Behind the iron curtain

Stwardson Opera Hall, Stewardson, Illinois. Close up view of the wooden backup after removal of the galvanized sheet-metal facade. Image courtesy of Tim Borntrager.

Stewardson Opera Hall, Stewardson, Illinois. Close up view of the wooden backup after removal of the galvanized sheet-metal facade by Mesker Brothers Iron Works of St. Louis, Missouri. Image courtesy of Tim Borntrager.

While its use as decorative facing for buildings was perhaps the most dramatic use of the material, the principal exterior application of ornamental sheet-metal in commercial architecture was for cornices. Prior to sheet metal, wood was the primary material for cornices in small towns, with the exception of when stone was used by wealthier building owners. Galvanized sheet-metal cornices quickly supplanted those made of wood for several reasons, including a higher level of durability and ornamentation and a lower cost. In addition, beginning in the 1860s new fire codes prohibited the use of wooden cornices and Mansard roofs rendering necessary the use of another material. Ironically, sheet-metal cornices and facades depended on a wooden backup for their structural stability. To address this, many architects and professional trade organizations promoted the use of steel supports and anchors, but wood was cheaper, more readily available and easily shaped on site, and therefore continued to be used despite being banned by fire codes. The practice continues largely to present day.

Because use of sheet-metal was decorative and not structural, it meant that this back up material, i.e. wood, was absolutely critical to provide structural stability and shape. Seen by most architects and critics as a flaw, this actually became one of sheet-metal’s greatest advantages. For example, in cornice applications a deep wooden backup (or lookout, as it was then called), bolted to or embedded in the top courses of a masonry wall, resulted in very deep cornice projections, not easily obtainable with other, heavier materials.

All ornamental sheet-metal manufacturers, not just Meskers, utilized various forms of the wood backup to support their sheet-metal creations. But only Mesker Brothers Iron Works had it patented (patent analysis at the end of the post). Generally speaking, facades by George L. Mesker & Co. utilize less projections and are flatter in appearance than those by Mesker Brothers Iron Works, suggesting a likewise simpler backup of mostly studs.

Although all sheet-metal products needed this backup in order to be installed onto a building, a Mesker Brothers ornamental sheet-metal facade required a particularly intricate wood frame, for which the company supplied a pattern so the wood could be cut on site. This frame was appropriate for new buildings, where it constituted the exterior wall construction of the upper floors, or for existing buildings where it was placed over a brick wall. Once the wooden backup was in place, the metal panels — marked on the back to correspond to a set of detailed instructions — were installed bottom up. While the overlapping vertical joints of the sheet-metal panels were nailed to the wood members, the horizontal connections were concealed within notched portions of the wood. The back up had to be specially shaped in order to conform to the cross-section of the facade and offer the maximum amount of support. The same was true for cornice applications. These horizontal joints (also patented, no. 435,906) prevented water penetration and obviated the use of fasteners at the edges of the panels, while enabling the metal to expand and contract freely without buckling or straining the connections. The final result was that of minimal number of visible connections, furthering the intended illusion of a stone facade.

This critical, but rarely seen component of a galvanized sheet-metal assembly must not be overlooked during maintenance, repair or restoration. When repairing sheet-metal cornices and facades, the wooden back up should be inspected for condition and stability. Generally speaking, the condition of the metal hints at the status of the material behind it. Hence if there is rust on the metal there is often water damage to the backup. Repairs or replacement can be challenging without disrupting the original assembly — so proceed carefully. Extreme caution should be taken when repairing the metal in situ, especially soldering or any other repairs involving a flame. The wooden backup is often dried up and bird and insect nests and other debris inside the cornice or behind the metal front are extremely flammable. A devastating fire can occur very easily. Furthermore, when salvaging sheet-metal cornices and facades it is critical to save at least an entire section of the wood backup so it can serve as a template for making a new one.

Patent analysis:

  • No. 478,974 — Building front (patented July 12, 1892, by August Brunkhorst, Arthur Wieden, and Charles T. Richards, assignors to Mesker & Bro.). This improvement relates to building fronts composed of a wooden foundation and a sheet-metal surface. The construction is simplified, concentrated, and cheapened, and at the same time strengthened at various points. The sills and heads of the window-frames are combined or embodied in the front. A prominent feature of the front is a wooden plate, which extends horizontally across the building between end studs at the sill and header level of each story. It serves not only as a principal member of the front to which the studs connect to, but it entirely replaces the sill and header as a separate piece and is made part of the window frame construction. A feature of the box frames is an inside finish board which extends above and below the stiles to connect to the horizontal pieces constituting the sill and the header of the window. At the sill level it is pitched higher at its back and the studs and stiles are beveled to fit with it. At the sides of the front, a sub-column in combination with suitable backing is used. It can also be used between the principal sheet-metal columns to modify the width of the front. The tops of the window frames also have an outside finish piece which extends downward to lap upon the outside window sash. The principal sheet-metal columns are combined with their respective box frames, which allows for a much thinner front than those of previous construction. The columns and box frames are brought closer together and the entire construction is concentrated in its depth. This means that the lintel at the bottom of the upper story does not need to be as thick as in previous construction; the lookout below the window sill does not need to project as far outward as previously and can still be sufficiently supported; at the top of the window frames, the entablature support can consist of a single row of studs, instead of two rows as was customary until now. When the building has more than two stories, an intermediate level of studs and horizontal supports of construction very similar to the bottom of the upper story (minus the sill) is inserted at each level until the desired number of stories is reached. An additional feature of the building front is associated with the portion immediately above the windows and columns. Flat metal panels are fastened to the wooden lookouts or studs, and ornamental projections, shaped as desired, are bolted to the flat panels and united with the sheet-metal panels below through interlocking joints. This patent is significant in its integration of sheet-metal and wooden pieces, including the window frames, to create a complete upper story front, made of less material, therefore cheaper, yet simpler and stronger than before.
Patent no. 478,974, for a building front. Issued on July 12, 1892, this. Image from the United States Patent and Trademark Office.

Patent no. 478,974, for a building front. Issued on July 12, 1892, the patent is significant in its integration of sheet-metal and wooden pieces to create a complete upper story front. Image from the United States Patent and Trademark Office.

Patent no. 478,974. Another figure from the patent, showing the cornice cross-section of the wooden backup with notches to conceal horizontal connections between metal panels. Image from the United States Patent and Trademark Office.

Patent no. 478,974. Another figure from the patent, showing the cornice cross-section of the wooden backup with notches to conceal horizontal connections between metal panels. Image from the United States Patent and Trademark Office.

Stewardson Opera Hall, Stewardson, Illinois. The profile of the wooden backup matches that of the sheet-metal front and provides the latter with structural stability.

Stewardson Opera Hall, Stewardson, Illinois. Close up of cornice bracket sans metal.

Stewardson Opera Hall, Stewardson, Illinois. The unglamorous but critical wooden backup was hidden since 1893 and exposed only to salvage the galvanized sheet-metal facade prior to the building’s demolition.

Section of the wooden lookout from the Stewardson Opera Hall, with a scale figure (me). Image courtesy of Tim Borntrager.

Stewardson Opera Hall, Stewardson, Illinois. Section of the wooden lookout with a scale figure (me). Note the similarity to the patent image above. Image courtesy of Tim Borntrager.

Opera Hall facade_Stewardson2

Stewardson Opera Hall, Stewardson, Illinois. Close up of the patented backup and its notches to conceal sheet-metal connections.

Image courtesy of Tim Borntrager.

Arcola, Illinois. New wooden backup based on the historic template was made in order to reinstall the salvaged and restored Stewardson Opera Hall facade onto a different building. Image courtesy of Tim Borntrager.

First State Bank, Winchester, Illinois. During the restoration of the cornice, manufactured by George L. Mesker & Co. in 1898, the corner bracket was removed to inspect the condition of the cornice's interior. Note the use of less expensive common brick behind the cornice.

First State Bank, Winchester, Illinois. During the restoration of the cornice, manufactured by George L. Mesker & Co., the corner bracket was removed to inspect the condition of the cornice’s interior. Note the embedding in less expensive common brick behind the cornice.

First State Bank, Winchester, Illinois. A look inside the cornice and the wooden backup that supports it. Note a somewhat simpler construction than found on the Stewardson Opera Hall by Mesker Brothers.

First State Bank, Winchester, Illinois. A look inside the cornice and the wooden backup that supports it. Note a somewhat simpler construction than found on the Stewardson Opera Hall by Mesker Brothers.

316 E. Adams, Springfield, Illinois. In this non-Mesker copper cornice repair, a new wooden cornice backup was needed for a new copper cornice section. Note how the profile of the backup matches that of the cornice.

316 E. Adams, Springfield, Illinois. In this non-Mesker cornice repair, a new wooden backup was needed for a new copper section. Note how the profile of the backup matches that of the cornice.

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