Brick won't work, if you're going to build a wall, you have to plaster it on the outside, otherwise after ten or twenty years those bricks will loosen.,Some people who are particular about things even use blue bricks for their kang beds. It's unnecessary, red bricks work just fine. The old man thinks they are even warmer than blue bricks.,He pulled out another thin slate and showed it to everyone: "There are also these kinds. The foreman at the quarry said that these slates can be used for heating floors."。