I have design books owned by my dad. The first time I used the floor plans was when I start building in TS2. And, it's always ended up not satisfying... as some have suggested, you can create your own ratio for the tiles or simply based on the windows/doors.
But now, I just used google images & plan my own floor plan for inspiration.. If I don't have any... I'll play with my legacy family.. and once I'm bored with them.. I start building... I always find it's hard to follow a floor plan... :/