John writes from Medford, Massachusetts: "Our home is 124 years old. The basement ceiling is not insulated. It also features varying widths between the joists with special surprises like nails and very old wiring stuffed here and there. Any advice?"

Answer: It can be insulated. First you would want to choose an R-value depending on the height of the floor joist. I would guess it's going to be R-19 to R-30. The most common widths for these products are 16" and 24". You need to determine the most common width to decide which will best fit. Since it seems the widths vary a great deal, I recommend using insulation netting. That will guarantee the insulation stays in place.