Unitised Façades: Improving Safety, Costs and Quality
One of the key design issues to look for at the outset in any potential construction scheme is its repeatability and potential standardisation of similar elements. Façades are one of the most significant areas where the opportunities for standardisation of elements for off-site construction can be seen, particularly with unitised façades. It is important however that the original scheme aesthetic is suitable for standardisation for without boundaries on façade design, clients may experience higher costs and lower quality in the design and installation of their building façade than anticipated.
Rather like a car production line, each identical façade element moves from work-station to work-station in a continuous flow with QAQC controlling each part of the process. Since the construction, the quality standards and the specification are the same for each element, offsite façade fabrication can have cost-savings benefits as well as the inherent quality control of repeatable design and manufacture.
Unitised vs stick façades
The important issue in façade design is to balance the needs of the aesthetic that the architect is trying to convey with the ability to unitise a product to save time and money.
There will be a point at which the design becomes too complicated to build offsite efficiently and unitisation becomes expensive and ultimately potentially impractical to achieve. This often leads to the need to go back to a traditional stick façade method.
However, stick systems become uneconomic at height. Depending on opinion, they can be achieved up to around 20 storeys. They become difficult to manage beyond that, with time and inefficiencies involved in the vertical distribution of materials problematic as well as the obvious potential safety issues of working with a kit of parts at height.
The benefits of unitisation
There are three main advantages that unitisation can offer when considering the façade of a building:
- Safety – this is the most important factor. Building at height, whether with scaffolders or mast climbers has the inherent danger of materials falling, so the more you can incorporate into a façade offsite, the safer the construction.
- Quality – every element that goes into façades, aesthetics, structural stability and interfaces, are manufactured in a controlled environment where they can be recorded and managed more easily than onsite, where construction is at the mercy of the elements.
- Cost – whilst the upfront costs may be higher, the time spent on site is significantly less and as is the quantity of site labour required. This reaps benefits in direct labour costs as well as prelim costs.
A unitised façade is built off-site, so every specified performance characteristic can be considered at design stage. U-values are especially important to consider as the cavity between façade and the metal framework of the building can be limited. Balconies also need to be part of that early conversation as they need to fit correctly on and around the façade.
Unitised facades in a post-pandemic world
The 2020 pandemic changed everyone’s lives and given us all pause to think about how we have done things in the past. In my view, the construction industry will be radically changed forever by its impact. Having fewer people onsite will continue to be a factor and the less work our construction teams need to undertake in close proximity to each other the better.
Working smarter will continue to mean support roles will continue to work online when they don’t need to be on construction sites and the potential to be more efficient at much less cost will drive this.
With this in mind, designers and architects can include these factors when considering the cost benefits of unitised façades and well as the quality and efficiency they bring to the construction site.
This article is based on an interview with Laurence McBeth, Sales & Commercial Director at Alumet Systems.
