It is easy to assume from the clean appearance of a beautiful glass curtain wall that it is a simple system using tried and tested components — but of course nothing in life is so simple. These systems combine aluminium, steel, rubber, glass and high tech sealants. Since there is virtually no formal education or trade apprenticeship scheme in the industry (the CWCT in Bath, in the UK is an important exception) these are designed and put together by people who have generally learned (or are in the process of learning) by trial and error. The company that won the contract to provide the curtain wall was most likely the lowest bidder with every incentive to keep their costs as low as possible with low cost components and cheaper labour and administration.
A second factor is that future repair or maintenance of the curtain wall is extremely costly and difficult. The movement joints and connections to the building are hidden in the spandrel areas, which are very difficult to inspect from either the inside or the outside due to the presence of interior finishes, fire separation in that space, back-pans behind the glass, thermal insulation etc. Although it is possible, curtain walls are rarely (perhaps never) designed to facilitate such inspections.
The curtain wall is expected to last the life of the building — it’s not like a roof which you replace after 20 years. The reasons are readily apparent: the curtain wall is a repetitive system of components and connections so if a fault shows up it’s likely to affect the whole building, but repairs requiring access to the spandrel areas are generally not practical. Replacement is very difficult: even if it could be done progressively there would always be an area of the building with no outside walls or protection from the elements. The spaces would have to be vacated, and all of the wall, floor and ceiling finishes adjacent to the curtain wall would have to be repaired or replaced. At the same time, access to the exterior of a completed building is difficult because the window washing system is not designed for lifting glass or unitized panels and temporary provisions have to be made, moved around the building and maintained while the work is done.
It can be assumed that problems which would require the replacement of the curtain wall would not occur until some time in the mid life of the building, at which time other systems, mechanical, electrical and finishes, which normally can be replaced over time, would also be tired. Since the building has been vacated, it would make sense to overhaul these at the same time as replacing the curtain wall. However this is going to add hugely to the cost — so much so in fact that demolition and building anew would look more attractive, particularly to lenders. It is not difficult to imagine that this crisis occurs at around the same time the original building finance is paid off and the income becomes really good. This huge loss of income over perhaps several decades could have been avoided by having a qualified facade consultant making sure that the original work was specified and executed properly with the correct materials. Looked at this way, Facade Consulting is about the best value for money insurance that you can find anywhere.