If you've seen a glass-wrapped office tower and wondered what's holding all that glass in place — the answer is almost certainly curtainwall. But "curtainwall" is one of those terms that architects, engineers, and contractors use freely while meaning slightly different things. This guide defines it precisely, explains how it works structurally and thermally, walks through the two main delivery methods, and gives you clear criteria for deciding when curtainwall is the right system for your building — versus when storefront or window wall will serve you better at a fraction of the cost.
What Is a Curtainwall System?
A curtainwall is a non-structural exterior wall system — meaning it carries no floor or roof loads from the building. Its job is entirely to enclose the building: keeping weather out, controlling energy transfer, and providing the architectural expression of the facade. The building's structural frame (concrete, steel, or masonry) does the load-bearing work; the curtainwall simply hangs off it.
This distinction matters a great deal. Because curtainwall is non-structural, it can be made almost entirely of glass and aluminum — thin, transparent, and visually open. The building structure behind it handles gravity loads, wind uplift, and seismic forces. The curtainwall handles everything at the skin: air infiltration, water infiltration, thermal performance, and the transfer of wind load back to the structure through its anchor points.
The term "curtain" is intentional. The glazing system literally hangs like a curtain from the structural frame, spanning floor-to-floor between anchor points rather than being supported by the slab edge the way window wall is. That spanning capability is what makes curtainwall suitable for high-rise construction — and what makes it significantly more expensive than other systems.
How Curtainwall Is Attached to the Building
Curtainwall is anchored to the building at each floor slab, typically using cast-in-place or post-installed anchors that attach to the concrete structure or structural steel. The system spans vertically between these anchor points, so each floor slab level has an anchor location but the glass and framing between floors are entirely self-supporting.
This floor-to-floor spanning is what distinguishes curtainwall from storefront (which is built up from the slab) and from window wall (which also sits on the slab edge but in a different configuration). Curtainwall bypasses the slab entirely — the slab edge is typically hidden behind a spandrel panel, shadow box, or insulated backup at each floor line.
The anchor detail is one of the most engineered aspects of a curtainwall system. It must accommodate thermal movement (the aluminum framing expands and contracts with temperature), building settlement and sway, and construction tolerances that can be significant on high-rise projects. ACG's curtainwall installation scope includes full engineering review of anchor conditions and coordination with the structural engineer of record on every project.
Curtainwall Performance Requirements
Curtainwall systems are tested and specified against three primary performance criteria. Understanding these helps you evaluate product submittals and hold your glazing subcontractor accountable to the right standard.
Structural Performance
The curtainwall must transfer wind loads — both positive pressure (wind pushing in) and negative pressure (suction pulling out) — back to the building structure through its anchors. Structural performance is expressed in pounds per square foot (PSF) of design wind pressure. For Florida projects, design wind pressure is determined by ASCE 7 and the Florida Building Code based on the building's location, height, exposure category, and component/cladding zone. High-rise projects in coastal markets can see design pressures of 80 PSF or more in corner zones.
Air Infiltration
Curtainwall is tested per ASTM E283 for air leakage. The standard maximum allowable leakage rate for most commercial curtainwall specifications is 0.06 CFM per square foot at 6.24 PSF test pressure. High-performance systems can achieve significantly lower rates. Air infiltration matters both for energy performance and for occupant comfort — excessive air leakage shows up as drafts near windows in cold weather and as humidity problems in Florida's climate.
Water Penetration Resistance
Water resistance is tested per ASTM E331 (static) and ASTM E547 (cyclic), measuring whether water penetrates the glazing system under simulated rain and wind conditions. The test pressure for water resistance is typically specified as a percentage of design wind pressure. A system that passes water testing at the correct pressure — and is installed correctly in the field — should not admit water infiltration under normal weather conditions, including tropical storms.
Stick-Built vs. Unitized Curtainwall: The Two Main Systems
When architects and contractors talk about curtainwall, the first decision is usually delivery method: stick-built or unitized. These are fundamentally different approaches to how the system is fabricated and assembled.
Stick-Built Curtainwall
In stick-built curtainwall, individual aluminum members — vertical mullions and horizontal transoms — are shipped to the job site as separate pieces and assembled in place, piece by piece. The glass is then set into the completed framing from outside, typically with pressure plates and glazing gaskets. Most of the assembly work happens on the building.
Stick-built is the dominant delivery method for low- to mid-rise commercial projects in Florida — office buildings, hospitality projects, multifamily podiums. It requires less factory lead time than unitized, is more flexible for field-fit conditions, and has lower tooling costs. For projects in the 3–12 story range, stick-built curtainwall is almost always the right answer.
Unitized Curtainwall
In unitized curtainwall, the system is factory-assembled into individual panels — each panel typically one module wide and one floor tall — with the glass already installed in the frame. These completed units are shipped to the job site and hoisted into position, stacking vertically and interlocking horizontally through a splice joint system.
Unitized curtainwall requires higher upfront tooling and setup costs but allows much faster field installation on high-rise projects. When you're glazing 20+ floors, the ability to hoist and set a complete unit in minutes (vs. assembling stick by stick) dramatically reduces field labor and scaffold time. Unitized is standard practice on high-rise residential, hotel, and trophy office construction.
The premium over stick-built reflects factory fabrication, more complex engineering, higher quality control requirements, and the tooling investment. On large high-rise projects, that premium is typically recovered through faster installation and reduced field labor.
Materials: Aluminum and Glass
Commercial curtainwall framing is almost universally extruded aluminum — typically 6063-T5 or 6063-T6 alloy. Aluminum is ideal for curtainwall because it's lightweight (important when you're hanging the facade rather than supporting it from below), corrosion-resistant, thermally processable into complex extrusion profiles, and available in a wide range of anodized and painted finishes.
The glass in a curtainwall is typically an insulating glass unit (IGU) — two lites of glass with a sealed air or argon gas space between them. In Florida, most curtainwall IGUs incorporate a Low-E coating to control solar heat gain and reduce U-value. In coastal markets and anywhere within the HVHZ, the outer lite of the IGU must be laminated to meet impact requirements. That produces a laminated-IGU assembly: typically heat-strengthened laminate on the exterior, with a tempered or heat-strengthened lite on the interior, with Low-E coating on one of the interior glass surfaces.
Spandrel areas — the opaque sections of curtainwall at floor lines and mechanical zones — use either opacified glass (painted on the back surface) or a metal panel insert to conceal the backup wall, insulation, and floor slab behind the facade plane.
When Does a Building Need Curtainwall?
This is the question that matters most for project budgeting. Curtainwall is substantially more expensive than storefront — typically 3–5x the installed cost for comparable square footage. That premium is justified when the building actually needs what curtainwall provides. It's wasted budget when a simpler system would perform equally well.
Use Curtainwall When
- The building is mid-rise or high-rise and the glazing spans floor-to-floor without slab support
- The facade elevation is predominantly glass with minimal opaque areas
- The design calls for flush, continuous glazing lines across multiple floors
- The project is in a high-wind-exposure location where storefront structural capacity is exceeded
- The architectural vision requires the precision, depth, and finish quality only curtainwall delivers
Use Storefront When
- The building is single-story or limited to one or two floors of glazing
- The glazed openings are bounded by opaque wall construction above and below
- The glazing height is within storefront structural capacity (typically up to 12–14 feet in standard products)
- The project is retail, restaurant, medical office, or single-story commercial
- Budget is a primary constraint and the architectural program can be met with storefront
For a detailed comparison including installed cost data, see our guide on curtainwall vs. storefront cost.
Curtainwall in Florida: Wind and Hurricane Considerations
Florida's wind environment is the most demanding in the continental United States for glazing design. The Florida Building Code (FBC) adopts ASCE 7 wind maps with additional requirements, and the High Velocity Hurricane Zone (HVHZ) covering Miami-Dade and Broward counties requires every product to carry a Miami-Dade Notice of Acceptance (NOA) demonstrating it has passed large-missile impact testing.
For curtainwall projects in Florida, this means the glass specification must address both structural wind load and impact resistance — and those are separate requirements. A curtainwall that passes structural testing doesn't automatically pass impact testing. The glass type (laminated, laminated IGU), the interlayer (typically .090" PVB or SGP), and the framing retention system all factor into impact performance.
ACG has completed curtainwall scopes across Florida's varying wind zones, from standard Exposure C in inland markets to HVHZ-compliant systems on coastal South Florida projects. Our estimating team confirms the applicable wind zone and product approval requirements at bid time — before drawings are issued for permit.
ACG's Curtainwall Work: Panther National Clubhouse
One of ACG's most technically demanding curtainwall scopes was the Panther National Clubhouse in Palm Beach Gardens — an architectural project where the glazing is the defining element of the building's expression. The project required floor-to-ceiling glass walls, careful coordination with structural steel framing, and a glass specification that balanced energy performance, impact resistance, and optical clarity for the sweeping course views.
Projects like Panther National demonstrate what curtainwall can accomplish when the system selection, the glass specification, and the installation quality all align. Browse our full project portfolio for more examples of curtainwall and high-performance glazing scopes across Florida.
What Curtainwall Costs: Realistic Ranges for Florida Projects
To summarize the cost picture for curtainwall in Florida as of 2026:
| System Type | Installed Cost Range | Typical Applications |
|---|---|---|
| Stick-built curtainwall | By scope | Mid-rise office, hospitality, multifamily podium |
| Unitized curtainwall | By scope | High-rise residential, hotel, trophy office |
| HVHZ premium | By scope | Miami-Dade and Broward counties |
These ranges are installed costs including glass, framing, hardware, shop drawings, engineering, fabrication, delivery, and labor. They do not include structural steel, rough openings, or perimeter sealant by other trades.
Use our Scope Engine for a preliminary estimate, or send us your drawings and we'll return a complete scope within 48 hours. Our team has installed curtainwall and high-performance glazing on 350+ projects across Florida. Contact us to get started.
Frequently Asked Questions
Is curtainwall structural?
No. Curtainwall is non-structural — it carries no floor or roof loads. It transfers wind loads to the building structure through its anchor points but does not function as a load-bearing wall. This is the defining characteristic of curtainwall and the reason it can be made predominantly of glass.
What's the difference between curtainwall and window wall?
Both systems span floor-to-floor, but window wall sits on the slab edge while curtainwall bypasses the slab entirely and is hung from anchors at each floor. Curtainwall is engineered for higher wind loads, larger spans, and more demanding performance requirements.
Can curtainwall be impact-rated for Florida?
Yes. Curtainwall systems can be specified with laminated or laminated-IGU glazing to meet Florida's impact requirements. In the HVHZ, the system must carry a Miami-Dade NOA covering both the framing system and the glass. Not every curtainwall product line has HVHZ approvals — confirming NOA status before specifying is essential.