Retrofitting wall insulation on 1930s cottage

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Q: We have a cottage built in 1935, and we want to insulate the walls and possibly the floor. Some contractors say I have to remove the siding, install fiberglass batts, then replace the siding with new material. Another said I could drill holes in the siding and put in foam insulation. Another wants to use treated shredded newspaper. I would be most grateful for your opinion. --Lucy D. A: If the siding is in generally good condition, having retrofit insulation blown into the walls is your most cost-effective option. On the downside, blowing in insulation requires that a series of holes be drilled in the siding -- one at the top of each stud cavity. These holes then need to filled and painted or otherwise covered, and I have seen some installations where poor workmanship left these holes very poorly concealed. Some other concerns with retrofit insulation include damage to old electrical wiring in the walls, especially an older type of wiring called knob-and-tube, which...