The traditional curtain wall system is made of a metal framework of vertical mullions and horizontal transoms, machined and then directly fixed to the building structure. This net supports infill panels and glass to form the building envelope.

• Mullions can be fixed in front of slabs or between them, along polygonal boundaries.
• Infills can be glazed materials or opaque materials such as metal sheets or stone, usually kept in place with pressure plates and cover caps.
• The system can accommodate openable items such as doors and windows.
• External appearance can be enhanced with sunshades, fins and cornices.