Anyone familiar with curtain wall facades used on commercial buildings knows that such walls are strictly ornamental features. In other words, they do not serve to help support the main load of the building itself. However, curtain walls must be able to handle other kinds of loads.

Curtain walls have become such a popular feature of modern architectural design that most lay people take them for granted. Although they are not part of the main support structure, they do add elan and panache to the facade of any building. They may not carry any or all of the weight, but they do carry loads of their own and therefore precise use of engineering is necessary in their design and construction to make them virtually invulnerable to potential stressors.

-- A curtain wall doesn't help carry the dead load of the building, but it must be able to handle its own dead load. The weight of its structural materials, along with the infill between panes (most usually glass) makes up a curtain wall's dead load. If a building's owner chooses to add sun shades to an existing structure, for example, this will add to the curtain's dead load and may not be feasible depending on its engineering.

-- An engineer must also take into account the potential wind load for a curtain wall, and this assessment greatly depends on the height of the building and especially on its geographic location. A curtain wall being erected in hurricane or tornado country must be able to withstand much higher loads than a similar structure in Idaho. Building codes provide guidelines, of course, but in high risk areas an engineer and architect may conduct strength tests using small-scale models.

-- A temperature-based thermal load is always taken into account when engineering curtain walls: gaps are built into the structure's joints to allow for the natural contraction and expansion of materials due to outside temperatures.

-- Certain areas are highly prone to seismic activity (i.e. California), and so greater care with handling seismic load must be taken into account when engineering walls being built in high risk locales.

All curtain walls' designs allow for a certain degree of natural sway, mainly due to wind. But in places where the chances of earthquake are likely, curtain walls may be at risk from the seismic forces from its adjoining building. Special attention is placed on strengthening curtain wall anchors in such cases, and if the curtain is attached to an older building, the existing structure is retrofitted to withstand seismic activity.