CONSTRUCTION' AND FIRE PROTECTION OF COTTON WAREHOUSES. 43 
In order to form a complete fire break the division wall in slow- 
burning construction must extend well through and above the roof, 
this projection usually being 3 feet. If the roof has a monitor or 
combustible skylight within 50 feet of the wall, the parapet should 
extend to the level of the top of such structure. Moreover, the ends 
of this wall must project through the eaves or cornice of the roof in 
the event that such combustible material overhangs the exterior wall 
This is shown by the drawing in figure 17. The portion of the wall 
projecting above the roof, or that extending above the bottom of the 
roof timbers, is known as a ^parapet " or "parapet wall,*' whereas" 
the extension of the ends through the cornice may be termed a "cor- 
beled extension," or u wing wall." Openings in the division wall- 
are quite as undesirable in this design as in fire-resistive construction 
and when openings are necessary they should be protected in an 
equally effective manner. 
All parapet walls should be finished on top with a suitable mate- 
rial to preserve the mortar joints there. This protection is usually 
supplied by a coping of terra cotta or concrete. Such copings are 
shown by Plate XXVI ; figure 2 shows a concrete coping and figure 
3 a terra cotta coping. 
THE EXTERIOR WALL. 
The exterior wall should be of the same material and design as 
described for similar walls of the bearing and curtain types for fire- 
resistive construction. The proportions stated there are sufheiem 
to resist the pressure of ordinary windstorms provided the wall is not 
excessively long and tall. 
used, a tapering buttress as indicated by the dotted lines will be cheaper, 
while the design shown is suitable for brickwork. 
The pilaster, such as is shown by Plate XXVI, figure 3, is of value in sup- 
porting loads carried by the; wall and gives some added stability to the wall, 
particularly if it is tall, but the pilaster is not a satisfactory substitute for 
the buttress in resisting buckling from expansion. 
Walls longer than 200 feet should contain expansion joints at intervals 
not exceeding 200 feet, and should have these free ends buttressed. 
The parapet height is not figured into the height of the wall for purposes 
of determining thickness. 
In the rare instances when a panel wall is used, the same principles should 
be applied to it except that the total thickness and breadth of each pilaster 
(or, .more properly, column) should be, at the bottom, equivalent to one- 
eighth of this height. At least one beam should be used near the top of the 
wall, the beam having a depth of 12 inches or more and a breadth equal to 
the greatest thickness" of the column but not exceeding* 24 inches. This broad 
beam should supply the necessary resistance to buckling from expansion. The 
thickness of the panel would be subject to the same limitations stated for 
similar use in the fire- resistive construction. 
Fire walls for one story buildings with a low story height of only 9 feet 
may be of 12 inch brickwork. 
