boxtops,I'm no expert but I would say your annex could be addressing issues that you've put to one side, either because life got in the way, or they are too painful to think about. It really depends on the Annex, is it large,intimidating, magnificent ,awe inspiring, small shabby, falling down? Then think how you feel when you look at the annex: happy,sad,frightened. Dream analysis and symbols are not one size fits all, thats why if you have a proper session the analyst chats for quite a while on how you feel about your dream. Often your unconscious or subconscious uses symbols you will recognise in your conscious state so an Annex to the side of your house would mean something belonging to you (aspirations,memories) not part of your everyday life but related in some way to your life. (or just the fact you've been thinking about getting an extension to your house, really dreams are sometimes just thoughts left over from your day to day life)