Terminology

• Awning: top-hinged, outswing sash
• Hopper: bottom-hinged, inswing sash, common in basements and transoms
• Project-out vent: commercial term for an awning sash in a fixed window or curtain wall
• Operator: crank or lever; chain operators for high units
• Limit stop: device restricting how far the sash opens
• Compression seal: perimeter weatherstrip pressed by the closed sash
• Stacked unit: awning mulled above or below a fixed or casement unit
• Ribbon window: horizontal band of awnings, often high on a wall
• Remote operator: pole, chain, or motor for units out of reach
• Interior screen: screen on the inside, since the sash opens outward

Standards

Sizes

• Usually wider than tall; sash height limited by hinge and operator capacity
• Opening projection limited by operator arms; clear opening is small relative to sash size
• Commonly combined with fixed units in mulled assemblies

Ratings

• NAFS class: R and LC common in residential; CW and AW project-out vents in commercial systems
• Air leakage: tight, similar to casements, because of compression seals
• Water: sash acts as a canopy, so the window can stay open in light rain

Test standards

• AAMA/WDMA/CSA 101/I.S.2/A440 (NAFS-22)
• ASTM E283, E331, E330
• NFRC 100, 200, and 400
• ASTM F2090: opening control devices where fall protection is needed

Materials

• Vinyl and fiberglass: residential awning and hopper units
• Clad wood: traditional and high-end residential
• Aluminum, thermally broken: commercial project-out vents in window walls and curtain walls
• Hardware: stainless operators and hinges in coastal and high-humidity locations

Detailing

• Keep sash projection clear of walkways, patios, and exterior shading
• Use limit stops where projection is a hazard or where wind exposure is high
• Coordinate operator reach for high units; specify poles, chains, or motors
• Flash and integrate with the WRB like any punched opening
• In commercial walls, align project-out vents with the mullion grid and interior ceiling

Uses

Specific uses

• Ventilation above fixed view glass
• High windows in bathrooms and kitchens for privacy with airflow
• Basement windows (hopper or awning) where they are not used as egress
• Classroom and office project-out vents in commercial window walls
• Wet climates where ventilation during rain matters

Pros and cons

Pros

• Ventilates in light rain
• Tight air and water seal
• Works well high on walls or stacked with fixed glass
• Good security when open, due to limited projection

Cons

• Small clear opening; usually not suitable for egress
• Outswing sash projects into exterior space
• Sash can collect debris and is hard to clean on upper floors
• Operator arms can limit screens and blinds

Manufacturing and cost

Construction

• Similar to casements: frame, sash, IGU, top hinges, operator, and locks
• Commercial vents fabricated into fixed window frames or curtain wall framing

Main manufacturers and suppliers

• Andersen
• Pella
• Marvin
• Sierra Pacific Windows
• Weather Shield
• Kawneer (commercial project-out vents)

Trade associations: Fenestration and Glazing Industry Alliance and Window and Door Manufacturers Association.

Typical costs

• Residential awning window, installed: $300 to $950 per window

Sources

• Fixr: window installation cost breakdown, https://www.fixr.com/articles/window-installation-cost-a-detailed-breakdown
• NerdWallet: replacement window cost, 2026, https://www.nerdwallet.com/home-ownership/windows/learn/replacement-windows-cost
• Ecoline Windows: awning, casement, slider, and hung windows compared, https://ecolinewindows.ca/replacement-windows-compared-awning-casement-slider-hung
• FGIA: NAFS-22, https://store.fgiaonline.org/101/I.S.2/A440-22/
• FGIA: performance class overview, https://fgiaonline.org/resources/technical-resources/performance-class-overview/
• Wikimedia Commons: Four Awning Windows.jpg, by Stilfehler (CC BY-SA 4.0), https://commons.wikimedia.org/wiki/File:Four_Awning_Windows.jpg