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Prairie Architects, Inc. |
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Wingspread Conference Center Racine, Wisconsin |
Limestone Masonry Systems -- Wingspread was detailed with Kasota, Minnesota limestone, ranging in color from pink (which Wright apparently favored for Wingspread) through creamy tan to yellow. The limestone was especially valued for its outstanding hardness and resistance to decay. However, decay of the stone was inherent to its very structure, being made up of layers of stone of varying hardness, some vulnerable to moisture penetration and consequent fracture. As the material becomes increasingly rare, adequate supplies for future repairs should be secured at this time. Prairie Architects surveyed all of the stones at Wingspread and prepared a repair program for Kasota stone using successful high technology materials. Wright had specified that the stone plinths upon which most of the building rests be set with a slope to drain standing water. However they were set level resulting in conditions promoting moisture access to the perimeter wood sills. In some locations, most notably at the east side of the Terrace Room, these plinths should be reset, sloping away from the building. Use of water repellants on masonry was not recommended except for extreme conditions, where they must be vapor permeable. Stucco on Wood Substrate -- Wingspread's exterior stucco was a two coat system with integrally colored stucco plaster, finished in a pattern known as Caen stone. With few exceptions, the present colors have faded from the original which almost matched the bricks and roof tile. Remaining original stucco is a significant historic element that should be carefully preserved. Most stucco, however, was in stable condition. Cracks should be monitored, caulked, or repaired, depending on their size, to protect the surface from further damage. Framing Systems -- The most serious potential wood problem at Wingspread was the possible development of fungal decay which could result in the rapid growth of structure endangering decay. The greatest opportunities occurred at perimeter sills, perimeter framing at windows, and framing members at grade. We recommended and have outlined a survey of wood framing members, especially at the exterior wall along the East Wing Corridor, locations where the exterior face of the stone plinth was buried in dirt in the past, as along the west side of the North Wing, and the west Kitchen wall, where the finish lawn was graded to the same elevation as the stone plinths. Framing at stone window sills should also be monitored. The survey includes moisture content measurements and core samples where indicated. Cypress Siding -- Natural weathering of Wingspread's cypress siding had resulted in a distinctive patina of bands of varying shades of predominately silver, grey, and black tones, each the result of exposure to sunlight, or activity of fungi which live in the wood. There was also a ubiquitous pattern of dark spots due to rusting iron nails. We outlined a maintenance program for the cypress siding that includes protecting framing members from water intrusion, replenishing natural preservative qualities of the wood, protecting end grain locations, and protecting face grain locations from deterioration due to rusting nails. Sealants -- Wright's practice was to always press the limits of construction technology. The most widely used compounds used today, silicone and urethane, did not exist at the time of the construction of Wingspread. Sealants of many different compositions were applied around Wingspread over the years. Multiple layers of sealants can mask underlying failures. We outlined a program of the general replacement of sealants at Wingspread. Balconies and Trellises -- Balconies and trellises provided one of the strongest connections between inner and outer spaces at Wingspread, but have proved susceptible to moisture damage. Balcony railings and tops of trellises have been the most vulnerable and copper flashings have been installed in many locations, deviating from Wright's intent to hide flashings. We recommended that 'sacrificial' cypress caps be installed above redetailed flashing on the east, west and north balconies. |
Exterior Conditions and Recommendations, Continued Page 2 |
Prairie Architects, Inc. -- 103 South Third Street -- Fairfield, Iowa 52556 |