When architects draw floor-to-ceiling glass on a commercial building, they might be specifying storefront, curtainwall, or window wall — three fundamentally different systems with very different engineering, cost, and performance profiles. Confusing them in a bid document leads to scope gaps, pricing disputes, and wrong-product installations. This guide explains each system clearly and tells you when each one is the right choice.
Commercial Storefront: The Workhorse System
Storefront is a stick-built aluminum framing system designed for low-rise, single-story applications. The term "storefront" refers to the system type — not just the front of a store. Commercial storefront systems are used on retail, restaurant, medical office, single-story institutional, and any low-rise commercial application where an aluminum-framed glass facade is needed.
How It Works
A storefront system consists of extruded aluminum horizontal and vertical framing members (called rails and mullions) that are assembled in the field. Glass is set into the framing using glazing gaskets and pressure plates. The system is anchored at the head (top) and sill (bottom) to the building structure. Most storefront systems are designed to span a single story — typically up to about 12 to 14 feet — though some systems are rated for greater heights.
Storefront Pros
Storefront is the most cost-effective commercial glazing system for appropriate applications. It's widely available from multiple manufacturers, installers are familiar with it, lead times are relatively short, and the installation process is well established. For single-story retail, restaurant, and low-rise commercial buildings, storefront is the correct system specification.
Storefront Cons
Storefront is not appropriate for multi-story applications where the glazing must span floor-to-floor. It has a lower structural capacity than curtainwall and is not designed to handle the thermal movement and differential settlement that occurs in taller buildings over time. Specifying storefront on a multi-story facade creates long-term water infiltration and structural risks.
Storefront Cost
Standard storefront with clear tempered glass in a non-HVHZ market sits at the low end of that range. Impact-rated storefront with architectural finishes in a coastal market sits at the high end.
When to Use Storefront
Single-story commercial buildings. Ground-floor retail in a mixed-use development. Restaurant storefronts. Low-rise medical and professional office buildings. Any application where the glazing height is contained within a single story.
High-performance commercial storefront on a restaurant project combines architectural finishes, impact-rated glass, and demanding installation tolerances in an occupied hospitality environment.
Curtainwall: The High-Rise System
Curtainwall is a non-load-bearing exterior wall system that is hung from the building structure — typically from the floor slabs — and spans floor-to-floor. It is the defining system for mid-rise and high-rise commercial buildings where the facade is primarily glass and aluminum. Think office towers, luxury residential towers, major hotels, and campus buildings with extensive glass facades.
How It Works
A curtainwall system can be either stick-built (assembled in the field from individual aluminum extrusions) or unitized (factory-fabricated into complete floor-to-floor panels). Both types are anchored to the building's floor slab edges at each level. The curtainwall transfers wind loads directly to the building structure rather than to the floor at the base of the system, which is what allows it to work at heights where storefront fails.
Unitized curtainwall — where complete pre-glazed panels are fabricated in the factory and hoisted into place on site — has become increasingly common on complex projects because it reduces field labor time, improves quality control, and allows faster installation once structural construction has reached adequate height.
Curtainwall Pros
Curtainwall is the appropriate system for multi-story facades. It handles thermal movement, differential deflection between floors, and wind loads at elevations where storefront and window wall cannot perform safely. It also offers the most architectural flexibility — nearly any geometry, glass composition, and panel depth is achievable in curtainwall.
Curtainwall Cons
Cost. Curtainwall is substantially more expensive than storefront or window wall. The engineering, factory fabrication, shop drawing complexity, and field installation time all add up. On inappropriate applications — particularly low-rise buildings where storefront would perform adequately — curtainwall represents unnecessary cost without commensurate performance benefit.
Curtainwall Cost
unitized), glass specification, architectural complexity, and project scale. Standard 2" x 4.5" stick-built curtainwall on a mid-rise commercial building sits at the lower end of that range. Complex unitized systems with deep shadow boxes, specialty glass, and custom extrusions sit at the high end or above it.
When to Use Curtainwall
Multi-story buildings where the facade must span floor-to-floor. Buildings over four or five stories in most applications. Any project where the architectural intent is a continuous glass facade without the slab-edge reveals that window wall creates. High-end projects where architectural flexibility and performance standards are paramount.
ACG's work at Panther National Clubhouse demonstrates the kind of complex, multi-system glazing scope that requires curtainwall expertise — high-performance glass, architectural integration, and demanding tolerances on a trophy project.
Window Wall: The Multifamily Standard
Window wall is the middle system — more capable than storefront, more cost-effective than curtainwall. It has become the dominant glazing system for mid-rise multifamily residential construction in Florida over the past decade, and for good reason: it offers floor-to-floor glass coverage at a cost point that makes sense for residential-over-podium and mixed-use projects.
How It Works
A window wall system spans floor-to-floor but, unlike curtainwall, bears on the building's floor slab at each level rather than hanging from it. The system sits in front of the slab edge and bears on a slab bearing angle. This distinction — bearing vs. hanging — is what separates window wall from curtainwall structurally. The slab edge is visible as a horizontal reveal between floors, which is the visual signature of window wall construction.
Window Wall Pros
Window wall is substantially less expensive than curtainwall for multi-story applications. It provides floor-to-floor glass coverage and can be specified with impact-rated products to meet Florida Building Code requirements. The slab-bearing design simplifies the connection to the building structure compared to curtainwall, reducing both engineering complexity and field installation time.
Window Wall Cons
The slab edge reveal — visible as a horizontal band across the facade at each floor — is aesthetically limiting compared to curtainwall. For buildings where a continuous, uninterrupted glass facade is architecturally required, window wall will not achieve that look. Window wall also has lower structural performance limits than curtainwall and is not appropriate for very tall buildings or extremely high wind-load applications.
Window Wall Cost
When to Use Window Wall
Mid-rise multifamily residential (typically 5-15 stories). Mixed-use buildings with residential above podium. Senior living, extended stay hospitality, and any application where floor-to-floor coverage is desired but curtainwall's cost premium is not justified. Projects where the slab-edge reveal is acceptable or can be incorporated into the architectural design.
ACG's work at Atlantic Fields Golf House is an example of the level of window wall execution ACG brings to high-specification projects — careful detailing, precise tolerances, and coordination with the building structure to achieve the architectural intent.
Side-by-Side Comparison
| Feature | Storefront | Window Wall | Curtainwall |
|---|---|---|---|
| Installed Cost (FL) | By scope | By scope | By scope |
| Typical Height Range | 1 story (up to ~14 ft) | Multi-story (5–15 floors) | Any height |
| Structural Principle | Bears at sill/head | Bears on slab edge | Hung from slab |
| Slab Edge Visible? | N/A (single story) | Yes (reveal visible) | No (continuous glass) |
| Engineering Complexity | Low | Medium | High |
| Best For | Retail, restaurant, low-rise commercial | Mid-rise multifamily, mixed-use | High-rise, trophy commercial |
| Impact Rating Available? | Yes | Yes | Yes |
Which System Does Your Project Need?
The system selection decision should follow the building design — not the budget. Using the wrong system to save cost is how buildings end up with chronic water infiltration, failed inspections, and owner callbacks that exceed the original cost savings. Here's a simple framework:
Single-story commercial building: Storefront. It's the correct system for the application, and there is no meaningful performance advantage to specifying curtainwall on a single-story structure.
Mid-rise multifamily (5–15 stories): Window wall is the standard system for this building type in Florida. It delivers the floor-to-floor glass coverage that contemporary multifamily design demands at a cost point that makes the math work. Curtainwall is appropriate if the architectural program requires a continuous facade without slab reveals — but that's the exception, not the rule, in residential construction.
Mid-rise to high-rise commercial office, hotel, or mixed-use above about 15 stories: Curtainwall. The structural demands, thermal movement, and performance requirements at this scale require curtainwall. Window wall's slab-bearing design becomes a structural liability at these heights.
Mixed-use buildings with distinct floors: Often two or more systems. Ground-floor retail gets storefront; residential floors above get window wall or curtainwall depending on height and program. Getting the system transitions right — the waterproofing, the structural connections, and the thermal continuity — is where experience matters.
ACG installs all three systems. We can help you evaluate which system is right for your project before you commit to a specification. Browse our project portfolio to see examples of each, review our services for system-specific information, or use our Scope Engine to start generating a preliminary estimate.
Frequently Asked Questions
Can you mix systems on the same building?
Yes, and it's common. Many mixed-use buildings use storefront at the ground floor retail level and window wall or curtainwall on the residential floors above. The key is properly detailing the transition between systems — waterproofing, anchor connections, and thermal continuity must be continuous across the transition. This is a design and engineering question that should be resolved in the drawings before bid, not resolved as a field question during construction.
Is window wall appropriate for a 10-story building?
In most cases, yes. Mid-rise multifamily in the 5–15 story range is the core application for window wall. Above 15 stories, wind loads and differential floor deflections begin to exceed what most window wall systems are designed for, and curtainwall becomes the more appropriate system. The engineer of record should confirm the appropriate system for any project over 10 stories based on the specific wind design criteria and structural design.