To use the house-style walls, you have to create double-thick walls and convert them.
First, draw some ground:
![Image](../../s1.postimg.org/5nynqg0ez/image.png)
Then, create the goofy double-thick wall thing:
![Image](../../s1.postimg.org/dea19bs4b/image.png)
Finally, convert the wall to the correct type by holding "w" and moving the mouse over the wall:
![Image](../../s1.postimg.org/mq153eazf/image.png)
Viola!