Dont do like they did on DayZ Origins...they ruined the game for everyday with that 5 day thing...that means you can be more then 5 days without playing or else everything you own...you cant go out, you cant be sick, you cant go on vacation, you cant take a break from the game, etc...make a way so people can destroy the houses if they want to...or make it like 60 days before they despawn...
Possibly make it so that EITHER 3/4 days total of ingame time OR 3 months real time your house will expire. This seems better, as if it's ingame time you must be done with it after that long and in real time, you must be done with the game for a while would probably be a little rusty (...) and should probably start anew anyway.