Construction glossary · Envelope and finishes

What is curtain wallin construction?

A curtain wall is a non-load-bearing exterior wall system, usually aluminum framing with glass and metal infill panels, that hangs off the building structure and carries only its own weight and wind load. It is taken off in square feet of system area by elevation, then broken down by panel type, vision glass, and spandrel. Because it is an engineered system, the estimator prices it by the panel and by the square foot, not as loose glass and metal.

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Updated August 2026 · Reviewed by the Ruh construction team

Installed cost $60 to $120 / sfGlass infill 1 in insulated unitLoad Self-weight only, non-bearingTypical grid 5 ft x 10 ft bays

Curtain wall mullion grid bay

The definition

Curtain wall, explained.

In commercial construction a curtain wall is an engineered, non-structural envelope system, typically extruded aluminum mullions framing infill of vision glass, spandrel glass, or metal panel, anchored back to the floor slabs or structure. It differs from storefront, which is a lower, slab-to-slab or floor-supported glazed system; curtain wall spans multiple floors and is designed for the building's wind and movement loads. The two common fabrication methods are stick-built, assembled mullion by mullion in the field, and unitized, where shop-built panels arrive and are hung as units. As an estimator you read the exterior elevations and the glazing details to get the overall system area, then break it into its parts: vision glass area, spandrel area, metal panel area, and the linear feet of mullion if the system prices that way. Each module or panel is counted, because the system is fabricated and priced as engineered units with their own glass makeup, finish, and performance ratings. Vision and spandrel differ in cost, and corner units, operable vents, and sunshades carry their own line items.

How it is measured

Curtain wall is quantified in square feet (sf) of system area off the exterior elevations, then split by infill type: vision glass sf, spandrel glass sf, and metal panel sf, since each carries a different unit cost. Panels or modules are also counted as each, because unitized systems price by the panel. You read the glazing elevations, the typical mullion details, and the glass schedule for makeup and performance. Mullion is measured in linear feet (lf) where the system is priced by frame. Record finish, glass type, and any operable vents, corners, or sunshades as separate items. Field area is taken net of any solid wall, and the panel count drives both fabrication and install sequencing.

Worked example

A worked curtain wall example.

Worked example

Take a storefront-height curtain wall elevation that is 60 ft wide by 14 ft tall, gross 840 sf, built from 5 ft wide unitized panels. At 14 ft tall and 5 ft wide, each panel is 70 sf; 60 ft / 5 ft = 12 panels, 12 x 70 = 840 sf, which checks. Of each panel, the lower 10 ft is vision glass (50 sf) and the upper 4 ft is spandrel (20 sf). Vision: 12 x 50 = 600 sf at an illustrative 85 dollars per sf = 51,000 dollars. Spandrel: 12 x 20 = 240 sf at an illustrative 65 dollars per sf = 15,600 dollars. System total = 51,000 + 15,600 = 66,600 dollars across 12 panels, an effective 79.29 dollars per sf blended. The panel count of 12 also sets crane picks and install labor, independent of the glass split.

How Ruh handles it

How Ruh handles curtain wall.

Ruh reads the exterior glazing elevations and the curtain wall details, measures the system area in square feet, and splits it by infill type into vision glass, spandrel, and metal panel, while counting the panels or modules as each. It prices each part on your own price book, flags corners, vents, and sunshades as separate items, and presents the panel-by-panel takeoff for the estimator to review against the elevations and glass schedule and sign off.

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Curtain wall: frequently asked questions

What is the difference between curtain wall and storefront for takeoff?+

Curtain wall is a non-load-bearing system that hangs off the structure and spans multiple floors, engineered for wind and movement. Storefront is a lower, floor- or slab-supported glazed system. They carry different unit costs and details, so they are taken off as separate systems.

Why split vision glass from spandrel in the area takeoff?+

Because they price differently. Vision glass is the see-through insulated unit; spandrel is the opaque panel hiding the floor edge or structure. Carrying one blended sf number misprices a wall where the two areas are not equal.

Do I count curtain wall by panel or by square foot?+

Both. Unitized systems fabricate and price by the panel, so you count modules as each, and you also carry square feet by infill type. The panel count drives install sequencing while the sf split drives material cost.

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Related terms

Storefront Glazing Facade Flashing

Keep going: read the full guide or explore glazing estimating software.

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