System selection

Storefront vs. curtain wall: the difference explained

Storefront is a non-load-bearing aluminum glazing system installed within a single opening, typically one story and up to roughly 10 feet tall, supported at the head and sill. Curtain wall spans continuously past floor lines and hangs off the building structure at each slab edge. The distinction is structural span and anchoring, not appearance or glass type.

What is the difference between a storefront system and a curtain wall? For owners and GCs reading a facade scope for the first time.

The defining distinction

Both systems are aluminum frames holding glass, and from the sidewalk they can look nearly identical. The difference is structural. Storefront sits inside an opening and transfers load to the head and sill of that opening. Curtain wall is a continuous skin, anchored back to the structure at each floor, spanning past the slab edges rather than stopping at them.

That difference dictates framing depth, anchor design, movement accommodation, fire-safing requirements at slab edges and, ultimately, cost.

Comparison

Factor	Storefront	Curtain wall
Span	Within one opening, typically single story	Continuous, multi-story
Support	Bears at head and sill of the opening	Hung from the structure at each slab edge
Typical depth	4" to 6" framing depth	6" to 10"+ depending on span and wind load
Slab edge	Not applicable — system stops at the opening	Requires fire-safing and smoke seal at every floor line
Movement	Perimeter sealant accommodates most movement	System-designed movement joints handle drift and thermal movement
Relative cost	Lower per square foot	Higher — engineering, anchors, access
Typical use	Retail frontage, lobbies, ground-floor commercial, low-rise offices	Multi-story office, institutional and residential towers

How to tell which one a project needs

The building answers this, not the budget. If the glazed area is confined to a single opening within a wall and does not cross a floor line, it is storefront. If the glazed area runs continuously past a slab edge, it is curtain wall regardless of how the drawings label it.

Two common edge cases are worth naming. A tall single-story lobby can exceed practical storefront span and require curtain wall framing even though it never crosses a floor. And a two-story retail base can be built either way — storefront in each floor's opening with a spandrel between, or a single curtain wall run — which is a genuine design and cost decision rather than a structural given.

Why the label matters in an RFP

Calling a curtain wall scope 'storefront' in a bid document produces numbers that are not comparable. Curtain wall carries structural engineering, anchor design, slab-edge fire-safing coordination and usually exterior access equipment. Bidders who read the drawings will price all of it; bidders who price the word will come in low and change-order later.

Name the system correctly, state the span and floor-line condition, and both numbers arrive on the same basis.

Can storefront framing be used for a two-story facade?

Not as a continuous run past a floor line. Two-story glazed areas either need curtain wall framing or need to be broken into separate storefront openings with a structural spandrel condition between them.

Is curtain wall always better?

No — it is a different structural solution. On a single-story retail frontage, curtain wall adds engineering, depth and cost for no performance benefit over a well-specified thermally broken storefront.