Care needs to be taken when insulating older homes. Some of these homes have an outdated type of wiring called knob & tube. This old type of wiring, if still being used, can be cracked and frayed. If insulation is installed in contact with this type of electrical system, there is the potential for a fire. This old wiring, if still activated, must not be covered with insulation.
From the attic or the basement, you can tell if you have knob and tube wiring. Rather than individual wires contained in one cable, two wires will be running parallel to each other and connected to ceramic tubes when running through rafters and joists and ceramic knobs if fastened to the framing. An electrician can tell for sure what type of wiring you have before insulating.
Also, insulating walls with moisture damage or active leaks from the roof or plumbing must be avoided. Potential structural damage or health risks could be created by insulating wet areas. Leaks must be fixed before insulation is installed.
