4.7. ROOT’S SKELETON-FRAMED MONADNOCK DESIGN

During the intervening years, Shepherd Brooks had managed to buy the remaining lots in the southern part of the block bounded by Jackson, Dearborn, Van Buren, and Custom House Place (now Federal Court), so the two brothers were now contemplating constructing one long building to fill the entire 400’ long block.  But in order to avoid any future disagreements among their heirs, this building would be planned to function both as one, continuous building, as well as up to four, separate buildings, if the heirs to their estates were at any time to split up the properties.  This also meant that Shepherd did not have to build all of the building at once but could choose to decide at any time to postpone construction on the southern parts until a later date.  Root now faced a similar problem that Jenney had in the past: the Monadnock would have to be designed for more floors to be added at a later date.  The only difference was, instead of adding the floors vertically, Monadnock needed to be designed so that it could grow laterally.

By May 1889, it was apparent that Aldis and Brooks had agreed that the time had come to take Monadnock off the shelf and get it ready for construction, if for no other reason than to secure a building permit before the impending height limitation ordinance was approved.  The big change between the final 1886 design and 1889 was an increase in the building’s total number of floors from 13 to 16.  During May reports about both the Manhattan and Eugene S. Pike’s building planned to be diagonally across Dearborn from the Monadnock, continually referred to both buildings as being planned to be 16 stories tall, hence Aldis’ desperate telegram on May 22, 1889, to Brooks (Peter Brooks disliked telegrams intensely) in one last, but ultimately successful attempt to get a final decision so the project could move forward: “MONADNOCK BETTER BE SIXTEEN.”  The additional three floors played havoc with Root’s prior design for one simple, unavoidable, reality:  the weight of the three extra floors, if constructed along the lines of the 1886 design, would push the loads on the building’s foundations beyond the 3000 pounds per square foot limit that was felt to be safe.  

Boyington’s Board of Trade Tower was already experiencing significant cracking as a result of its excessive settlement.  Adler had tried as best as he could to minimize the settlement of the heavy, 17-story tower in the Auditorium, but even he couldn’t overcome gravity or the capriciousness of the building’s owners.  Chicago architects had finally come face-to-face with the primary challenge for which they had been preparing for over the past eight years.  The weight of a skyscraper would have to be minimized so that it could continue to safely grow taller than ten stories, without generating excessive settlements in Chicago’s weak soil.  At the same time, it still had to be as fireproof as a solid masonry structure. This problem would be solved only by replacing the masonry bearing wall with the iron skeleton frame, which is why Peter B. Wight’s invention of a system of terra cotta fireproofing for the iron frame following the 1874 fire had been so pivotal to the future of the skyscraper in Chicago.

Wight’s former draftsman, Root, inherently understood the interrelated aspects of these technical issues and immediately changed the design of the 16-story Monadnock to all iron framing for just this reason, as was Jenney using in the Manhattan.  Root finally had his chance to show how to put the Rookery’s lightcourt elevations on the exterior of a building. (Why he chose not to do so in the Rand-McNally building is an open question, and yes, Holabird & Roche had done their best with the Tacoma Building, but see the Inter-Ocean’s comment on this below.) On June 9, 1889, (two days after the Manhattan’s permit was approved, revealing that the designs of these two buildings were on a parallel time track) the Inter Ocean published a complete description of Root’s new redesign for the Monadnock:

“The new structure will be strictly utilitarian.  The object has been to secure the greatest strength with the least weight, the most floor space with a maximum of light and air, the entire construction being held subsidiary to complete fire-proofing.  The building materials will be steel, sewer brick, Portland cement, red granite, hollow tile, and terra cotta.  The frontages of the ground and sixteenth floors will be flat, the intermediate stories [floors 2-15] being provided with bay windows.  The entire frontages will be covered with red terra cotta, and the building will not be unlike the Tacoma, although straight lines will predominate… [my emphasis]

“A hallway will extend the length of the building on each floor, suites of offices being arranged on either side.  A feature of the building will be four great walls, arranged equidistant of the greater length of the building, which will add much to its stability and give masonry the preponderance in its construction over steel.  The entire weight of the block will equal one and one-half tons (3000 lbs.) to each square foot of the deepest-laid foundation stones.  This is perfectly safe, the architects claim, but practically the limit.

“It is claimed by authorities on such subjects that the limit on what is known as office fireproof construction is sixteen stories, each of twelve or thirteen feet.  It is claimed that the weight of a building of this character will equal, when extended 200 feet into the air, one and one-half tons for each square foot of footing, which is the limit of the strain which the soil will bear.  An iron and steel skeleton, combined with masonry, is understood when fireproof office construction is referred to.

Whereas Jenney would take the final leap to shed all the masonry walls in the Manhattan Building, Root was using Shepherd’s requirement to break the building into separate entities with walls to his advantage to help resist the wind loads.  This was, more than likely due to the more “open” nature of Root’s planned exterior to echo the design of the Tacoma Building, while Jenney’s elevations comprised of more masonry and would offer some lateral stiffness as discussed earlier. Burnham & Root’s new 16-story design can be imagined as the plan of Baumann & Huehl’s Chamber of Commerce wrapped with the bay windows of the Tacoma Building but without the balcony extension of the bay windows at the top floor. 

Burnham & Root. Left: Argyle Apartments, northwest corner of Michigan and Jackson, 1886. Right: Pickwick Flats, southeast corner of Michigan and Twentieth, 1886. (Hoffmann, Root)

Actually, its lineage could be traced back to Root’s Argyle Apartments of early 1886.  The Economist continued with more details of Root’s latest design:

“The walls will be of steel covered with brown brick.  At the corners for two stories will stand heavy red granite columns and for the upper fourteen stories solid masonry columns of brown brick.  Between these columns there will be three-foot bay windows…  The four corners of the structure will each be in the form of a tower rising a short distance above the top of the building… The structure will have no ornamentation whatever, depending for its effect on its massiveness and the correct relation of its lines.”

Owen Aldis was completely sold on the efficiency of its plan, which he relayed to Brooks:

“Numerous bays for extra floor space, built of iron and brick… The actual renting space is 68 per cent of floor space, as against 50 to 55 in the Rookery and 45 per cent in Home Insurance!…  I am satisfied that such a building built in the plainest and simplest manner, without one round arch or any ornament, would be of greater value than the Rookery…”

Unfortunately for Burnham & Root, but maybe fortunately for posterity, Shepherd Brooks squashed the entire design because he did not trust the long-term stability of this new-fangled idea of iron framing:

“As to erecting a tall building entirely of steel, for a permanent investment, I should not think of such a thing. It would no doubt pay well for many years but there is so much risk and uncertainty in regard to its lasting strength.”

In fact, Brooks wasn’t even certain that the building should be 16 stories high, “I do not think it a fixed fact yet, that buildings as high as 16 stories are altogether desirable.”

The Monadnock would be a 200’ high pile of bricks.

FURTHER READING:

Hoffmann, Donald. The Architecture of John Wellborn Root. Baltimore: Johns Hopkins University Press, 1973.

(If you have any questions or suggestions, please feel free to eMail me at: thearchitectureprofessor@gmail.com)

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