Envelope components, as well as individual layers thereof, must, as a rule, be superficial and continuous in order to fulfil their tasks. This presupposes the creation of large-area two-dimensional, mostly planar layers of material, for which various manufacturing, geometric, and constructional variants can be used, which are to be treated in the following. The first step in this chapter is to combine individual parts within the component surface, i. e. in the two dimensions, length and width (◘ Fig. 1.1). Individual leaves or layers of a multi-layered envelope structure will be investigated separately with regard to their specific constructional subfunctions (as on ◘ Fig. 1.2). The composition of the surface from identical parts is considered in each case. This corresponds to standard building practice. Constructional transitions between different elements within a particular functional leaf or layer (such as on ◘ Figs. 1.3 and 1.4) must be carefully planned and executed. The seam or joint formation itself is deepened in Volume 3, Section 1 by incorporating geometric, mechanical, and sealing techniques. In Section 2 the constructional composition of the assembled component is considered in detail with regard to the layering in the third dimension, i.e. the thickness.