You should definitely put all of your house logic into a single layout. If the houses are to do different things, you can use another global variable, 'Housenumber' or whatever. Then when you're going through your house layout (which now controls any house), if there's something specific to the house you're currently in, you'd just add..
'Housenumber = 1' to the event, so that event only triggers when you're inside house 1, but not any other house.
But then if you have stuff which can happen in ANY house, you can just leave the housrnumber variable out of the event and the event will trigger in all houses.
You just need to wrap your head around the way these things work. Sometimes it seems easy to do the same piece of logic 10 times, but in reality there's always a way to do that piece of logic once and just add different conditions to ensure it only triggers when it should. Otherwise, things will quickly become very unwieldy.