Laminated glass
See: Impact resistant glass.
Large missile impact
A product is tested as large-missile resistant after it has been exposed to various impacts with a piece of lumber weighing approximately 9 pounds, measuring 2" x 4" x 6' (no more than 8') in size, traveling at a speed of 50 feet per second (34 mph). Then the product must pass positive and negative wind loads for 9,000 cycles, with impact creating no hole larger than 1/16 x 5" in the interlayer of the glass. If you live in a building where doors and windows are located 30 feet or less above grade (above ground level) then the products must pass the large-missile test. If the
doors and windows are more than 30 feet from the ground then they must be either large or small missile compliant.
Latch
(Catch) - (Lock) - A device which holds a window shut, such as the latch at the meeting rail of a
double-hung window or one mounted on the stile of casement windows, often referred to as a lock.
Lead light
(Lead glazing) - (Stained glass) - Window with small panes of glass set in grooved rods of cast lead (or came). The glass can be clear, color, or stained.
Light
(also spelled lite) - Glazing framed by muntins and/or sash in a
window or door. For example:
Double-hung windows are designated by the number of lights in upper and lower sash, as in six-over-six.
Light to Solar Gain ratio (LSG)
The ratio is equal to the Visible Light Transmittance divided by the Solar Heat Gain Coefficient. The Department of Energy's Federal Technology Alert publication of the Federal Energy Management Program
(FEMP) views any LSG of 1.25 or greater to be green glazing.
Light transmission (also, visible light transmission)
The percentage of the visible spectrum transmitted through a glazing and perceived by the human eye.
Lintel
Horizontal member (wood, steel, or stone) over a window or a door opening to support the weight of the wall above (also see: Header).
Lock
A fastening device in which a bolt is secured and can be operated by a key. Commonly used to refer to Latches or Catches.
Lock rail
See: Meeting rail.
Lock stile
The vertical member (stile) of a casement sash which closes against the surrounding frame.
Low-emissivity (low-E)
Coatings applied to glass which allow transmission of light through glass but reflect thermal energy. Emissivity varies from 0 to 1; the lower the emissivity, the lower the resultant.
