Ravi draws a house with a roof that sticks out past the walls and a door in the middle. What is the least number of straight lines he needs?

The roof's base runs straight across the top of the wall, so it is 1 line; the 2 roof slopes, 2 walls and the floor make 5 more; the door needs 3 lines (its bottom lies on the floor). Total $1+5+3=9$.