Master Lee, Sorry that I have not made myself clear, yes I have read on how to get the center line but there is one sentence: "Tip 1: Take into consideration only `living' quarters i.e. exclude the garden and the drive-in garage." So is the Terrace/Balcony considered as a "living quarters"? Also, I am thinking of requesting for an on-site visit of home and company, can you let me know the cost by separate e-mail? Thanks Victor