NINETY STOREYS.

Press, Volume LXIV, Issue 19212, 19 January 1928, Page 12

NINETY STOREYS.

ECONOMICAL SKY- | SCRAPERS. NEW YORK LOOKS AHEAD. Skyscrapers seventy-five storeys high and costing 42,000,000 dollars to erect may be expected in the future in some of New York's leading business districts. This will be the minimum height if the builder expects to obtain a fair return on his investment. As the income will be greater at ninety storeys, it is natural that the builder who can gathep 42,000,000 dollars and plans a seventy-five storey building will not hesitate to pile fifteen more on top. Studies which have been completed by leaders in the various lines of construction, management, and renting, have decided that to erect a structure of fewer storeys in the leading business zones would not be economical unless the present tax structure is altered and the level of land values adjusted, which is not probable. The American Institute of Steel Construction some time ago asked W. S. Clark, economist, of S. W. Shaw and Co., to build a hypothetical building that would solve all the evils of the skyscraper which meant much more than running up a .structure. Mr Clark called upon a well-known firm of skyscraper architects to assist him in the planning, and then asked the assistance of the Building Manager and Owners' Association to see that the building met all the requirements of the city ordinances, and would bo profitable to the builder. A block in the Grand Central section was selected, and on this was erected the hypothetical structure.

Greatest Efficiency. When the studios were begun, seventyfive storeys was the height arbitrarily selected by Mr Clark and his collaborators as beyond the probable maximum of height to secure the greatest economic efficiency for this specific site. Much to their surprise, however, the studies showed that at seventy-five storeys the curve of economic efficiency was still mounting upward, and, had the survey continued, a height of 85 or 87 storeys might have been found to be even more profitable than seventy-five storeys. "Sane regulation of building heights in the interest of public health is to be desired, but any attempt to put into effect a flat level restriction of eight or ten storeys will result inevitably in a severe deflation of land values and a complete disorganisation of the whole tax structure," Mr Clark's report, says. "Moreover, despite frequent claims to the contrary, the deflation of land values in liie central business districts will not be offset by a corresponding appreciation of values in the outlying sections, for the decentralised city will be found to bo not only a less efficient but also a more expensive mechanism for carrying on commercial and certain typos of industrial activity. . "In the case of certain plots of very large size and appropriate location the most economical development may involve soaring a structure skyward to tho height of seventy-five or more storeys. Tor the normal plot of moderate size, even in the central business section of New York, tho principle of diminishing returns usually sets an economic limit considerably below this giddv height, while the average plot, in the city, as a whole, will still probably find its most economical utilisation in a structure of perhaps four to ten or twelve storeys." Nearly 1000 Feet High. "The hypothetical development of a solid block in the vicinity of the Grand Central Terminal was chosen, partly because under tho New York zoning law the really tall building gets a fair chanco only on a very large site, and also - because it was believed tliat the trend of the futuro is towards this type of development. Preliminary analyses of the data obtained indicate that on a plot of 200 x 405 feet, with land value approximating 200 dollars a square foot, the most economical development was the seventy-five storey building rising 917' l'eet 10 inches from the sub-basement floor, and with a tall central tower representing in itself a large building of approximately ideal proportions. Increased' cost of steel, elevators, mechanical equipment, etc., increasing'wastage of net rentable area for the various building utilities (particularly the elevators, every added one of which wastes a considerable plot of otherwise rentable area on every floor) and the mounting burden .of "carrying charges" .npon the huge investment during the lengthening construction period, brought what the economists are wont to call "diminishing returns" as the building soared. These increases, however, were less rapid than had been expected, because of the large size of the building, and were also in part offset by the improved light and air and the superior efficiency of rentable space on the higher floors.

Estimated Returns. The estimated net return upon the 42,000,000 dollar investment involved in the seventy-five storey structure was 9.1 per cent., as compared with 8.8 per cent, for the sixty-three-storey building, and 8.4 per cent, for the 50-storey building. The heavy burden of taxes and interest charges upon the land reduced the net income of the eight and fifteen-storey buildings'to 2.8 per cent, and 4.9 per cent, respectively.It is obvious that on a smaller plot the economic limit would have been reached at a lower level. The smaller the plot the more rapidly will the principle of diminishing returns accomplish its result, and the sooner will the true economic height be reached. Each city plot presents an individual problem, and. its most economical development must be determined in each case by a careful consideration of all the governing factors." In addition to size of plot, numerous other factors bear upon the problem, such, for instance, as the shape df the plot, character of the location, the type of " improvement, the efficiency of the architectural and engineering plans, the value of the land, and the level of construction costs, of rents,"and of interest, rates, etc. "This.is by no means a blanket endorsement of tall buildings," says the teport. "Some tall buildings, existing or proposed, are doubtless ;ustly characterised as 'frealc' structures, but the attempt to further height restriction legislation by the contention that the tall building is an economic fallacy should be roundly condemned."