The shell construction covers all work that creates a building's basic structure. This includes excavation and foundations, the floor slab, the load-bearing walls (in masonry or concrete), the floor ceilings, the staircase and the roof frame. A distinction is made for the 'closed shell', where windows, exterior doors and the roof covering are also installed so the building is sealed against wind and weather. Only then does the interior fit-out begin with electrical, plumbing, heating, plastering, floors and painting.
The process follows a clear order: after excavation the foundations and floor slab are built, then the walls rise floor by floor, followed by the ceilings and finally the roof. For a single-family house the shell typically takes about two to four months, depending on the construction method and weather. It is carried out by construction companies with masons, concrete workers and carpenters, coordinated by the site manager or architect.
The term matters for clients building new or extensively renovating, and when buying a property in shell condition. A well-executed shell is decisive for the statics, thermal insulation and the building's later dryness — mistakes in this phase can only be corrected expensively later.
The shell makes up roughly 40 to 50 percent of total construction costs, though the exact share depends heavily on construction method, finishing standard and region. Reliable per-square-metre or per-cubic-metre prices can only be given per project, which is why no flat guide value is stated here on purpose — request a detailed quote based on the building specification.
Insist on a clear building specification, defined interfaces between the trades and a proper shell acceptance before the interior fit-out starts. Moisture in the masonry must be sufficiently dried out before plastering.