Originally Posted by PAbugman
your last sentence indicates that rats may still be present and chewing. Rats are noisier and leave more visible evidence than mice do and since you were aware of the rats initially I think that you would know if they were there. Look around the exterior perimeter for burrows,clean runways, bits of insulation on ground, etc. They were probably just harboring in your attic as it was safe, prior to your actions, and venturing to their food source. Rats will travel a long way to eat and return to safety. Set some rat snap traps in attic and maybe elsewhere and see if you get any action. Do any neighbors feed pets outside or have bird feeders? These are common sources for rat food; even under dog houses. Rats aren’t afraid of dogs and will live in proximity to them.
No, I don't think I have rats right now. I have not heard anything in walls, from attics since I moved in. All entry points are sealed and there are 8 traps set up in the attic which I check every week.
I asked the question because I am just curious why the previous rats didn't do any chewing damage in the attic. I have been to all the corners in the attic multiple times already.