L+I downtown is very busy, but the local inspector is walking around your neighborhood every day. I would get to know him. Can't hurt.

If this work isn't visible from the front or sides of the house, and your neighbors are supportive and you aren't doing anything too close to their house, just proceed imo.

If you get a "cease and desist order" then you will need the permits.

I agree that there is a lot of work done without permits, but when you get a halt order, it just messes up your timeframe and money....

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