Pressure Wall vs Unitized Curtain Wall: Understanding the Key Differences

Curtain wall systems are popular for commercial building envelopes due to their aesthetic appeal, performance, and design flexibility. Two of the most common types of curtain walls are pressure walls and unitized curtain walls. While they share some similarities, there are essential differences architects and builders should understand when selecting the right system.

What are the Main Differences Between Pressure walls and Unitized Curtain walls?

Installation Method

The most significant difference between a pressure wall and a unitized curtain wall is the installation method.

Pressure wall systems are installed piece by piece. Aluminum mullions and transoms are anchored to the building structure. Then infill panels, typically made of glass or metal, are glazed into each frame opening on site. This provides flexibility but can be more time-consuming.

Unitized curtain wall systems are pre-assembled in a factory into large units (up to 10 feet wide and 30 feet tall) that include frames, infill panels, and glazing. These units are then shipped to the job site craned into place and connected to the building structure. Unitized systems install much faster, but modifications on-site are limited.


Both pressure wall and unitized curtain walls can meet high thermal performance requirements using industry-leading frames and glazing.

Unitized systems may achieve U-Factors as low as 0.25 with 1″ IGUs by minimizing thermal bridges between panels. High-performance pressure wall systems can achieve U-Factors as low as 0.24 with 1″ IGUs.

Pressure wall systems can more easily accommodate triple glazing to reach U-Factors in the 0.20 range if ultra-high thermal performance is required.

Wind Load Resistance

Both curtain wall types can be engineered to withstand high wind loads. Unitized systems may have a slight advantage as the interlocking panels distribute forces across the entire unit.

Pressure wall systems rely more on the strength of each vertical mullion to resist wind forces. However, mullions can be designed to withstand hurricane-force winds exceeding 130 mph.


Water drainage is handled at each mullion frame in pressure wall systems. Weep holes and internal drainage channels redirect water to the exterior.

Unitized systems collect water within the frame of the entire unit. Large weep holes at the base of each unit drain water to the exterior.


Unitized curtain walls will generally have a higher initial cost due to the offsite fabrication and installation requirements. There are additional transportation costs as well. However, there is a time-saving advantage when using a unitized system.

Pressure wall systems take more time to install on-site but have lower material costs upfront.


Both curtain wall types offer extensive design flexibility through a range of finishes, colors, and glazing types. Unitized systems may have a sleeker appearance as the joints between units are minimal.

The pressure wall allows for more modulation in the facade design because each mullion can be placed independently.

FreMarq Offers Both Unitized and Pressure Wall Curtain Walls

FreMarq manufactures high-performance pressure wall and unitized curtain wall systems to meet a variety of building design needs. Both of our systems can achieve exceptional thermal performance using innovative warm-edge spacers and thermally broken frames.

Our pressure wall and unitized curtain wall systems accommodate a multitude of glazing types, including triple glazing, and are engineered to withstand heavy wind loads. They can be customized with a range of glazing and finish options. We are the only company that can meet recent Stretch Code requirements using 1″ IGUs – our competitors require triple glazing.

No matter your project requirements, FreMarq can provide an optimized curtain wall solution to realize your architectural vision while meeting the latest energy codes. Contact us for a quote on our pressure wall or unitized curtain wall systems.

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