Curtain walls are products, which are developed having a thin thickness and are usually made from aluminum frames while containing fills of metal panels, delicate stones, or glass. The frame is generally bonded to the construction’s structure; thus, it does not carry the load of the roof and floor of the building. The load caused by environmental factors such as gravity and wind is typically transferred to the structure’s floor line. This product development started in the 1930s, and the manufacturing services expanded rapidly after World War II. It was first utilized for military purposes, and then designers turned it into a suitable exterior product like other industrial materials such as ACP.
Architects and builders use a wide range of curtain wall systems to specialize in custom walls. These products have become a cost-effective solution and a strong competitor to other standard walling systems.
A Brief Description
Curtain wall systems are classified by their installation and fabrication methods into two main categories, which are unitized and stick systems. In the stick system, the frame and opaque or glass panels need to be connected piece by piece, and then the installing process must be completed afterwards. On the other hand, curtain walls that follow unitized systems are composed of large units glazed and assembled in the manufacturing factory and then shipped or transported to the construction site. Adjoining modules attach the vertical and horizontal mullions together. These modules are generally created with a longer length and are often five to six feet wide.
Another method for classifying curtain walls is considering them as pressure-equalized or water-managed systems. All types of these walls are designed for both interior and exterior glazed systems. Interior systems are used to allow the opaque or glass panel to be installed into the wall opening from inside the building. Due to the air infiltration issue, the interior glaze system does not provide details. It is suitable for applications with limited inner obstructions for providing adequate access to the inside of the wall. Outside glazing is specified for low altitude buildings with easy access to the construction.
In some specific cases, the interior curtain type is used for high-rise buildings to provide glass replacement logistics from a swing stage. Glass panels need to be installed from the outside of the wall in exterior glaze systems. These systems require scaffolding access to the outer space of the wall for replacement and repair purposes. Some of the designs can be glazed from both interior and exterior areas.
Glass panels used in curtains are predominantly insulating and are usually fixed or glazed into operable frames placed in the wall system. Metal panels are varied in aluminum plates, stainless steel, or other corrosion-resistant materials such as aluminum composite panels created from two sandwiched layers. Panels that are made from stone substances are usually granite.
Beneficial Characteristics
Curtain wall systems provide many advantages for any construction project. Thus their popularity is still growing day-by-day. Determining these products main benefits can help architects and building owners create their unique and efficient facility. Followings are the most beneficial characteristics of Curtain walls.
Back Pan Insulation and Thermal Performance
Back pans are metal sheets, which are usually made of aluminum or galvanized steel. These sheets sealed when attached to the curtain wall framing. They act as an air and vapor barrier when the insulation is installed between the exterior cladding and back pans in colder climates. They also create an additional defense against infiltration for areas that are not easy to access. Curtain walls are trendy for their high thermal performance. This is due to the conductivity of aluminum. It is common to use thermal breaks of low conductivity for improving the performance of these products. They can prevent the heat infiltration and save a tremendous amount of energy. This is due to the presence of an extra layer across the building. Thus, these type of walls can stabilize the overall temperature of the building. Additionally, UV light, which can increase the pace of fading or degrading the building, can be significantly reduced by curtain walls.
Water Penetration and Condensation Resistance (Moisture Protection)
Water penetration resistance of curtain walls results from glazing details, drainage details, frame gaskets, weather-stripping gaskets, interior sealants, and flashings. Water can penetrate through the building’s exterior cladding system employing five important forces: kinetic energy, gravity, air pressure, capillary action, and surface tension. To decrease the water penetration, these forces should be considered in the building’s design. Curtain walls usually cover large areas of the wall without flashings, and this makes them a better choice compared to small and discontinuous windows.
Visual Aesthetics
Sightlines and glazing appearance of curtain walls is the key feature of these products. Visual profile of the horizontal and vertical panels are defined as sightlines. They create both the width and depth of the curtain wall frames. Most modern buildings require curtain systems due to their unique, clean, and sophisticated appearance. The installation systems for these beautiful products are commonly better, faster and more cost-effective than other cladding products.
Sound Insulation
Another function of the internal seals used for preventing air leakage is the acoustic of curtain walls. This characteristic can be improved by installing sound attenuating infill. The incorporation of glasses with different thicknesses will also help in exterior sound deadening. This is achieved by increasing the glass or opaque thickness or utilizing a laminated layer with an interlayer, which has noise-reduction specification. These layers are typically made of PVB or polyvinyl material.
Read the Fundamentals of Curtain Walls for more detailed information about these products.