When is it time to rewire an older house?
Several months ago I purchased a home built in 1962. The H.I. identified a few minor problems (which were corrected). So far I have replaced and upgraded the breaker panel to 200 amp service, external wiring placed in conduit and an earth ground added. The bathrooms, kitchen, garage and utility are on grounded GFCI circuits, much of which was rewired ~10 years ago. The basement has also been wired with grounded wire.
Existing wire is cloth-covered copper with no ground wire except on the new circuits, which are plastic covered copper.
So far so good. I need to add a couple of grounded circuits. As of now my attic has NO insulation at all, so I want to finish any wiring upgrades before I bury it in insulation. I have an electrician coming out to add those circuits and inspect all the existing wiring, but I'm trying to prime my BS detector in case the electrician smells (another) fat paycheck. Lots of old threads in this forum have helped a lot! (And yes, I would get a 2nd opinion anyway.)
But surfing the web has not been very helpful; one site said a house needed to be rewired every 20 years. (Guess what they were selling?)
I have no immediate reason to believe the wiring is inherently unsafe, and construction quality and the materials originally used on the house are very high. Barring the electrician finding any portions of the wiring which are deteriorated or damaged, is there a rule of thumb when the home will likely need to have the wiring replaced? If I knew, for example, that the wiring would likely need to be replaced in 5 years, I might do it now before insulating, or it might affect my choice of insulation type.
Perhaps I can't find a rule of thumb because there isn't one -- but just knowing that for sure would be a help.