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Fig.2: Curtain Wall Construction. Functions of Curtain Walls in Buildings. Elimination of Water Penetration. Water penetration is the fundamental function of a facade. Here bringing a completely impermeable sealed curtain panel system is not possible. Hence two stages of prevention are placed.
- Introduction
- Description
- Fundamentals
- Applications
- Details
- Emerging Issues
- Relevant Codes and Standards
- Additional Resources
A curtain wall is defined as thin, usually aluminum-framed wall, containing in-fills of glass, metal panels, or thin stone. The framing is attached to the building structure and does not carry the floor or roof loads of the building. The wind and gravity loads of the curtain wall are transferred to the building structure, typically at the floor lin...
The following are brief descriptions of commonly used curtain wall framing methods and components. Curtain walls can be classified by their method of fabrication and installation into the following general categories: stick systems and unitized (also known as modular) systems. In the stick system, the curtain wall frame (mullions) and glass or opaq...
System Types
Face-sealed, water-managed and pressure-equalized rainscreen systems are the three systems that are available. Normally, pressure-equalized rain screen systems provide the highest levels of resistance to air and water infiltration, with water-managed systems the next most reliable. Pressure-equalized rain screen systems function by blocking all of the forces that can drive water across a barrier. See the article on Moisture Protection for a complete explanation of how pressure-equalization re...
Thermal Performance
Overall curtain wall thermal performance is a function of the glazing infill panel, the frame, construction behind opaque (spandrel and column cover) areas, and the perimeter details. Curtain wall frame conductance is a function of the frame material, geometry and fabrication (e.g. thermal break). Aluminum has a very high thermal conductivity. It is common practice to incorporate thermal breaks of low conductivity materials, traditionally PVC, Neoprene rubber, polyurethane and more recently p...
Water penetration resistance is a function of glazing details (see Glazing), frame construction and drainage details, weatherstripping and frame gaskets, interior sealants (for operable windows, see Windows), and perimeter flashings and seals. Water can enter the exterior wall system by means of five different forces: gravity, kinetic energy, air pressure difference, surface tension, and capillary action. To mitigate water infiltration, all of these forces must be accounted for in the system...
Establish System Track Record
Select a curtain wall with a demonstrated track record in similar applications and exposures. Verifying track records may require significant research by the designer. ASTM E1825 provides guidance. Review laboratory test results of systems or similar custom systems for air, water, and structural resistance, heat transmission, condensation resistance, sound transmission, and operability. Verify that tests pertain to the system under consideration and not a version of the system with the same p...
Curtain wall design should start with the assumption that external glazing seals, perimeter sealant joints and curtain wall sills will leak. The following summarizes recommended features: 1. Select frames with wept glazing and pocket sills sloped to the exterior to collect water that penetrates the glazing and drain it to the exterior. Do not use vertical mullions as drain conductors. Each glazing pocket should be fully isolated from adjacent glazing pockets. Provide a sill flashing with end...
Glazing Methods and Their Impact on Performance
Pressure Plate Glazing: In this system the glass and infill panels are installed from the exterior, typically against dry gaskets. The outer layer of gaskets is installed and the gaskets are compressed against the glass by the torque applied to fasteners securing a continuous pressure plate. The plate is later typically covered with a snap-on mullion cover. This system provides reasonable performance but is susceptible to leaks at corners or joints in dry gaskets. For improved performance fou...
The following details can be viewed online in Adobe Acrobat PDF by clicking on the PDF to the right of the drawing title. The details associated with this section of the BEDG on the WBDG were developed by committee and are intended solely as a means to illustrate general design and construction concepts only. Appropriate use and application of the ...
"Smart" Curtain Walls, like smart windows, control visible light transmittance by employing electrochromic or photochromic glass coatings; see the discussion in Glazing. Double-skin systems, which employ a ventilated space between the inner and outer walls are rare in the U.S., but have been constructed in Europe and Asia where energy costs are muc...
Curtain Wall Design and Selection
1. AAMA Aluminum Curtain Wall Design Guide Manual
Thermal Performance
1. AAMA 1503 Voluntary Standards for Thermal Transmittance and Performance 2. AAMA 501.5 Test Method for Thermal Cycling of Exterior Walls 3. NFRC 100 Procedure for Determining Fenestration Product U-Factors
Solar Heat Gain Coefficient
1. NFRC 200 Procedure for Determining Fenestration Product Solar Heat Gain Coefficient and Visible Transmittance at Normal Incidence
Organizations
1. American Architectural Manufacturers Association (AAMA)—information on aluminum curtain walls. NOTE: Photographs, figures, and drawings were provided by the original author unless otherwise noted.
The wall transfers lateral wind loads upon it to the main building structure through connections at floors or columns of the building. Curtain walls may be designed as "systems" integrating frame, wall panel, and weatherproofing materials. Steel frames have largely given way to aluminum extrusions.
Feb 19, 2024 · Efficient Construction: Utilize dry construction methods, potentially streamlining the building process and minimizing disruptions at the site. Structural Optimization: Minimize the additional load placed on the building’s primary structure by the cladding system, enhancing overall structural efficiency.
of the Curtain Wall. • Building design, construction methods, building materials and site conditions unique to your project may require methods different from these instructions. • Choosing the appropriate method is the responsibility of you, your architect, or your construction professional.
Mar 7, 2017 · The Basics Of Curtain Wall System Construction. How the glass and the frame are manipulated, including proportion, properties, and anchorage, constitutes the essential distinction among glass curtain wall systems. March 7, 2017. By Russell M. Sanders, AIA and Craig A. Hargrove, AIA LEED AP.
Feb 5, 2024 · Curtain wall construction is a method of building where a non-structural, lightweight exterior wall is installed to enclose a building’s facade. Unlike traditional load-bearing walls, curtain walls are designed to support their own weight and the forces applied to them, such as wind and seismic loads.
