“Casa Vertical” is a single-family house located in the city of Porto, Portugal, on a narrow plot in the downtown area of the city. The organization of the various spaces is done vertically and develops around a central staircase with the rooms distributed in half floors. The staircase unifies the intervention, where the guardrail unfolds like an origami piece. The house facade refers to the typical “Porto urban house” elevation composition. Raw materials such as cement on all floors and soft wood for doors, cabinets and guardrails reinforce the unity of the residential project.