Soon the construction of chimneys leaning against the wall created technical problems. It began by building chimneys called "pavilion", projecting completely to the wall and equipped with a shelf with a large hood.
At the end of the 14th century, this type of cumbersome chimneys was placed in the kitchens but presented draw problems: so began the construction of chimneys completely inserted into the wall.
But they needed thick walls: it was then thought of a third solution ie chimneys only partially built into the wall.