prevent drafts. The interior walls probably wouldn't have any of this stuff, it's just not necessary. Then honestly it seems like the hardest part is the drywall. You buy drywall in this big sheets, each of them have a buttjoint which is basically just a tapered edge and another edge which is flat called the manufactured edge, and you join them butt to butt, which is important because then you have a little area of the wall that's tapered in, which is important because ultimately you want a flat wall and you _have_ to obviously fill that gap between the two sheets before you paint it, so you have to then tape those gaps and put some drywall mud on it, then you do another couple layers after the prior ones dry. Basically you just use the mud of varying thickness (how much water is mixed in) everywhere you want to fill gaps in the walls, so like even between the drywall and the floor if there's a gap and that kind of thing. You put down some trim on the floors, maybe you do some fancy trim on the ceiling called "crown molding". Then you sand things down to make them even, then you paint with primer, then final paint, and you're done you just built a house. 

The old way with plaster was much more involved and required more work. The reason drywall is called what it is is because it's applied dry, not wet. Which plaster came before and was applied wet. You'd do your studs, then you'd put lathes (just wooden means) between the studs, and a ton of them, then you'd spread plaster on the lathes and then wait a long time for it to dry, and you'd do a ton of layers of these things. 

The other thing I learned is that you really just want to spread out the weight of a screw or whatever when it's going right up against drywall. That's exactly why those snap toggle bolts are used when you're mounting just against drywall. It's that spread that prevents it from getting pulled out. But the drywall itself is pretty strong, so like if it's just force going basically straight down, that's why you're fine. But getting pulled it requires a lot less force to get pulled out. 

The drywall is affixed to the studs via screws, and that's exactly how the magnetic studfinders detect the studs. It just looks for the screws. There are other ones that actually do it based on the mass behind the thing and all that, those are electronic and need batteries. 

There are certain regulations for how deep wires need to be, for instance if they're passing through a stud, so that if someone tries to mount to the stud they don't hit a live wire. In general you can expect wires going directly above and below an outlet, so give it some space don't mount super close to that stuff. As part of this, you also don't want to use screws or drill beyond a certain length. If you drill the expected length and you hit wire, then the electrician fucked up and they are the ones who have to pay for the repair. 

It's recommended to keep lights on when drilling and everything, that way you know immediately if you hit a wire. The drill itself it seems is insulated so you'll be fine if you hit a live wire, and they also said it's incredibly rare. In general, when you're drilling the wire wouldn't really ever cut or damage the wire anyway, it just kind of pushes it out of the way (the wires are supposed to be somewhat loose so that if they are drilled near they move out of the way and don't get drilled into). 

If you have a screw popping out of a wall, you should actually drill it out further, then put two screws in above/below it (into the same stud) and then drill it in further and then cover it with mud. This is the way you prevent it from just popping back out again.