Glass has been enhanced to perform amazing and multiple functions such as style, comfort, light and space – design elements that may require more than just brick walls and concrete facades. Glass makes a building stand out and allows its character to shine. It’s welcoming and powerful, expressing the mood that you want visitors or occupants to feel as well.
Curtain walls and window walls are two exciting ways on how glass can be installed in a commercial or residential building. Both create amazing and modern facades, yet are very different from each other. Let’s look at the two respectively:
What are curtain walls?
Curtain walls are installed on the outside of a building, on their own frame. Though the frame is secured to the main building’s slabs at certain points, curtain walls stand entirely on their own structure. They are installed from the outside and the effect is an outside view that can almost look like seamless glass.
There are two types of curtain walls, said Aluglass Bautech’s Liesl Botha:
“In curtain wall you get pressure glazed and flush glazed versions. The difference is that on a flush glazed wall you see just the glass outside, with a little silicon join between the panes. On a pressure glazed wall, the aluminium frame holding the glass is exposed, so you see the framing from the outside.”
What are window walls?
Window walls are installed touching the top and bottom of a floor. In industry jargon, they are installed between the slabs, meaning the concrete slabs that define a building’s different floors. Unlike a conventional window, they reach from the ground to the roof of the floor, and architects can cover up the exposed slabs or use them in a creative way. The result is very good light with large panes of glass, said Liesl:
“Window walls will touch the top and bottom slabs, with minimal frames, so you get that full view. These are a popular way to bring natural light into your work or living environment.”
How do you choose the best fit?
The difference has been highlighted between a curtain wall and a window wall and that is noticeably how they are installed: one uses an external frame, while the other is fitted between the buildings’ slabs. The choice is a matter of taste and style because each has their benefits.
Both also have their considerations. Curtain walls are more elaborate, but they are useful for creating large glass surfaces – such as the entrance of a mall – without the immediate support of the main structure. One possible disadvantage is that the frame being separate from the slab placed in front of it can transfer sound into the next floor of the building and even create a path for fires. But sound and fire breaks at crucial points resolve this problem.
Window Walls, supplied by Aluglass Bautech, can reach up to 12 meters without support. They don’t provide the same powerful effect of a curtain wall. But they are easier to install and offer modification choices such as adding balconies. Both can be created with a variety of glass, including laminated and toughened glass, which can impact factors such as double glazing, sound dampening and heat transferral.
“You can use laminated, toughened, coated glass and even double glazed units, depending on the project,” Liesl explained. “It really comes down to the u-value of the project. A thermal energy consultant or architect would typically supply the u-value that they would like the glass facade to achieve, to the facade manufacturer. They, in turn, need to apply this to the design. But maintenance should also be considered, especially of flush-glazed curtain walls. If a pane starts delaminating, it can become dangerous thus difficult to replace.”
Both systems can also be retrofitted to a building. A curtain wall is arguably easier, as it stands on its own frame. Likewise, window walls can be added to a building later. But as is always the case with late changes, this can be more costly than deciding on the system at the design stage.
“One system that has a great advantage with respect to retrofitting is the HBS explorer system, which is used by Aluglass Bautech. With this product, it is possible to install both frame and glass from the inside of the building. It covers most of the building envelope. A range of systems are available from domestic houses to high-rise buildings.”
Curtain walls and window walls both look stunning. But they are very different to each other. Architects and designers should weigh their merits carefully and see which best fit their project. With the right knowledge, consideration and advice, such a window system can create beautiful buildings for generations.