Construction types
Masonry Noncombustible construction is ISO Class 4. ISO Class 4 encompasses IBC Type Type IIA (protected).
Masonry
non-combustible
buildings are buildings
with exterior walls of
masonry material and
with noncombustible or
slow burning floors and
roofs.
buildings with exterior
walls of masonry — not
less than four inches
thick, or
buildings with exterior
walls of fire-resistive
construction — with a
rating of not less than
one hour, and
noncombustible or
slow-burning floors and
roofs — regardless of
the type of insulation
on the roof surface
Uses floors and roof supported by superior exterior bearing members that provide for stability and are less likely to collapse during a fire
Uses materials that don’t readily burn
Disadvantages:
Uses unprotected steel for interior members of floors and roof, and steel loses strength and becomes less stable and more damageable at high temperatures
Uses slow-burning materials that do burn — adding fuel to a fire