How do you extend your house on Harvest Moon DS?

You have to call Gotz The Woodcutter on your phone and ask him for a house extension. To get the option to expand your house you must first buy the Table. If you do not have the Table you will not be able to expand your house. He is open from 11 am - 4 pm but he is closed on Saturdays. Construction will begin the day after you order. You can upgrade your house twice.