Then insulate with minimum R19 and have air gaps above and below the insulation, and finally hang double or even triple layers of thick sheet rock on the ceiling, like this:Even with all that done, your sound barrier is only as good as it's weakest point.

You can never completely insulate yourself from risk but you need to do your best to balance it.I can see why you'd want to pass on this tenant though.

So, knowing this, the attic insulation is bad and the flooring on the first floor may have had some water damage.

Their primary job is to take the emotional baggage out of your business decisions, and to insulate you from those situations.

The house, built in the late '60s in Northern California, had no insulation in the exterior walls.

In a 2nd story apartment building that is as old as yours, there probably isn't good insulation, or double pane windows.

If you want a well insulated door (R14) - if it makes sense in the property - you may need to add $100 to Jerry's number above.

We had to take the entire end of the house back to the studs (even the insulation smelled of smoke); prime and seal all of the framing and cladding (employing a primer used by fire restoration contractors)  and rebuild.

Very well could be moldy insulation.  

We have a lot of trains, and you can hear them through the night sounding their horns from any part of the city, no matter how well insulated your home may be.But right up against the tracks is a different story.The city is contemplating some sort of fix that would allow trains to go through without the horns, which would make renting properties near the tracks much easier.Any advice about purchasing near train tracks?