To unlock the option to expand and add rooms in Animal Crossing: Happy Home Designer, you need to purchase and complete the “Choosing a Layout” course in the Happy Home Handbook for 5 Play Coins. Click here for more information on the Happy Home Handbook.
When the “Choosing a Layout” course is completed, you can select between different home layouts when building a new house for a character. To change layouts for a pre-existing home, talk to the character and ask to rebuild their home.
Some larger layouts are only available after rebuilding a home from another layout, such as layouts including a second floor or basement. Make sure to keep picking the “A big house” option until you see the layout you want. You may need to rebuild multiple times through increasingly larger layouts.
Below is a list of all the room layouts that we’ve seen in the game. Again, you may need to rebuild multiple times using the “A big house” option to access the larger ones.