The building limit?

  • So i just noticed while building my 7x14 house (a great hall) that I did 2 Walls and 2 Slanted Roofs high and was planning on doing a flat roof after that so i didnt exceed the build limit, but i cant place the flat ceiling, but i can place another slanted roof, and that makes my base 2 walls and 3 slanted, issue here is that i cant seal the roof off because it doesnt allow me to place another wall and and then another slanted, so how come i can place another slanted roof to make my base 5 high and not a flat roof that would make the base 4 high?