Curtain walling is a non-structural outer covering of a building’s facade, typically composed of lightweight materials such as glass, aluminium, or steel. Unlike traditional load-bearing walls, which support the building’s weight, curtain walls are designed to only support their own weight and withstand wind loads and seismic forces while providing aesthetic appeal and allowing natural light to enter the interior spaces.

Usually, curtain wall systems consist of a lightweight aluminum framework ‘stickwork’ containing in-fill glass, metal panels or thin stone panels. These in-fill panels are often referred to as ‘glazing’. These panels do not carry any structural weight and any loadings such as wind or gravity are transferred to the building structure, typically at floor/slab level.

In this article, we will highlight some of the advantages of one of our services, as well as further articles in the upcoming weeks to cover some more details related to curtain walling.

Curtain walling can be split into two categories:

  • Stick systems
  • Unitised systems

Even though it is almost impossible for the untrained eye to tell which one is which on a building, the main difference between these three is the aesthetics of the final design, the construction method and the design of the system. As a minimum, each system is designed to meet the building design load requirements.

Stick systems

Stick systems are assembled from individual vertical and horizontal members, referred to as mullions and transoms respectively. A typical stick system would span from floor slab to floor slab with large glass panes to maximise the light inside the room and would have opaque spandrel panels to hide the structure at slab level.

Transoms and mullions are generally extruded hollow aluminium sections, which can vary in size, colour and finish. They are pre-cut to size in the manufacturing unit and the only thing left on the construction site is to assemble the curtain walling. The members are normally assembled by using screws, toggles, cleats or pins. All different methods to connect them depend on loading, glass weight and required design finish. The stickwork is then fixed to the slab followed by installation of the glass and spandrel panels. These are held by either pressure plates and caps fixed to the stickwork or glazing toggles and then finished by mastic/silicone.

Due to the higher cost of traditional window systems, these systems are typically used in low-rise buildings, shopping centres and shopfronts.

Elements of a stick curtain walling system

Elements of a stick curtain walling system

Unitised systems

Unitised systems use similar components to the stick system, but this time these components are pre-fabricated into individual units and delivered straight to the construction site to be fixed into the structure.

Pre-fabrication of unitised curtain walling means that we save up to 80% of the time spent at the construction site, but that comes with an additional price. Additional time spent in the factory and higher upfront costs, as well as additional design work and specialist delivery vehicles.

Unitised curtain walling units are exactly equal to the height of slab to slab, which allows for up to 60% faster installation times on-site. Also, external scaffolding support is not needed, as unlike stickwork systems here, all the work is done on the inside of the building. Although you would need a crane to lift the unitised units.

Unitised curtain walling systems are well suited to high-rise buildings requiring high volumes of cladding and where there are high costs associated with access or site labour (e.g. high-rise buildings in London and New York).

Elements of a unitised curtain walling system

Elements of a unitised curtain walling system

Doors within glass façade

For each of the curtain walling systems, doors will need to be incorporated within the façade. The doors are typically made from a single pane of glass and can be single-leaf, double leaf or turnstile. The doors will be fixed to the supporting frame, which in our case is the curtain walling. The door leafs themselves can be framed i.e. support on 4 sides with a metal frame around the door leaf, or unframed where the glass edges are exposed. Take a look at some of our portfolio projects to find out more.

What are the benefits of curtain walling?

Capable of bearing their own weight

These glass structures effortlessly support their own weight and any additional loads, such as those induced by seismic or wind forces.

Flexibility in design

Influenced by the lightweight nature of the aluminium, curtain walls can be tailored to various options for glazing, panels, textures, and finishes. It is this adaptability that makes the technique particularly effective for iconic structures like The Gherkin.

Abundance of natural light and enhanced external views

The lightweight composition of a curtain wall system allows for smaller frames, facilitating ample natural light even in modest structures, all while offering stunning panoramic views of surrounding gardens and landscapes.

Outstanding thermal performance

Compared to other building elements, aluminium possesses a high heat transfer coefficient, making it an efficient conductor of heat. However, this conductivity can lead to significant heat loss through aluminum curtain wall mullions unless thermal breaks are installed to mitigate it. In essence, thermal breaks act as a barrier between the exterior and interior metal and are commonly crafted from materials like polyvinyl chloride (PVC).

Thermal breaks can substantially reduce the thermal conductivity of a curtain wall, and luckily you would struggle to find a non-thermally broken aluminium curtain walling system available on the market.

Cutting-edge aesthetics

Our curtain walling not only boasts aesthetic advantages but also sets the benchmark for technical performance. Our toughened, laminated double-glazed Low-E units come with optional self-cleaning and solar control glass, while the frames are available in an array of colours customizable to meet individual technical specifications.

How to decide which one is right for my project?

Well, that depends on many factors, such as budgets, location, required design, project delivery times etc. And there is no right answer until a professional assesses your requirements.

Whether you’re an architect, builder, or main contractor, choosing the right curtain walling system is critical to the success of your project. At Camino Contractors Ltd, we have extensive experience in all aspects of curtain walling, from design and installation methodology to cost exercises and manufacture. We work closely with our clients to ensure that our solutions are feasible within their budget, and we provide ongoing remediation and maintenance support to ensure long-term performance. Call us now on 020 3633 8248 to receive expert assistance with your curtain walling project from Camino Contractors Ltd.