- Q: What is a Curtain Wall?
- A: Curtain wall is a term used to describe a building façade element, generally assembled with aluminum and glass, which spans multiple floors, and take into consideration design requirements such as: thermal expansion and contraction; seismic motion; building sway and movement; water diversion; and thermal efficiency for cost-effective heating, cooling, and lighting in a building.
- Q: What is a Window Wall?
- A: Horizontal strips or ribbons consisting of an array of stacking windows that create a horizontal band around or partially surrounding the building.
- Q: What are Punched Windows?
- A: Square or rectangular windows consisting of one or more pieces of glass surrounded by window framing. Punched windows usually “dot” the building façade unlike the ribbons of window wall. Punched windows can be quite large, and can constitute a significant façade feature.
- Q: What is Storefront?
- A: Storefront is a general term applied to the framing material and doors generally associated with the display windows of retail stores. Storefront generally contains some form of glass and the framing can be manufactured from several materials including: Aluminum, Steel, Wood, or can be all glass as typified by the majority of Mall retail storefronts.
- Q: What is Unitized construction vs. Stick construction?
- A: The expressions Unitized and Stick refer to the method of construction of a framing system for any glazed components within a building façade. Stick construction generally refers to components that have been factory prepared, shipped to the jobsite, and then erected piece by piece on-site. Unitized construction conveys that the components have been factory prepared and assembled then shipped to the jobsite as a completed unit. Each unit is then connected together to form the façade. Stick construction takes less time in the factory but takes longer to assemble on-site and presents some quality control issues. Conversely, Unitized construction takes longer to manufacture in the factory, however quality control can be strictly monitored, and it does accelerate the erection of the façade on-site.
- Q: How much will aluminum expand when heated?
- A: A rough rule of thumb for the expansion of aluminum is ¼” for every 20’-0” of length. For an exact calculation, the formula is 0.0000128 x Length (In) x Degrees of Temperature Rise (°F). Using this formula, a 20’-0” long piece of aluminum will expand ¼” when the temperature rises 80°F from the temperature that that piece of aluminum was first cut.
- Q: What are the normal limits of deflection for glazed aluminum framing systems?
- A: Typically, the most common deflection limits specified for glazed aluminum framing systems is L/175, where “L” is the length of the framing member supporting the load. The American Architectural Manufacturers Association (AAMA) provides an alternative, and more realistic deflection limit in their Technical Interpretation Report (TIR) A11-04 - “Maximum Allowable Deflection of Framing Systems for Building Cladding Components at Design Wind Loads”. This document offers the following deflection limit criteria: Frames <= 13/-6” limit deflection to L/175, Frames > 13’-6” limit deflection to L/240 + ¼”.
- Q: What is Live Load deflection?
- A: Live Loads are loads produced by use and occupancy of the building or other structure and do not include construction or environmental loads such as wind load, snow load, ice load, rain load, seismic load, or dead load. An example of a Live Load is when a parade is passing a building and all the occupants move to the window to watch. The floor slab will move down (deflect) under the weight of all the people. After the parade has passed, and the occupants return to their normal locations, the floor slab will return (move up) to its normal position after the Live Load (the concentrated weight of the people) has been removed.
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- Q: What is Design Pressure?
- A: The Design Pressure (DP) is the pressure (measured in Pounds per Square Foot [PSF]) that a building or building component should be designed to accommodate without failure. Specifications for glazing systems will generally indicate the DP in one of three manners: 1) Offer a specific DP (flat walls, parapets and building corners will each generally have a different DP), 2) Refer to a governing Building Code for standard methods of determining the DP, or 3) Refer to a Wind Load Study performed on a scale model of the structure, that yields the DP for various locations on the structure.
- Q: How to convert Design Pressure to Miles Per Hour (MPH) ?
- A: MPH = v PSF/0.00256
- Q: How to convert Design Pressure to Inches of Water (In H2O) ?
- A: H2O = PSF/5.2
- Q: What is Dry Glazing?
- A: Also called compression glazing, a term used to describe various means of sealing monolithic and insulating glass in the supporting framing system with synthetic rubber and other elastomeric gasket materials.
- Q: What is a Kilowatt-hour?
- A: The kilowatt-hour (symbolized kWh) is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time. A typical home will use 30 kWh of electrical energy in a day.
- Q: What is Condensation?
- A: The appearance of moisture (water vapor) on the surface of an object caused by warm moist air coming into contact with a colder object.
- Q: What is Dew Point?
- A: The critical temperature at which vapor condenses from the atmosphere and forms water.
- Q: What is Double Glazing?
- A: In general, any use of two lites of glass, separated by an air space, within an opening, to improve insulation against heat transfer and/or sound transmission. In insulating glass units the air between the glass sheets is thoroughly dried and the space is sealed, eliminating possible condensation and providing superior insulating properties.
- Q: What is Edge Clearance?
- A: Nominal spacing between the edge of the glass product and the bottom or side of the glazing pocket (channel) of the framing system.
- Q: What are Elastomeric products?
- A: Products of or pertaining to any of the numerous flexible membranes, sealants or gaskets that contain rubber or plastic.
- Q: What is Emissivity?
- A: The measure of a surface’s ability to emit long-wave infrared radiation. The Low E (Low Emissivity) coatings of many modern insulated glass units (IGU) are designed to control the amount of long-wave infrared radiation (heat) passing through the IGU.
- Q: What does EPDM stand for?
- A: EPDM rubber (ethylene propylene diene monomer rubber) is an elastomer which is characterized by wide range of applications. EPDM rubber is used in automotive weather-stripping and seals, glass-run channel, radiator, garden and appliance hose, tubing, washers, belts, electrical insulation, roofing membrane, geomembranes, rubber mechanical goods, plastic impact modification, thermoplastic, vulcanizates, motor oil additive, pond liner, electrical cable-jointing and chainmaille applications.
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