Q1: I have no idea when our house was exactly built (1993 or 1994?). Is it important to know it? If so, why?
It is important because every twenty years, yearly and even monthly, the two flynig stars will changes their position. Thus, knowing the exact year in which it was built or had a last major renovation done is very important.
Q2: How about the date when we moved here(1987).or when our roof was changed(1990's). is it important?
Yes, if it the entire roof then you can consider your building to be last renovated in 1990's which is still under the period 7. But it is easy to remember that period 7 is from 1984 to the year 2003 and any renovation done during this period is still in period 7!
Whenever I do a Feng Shui audit, the first question for example I ask is when the building built? As most buildings I access in Singapore are relatively `new' if the owner says it is built in 1993, I need not `worry' anymore! Even if there was a major renovation done in 1993 and a subsequent one in 1999, it is still under period 7. Hope " logic " this helps and you need not `scratch' your head to find out.
Center for Feng Shui Research