Upvote:1
These are load bearing walls. The top floor walls support only the roof, so the walls are the thinnest. The bottom floor walls support the whole building so theyβre the thickest. You can either have extra space on the inside or outside. Here, the streets are thin, so tilting the exterior side of the walls back allows more light and air on the street. Itβs similar to the setback laws they enacted in NYC when skyscrapers got taller. The widespread use of this technique speaks to strict zoning. I actually donβt know for sure, having never read Parisian zoning documents, but as an architect, this makes the most sense.