324 



SELLING LUMBER 



Steel Substi- 

 tuted for 

 Structural 

 Timbers 



Steel and 

 Wood in Fire 



Where Steel 

 Has Increased 

 Use of Wood 



structural timbers. The principal objection to the use of steel 

 for this purpose is that it is more costly, is a more difficult type of 

 building to alter, and in case of fire, unless the steel is protected, 

 is a total loss. In this connection it is interesting to note what has 

 been said by the National Board of Fire Underwriters in their 

 "Code of Suggestions for Construction and Fire Protection :" 



"An unprotected steel beam when attacked by fire is 

 not as reliable as a wooden beam. The reason is that 

 steel loses its strength very rapidly when heated in excess 

 of 500 to 600 degrees F., and such temperatures are easily 

 attained in an ordinary fire. On the other hand a wooden 

 beam of large cross section would burn fiercely over its 

 whole surface, but the actual rate of penetration would be 

 slow, consequently considerable time would be required for 

 the beam to burn sufficiently to produce collapse even in a 

 hot fire. This fact indicates the necessity for protecting 

 steel beams, but does not warrant the substitution of wood- 

 en beams for steel. Other considerations may at times 

 justify the use of timber construction instead of steel 

 work, but unless protected by sprinklers, or covered with 

 some non-flammable material it adds to the fire hazard 

 in the room in which it is exposed. If necessary to use 

 a heavy wooden beam in a cellar as above suggested, it is 

 recommended that if not protected by sprinklers it be cov- 

 ered with metal lath and plaster, or with asbestos or plas- 

 ter board. 



"For the reason herein explained, it is necessary that 

 all metal structural members used in dwelling house con- 

 struction should be fully encased in fireproof material, 

 the same as would be required in other buildings." 

 In some ways steel has increased the use of wood. For ex- 

 ample, steel has made possible the construction of our skyscrap- 

 ers, and as these buildings require very large quantities of interior 

 trim they have necessarily made a greater demand for the use of 

 wood for this purpose, principally hardwoods. 



Steel has also displaced wood very largely in the construction 

 of bridges which formerly required very large amounts of struc- 

 tural timber. In this connection, however, it is of interest to learn 

 that the railroad engineers are now turning to wood instead of 

 steel, owing to the fact that steel now costs just about twice what 



