Everything You Need To Know To Find The Best Commercial Curtain Wall

When you look at a modern high-rise or a sleek office tower shimmering under the sun, chances are you’re looking at a curtain wall. These glass-and-metal façades don’t just make buildings look amazing—they play a big role in how those buildings perform.

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In recent years, curtain walls have become the go-to solution for architects and builders who want both form and function.

Whether it’s about bringing in more natural light, improving energy efficiency, or simply creating a striking exterior, curtain wall systems are leading the way.

But with so many types, materials, and technical considerations involved, understanding curtain walls can feel a bit overwhelming, especially if you’re trying to figure out what’s best for your project.

What Is a Curtain Wall?

A curtain wall is an outer covering of a building that’s designed to protect, perform, and impress—without bearing any structural load from the building itself.

Unlike traditional walls that support floors or roofs, curtain walls are non-structural. They’re attached to the building’s frame and hang like a curtain—hence the name. Most commonly made from glass, aluminum, or other lightweight materials, curtain walls form a sleek envelope that wraps around modern buildings.

Key Benefits of Curtain Walls

• Aesthetic Impact: Glass curtain walls deliver a clean, modern appearance. They can make buildings look taller, brighter, and more impressive.

• Environmental Protection: These systems provide excellent defense against weather conditions—keeping out rain, dust, and cold while allowing natural light in.

• Energy & Acoustic Performance: With the right glazing, curtain walls can reduce heat transfer, block UV rays, and even cut down on exterior noise.

• Design Flexibility: Whether your project calls for dramatic curves or minimalist lines, curtain wall systems offer the adaptability to bring creative visions to life.

Types of Curtain Wall Systems

Not all curtain walls are built the same. Depending on the size of your project, your design goals, and your timeline, the right system can make a big difference in how the curtain wall is installed—and how it performs.

1. Stick-Built Curtain Wall

Stick-built systems are assembled piece by piece on-site. The vertical mullions are installed first, followed by horizontal transoms, and then the glass panels.

This method offers more flexibility in handling unique shapes or tricky site conditions but requires more labor and time. It’s a great fit for smaller or medium-sized buildings, especially those with complex façades.

2. Unitized Curtain Wall

In a unitized system, entire sections of the curtain wall are pre-fabricated in a factory, including glass and framing. These large panels are then shipped to the site and installed quickly, often using a crane.

This system reduces on-site labor, speeds up construction, and ensures consistent quality. It’s ideal for high-rise or large-scale projects with repetitive floor plans.

3. Semi-Unitized Curtain Wall

A hybrid of the previous two, semi-unitized systems combine factory-assembled panels with some site assembly. It strikes a balance between cost, speed, and design flexibility—especially useful when full unitization isn’t practical.

4. Spider Glass Curtain Wall

Spider systems use point-fixings and stainless steel spiders to hold glass panels in place, creating a frameless, minimal look. This type of curtain wall is all about visual transparency and is often used in luxury buildings, airports, and modern storefronts.

5. Double Skin Curtain Wall

This system features two layers of façade, often with a ventilated air space between them. The result? Enhanced thermal insulation, better sound control, and a more energy-efficient building.

Double skin systems are growing in popularity, especially for projects prioritizing sustainability.

6. Glass Fin Curtain Wall

Instead of metal mullions, glass fins are used to support the façade. The result is an ultra-clear, futuristic appearance often used in high-end commercial spaces where aesthetics are everything.

7. Cable Net Curtain Wall

These systems use tensioned steel cables instead of traditional framing. They allow for large spans of uninterrupted glass and a very lightweight appearance—ideal for atriums, museums, and feature walls.

8. Custom Curtain Wall Systems

Sometimes, a project demands something completely unique. Custom systems are tailored to your specific building shape, performance needs, and design vision. They often combine materials, glazing types, and support structures in creative ways.

Curtain Wall Components and Materials

Curtain wall systems may look sleek and simple from the outside, but behind that clean glass surface is a carefully engineered combination of parts—all working together to keep the building protected, efficient, and beautiful.

Mullions and Transoms

These are the framework of the curtain wall.

• Mullions are the vertical bars that run up and down the façade.

• Transoms are the horizontal bars that cross between them.

Together, they form the structural grid that holds the glass or other panels in place. They also help distribute wind loads and support the curtain wall’s overall stability.

Vision Glass and Spandrel Panels

Curtain walls typically alternate between two types of panels:

• Vision glass is the transparent part that allows natural light to enter and provides views from inside.

• Spandrel panels are opaque and cover areas where there are no views—like between floors or behind structural elements. These can be made from glass with a coating, or from other materials like metal or stone.

This combination gives the building a clean, unified appearance while hiding mechanical elements or insulation where needed.

Anchors and Fasteners

These are the unseen connectors that hold everything together.

• Anchors attach the curtain wall to the building’s structural frame.

• Fasteners secure the different components, like mullions to transoms or panels to framing.

They must be precisely engineered to handle movement, weight, wind, and even seismic forces—while remaining hidden from view.

Pressure Plates and Snap Covers

These are part of the system that holds and seals the glass panels in place.

• Pressure plates are clamping elements that press the glass against the framing, often paired with gaskets for airtightness.

• Snap covers go over the pressure plates to hide them, giving the wall its finished, seamless look.

They also help with weatherproofing and improving thermal performance.

Common Materials Used

The choice of materials affects the system’s weight, strength, insulation, and appearance. Here are some of the most common ones:

• Aluminum: Lightweight, corrosion-resistant, and easy to shape—this is the most common curtain wall framing material.

• Steel: Stronger and heavier than aluminum, used when additional strength is required.

• Timber: Offers a warm, natural look. Usually used in hybrid systems where aesthetics are a major priority.

• Stone veneer: Adds a classic or upscale look, often used in spandrel areas.

• Terracotta: A ceramic material used for its texture, color options, and durability.

• FRP (Fiber-Reinforced Plastic): Lightweight and durable, used in specialty designs for added performance or unusual shapes.

Glazing Methods: Interior vs. Exterior

When it comes to installing the glass panels in a curtain wall system, there are two main approaches: interior glazing and exterior glazing. The method you choose can affect everything from labor costs to installation speed and even site safety.

Interior Glazing

As the name suggests, interior glazing is done from inside the building. Installers set the glass panels into the framing from the interior side, which makes it a popular choice for low-rise buildings or areas where interior access is easy and unobstructed.

Key benefits:

• No need for scaffolding or lifts outside the building

• Safer and more comfortable working conditions

• Ideal for buildings still under construction or with large open interior spaces

Exterior Glazing

With exterior glazing, the glass is installed from the outside of the building. This method is more common for high-rise structures, where access from the interior is limited or where prefabricated systems like unitized curtain walls are used.

Key benefits:

• Suitable for taller buildings

• Allows for large pre-glazed panels to be installed by crane

• Often faster for repetitive designs and large façades

What to Consider When Choosing a Glazing Method

Choosing between interior and exterior glazing depends on several factors:

• Building height and design: Taller buildings or complex façades often lean toward exterior glazing.

• Site access and safety: If the site has limited access around the perimeter, interior glazing may be safer and easier.

• Labor costs and equipment: Interior glazing reduces the need for exterior equipment, while exterior glazing may require cranes or swing stages.

• Construction schedule: Unitized panels with exterior glazing can speed up installation on fast-track projects.

Structural and Performance Design Considerations

Behind the sleek look of a curtain wall lies a lot of engineering. These systems don’t just need to look good—they must also perform reliably under real-world conditions like wind, temperature changes, and weather exposure.

1. Structural Integrity

Curtain walls may not carry the weight of floors or roofs, but they must withstand strong forces, especially wind.

Wind Load Design (ASCE/SEI 7)

Engineers use the ASCE/SEI 7 standard to determine wind loads based on the building’s height, location, and shape. These wind pressures help define how strong the curtain wall must be to remain safe and stable over time.

Frame Deflection Limits (L/175, L/360)

To keep the glass panels safe, the framing must limit how much it bends (deflects) under pressure. Industry standards typically require:

• L/175 for general conditions

• L/360 when finishes like drywall are involved

The smaller the deflection, the better the glass alignment and seal performance.

Structural Testing (ASTM E330)

Curtain wall systems are often tested under uniform static air pressure to simulate wind. This test (ASTM E330) helps verify that the system can withstand design loads without permanent damage or dangerous movement.

2. Movement and Expansion

Buildings move—and curtain walls have to move with them.

Thermal Movement of Aluminum vs. Glass

Materials expand and contract with temperature. Aluminum expands more than glass, which can cause stress at joints if the design doesn’t allow for that movement.

Accommodating Differential Movement

To avoid seal failure, cracked glass, or noisy panels, curtain walls must be designed to absorb daily and seasonal expansion and contraction. That means careful attention to anchor points, joint sizes, and flexible gaskets.

3. Air and Water Resistance

Keeping water and air out of the building is one of the most important jobs of a curtain wall.

Internal Drainage vs. Pressure-Equalized Systems

There are two main strategies for water control:

• Internal drainage systems use gutters and weep holes to redirect water that enters the wall.

• Pressure-equalized systems add a ventilated air chamber behind the outer layer to balance air pressure and prevent water from being pulled in. This method offers superior resistance to leakage.

Gasket Performance and Weep Holes

Gaskets form tight seals between glass and frame, but even with good seals, water can find its way in. That’s why proper weep holes are critical—they give any moisture inside a way to escape.

ASTM E331 & E283 Testing

To make sure the wall performs, manufacturers use:

• ASTM E331 to test resistance to water under wind-driven conditions

• ASTM E283 to measure air leakage through the wall under pressure

These tests help validate that the system will perform as expected—even in tough weather.

Energy Efficiency in Curtain Wall Systems

Energy performance is one of the top considerations in modern curtain wall design. A well-designed system can significantly reduce heating and cooling costs, improve comfort, and support building code compliance.

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Low-E Coatings and Insulated Glazing

Low-emissivity (Low-E) coatings are thin, invisible layers applied to glass that reflect heat while still allowing light to pass through.

When combined with double or triple glazing, Low-E coatings help regulate indoor temperatures by:

• Reducing heat loss in winter

• Blocking heat gain in summer

• Minimizing glare and UV damage

These high-performance glass types help create a more comfortable indoor environment while lowering energy bills.

U-Values and Condensation Resistance (CRF)

U-value measures how much heat passes through the glass and frame. The lower the U-value, the better the insulation. Curtain wall systems are designed to meet specific U-value targets based on climate and building codes.

Another important factor is the Condensation Resistance Factor (CRF). This rating indicates how well the system resists interior condensation on cold days.

• A higher CRF = better resistance to moisture buildup

• This improves long-term durability and occupant comfort

Tolerances and Building Integration

Curtain wall systems may be factory-made with precision, but once they reach the job site, they have to fit into the real-world building structure—which often comes with its own set of imperfections. That’s where tolerances and clearances come into play.

Tolerances vs. Clearances

These two terms are often used together—but they mean different things:

• Tolerances refer to the acceptable amount of variation in the dimensions of a component or system. For example, how much a mullion can vary from its intended position and still be considered correct.

• Clearances are the intentional spaces left between components to allow for movement, thermal expansion, or ease of installation.

Both are essential. If tolerances are too loose or clearances too tight, panels may not fit correctly, and the system could suffer from misalignment, leaks, or stress.

AAMA-Recommended Installation Tolerances

The American Architectural Manufacturers Association (AAMA) provides clear guidelines on allowable deviations during installation. These cover:

• Plumb (vertical alignment)

• Level (horizontal alignment)

• Flatness and straightness of members

• Coplanar alignment (how flush adjacent panels are with each other)

For example, the maximum allowable offset between two adjacent framing members might be 1.5 mm, and corner joints should stay within 2 degrees of true alignment.

Coordinating with Concrete and Steel Structures

Curtain walls are often installed on buildings made of reinforced concrete or steel, and these materials come with their own construction tolerances too.

• For concrete frames, tolerances are typically governed by ACI 117 (American Concrete Institute)

• For steel frames, refer to AISC 303 (American Institute of Steel Construction)

Because field conditions are rarely perfect, curtain wall designs must anticipate worst-case alignment scenarios and provide proper clearances to avoid last-minute adjustments or delays.

Coplanar Alignment and Joint Spacing

Even small misalignments between curtain wall panels can impact the building’s appearance and weather resistance. That’s why:

• Panels must be installed as coplanar as possible, especially at corners and transitions

• Joint spacing must be consistent to allow for drainage, expansion, and clean visual lines

Attention to these details doesn’t just make the façade look sharp—it also improves long-term performance and reduces maintenance issues.

Applications of Curtain Walls

Curtain walls have become a signature feature in modern architecture—not just for their sleek looks, but for how well they perform in all kinds of environments. From corporate towers to cultural landmarks, they’re used across a wide range of building types.

#1 Commercial Buildings and Skyscrapers

Curtain walls are practically the standard for office towers and high-rise commercial buildings. They allow for expansive glass façades that create a clean, professional look while delivering natural light deep into the building. In dense urban areas, curtain walls also help maximize views and minimize environmental stress from wind, rain, and noise.

#2 Luxury Residential Towers

High-end residential buildings often feature curtain walls to create floor-to-ceiling glass views, open interiors, and a strong connection to the outdoors. Residents enjoy brighter spaces and panoramic cityscapes—without sacrificing energy performance or comfort.

#3 Educational Institutions

Universities, libraries, and research centers use curtain wall systems to create welcoming, light-filled environments. The natural light enhances learning spaces while reducing energy costs, and the modern design reflects the forward-thinking values of many schools.

#4 Healthcare and Hospitality Projects

Hospitals, clinics, hotels, and resorts benefit from curtain walls by creating bright, calming spaces for both patients and guests. The increased natural light and improved acoustic performance make a real difference in how comfortable the space feels.

#5 Cultural Landmarks and Public Spaces

Think museums, theaters, galleries, and stadiums—curtain walls help these buildings stand out as architectural icons. They allow designers to play with transparency, shape, and scale while still meeting performance and safety standards.

Maintenance, Repair & Lifecycle Considerations

Curtain wall systems are built to last—but like any part of a building, they still need regular care to stay looking great and performing at their best.

Cleaning Protocols

Over time, curtain walls can collect dust, grime, and pollution—especially in urban areas. Routine cleaning not only keeps the glass looking clear and streak-free, but also prevents the buildup of materials that could damage seals or finishes.

• Glass panels should be cleaned using non-abrasive solutions and soft cloths or squeegees.

• Aluminum framing may need occasional washing to remove corrosive residues and preserve the finish.

Depending on the building height, this could mean using swing stages, rope access, or extendable tools.

Sealant Checks and Replacement

Sealants are the invisible heroes that keep water and air from getting through the gaps between glass and frame. But they don’t last forever.

Over time, UV exposure, movement, and weathering can cause sealants to crack or lose adhesion. Routine inspections (every few years) can help identify issues early. Replacing sealant when needed helps maintain airtight and watertight performance—and avoids bigger problems later.

Panel Damage Repair Procedures

Accidents happen—whether it’s from wind-blown debris, impacts, or unexpected stress. If a glass panel cracks or breaks:

The damaged panel should be removed and replaced as soon as possible to maintain structural safety and appearance. Repairs must be done carefully to avoid damaging the surrounding frame or seals.

Working with an experienced curtain wall contractor ensures the repair is safe, secure, and up to spec.

Long-Term Durability Strategies

Want your curtain wall to perform well for 30+ years? It starts with good design, but continues with proactive upkeep:

• Stick to a regular inspection schedule (ideally annually)

• Address minor issues early before they become major repairs

• Use high-quality replacement parts and materials

• Keep maintenance records for future planning

Choosing the Right Curtain Wall System

With so many types of curtain walls available—from stick-built to unitized to double-skin systems—it’s easy to feel overwhelmed when deciding what’s best for your project. The good news? You don’t have to make that decision blindly.

#1 Project Size and Building Height

• For high-rise buildings, unitized systems are often the best fit. They’re pre-assembled off-site and quickly installed with cranes, saving time and improving consistency.

• For low- to mid-rise buildings or complex façades, stick-built systems offer more on-site flexibility and lower initial material costs.

#2 Budget and Timeline

• If you’re working with a tight schedule, unitized systems are faster to install but may have higher upfront costs due to factory assembly and transportation.

• Stick systems are more labor-intensive but can reduce shipping and storage costs, especially for smaller projects.

#3 Design Complexity

• Got curved surfaces, angles, or an unconventional shape? Stick systems provide greater on-site adjustability.

• Need a minimalist, frameless look? Consider spider glass or glass fin systems for maximum transparency and modern aesthetics.

#4 Environmental Conditions

• For projects in high-wind zones or seismic areas, look for systems tested for structural performance and equipped with flexible anchoring.

• In hot or cold climates, choose glazing with Low-E coatings and frames with thermal breaks for better energy performance.

#5 Performance Requirements

Ask yourself:

• Do I need superior thermal insulation?

• Is sound control important for this location?

• How critical is airtightness and waterproofing?

Answering these will help you narrow down systems that meet your technical goals while still supporting your design intent.

#6 Building Codes and Certifications

Your curtain wall system must comply with local building codes, energy standards, and possibly LEED or other green certifications. Always check with your architect, façade engineer, or local authority early in the process.

#7 Long-Term Maintenance and Access

Think ahead—how easy will it be to clean, inspect, and repair your curtain wall system?

Systems with removable covers, clear drainage paths, and accessible anchoring will simplify long-term maintenance. In tall buildings, unitized panels may allow for easier replacement down the road.

Looking for the Right Curtain Wall Partner for Your Project?

Choosing the right curtain wall system is only the beginning—finding the right partner to design, supply, and support your project is just as important.

Whether you’re planning a commercial tower, a residential development, or a cultural landmark, our team is here to help. From expert recommendations to technical support, we’ll guide you every step of the way.

Need help choosing the right system or want advice for your project? Reach out to us today—we’d love to hear more about your goals and how we can support your curtain wall needs.

FAQs About Curtain Walls

A large portion of our glazing work at Giroux Glass involves installation of curtain wall – the non-load-bearing exterior wall that functions as a protective façade of many a skyscraper, office building, or other commercial construction. Named for the fact that it hangs (like a curtain) from the face of a floor slab, curtain wall can be constructed from any type of frame, cladding, or covering material. In glazing, however, the term “curtain wall” typically refers to aluminum-framed systems, set with recurring units of glass, panels, or other building materials.

Curtain Wall vs. Window Wall and Storefront Glass

In regards to glazing, curtain wall differs from other large-scale glass installations like storefront and window wall in size, application and drainage methods.

Unlike window wall, which sets units of glass within the structural components of a wall, curtain wall systems are suspended over the building’s structural elements, providing cover, but no support. Because of this, each unit is longer than a window wall unit – 14 feet or higher – and extends beyond the length of one floor. Curtain wall units are also taller than the typical storefront unit, which generally measures 10-12 feet in height.

Curtain wall can be applied over any story of a building, while storefront is only installed along the bottom floor, and window wall can only be set at the second story or higher. And unlike storefront and window wall systems, which channel water across the horizontal and vertical perimeter of the installation as a whole, each unit in a curtain wall system drains individually. This system is advantageous, as it distributes water across a broader surface, which reduces wear and tear.

Unitized Curtain Wall vs. Stick Curtain Wall

Generally speaking, there are two main types of curtain wall systems, unitized curtain wall and stick curtain wall. Though aesthetically similar, the two are manufactured differently, and are better suited to specific types of projects.

Related Read: 3 Influential Curtain Wall Projects

Unitized Curtain Wall

In unitized curtain wall systems, units are assembled and glazed at a manufacturing facility, then shipped to the work site for installation. Glaziers at the job site then connect the units together horizontally and vertically, using a system of anchors and mullions. Because they’re pre-assembled at a facility, these units tend to be extremely uniform.

Due to their uniformity, unitized systems are better equipped to handle environmental stress, allowing for thermal expansion and contraction, differential movement between floors, concrete creep, column foreshortening, and/or seismic movement. Most unitized curtain wall systems are installed in a sequential manner around each floor level, moving upward from the bottom to the top of the building.

Stick Curtain Wall

Unlike unitized systems which arrive somewhat pre-constructed, stick curtain wall systems are shipped directly to the worksite in pieces, where they are assembled, glazed, and installed all together. Constructing systems this way does allow more room for error, however, it also affords more customization. Because they arrive in pieces, the components of a stick curtain wall may be cut, machined, assembled, and sealed to meet the specific dimensions of the project. And while unitized systems can to extend to a maximum height of merely two floors, stick-built systems can be split and extended to reach far greater heights. Frame assembly requires the use of specialized connections to ensure proper installation.

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A curtain wall system’s performance is only as good as the workmanship that goes into its fabrication and construction. There are many issues that can affect the final quality and durability of these installations, from repair accessibility to weather conditions, to the presence of dirt and dust on the job site. That’s why it’s imperative to hire a highly experienced, qualified glazing company to handle your curtain wall fabrication and installation.

Our team at Giroux Glass has over thirty years of experience installing all types of curtain wall. We have in-depth knowledge of every system and supporting technology on the market, and have developed strict protocols to minimize risks and other variables that can compromise the quality of your curtain wall system.

Contact us to discuss your requirements of Aluminum Flat Panel Curtain Wall. Our experienced sales team can help you identify the options that best suit your needs.