Kitchen: You need this extension if you want to get married. See
"Marriage" section. It adds a room with a fridge, table and a bench, a sink, and two books to record your recipes and power berry's in.
Bathroom: This adds a room with a spa, toilet, and a sink. The spa is just like the hot springs.
Stairs: This extension makes a staircase to your roof from the main part of your house.
Baby Bed: This adds a baby cradle at the foot of your bed. You need this if you want a baby. See
"Family" section.
Greenhouse: In the Greenhouse you can plant any kind of plant all year round you have space to plant 16 squares of crops. See
"Crop" section.