The thickness of hollow-tile walls should be the same as for walls of
brick. The construction of light 10-inch and 8-inch walls, while strong
enough as a substitute for a frame dwelling, is not strong against
weather or fire. The only justification for thin walls is the slightly
reduced cost of materials. Hollow blocks, as a rule, are not used
for foundations, although they are satisfactory under buildings not
higher than 40 feet. It is better to fill such walls with concrete and
waterproof them on the exterior.
_Concrete House_
The development of the concrete house has been stimulated by large
corporations erecting towns of them in one locality. The erection of
concrete houses by individual builders cannot, as a rule, follow those
systems which are adapted to group construction. The use of large
precast units may be satisfactory for a development of a hundred or
more houses, but it is not economical for a single operation. The use
of heavy steel forms for casting monolithic houses of concrete, while
under certain favorable labor conditions may be satisfactory for a
small job, yet as a rule is better adapted to large enterprises. Such
steel forms are represented by the Lambie forms and the Hydraulic
forms. Even wood forms of heavy construction, like those used in the
Ingersoll system in work at Union and Phillipsburg, are not adapted
to an operation involving less than fifty identical houses. Another
system, combining both the precast and the cast-in-place work, called
the Simpsoncraft system, is not economical for small operations. This
uses thin precast slabs for walls and floors, and precast concrete
beams. The precast parts are tied together by casting in place
reinforced studs of concrete.
Practically the only available systems which are useful for the small
operation are (1) monolithic houses, built with light, portable steel
forms or wooden forms, and (2) the concrete block house.