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[April 14, 2012]

The Textile Block System [Concrete International]

(Concrete International Via Acquire Media NewsEdge) An overview of Frank Lloyd Wright's mono-material concepts for middleincome housing Although Frank Lloyd Wright is well known for his iconic works such as Fallingwater and the Guggenheim Museum and being a major proponent of Prairie School Architecture, his textile block system is perhaps less well known. This system arose from Wright's desire to wed machine-age production techniques with organic architecture-the principle that a structure should look as though it naturally grew on a site-so as to make his designs affordable to people of modest means.

This article explores a few of his textile block homes designed in accordance with Wright's Usonian concepts for middle-income housing: many were small, single-story dwellings without a garage and were generally L-shaped to fit around a garden terrace. Usonian homes were also constructed with native materials and had flat roofs and large cantilevered overhangs, clerestory windows to provide daylighting, and radiant-floor heating. Most of the houses were built in the 1920s through the 1950s throughout the U.S., but the plans for one are being used to construct a modern building on the Florida Southern College campus, Lakeland, FL, a setting with a number of other Wright textile block structures.

Modularity, Simplicity, and Integrity From early on in his career, Wright designed within a module. The base module varied according to the particular project, but once set, all dimensions were tied to it. Because a plan could be laid out quickly on grid paper without dimensions, the module was as much a design shortcut as an organic principle.

The module helped facilitate other ideals, such as providing a unified appearance, simplicity, and affordability through prefabrication and ease of construction. The basic module dimension, whether 4 ft (1.22 m) for the Usonian houses or 6 ft (1.82 m) for the Florida Southern College campus, was struck into the base concrete floor slab. These joints were left visible as a reminder of the organization of the building units into a unified whole.

According to Wright's organic theory, all components of the building should appear unified, as though they belong together. Nothing should be attached to it without considering the effect on the whole. To unify the house to its site, Wright often used large expanses of glass to blur the boundary between the indoors and outdoors.

According to Wright: "My sense of 'wall' was no longer the side of a box. It was enclosure of space affording protection against storm or heat only when needed. But it was also to bring the outside world into the house and let the inside of the house go outside. In this sense, I was working away at the wall as a wall and bringing it toward the function of a screen, a means of opening up space which, as control of building materials improved, would finally permit the free use of the whole space without affecting the soundness of the structure."1 Wright's mono-material textile block was intended to provide these qualities of simplicity and integrity. What is seen on the outside is true to what is inside. Integrity in a person can be described as "who you are when no one's looking." So it is with a building. Is the structure supported in the manner that it appears to be supported? Are the walls really made of stone or is the stone just a veneer? An organic house does not pretend to be something it is not.

The Storer House (1923) Wright first used his textile block system on the John Storer House in Hollywood, CA, in 1923, with his son, Lloyd Wright, supervising construction (Fig. 1). According to the original specifications, the blocks were to be made from one part portland cement to four parts sand or decomposed granite. Consistency was to be such that the mixture would hold its shape when squeezed by hand, and it was to be used within a half hour. Blocks were to be formed on site by pressing the stiff mixture into machined metal molds. A freshly formed block was to be removed immediately from the mold and kept moist for at least 10 days.2 The module for the Storer House was 16 in. (406 mm) and the actual block dimensions were exactly 16 x 16 in. with no tolerance. There was no mortar joint between the blocks-a formed reveal was used to give the appearance of a tooled joint-so precision-machined molds were required. The wall system consisted of a double-wythe precast block wall with an air gap between the outer and inner wythes. The blocks were stacked and reinforced horizontally and vertically with a "fabric" or mesh of grouted reinforcing bars, 16 in. on center.

The Freeman House (1923) Also in 1923, Wright was commissioned to design a home for Samuel and Harriet Freeman in the Hollywood Hills neighborhood of Los Angeles, CA (Fig. 2). This was to be a relatively small house for a client of modest means. Because his new textile block system used inexpensive materials and could (at least in theory) be assembled using unskilled labor, Wright undoubtedly felt that the Freeman project would be a good test case.

Unfortunately, the cost of completion was almost two and a half times Wright's original estimate. The cost overruns were probably due to excessive labor costs resulting from not having a concrete mixer on site,2 Wright's penchant to embellish his designs and refuse compromise, and delayed communications with the contractor when Wright returned to Wisconsin. Wright's original estimate stated that 9000 blocks would be required at a cost of 30 cents each, totaling $2700. The project actually required 11,000 blocks at 66 cents each, for a total cost of $7260.3 In spite of the cost overruns, the Freemans loved their house and remained the only owners and occupants until it was bequeathed by Harriet Freeman to the University of Southern California School of Architecture, Los Angeles, CA, in 1986.

The Ennis House (1923) Later in 1923, Wright had the opportunity to further test the limits of the textile block system when he received a commission from Charles and Mabel Ennis to build a home on a hillside in the Los Feliz area of Los Angeles, CA (Fig. 3). Because the Ennises had the resources for a large house on a grand scale, Wright's budget would not be as constrained as it was with the Freeman House. Wright took the opportunity to further flesh out his mono-material concept.

Visually, the house is monumental in scale and posture- uncharacteristic for Wright. It's no exaggeration to say that it dominates the hillside in an almost brutal fashion. Inspired by Mayan ruins, Wright used offset blocks to form battered walls. He made extensive use of textile block for floor structures, using ceiling blocks as stay-in-place forms for a reinforced concrete structural slab. Similarly, textile blocks were used as stay-in-place forms for reinforced concrete posts and beams.

As the project progressed, the designer and the owners had significant aesthetic conflicts: *Although Wright specified corbeled arches over door and window openings, the owners demanded horizontal lintels; *Although Wright specified that the stained glass windows were to be fabricated in a pattern that mimicked the block module, the owners wanted (and got) a delicate pattern; *Although Wright wanted the floors to have textile block finishes, marble was used for the room floors and ceramic tile was used in the baths; and *Although Wright typically controlled the design of light fixtures and furnishings on his projects, the owners demanded traditional chandeliers and furniture.

Eventually, the conflicts between the designer and the owners led Wright to resign from the project.2 Even so, the Ennis House arguably stands as one of the most complete built examples of Wright's modular, mono-material, machine-age vision.

The Arizona Biltmore Resort (1928) Early in 1928, Wright received an inquiry from a former apprentice, Albert Chase McArthur. McArthur's family was developing a million-dollar project: a resort in the desert north of Phoenix, AZ. McArthur was familiar with Wright's Los Angeles houses, wanted to adapt the textile block system for the resort, and so he asked for details on the method. With no other significant commissions in the offing, Wright wired back, essentially inviting himself to Phoenix: "Should I come out to help you start perhaps?"4 Even though he had misgivings stemming from his firsthand knowledge of Wright's commanding ego, McArthur accepted Wright's proposal.5 Just as he had feared, the collaboration was rocky. Wright, never one to compromise, was not happy with the way his textile block system was used on the project. He recommended a 16 x 16 in. (406 x 406 mm) block module as was used for the Los Angeles houses, but he was overruled in favor of an 18 x 13.5 in. (457 x 343 mm) block (Fig. 4). Worse, the project's engineers specified a steel and concrete frame to support the four-story hotel, so the blocks became little more than aesthetic treatments. As Wright explained: "Albert McArthur, one of my boys in the Oak Park workshop, was commissioned to build the building. Albert, at the psychological moment, appealed to me for help to establish the block system in the plans for the project. A wanderer myself, I turned into quarters at Phoenix and worked six months with Albert. The plans were finally made, but Albert encountered the usual opposition to the unusual in design and construction; he was unable to stem the co-lateral tide of suggested changes in technique which soon robbed the system of all economic value and left it standing as a novel and beautiful outside for an unintelligent engineer inside, whereas great technical economy was first and foremost a feature of the system had it been naturally allowed to work. Having no authority myself beyond bullying or by way of 'suggestion,' I was powerless to prevent the tragic waste. In the building of the hotel cottages, however, the details of the system itself were better followed with better results." 6 The cottages that Wright refers to are 11 outbuildings that originally served as quarters for the children of guests, their nannies, and other household servants (Fig. 5). According to historical photos of the cottages' construction, it appears that a single exterior wythe of the textile blocks did indeed serve as the structural support for the cottages' roofs. The interior finish consists primarily of wood studs, lath, and stucco, but interior concrete block fireplace walls echo the exterior façade. Unfortunately, the cottages have since undergone extensive remodeling to divide them into resort rooms, and the visible interior blocks at the fireplace have been painted or covered with gypsum wallboard.

Florida Southern College Campus (1938 to 1954) The Florida Southern College Campus is Wright's only college campus. Over a period of 16 years, the college built a total of 10 textile block buildings exhibiting the most elaborate use of patterns with the textile block system. Even the most basic block is not plain, as it has dentils along the short edges. The standard block is 3.5 in. (89 mm) thick, 36 in. (914 mm) wide, and 9 in. (229 mm) tall and fits the 6 ft (1.83 m) basic module used for the campus. A typical wall consists of two wythes with a 2 in. (51 mm) air gap, resulting in a total thickness of 9 in. (229 mm).

Undertaking the project at the end of the Great Depression and during World War II forced the college to make every effort to contain costs. They did this by using student labor to construct the initial buildings, using sample blocks in the final construction (Fig. 6), and delaying Wright's commission payments.

Unfortunately, Wright's system has not fared well in the humid Florida climate. The long horizontal channels must have been difficult to fill with grout, especially for the inexperienced student labor that constructed some of the early buildings. The joints were therefore susceptible to water penetration, causing corrosion and spalling (Fig. 7). Not long after construction, the upper-level walls on the Annie Pfeiffer Chapel were covered with stucco to stop water leakage and protect the blocks (Fig. 8).7 Block deterioration continues to be a problem on other campus structures. For example, restoration of the Roux Library was undertaken in 1981 (Fig. 9), but the repairs are now showing distress. The deterioration is so severe that in 2008 the World Monuments Fund placed the campus on its list of the 100 most endangered sites and convened a conference at the college to discuss textile block construction.8 Eric Lloyd Wright, the designer's grandson and an architect in his own right, was in attendance to advise and lend support.8,9 Florida Southern College Campus (2011 to 2012) By 1938, low-cost Federal Housing Authority (FHA) loans had become available for single-family homes. The college wanted to take advantage of this program, so they asked Wright to design a prototype for a faculty house, with the potential for building up to 20 more. Wright designed a single-family Usonian house, but the school's application for an FHA loan was denied-the design was apparently too radical, and the house was never constructed.

Recently, however, the college commissioned a new textile block building, based on Wright's house plans, for use as a tourism and education center. The new 1700 ft2 (158 m2) building is being touted by the college as the "first Wright structure constructed for the original client on the original site since 1966."10 About $2,000,000 in donations have been received to fund the project.

Construction started in the spring of 2011, with completion expected by the summer of 2012. According to Wayne Koehler, Photographer and Assistant Webmaster at Florida Southern College, construction will require about 2000 blocks in 47 different patterns.

Block production is taking place at a precast concrete production facility in Massachusetts, around 1300 miles (2092 km) from the project site. The blocks are being cast in plywood molds with polytetrafluoroethylene (PTFE) inserts cut to precise specifications on a computer numerically controlled (CNC) mill (Fig. 10). Because the inserts are removed after the block is released from the form, cracking is avoided and the fine detail is preserved. There are some durability issues with the plywood molds, however, so PFTE-coated steel or aluminum is being considered for future base molds.

The concrete mixture design was selected with the goal of providing a durable wall while maintaining the same look as the original blocks. According to the Florida Southern College Architect Jeff Baker, dry-casting was investigated, but the resulting blocks didn't have the required detail (especially at the perforations) and the blocks were susceptible to water penetration. Wet-casting was selected to obtain the necessary detail and low permeability. Forms are removed after 2 hours and the blocks are acid-etched to simulate an open-pore dry-cast look. The blocks are also pressure-washed on site.

The blocks are assembled in a manner similar to that used for the original textile block buildings, but the materials have been improved (Fig. 11). Silicone sealant is used to set the blocks and prevent the grout from oozing out (in the original projects, clay was used for this purpose). Vertical reinforcing comprises stainless steel threaded rods with couplers, horizontal reinforcing consists of epoxycoated reinforcing bars, and the wythes are held together using custom-designed stainless steel connectors that span between the inner and outer wythes (in the original projects, uncoated mild steel was used throughout). The grout channels formed at the block joints are being filled by pumping.

The cavity between the wythes is filled with a polyurethane foam rather than being left open as it was in the original projects. A wall assembly has been tested and shown to be resistant to wind-driven rain. According to Baker, tests have also verified that the sprayed-in-place insulation adds strength to the wall; the foam transfers some shear between the concrete wythes and results in significant composite action.

The plans for the houses did not include any details for the block patterns, so patterns were based on block designs in other campus buildings. Six generations of block designs were required before the right one was found. The construction is expensive, but Baker attributes the system's high costs to tooling up from scratch for one small building. The unit cost of additional buildings should be reduced dramatically.

Parkwyn Village and Galesburg Country Homes (1948 to 1950)11 These subdivisions in and around Kalamazoo, MI, were constructed in the late 1940s and early 1950s, the height of Wright's Usonian period (Fig. 12). Here, the block system was apparently intended to be a way for home owners to save money by using "sweat equity." Less consideration was given to using the textile block system as a mono-material, as wood was used for the ceilings and other components (Fig. 13). Still, the block serves as the structure, the exterior finish, and the finished surfaces at penetrations.

The Usonian Automatic Wright's ultimate expression and final word on the textile block system was the Usonian Automatic: "We are often asked how a young couple, with a limited budget, can afford to build a house designed on the basic principles of organic architecture....This problem will probably always exist in one direction or another. But we have gone far in solving this generic problem by the natural concrete block house we call the 'Usonian Automatic.' This Usonian house incorporates innovations which reduce most of the heavier costs, labor in particular."1 After some further experimentation in the late 1940s with rectangular block in a 3-to-4 aspect ratio (refer to Parkwyn Village), Wright settled on the 12 x 24 x 3-1/2 in. (305 x 610 x 89 mm) Usonian Automatic block. In the Usonian Automatic system, the walls, pilasters, ceilings, roof, and even the glazing would be constructed using the basic block module. His intent was to find a manufacturer that could produce the system economically to the precision required for blocks with no dimensional tolerance.

According to Eric Lloyd Wright, "Although steel forms were used to create the blocks for the Automatics, the blocks still could not be made with the precision necessary to lay them without shimming. It was my grandfather's desire that, ultimately, these blocks could be picked up in any building supply yard and stacked up by individuals wanting to build their own houses....He realized that only if the blocks were machine made would it be possible to lay them out without shimming, but he was never able to interest anyone in taking on the manufacture of the blocks."12 Most of the Automatics were constructed with a single wythe wall. The inside coffered face of each block, which was hidden on previous textile block houses, was left exposed for decorative effect or covered with an inch of rigid insulation and 3/4 in. (19 mm) mahogany plywood panels.12 The Automatics are perhaps most notable for the use of coffered concrete blocks for the construction of the ceiling and roof structures. Six in. (152 mm) deep, 24 x 24 in. (610 x 610 mm) coffered blocks were used as stay-in-place forms for the roof structure. The 200 lb (91 kg) blocks were hoisted and placed on a temporary platform. When placed together, the blocks created troughs for reinforcing and cast-in-place concrete at the abutting edges, so the roof was essentially a concrete waffle-slab with precast stay-in-place forms. Whether it made economic or structural sense to place significant dead load in the roof structure is a subject of debate, but the use of the blocks as concrete forms for the roof structure took Wright's mono-material concept further than in his previous designs.

The Turkel House (1955) The Turkel House in Detroit, MI, is the only two-story Usonian Automatic house in existence. The two-story scheme reduces the house's footprint on the lot. Wright further maximized yard space by tucking the building into a corner of the building lot.

Ignoring the original owner's wish to minimize the number of windows and doors, Wright's design includes 19 exterior doors (none more than 24 in. [610 mm] wide) and over 400 windows. In Wright's view, these weren't windows as punched openings, but rather, they were perforated blocks which admitted light and views, as well as providing ventilation, support, and shelter. This can be seen in the home's dramatic colonnade that faces a large garden space (Fig. 14). While the columns look fragile, especially with the mitered glass corners, they actually support the heavy concrete structures of the cantilevered second floor and roof.

The house has recently been carefully restored to its former glory by the current owners (Fig. 15). Some enhancements to the original construction include the addition of thermal pane insulated glass for all the perforated blocks and the installation of an enhanced perimeter radiant heat system to reduce condensation on the windows.

Closing Remarks According to Eric Lloyd Wright: "You can see that in every period of his career after Olive Hill (Hollyhock House), he never let it go. There is always some kind of concrete textile block system. But he couldn't swing (the industry) over. I always thought it had great potential, but there was the issue with the forming, and with the accuracy of the block (dimensions), because you don't have a mortar joint to make up differences. My grandfather could never get any companies interested in developing machinery to make the block....These blocks were handcrafted. The idea hangs on, because there is something innate about it that strikes all of us as something worth pursuing. The whole thing is unified."13 Frank Lloyd Wright once stated that, next to designing a theatre for live performance, solving the middle-income housing problem was the issue closest to his heart.1 He had hoped that his precast concrete modular block system would do just that. Lately, there has been a resurgence of interest in Wright's life and work. It could be that his pioneering experiments will yet provide an inspiration for the development of a viable precast concrete residential building system.

References 1. Wright, F.L., The Natural House, Horizon Press, New York, NY, 1954, 223 pp.

2. Sweeney, R.L., Wright in Hollywood: Visions of a New Architecture, the MIT Press, Cambridge, MA, 1994, 271 pp.

3. Chusid, J.M., Historic Structure Report: Samuel and Harriet Freeman House, Hollywood, California, Frank Lloyd Wright, 1924, USC School of Architecture, 1989, 293 pp.

4. "Jewel of the Desert, the Arizona Biltmore Hotel," Biltmore Press, Phoenix, AZ, 2009.

5. Cheek, L.W., Frank Lloyd Wright in Arizona, Rio Nuevo Publishers, Tucson, AZ, 2006, 72 pp.

6. Wright, F.L., Frank Lloyd Wright: Collected Writings-Vol. 2, Rizzoli International Publication, Inc., New York, NY, 1992, 384 pp.

7. MacDonald, R.M.; Galbraith, N.E.; and Rogers Jr., J.G., The Buildings of Frank Lloyd Wright at Florida Southern College, Arcadia Publishing, 2007, 128 pp.

8. Chusid, J.M., Preserving the Textile Block at Florida Southern College, World Monuments Fund, New York, NY, 2011, 42 pp. ( project/florida-southern-college) 9. Freitag, A., "Site Visit: Frank Lloyd Wright's Florida Southern College," WMF Journal, June 2, 2009.

10. Florida Southern College News, June 23, 2011.

11. Heinz, T.A., Frank Lloyd Wright Field Guide: Includes All United States and International Sites, first edition, Northwestern University Press, Dec. 30, 2005, 528 pp.

12. Hess, A.; Weintraub, A.; Frampton, K.; and Hines, T.S., Frank Lloyd Wright: The Houses, Rizzoli, New York, NY, 2005, 544 pp.

13. Author conversation with Eric Lloyd Wright, May 14, 2011.

Edward Losch is both a licensed structural engineer and an architect. He founded Losch Engineering Corporation to provide engineering services to the precast concrete industry. He recently chaired the Precast/Prestressed Concrete Institute Sandwich Wall Panel Committee and has developed software for concrete sandwich wall design that has become a standard in the industry. Losch is currently a PhD Candidate in building science at the University of Southern California School of Architecture, Los Angeles, CA .

(c) 2012 American Concrete Institute

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