397Fires
It is, however, true that the re spread in a mobile home is much more rapid aer
ashover because of the low ceiling, the tubular construction, and the lack of re stops
and headers above hallway openings. In this context, it is important to understand what
is meant by the term ashover. According to NFPA 921, ashover is dened as a stage in
the development of a contained re in which all exposed surfaces reach ignition tempera-
ture more or less simultaneously and re spreads rapidly throughout the space. During
the early stages of development of a re, convection is the major transport vehicle for the
spread of the hot gases. As this process continues, radiation begins to increase its eect
so that at and aer ashover, both rad ...