I’m very interested in getting insulation blown into the exterior walls of my old house. I’ve read in many places that this shouldn’t be done if there is knob-and-tube wiring, as it’s an extreme fire hazard. Much of the knob-and-tube wiring was replaced prior to mow moving in, but when I asked the electrician if it was all gone now, he said there was now way of knowing for sure unless they opened up all the walls to check. Is this actually what people do when they have insulation blown into the walls of old houses? I have not actually talked to an insulation contractor yet, mostly because I am afraid they will mislead me to do something unsafe just so they can get the sale. Maybe it isn’t as big a deal as it sounds to me? It just seems like busting open all my walls “just to be sure” isn’t a desirable thing. But I do want to be warmer and save heating costs. Any advice welcome.