Over penetration is a viable concern in today's over litigated society. You are responsible for whatever happens when you pull the trigger. Many of today's homes are horrible for stopping most any kind of round capable of penetrating. I know there are these forums that test these things out like "Box-O-Truth", and the like. But I personally wouldn't stake my chances legally on some of that stuff. If they are wrong it will be your ass in the legal ringer.
My home is a cookie cutter, stucco exterior frame model, like so many here in the southwest and California. I could literally kick my way through an exterior wall with a pair of steel toed combat boots. That is why I keep my house shotgun loaded with Trap loads. 1 1/8 ounce of #8's at 1,200 FPS. A lot of people say that is not sufficient. "Bird shot is for the birds", and all that crap. Indoors the longest shot I could possible be faced with is around 20 feet. In that distance 1 1/8 ounces of lead is going to hit like a freight train. Yet the possibility that it could over penetrate into someone else's home is quite remote. Slugs and 00 buck are simply not needed.
Some years back my wife and I were shooting a round of trap at our local gun club. I was at station 2, and my wife at station 3. The fellow at station 1 had an accidental discharge when he closed his action. (Beretta A-390 semi auto). Luckily the gun was pointed at some evergreen shrubs about 10 feet away, on the side of the field. It completely sawed off a small evergreen that had a trunk about 4 inches in diameter! Had someone been standing in that same spot, it would have sawed their leg completely off. This was load of 1-1/8th ounce of #8 shot at 1,200 FPS. A standard Winchester AA Trap Load. Bill T.