CONSTKUCTION AND FIRE PROTECTION OF COTTON WAREHOUSES. 23 
story should not be less than 12 inches thick, In applying the rule 
for increased thickness for long walls, only that portion of the ex- 
terior wall which is between division fire walls need be considered. 1 
Windows in the exterior wall should consist of steel sash glazed 
with wire glass and should be stationary unless ventilation is needed. 
They need not be fitted with fire shutters unless the exposure is se- 
vere. The windows should be placed high so as to throw light over 
the top of the cotton bales. Windows may be omitted and light sup- 
plied by skylights in the case of the single-story warehouse. If ven- 
tilation is to be supplied by the window the opening should be 
screened, and the sash hinged at the top and controlled by a fusible 
link and hook. The window has one advantage other than supply- 
ing light in that it affords a ready opening through which a hose 
1 Curtain walls may be of the same material as the bearing wall ; or clay 
wall tile or cement blocks may be used, provided the thickness of the wall is 
made the same as for brick and in addition provides exterior pilasters having 
a projection of one-third the wall thickness and spaced at intervals not ex- 
ceeding eight times the width of the pilaster. For example, a single-story 
building having a story height of say 13 feet, or not exceeding 18 feet, should 
provide an exterior wall of 12 inches thickness, which could be of brick, con- 
crete, stone, cement blocks, or clay tile, but if the wall is of cement blocks or 
clay tile, it should be stiffened and braced on the outside by pilasters having a 
projection from the wall of 4 inches — that is to say, the thickness of the wall 
measured through the pilaster should be 4 inches greater than that of the 
space between pilasters. If the pilasters are 2 feet wide, they should be 
placed 16 feet apart, while if they are only 1 foot wide they should be placed 
8 feet apart — measuring from, the center of one pilaster to the center of the 
next. However, the usual concrete wall column, if extending entirely through 
the thickness of the wall, is a satisfactory substitute for a pilaster of 3 feet 
width. 
Panels for the exterior wall may be of less thickness than was stated for 
the division fire wall, panels of reinforced concrete may be only 6 inches 
thick, while panels of brick and. plain concrete may be of 8-inch thickness 
provided the height of the panel does not exceed 12 feet, though for cement 
block, clay tile and stone masonry panels, the height should be limited to 10 
feet for an 8-inch thickness, additional height necessitating the usual pro- 
gressive increases in thickness as stated for bearing walls. 
Clay tile should, be laid with cement -lime mortar and joints three-quarters 
or 1-inch thick as the mortar serves as a cushion and. tends to prevent crack- 
ing of the tile from heat. Better work usually will be secured by laying the 
tile on side rather than on end, as the narrow surface of the tile shell affords 
but little area for mortar, making it difficult to secure the thick joint desirable. 
Door openings in the walls should be formed of brick as otherwise the corners 
of the tile are likely to become badly broken from trucking, thus affording 
an opportunity for entrance of sparks as well as being unsightly. For walls 
which do not contain windows, tile offers some advantage in that it can be 
broken through readily to provide an opening for hose streams. 
