<p>Shell which can be adjusted in height in steps comprises several shell elements together forming the formwork shell (7). Each shell element has several vertically arranged interconnecting parts extending over the width of the shell element. A reinforcing unit (14) adjoining and optionally connected to the upper (2) and the lower edge (3) of a main part (1) of the shell element protrudes from the rear side of climbing parts (4) lying opposite the shell surface of the formwork shell and is fixed on the climbing parts. The reinforcing unit also forms a working platform. Preferred Features: The reinforcing unit has at least one horizontal flat stiffening element (17) extending at least over a large part of the width of the climbing element.</p>
