Many residents, even engineers, feared the building would collapse from wind or concrete shrinkage. But Ernest L. Ransome, who designed and built industrial structures, championed reinforced concrete. He introduced joists, casting slab, beams and joists as a single homogeneous element and invented twisted rebars of square section to achieve good bonding.

Local architects Elzner and Anderson chose concrete construction for the Ingalls because it would cost less than steel frame construction and had fireproofing advantages. For design, they turned to Henry N. Hooper, chief engineer at Ferro-Concrete Construction Co., Cincinnati. The new firm had built no major structures but Hooper was up to the challenge.

The engineer designed a monolithic structure, which allowed him to use each floor slab as a rigid diaphragm to deal with part of the wind forces. Beams and girders were cast monolithically with the floor slabs.

The concrete mixing machine produced 100 cu yd for a 10-hour shift. This was less than capacity but as much as workers could place. The mix was made wet to insure complete filling of all interstices around rebars and then made further wet to insure that columns had uniform density around the reinforcement. Floor slabs were built in a single pour to avoid joints. Typical progress was three stories per month.

Columns for the first 10 floors were 30x34 in. and 12 in. sq for higher floors, and were linked to floor girders with reinforcing rods. Three sets of forms were used, the lower set moving to the top as its concrete gained strength. Ingalls, completed in eight months, proved more economical because there was no receiving, unloading, storing and placing of huge lengths of steel. Since its completion, it has been in constant use.