Lap: that part of roofing, waterproofing, or flashing component that overlaps or covers any portion of the same or another type of adjacent component.
Lap seam: occurs where overlapping materials are seamed, sealed or otherwise bonded.
Liquid-applied: application of bituminous cements, adhesives or coatings installed at ambient or slightly elevated temperatures.
Liquid-applied built-up roof: a continuous, semi-flexible roof membrane, consisting of multiple plies of felts, mats or fabrics laminated together with alternate layers of roof cements and surfaced with a liquid-applied coating with or without aggregate surfacing.
Low-slope roofs: a category of roofs that generally include weatherproof membrane types of roof systems installed on slopes at or less then 3:12 (14 degrees).
Low temperature flexibility: the ability of a membrane or other material to resist cracking when flexed after it has been cooled to a low temperature.