They use this method in Elemental: Fallen Enchantress for map-making, they call these "stamps". You can combine any amount of stamps to create visually stunning maps, such as a building, an impassable terrain feature and so on. These stamps can be created and modified at will.
In Construct 2, your best bet would be to define those rooms as lists of objects with relative coordinates. These rooms would have absolute dimensions and position as well as any other meta data (passability, environment etc.).
I would suggest creating some kind of room/stamp editor that can generate the necessary encapsulated data for you, you just need to place objects together.
And in the game, you could use placeholder sprites with references to those rooms.Mipey2012-11-22 15:20:33