Curtain walling

In historical terms a curtain wall formed the enclosure to a fortification.

The current use of the term describes a weatherproof, non-load-bearing enclosure of windows or metal panels in a light metal framework that is fixed back to the structure of a building, usually at intermediate floor levels. Curtain walling is a form of cladding, providing a weatherproof enclosure and increasingly serving as a means of controlling the internal environment of a building.

The science and technology of cladding is fairly complex. Therefore the cladding industry is often plagued with design or workmanship problems. Over recent years, dozens of cladding manufacturers and installers have failed, often as a result of difficulties with particular projects. One major cladding manufacturer is reputed to have purchased an entire office building from the employer as a means of resolving a dispute. It is unsurprising therefore that many surveyors shy away from cladding inspections, preferring to leave the inspection and resolution of defects to those with appropriate skills.

The cladding supply chain is also complicated - populated with a large number of specialist contractors of varying degrees of competence and a smaller number of correspondingly larger manufacturing organisations. Frequently (and especially with window systems) the components of the system are supplied by the manufacturer to a franchised fabricator, who may decide to introduce non-franchised components into the system and produce an installed product that is not fully in accordance with the manufacturer's specification or design.

There may be an infinite number of variations of cladding designs, but there are some fairly basic concepts that are worth examining as they help develop an understanding of how cladding works and why it can go wrong.