Lightweight Insulating Concrete Systems
Lightweight Insulating Concrete (LWIC) Roof Deck Systems are a logical choice for a proven, high performance building roof enclosure for new steel and concrete construction as well as reroofing applications. The LWIC System is typically composed of LWIC and expanded polystyrene insulation embedded within the concrete.
The Ideal Insulation
Over the past 30 years, various groups have detailed the characteristics for an ideal roof insulation. These characteristics are included in the National Roofing Contractors Association (NRCA) Roofing Manual—4th Edition. Let’s review the characteristics of LWIC Systems in light of these criteria.
Compatibility with Bitumen and Other Adhesives: It is able to withstand the effects of being in contact with adhesives, solvents, and hot bitumen at the application temperatures required for installation of the roof membrane.
LWIC is an inert material that protects the embedded expanded polystyrene (EPS) insulation board from adhesives, solvents, and hot bitumen with a minimum 2” thick cover.
Impact Resistance: LWIC has the strength, rigidity, and a density great enough to resist impact damage.
LWIC is stronger than insulation board and resists impact damage during construction and the service life of the membrane. This difference between LWIC Systems and rigid insulation board is readily apparent from just walking on the system.
Fire Resistance: LWIC is non-combustible and the system provides hourly fire resistance ratings that comply with the requirements of insurance underwriters and building codes.
LWIC provides a Factory Mutual Class I and UL Class A Fire Rating with many systems listed in the UL Fire Resistance Directory. Furthermore, since LWIC fills the flutes on steel deck systems, fireproofing the underside of the steel decking is not necessary. Rigid insulation board roof decks require underside fireproofing of the steel deck for many building code classifications.