I live about 1300 feet from the train tracks, and the train track noise is not too bad at all. But, the lines are busy and the horns blare at about 110dB from the tracks, very very nasty. I measure about 70dB by the time it reaches my house, and I'm trying to insulate my whole house to the deal with the noise, including the family room where we watch movies (don't have a dedicated basement for an HT). The horn harmonics seem to be peaking between 100Hz-300 Hz and then again at 1000Hz+. At the very low end below 100 Hz, the horn noise seems to be less than 30dB if my octave logging meter is right. I'm shooting to get the house as quiet as possible within reason (can't spend 100s of thousands of dollars). The construction of the exterior wall is single stud, 16 inches apart. Here's what I'm thinking of doing, and any advice would be much appreciated:
1. Dual pane windows with glasses of different thickness (or one pane laminated). Here I am confused as to what thicknesses to use for the 2 panes. There seems to be some evidence that "thicker is better", but I can't go to above 1/4 inch glass without incurring great expense. There's also some evidence two panes with different thicknesses are better at dealing with train noise than two panes with same thickness. So I'm figuring one plane of glass has to be 1/4 inch, but the other pane can be 1/4, 3/16, or 1/8. I am not sure what to use - advice?
2. The siding of my house is old redwood, full or cracks. I'm thinking that I want to change it to cementboard siding instead of wood siding. Cement/concrete seems like a good way to deal with this kind of noise, I figure it's just like having a concrete wall of 5/8 inch thickness. Please do correct me if I'm wrong. Here's the spec from the cementboard guys:
4. 2 layers of drywall with greenglue or quietglue (I can't tell any difference between the two) or quietrock . I would really like to save the half inch of floor space (don't ask), but quietrock doesn't seem to cut it at the lower end w.r.t insulation. On the other hand, I have to verify with an architect whether it's ok to use 2 layers of drywall inside and cementboard outside - cementboard is very heavy, and I don't know if single-stud-16-inch construction can bear all that weight of cementboard and 2 layers of drywall.
Also, assuming I go with greenglue/quietglue, can I use one panel of drywall at 5/8 inch thickness, apply glue, and use 1/4 inch drywall for the second panel? This would help with both reducing the weight and saving that tiny bit of space - if this is more or less as effective as 5/8 over 5/8, I'd be very inclined to go this way.
5. Doors - I'm more or less confused about this. Should I go for a masonite fiber door, or solid wood door, or dual pane glass door with the glass thicknesses like for windows? I can't find enough info to make a call one way or another.