Shift + right click on an interior wall to bring up your House Interior Options menu, then select Access. At the top of the menu, you'll see a drop down window. Click on the window and you'll see several levels: Visitor, Guest, Resident, Tenant, Acquaintance, Associate, Friend, Ally and Partner. Select your desired level and assign permissions (there are no inherit rights associated for any level. Rather, these serve as permission templates). Click Accept. Now, click on the Friends button on your House Interior Options menu. Here you'll see a list of all your housefriends. Click on the drop down menu to the right of each housefriend and choose the appropriate access level. Click Accept, and access will be granted.