Although not always considered an important detail, the joint plays a crucial role in the personality and identity of an architectural project.

The joint can be reduced to a thread to emphasize the lightness and transparency of a glass structure, or exaggerated to become part of the design, like a driving force or a generating element. It is possible to obtain a minimal style using “hidden” joints within a curtain wall, or stress the constructive honesty of the application by emphasizing the structural grid as part of the design. Design professionals can play with the depth of the joint. Glass blocks with a flush joint will produce a full, complimentary and clean effect; whereas a partially retreated joint gives the opposite effect, a dynamic and complete interpretation of the wall, accentuating each individually embossed block. There are joints with technological values where the discontinuities between the glass blocks generate canals (as seen with the trapezoidal block), and provide a space in which to house the architectural auxiliaries.

Each constructive material, such as aluminum, wood, plastic, and traditional cement mortar, require careful selection and are important contributors to the glass block structure. Seves can guarantee the regular size of a joint with mortar, thanks to a study of spacers created ad hoc to obtain a linear and curved installation, in prefabricated or traditional mounting methods, with varying glass block formats.

The minimum limit for a joint (2–5 mm depending on the format) is the threshold at which technical error can be avoided; any joint size under the limit would allow contact between the glass blocks and cause tension damages.

A vital component of the glass block wall, as much as the glass blocks themselves, the joint can be customized in favor of flexibility and variety, to fit any project.