Every element of construction has its own characteristic vulnerabilities and curtain wall facades are no exception. All of the issues mentioned below can occur in the most eye catching curtain wall – but you don’t want them to happen in your installations. Some curtain wall failures are easily fixed but others can require lengthy and costly remediation works. They are often caused by relatively simple mistakes in the fabrication process or during installation.
Failures can range from mere discomfort factors, such as excessive glare or poor temperature control, through to structural failures resulting in the collapse of a section of the curtain wall. Forewarned is forearmed and each one represents a risk that requires planning for and mitigation against. As construction technology improves, advances in product design and component quality should reduce and minimise the probability and impact of these bugbears but nothing replaces good, in-depth planning and design, and stringent quality assurance and quality control at every stage of the process, from sourcing components, through fabrication to eventual installation and the ongoing maintenance program. Adopting Best Practices from start to finish is the best defence against failures.
1) Inadequate Wind Load And Movement Resistance
The façade must be able to withstand lateral forces as well as the dead load of the components of the curtain wall. This is especially true of taller buildings. Extreme winds not only apply force to the surface of the curtain wall but can lead to movement or swaying in the building structure itself. Glazing pockets must demonstrate a level of flexibility to handle this type of movement and the forces and torque that it unleashes. Therefore wind load calculations are a very basic and vital element of the initial design.
2) Premature Weathering
This is often attributable to design errors and omissions, such as choosing inappropriate materials or systems. Weathering may go deeper than simple visual deterioration of detail. On occasion, technologies such as new glazing coatings may not have been sufficiently field tested by the manufacturer before being released onto the market. Deficiencies may not become apparent for several years until weathering and exposure eventually reveal the weakness or fault. Tried and trusted is the mantra to adopt when selecting components. Premature weathering may also be attributable to the wrong surface treatment /powder coating for the curtain walling and windows, that is unsuited to the local environment. For example, coastal areas can be a relatively hostile environment and require marine grade paint, which is a thicker coating, to prevent corrosion of the aluminium. Paint thickness needs to be 60 microns as a minimum, whereas normal powder coating thickness is 40 microns. All Logic Aluminium powder coating comes with a 25 year guarantee.
3) Inadequate Bracketry
Bracketry, such as perimeter anchors, should be fully compatible with the system being installed. Ideally they should be engineered specifically for that system to ensure total compatibility and reliability. Sub-optimal performance levels in these critical components will become apparent under stress and anything less than total fitness for purpose may be cruelly exposed resulting in damage to, and failure of, the curtain wall. The system must be correctly secured to its surrounds.
4) Air And Water Leakage
All too often, frame sealants, especially at corners and intersections, are not installed according to the manufacturer’s instructions. They have been known to be systematically deficient – sometimes completely missing in sections of the installation or discontinuous in some manner. That leads inevitably to leakage, either localised or widespread. Failure to install a relatively tiny amount of sealant in a critical location in the framework can result in leakages that may require disassembly and stripping down of large sections of the entire curtain wall. This is an area where robust and stringent project management, inspection and quality control is the equivalent of an insurance policy against failures.
5) Incorrect Gasket And Seal Choices
Gaskets perform two primary functions: they act as a watertight seal when they are compressed between the frame and the glass, and they also cushion the glazing from the effects of movement from wind etc. Gaskets are designed to survive the life span of the curtain walling – no replacement or maintenance should ever be required. Therefore it is vitally important to select the correct gasket to match the system being installed.
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