In architecture, the facade of a building is often the most important aspect from a design standpoint, as it sets the tone for the rest of the building. From the engineering perspective of a building, the facade is also of great importance due to its impact on energy efficiency.
In modern high rise building, the exterior walls are often suspended from the concrete floor slabs. Examples include curtain walls and precast concrete walls. The facade can at times be required to have a fire-resistance rating, for instance, if two buildings are very close together, to lower the likelihood of fire spreading from one building to another.
In general, the facade systems that are suspended or attached to the precast concrete slabs will be made from aluminium (powder coated or anodised) or stainless steel. In recent years more lavish materials such as titanium have sometimes been used, but due to their cost and susceptibility to panel edge staining these have not been popular.
Whether rated or not, fire protection is always a design consideration. The melting point of aluminium, 660 °C (1,220 °F), is typically reached within minutes of the start of a fire. Firestops for such building joints can be qualified, too. Putting fire sprinkler systems on each floor has a profoundly positive effect on the fire safety of buildings with curtain walls.