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What is storefront. What is curtainwall.
Storefront
Storefront is a center-set aluminum glazing system, typically 1¾" or 2" deep, that sits on the floor and transfers load downward through its sill. It uses extruded aluminum mullions and horizontals, with glass installed via gaskets and snap-on stops. Height limits depend on framing series, glass spec, and wind load — practical limit is around 10 ft and one story.
Common applications: retail strip centers, restaurant fronts, bank branches, ground-floor lobbies, vestibules, small office buildings. The ESWindows ES-9500 and equivalent ESWindows ES-8000 are typical storefront lines. We install Euro-Wall DirectSet for impact-rated storefront work in Florida.
Curtainwall
Curtainwall is a non-load-bearing exterior wall system that hangs off the building structure rather than sitting on the floor. It attaches at slab edges via anchors and transfers load horizontally to the structure. Curtainwall framing is deeper (typically 4½"–7½") to span longer distances and resist higher wind loads. It can be stick-built on site, pre-assembled into ladders, or unitized as factory-glazed panels.
Common applications: office towers, hotels, hospitals, multi-story mixed-use, government buildings. Stick-built curtainwall is the most common Florida commercial install. Unitized is used for high-rise. We install ESWindows ES8000 series, Euro-Wall pressure-cap curtainwall, and equivalent systems for projects across Florida.
Side-by-side comparison
| Attribute | Storefront | Curtainwall |
|---|---|---|
| Practical height | Up to ~10 ft | 10 ft to full tower |
| Span | Floor-supported | Floor-to-floor or multi-story |
| Framing depth | 1¾"–2" | 4½"–7½"+ |
| Deflection limit | L/175 typical | L/240 typical |
| Load path | Down through sill | Horizontal to slab edges |
| Installed cost (FL 2026) | $55–$110/SF | $95–$180/SF |
| Thermal performance | U-0.42–0.55 | U-0.28–0.42 |
| Water resistance | Gasket / wet-seal | Pressure-equalized rain screen |
| Visual look | Centerline grid, visible mullions | Can be SSG (flush) or pressure-cap |
| HVHZ NOA available | Yes | Yes |
| Lead time (2026) | 6–10 weeks | 10–18 weeks |
Decision framework — 6 steps
Step 1 — Measure overall height
If the assembly is ≤10 ft and one story, default to storefront. If it spans floor-to-floor (typical 10–14 ft per floor) or stacks multiple stories, you need curtainwall (or window wall — see below).
Step 2 — Run the wind load math
Use ASCE 7 / Florida 8th Edition design wind pressures. Calculate the required deflection and check against the framing manufacturer's published span chart. Storefront deflection limit is typically L/175 (which means a 10 ft member can deflect 0.69"). Curtainwall is L/240 or L/175 depending on glass and spec. If your span/load combination falls outside the storefront chart, you need curtainwall.
Step 3 — Determine impact requirement
In Florida HVHZ (Miami-Dade, Broward, and parts of Palm Beach by AHJ), the entire assembly — frame + glass + anchorage — must hold a Miami-Dade NOA. Both storefront and curtainwall have NOA-listed configurations. Outside HVHZ, the rest of Florida requires Florida Product Approval (FPA) but not NOA. Inland projects in other states (Tennessee, Georgia, Alabama) use IBC wind speed mapping.
Step 4 — Check thermal performance target
If the project is chasing LEED, NGBS, ASHRAE 90.1 energy targets, or the FL energy code envelope path, you may need U-factor in the 0.28–0.36 range. That usually requires curtainwall framing with a deeper polyamide thermal break and a high-performance Low-E IGU. Storefront can hit 0.42–0.55 with thermal break; standard storefront (no break) is 0.65+.
Step 5 — Compare installed cost
If both systems technically work, compare cost. On a 10,000 SF assembly in Palm Beach: storefront at $100/SF = $1.0M. Curtainwall at $140/SF = $1.4M. That $400K delta should buy real performance value — better thermal numbers, better water performance, a flush SSG aesthetic — otherwise you're over-spec'ing.
Step 6 — Confirm with your glazing contractor
Before final spec, send drawings to a licensed commercial glazing contractor. Florida statute requires a CGC (or specialty glass license in some AHJs) for commercial glazing over a specific dollar threshold. We do system-selection review on every bid — often it saves the owner 20–30% by catching over-spec'd curtainwall on storefront-appropriate work.
Cost difference, in dollars
Real numbers from ACG project records, 2024–2026:
| Project size | Storefront (impact) | Curtainwall (HP) | Delta |
|---|---|---|---|
| 3,000 SF retail | $285,000 | $465,000 | +$180,000 (+63%) |
| 8,000 SF restaurant | $720,000 | $1,180,000 | +$460,000 (+64%) |
| 15,000 SF office (low-rise) | $1,275,000 | $2,100,000 | +$825,000 (+65%) |
| 25,000 SF hotel envelope | n/a (not technically viable) | $3,500,000 | — |
The lesson: when storefront works technically, it saves 30–40%. When curtainwall is required, it's required — no shortcut.
Where window wall fits
Window wall is a third option that's often confused with curtainwall. Window wall is slab-to-slab — installed between the slabs rather than hanging off the slab edge. It's common in multifamily and condo construction because it's less expensive than curtainwall and simpler to install. Limits: typically one-story height per panel, lower span capacity, less robust water management.
Use window wall on residential-spec multifamily up to ~10 stories. Use curtainwall on commercial mixed-use, hotel, office, hospital. The cost spread: window wall is $70–$110/SF in Florida 2026, between storefront and curtainwall.
HVHZ and Florida-specific notes
Florida's High-Velocity Hurricane Zone (Miami-Dade, Broward) requires Miami-Dade Notice of Acceptance (NOA) on every assembly. Key implications:
- You must use an NOA-listed frame + glass + anchorage combination. You can't mix-and-match across NOAs.
- NOA assemblies cost ~20% more than non-NOA Florida Product Approval (FPA) assemblies.
- Field testing per AAMA 502 (water) is often required, plus mock-up testing on large projects.
- Both storefront and curtainwall have NOA-listed product lines. ESWindows ES7000/ES8000, Euro-Wall Vista series, ESWindows ES-9500 are common NOA options.
- The rest of Florida outside HVHZ uses Florida Product Approval (FPA), which is similar but less restrictive. Our FPA/NOA index lets you look up specific assemblies.
5 specification mistakes I see most
1. Specifying curtainwall on 8-ft retail storefront
The most expensive mistake. A 1-story strip-center build that gets spec'd with stick-built curtainwall when storefront would meet all code and performance — adds 30–40% to the glazing line item with no functional gain. Catch it in design review.
2. Mixing NOAs
Using one manufacturer's NOA-listed frame with another's NOA-listed glass and assuming the combination is also NOA-listed. It is not. NOAs are tested-assembly-specific. Engineer-of-record signoff is required if you deviate.
3. Ignoring deflection on tall storefront
Trying to push storefront to 12 ft to save money. The deflection at peak design wind will exceed L/175 and the glass will bow visibly or fail. Move to curtainwall above 10 ft, period.
4. Wrong glass spec for the system
Specifying 1¼" IGU on a 1¾" storefront — the system can't accept that bite. Always verify glass thickness against framing channel depth before sealing the spec.
5. Forgetting field testing
On projects over a certain size (varies by AHJ), AAMA 502 field water testing is required. Schedule it. Some projects also require AAMA 503 air infiltration testing or a full mock-up. Build the cost ($8K–$25K depending on scope) into the bid.
Frequently asked questions
Can storefront be used above one story?
Generally no. Once you span floor-to-floor in a multi-story building, you need curtainwall or window wall. Some short two-story atria can use stacked storefront with intermediate horizontal supports, but it's case-by-case.
Is curtainwall more energy-efficient?
Usually yes. Curtainwall framing is deeper, allowing for a more substantial polyamide thermal break, which improves U-factor from typical storefront 0.42–0.55 down to 0.28–0.42 with a high-performance system.
How long does each system take to install?
Storefront: 2–4 weeks crew time for a typical 5,000–8,000 SF assembly. Curtainwall: 6–12 weeks for the same area, longer if unitized. Lead time for materials: storefront 6–10 weeks, curtainwall 10–18 weeks in 2026 market conditions.
What about all-glass storefront / butt-glazed?
Butt-glazed (or "frameless") storefront uses structural silicone joints between glass lites with no vertical mullion. It's a storefront subtype — still ground-supported — and works to ~10 ft. Cost premium: 15–25% over standard centerline storefront.
Who decides between storefront and curtainwall — the architect or the glazier?
The architect specifies, but the glazing contractor should review before construction documents go out. We've caught dozens of misspecifications on bid drawings. Most architects appreciate a free system-selection review; it protects the budget and the schedule.
Need a system-selection review on a specific project?
Send drawings to ACG. We'll review storefront vs curtainwall vs window wall against your spec, wind load, and budget — no charge. Florida CGC #1531993. 350+ projects.
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