|
small (250x250 max)
medium (500x500 max)
Large
Extra Large
Full Size
Full Resolution
|
|
The Historic Dimension Series A student publication series by the UNCG Department of Interior Architecture A Stone’s Throw: Asheville’s Legacy of Pebbledash & Roughcast by Sunny Townes Stewart Spring 2013 While the Appalachian Mountains may be known for their quintessential log cabins, the dominant architectural style of Asheville, North Carolina—located in the southwestern corner of the state near the Tennessee border—does not fit the traditional stereotype. Instead, the hilly streets of the city’s suburbs are dotted with quaint, picturesque homes reminiscent of English cottages, clad in false half-timbering, wooden shake siding, exposed stone, and a coarse stucco that many in Asheville call pebbledash (though most examples in the city are more accurately a related rendering style called roughcast). Introduced to the region by English architect Richard Sharp Smith (1852-1924), pebbledash is abundant in neighborhoods that were built at the turn of the twentieth century, such as Biltmore Village (see Figs. 6 and 7) and Montford (see Figs. 8 and 9). Smith is regarded as Asheville’s most influential architect during the late nineteenth and early twentieth centuries—a period marked by rapid population growth and construction—and other designers and builders quickly adopted his distinctive styles. By the 1930s, the “earthy, richly textured pebbledash” had become a defining characteristic of Asheville’s residential districts (Asheville-Buncombe HRC). History of Pebbledash Pebbledash and roughcast are heavily textured and durable forms of stucco, a plastering technique used by builders in ancient Egypt, Greece, and Rome (Millar, 2). While most interior and artistic plaster is smoothed flat, stucco—often used for outdoor surfaces—includes a sandy substance to provide a “sugary texture” (see Fig. 3). Pebbledash and roughcast (see Figs. 4 and 5) feature a more prominent aggregate like gravel or pebbles, glass, shells, broken pottery, or mineral shards, depending on what was locally available in the region (Taylor). The technique was common in England, particularly in coastal regions and other areas with harsh weather. According to Anne Grimmer, author of the National Park Service (NPS) Preservation Brief on historic stucco, render of all types was a weather-repellent coating that offered a layer of insulation and protected the building from wind and rain penetration, as well as fire. As such, stucco as an architectural feature “probably has a history as old as lime mortar itself” (Taylor). Roughcast render was often used during the Middle Ages to cover the panels between buildings’ timber framing (see Fig. 2). In his 1897 treatise Plastering: Plain and Decorative, craftsman William Millar noted that roughcast was “one of the oldest forms of external plastering” because of its durability (210). Though it was often shunned during the Victorian era, the roughcasting tradition was renewed with the cottage ornée (or decorated cottage), Tudor revival, and Arts and Crafts movements of the nineteenth century (Taylor). According to architectural “Roughcast, as conservationists prefer to call the earliest material, probably has a history as old as lime mortar itself.” -Jonathan Taylor, conservator “Plastering is one of the earliest instances of man’s power of inductive reasoning, for when men built they plastered: at first, like the birds and the beavers, with mud, but they soon found a more lasting and comfortable method, and the earliest efforts of civilisation were directed to plastering.” -William Millar, nineteenth-century craftsman UNCG The Historic Dimension Series: 2 Fig. 2: A seventeenth-century cottage featuring half-timbering and roughcast render in Hampshire, England. conservator Jonathan Taylor, however, it was Richard Norman Shaw’s popular Queen Anne style that was likely most responsible for roughcasting’s popularity. Its “asymmetric composition of steeply pitched roofs, jettied floors, small-paned windows and rough textures evoke an atmosphere of cosy cottage comforts with roaring log fires” (Taylor). All of these late nineteenth and early twentieth century styles tend to combine a variety of textures, including brick, tile, wooden shingles, exposed wood timbers, native stone, and roughcast renders. It is obvious that Richard Sharp Smith was influenced by the popularity of these styles before immigrating to the United States, as he often mixed their motifs into his designs (see Figs. 6-9). He moved to Asheville in 1888 (from England via New York) to supervise the construction of Biltmore, George Washington Vanderbilt’s sprawling French chateau retreat that was designed by Smith’s employer, Richard Morris Hunt. After its completion, Vanderbilt commissioned Hunt and Smith to design a village that would support the operation of the mansion. Embracing its role as a manorial village, of sorts, the architects utilized designs reminiscent of medieval England. They blended arts and crafts, Tudor revival, and cottage ornée styles featuring steeply pitched, gambrel roofs; false half-timbering; decorative bracketing; and roughcast siding (see Figs. 6 and 7). After Hunt’s death, Smith settled permanently in the mountains, continuing to utilize similar motifs in the hundreds of homes that he designed throughout the late nineteenth and early twentieth centuries. The rough, rustic nature of the technique of roughcasting and or pebbledash complemented the natural surroundings and the other decorative elements. By the turn of the century, the technique had been adopted by other architects in the region, entering into the “building vocabulary” of Asheville (Bishir et al., 429). Techniques for Mixing and Application The techniques for pebbledash and roughcast renders are very similar, and in fact during the Arts and Crafts era were often used interchangeably, though there were regional variations (for example, Millar notes that harling was the term of choice in Scotland). Like other forms of plaster, both require multiple coats. When the pebbledash is used to cover textured masonry like brick, stone, or concrete block, the first layer is applied directly to the wall. In other instances, like when it is being used to cover log construction or smooth panels, lath—either small wood slats or, especially in the late-nineteenth and early-twentieth centuries, metal meshing (see Fig. 11)— is necessary to encourage the render to form a strong bond, or key (Grimmer). Millar called the makeup of the first layer coarse-stuff because it included sand and horse or ox hair to encourage the plaster to form a stronger key. Before it dried, the craftsman usually scratched the surface in order to encourage the second coat to key (Millar, 210). During the application, it is necessary to keep the surface being covered—be it wood lath, masonry, or a layer of cured render—damp to “ensure a good bond ... [and] prevent them from pulling moisture out of the stucco too rapidly, which results in cracking, loss of bond, and generally poor quality stuccowork” (Grimmer, 7). The difference between the application of stucco, roughcast, and pebbledash comes with the next step. With regular stucco, a more refined mixture would be used to form the third and final, skillfully textured layer (Fig. 3). For traditional roughcast or pebbledash applications, however, the aggregate was thrown forcefully onto the still-soft second coat of stucco, as the names (pebbledash and roughcast suggest). Millar instructed that the material to be dashed should be no Fig. 3: Traditional stucco Fig. 5: Roughcast Fig. 4: Pebbledash UNCG The Historic Dimension Series: 3 more than ¼- and ½-inch in size, which he said should be placed in a tub of hot lime and water in a “semi-fluid state” (210). The craftsman should retrieve the material as needed, Millar continued, and then “quickly and evenly throw or dash [it] on with a ‘scoop’ or hollow trowel, then brush [it] with liquid to give a uniform tint. A good craftsman can dash the shingle very regularly, and leave the face of the work with a uniform, though rough surface. The dashing should be begun at the top, gradually working down, taking in all angles and sides of panels” (210). Today, though some craftsmen continue the tradition of dashing, it is more common for the aggregate to be added to the mixture before application and painted after it dries (see Fig. 10). Though weatherproof by nature, renders were often made even more protective with coats of wax or oil (Grimmer). Millar provided instructions for different tints to add to the dash, if desired. For a buff color, for example, he suggested craftsmen add copperas and fresh cow manure, noting that adding an alum solution “will give brilliancy and permanency to the colours” (558). Though the terms were (and still are) often used interchangeably, when textured render is left natural or tinted, it is generally called pebbledash (Fig. 4) and when it is painted it is called roughcast (Fig. 5). Evolution of Binders Millar notes that the Egyptians, Greeks, and Romans all used plaster “of most exquisite composition” (4). Ancient builders used plasters bound with either burnt gypsum, a naturally occurring, crystallized mineral mined from ancient lake and sea beds, or lime, a chemical compound formed by grinding and heating limestone (4). Quicklime—or ground and heated lime ready to be mixed for plaster—is highly reactive and must not be allowed contact with the air before it is time to mix it with water (a process called slaking the lime), and the resulting plaster takes several months to dry completely. On the other hand, natural gypsum-based cements, like plaster of Paris, cure quickly, set in minutes, dry completely in two to three weeks, and make a more rigid plaster. However, there were downsides to gypsum-based plaster, including vulnerability to water damage and a less-adhesive nature. Whereas lime plasters “could survive occasional wind-driven moisture or water wicking up from the ground. Gypsum plaster needed protection from water. Furring strips had to be used against masonry walls to create a dead air space, [preventing] moisture transfer” (MacDonald, 4). As such, lime, which Millar called “one of the most important materials in the building trades,” would continue to be the main ingredient in renders of all types throughout the nineteenth century (38). In Millar’s manual—which has provided modern-day scholars and practitioners insight into traditional Victorian methods for mixing and applying various kinds of renders (as well as their histories and relative strengths)—he noted that “100 yards superficial of rough-casting (two coat on lath),” called for “25 cubic feet of lime, 50 cubic feet of sand, 16 lbs. of hair, and ¾ yard of prepared gravel for the dash coat. A quarter tub of lime putty should be mixed with every tub of gravel for the dash” (558). The development of portland cement, however, quickly made builders less dependant on lime renders. Developed by a bricklayer and plasterer in Leeds, England in 1824, it was first manufactured in the United States in 1871 (Millar, 55). When Millar published Plastering: Plain and Decorative in 1897, he noted that portland cement could be substituted for the first layer of coarse stuff (210). By the twentieth century, craftsmen Fig. 6: A front elevation drawn by Smith c. 1900 for a Montford home featuring a roughcast render (see detail). Fig. 7: A Biltmore Village cottage featuring the signature Richard Sharp Smith roughcast exterior. UNCG The Historic Dimension Series: 4 had transitioned to stucco composed of mostly portland cement bases mixed with a small quantity of lime (Grimmer). Millar notes that the advantages of portland cement were “its hydraulic properties [i.e., its ability to harden when combined with water], great strength at comparatively early dates, its continually increasing strength, and its power of carrying very large proportions of sand or other aggregate when made into mortar or concrete” (55). Grimmer also highlights the ways in which renders improved after the introduction of portland cement: “No longer used just as a coating for a substantial material like masonry or log, stucco could now be applied over wood or metal lath attached to a light wood frame. With this increased strength, stucco ceased to be just a veneer and became a more integral part of the building structure” (Grimmer, 3). Ultimately, the more coarse stuccos were “ideal for a portland cement render” (Taylor). More finely finished stuccos made with cement often cracked quickly after application because the heavy troweling needed to achieve the smooth finish pulled the aggregate and the moisture to the surface. According to British conservator Jonathan Taylor, pebbledash and roughcasting mixed with cement are less likely to crack because the mixture does not require much troweling and the stone aggregate actually strengthens the binding. Assessment of Damage and Deterioration Like other kinds of render, pebbledash and roughcast are assumed to be more resilient and weatherproof than plain stucco, but they suffer from many of the same issues as its less-textured cousin. According to Grimmer, “age and lack of maintenance hasten the deterioration of many historic stucco buildings. Like most historic building materials, stucco is at the mercy of the elements, and even though it is a protective coating, it is particularly susceptible to water damage” (1). Most often the water infiltrates the building from joints and seams in its construction— such as the roof, around chimneys, and windows and doors—or rising damp. Underlying issues should be taken care of before addressing the necessary stucco repairs. When assessing historic stucco of any variety, it is important to determine what kind of base was used in the original mixture. Lime renders are rarely used today; however, using gypsum plaster to repair work originally done with lime can be problematic. Experts caution that binders behave differently, and if two different binders are mixed (using gypsum plaster to repair historic lime-based render, for example), the surface will soon crack where the two come together (Howell). Grimmer notes that it is important to watch out for deterioration caused by previous badly done repairs “particularly if executed in portland cement, which tends to be very rigid, and therefore incompatible with early, mostly soft lime-based stucco that is more ‘flexible’” (7-8). It is also important to be aware of vibrations caused by nearby traffic or construction, as well as foundation shifts and settlement. All of these factors can contribute to failure of the material. Once the stucco begins to crack, water accumulates and can cause further damage from freeze-and-thaw cycles, especially in harsh climates like Asheville. Taylor warns that this can “cause render to fall away in sheets” or allow salt crystals (left behind from evaporated water) to grow in the substrate. To determine how extensive the damage is, gently tapping the surface with a wooden handle will identify unsound areas (Taylor). Maintenance and Repair Because of the general resilience of the material, general preventative maintenance and monitoring for deteriorating should keep textured renders sturdily in Fig. 9: Small batches of concrete and aggregate are mixed for application. If patching historic roughcast, modern materials are acceptable, but care must be used. Fig. 8: The Carolina Bed and Breakfast, located in Montford Historic District in Asheville, which used pebbledash in a recent renovation (Figs. 8-13). UNCG The Historic Dimension Series: 5 tact. Harsh chemicals and pressure washers should be avoided; if cleaning is absolutely required, the gentlest means possible should be employed. Harsh methods can cause the aggregate to break apart, causing the potential for further damage. Because stucco is often applied on top of masonry or wood, it is possible that it is hiding deterioration that can cause water to penetrate the structure. A close inspection at the point of water entry should reveal underlying problems. The render may have to be removed (as gently as possible) in order for the issue to be resolved and then re-applied. Repair. Finding the materials for and/or the craftsmen who are familiar with historic rendering techniques, however, can be challenging. When repairing pebbledash and roughcast renders, the heavy texture is far more forgiving than stucco, and therefore, less likely to show imperfections arising from mismatched materials. Grimmer addresses the difficulty in accessing historically accurate components in the NPS brief on historic stucco. She encourages the use of substitute materials, noting that “it may not be worthwhile, nor in many instances possible, to attempt to duplicate all of the ingredients,” unless authentic reproduction is absolutely necessary (Grimmar, 8). As noted, it is important to match the strength and flexibility of the binder used in the historic material. Research on the structure’s history might provide some insight, though Grimmar warns that the timing of the switch from lime to portland cement is imprecise. A more accurate method is to analyze the historic stucco to provide useful information on its basic ingredients. For example, “a dilute solution of hydrochloric (muriatic) acid will dissolve lime-based stucco, but not portland cement” (8). Products to avoid. Modern caulking products should be avoided, as they tend to attract more dirt, making them “highly visible and unsightly,” though a commercial bonding agent can be used to fill hairline cracks. (Grimmer, 9). Small cracks can be filled with a “thin slurry coat consisting of the finish coat ingredients, or even paint or whitewash” (Grimmer, 9). Larger cracks will have to be cut out. Rarely does an entire wall need to be recast. Whatever the case, the heavy texture of roughcast and pebbledash requires slightly less precision, though the difficult nature of the technique is best executed by a skilled professional. When modifying an existing structure (like the window being resized in Figs. 13-15) or a new addition constructed, the plasterers should be diligent in matching materials and colors of the historic materials. Patching. When patching is necessary, the area to be repaired is often squared off; however, clearing off an irregular-shaped section cut on an angle can sometimes make the patch less obvious and encourage a stronger bond between the historic and replacement render. Grimmer stresses the need to use sharp tools (such as a cold chisel, hatchet, diamond blade saw, or masonry bit) when cutting away and clearing damaged stucco, lest oversounding, or “breaking keys of surrounding good stucco,” occur (Grimmer, 9). A bristle brush should be used to clean the damaged area, clearing away the loose render and aggregate down to the lath or bare masonry. To ensure that the patch forms a strong key, the area to be patched should be cleared of all dirt, loose paint, and other contaminants Fig. 10: The first layer of stucco is applied in small sec-tions to mesh lath. Scratching the surface allows the second, roughcast layer to form a key, or strong bond. Fig. 11: Though it seems like it would be forgiving, the messy job (see Fig. 1) of dashing the roughcast is dif-ficult to master. UNCG The Historic Dimension Series: 6 and, if the substrate is brick or stone, the mortar joints should be scraped back approximately half an inch. Deteriorated lath should be either repaired or replaced with wire mesh. Grimmer instructs that the patch and the old stucco must not overlap. Removal. Homeowners not enamoured with the effect of the textured stucco may wish to remove it. Though revered in places like Asheville as a nostalgic, rustic material, in some places—particularly the United Kingdom—it has earned the reputation as a tacky, drab cover-up for shoddy construction. According to Taylor, one architectural critic wrote in 1962 that “‘one often recoils with acute distaste from [pebbledash’s] coarse and lumpy texture and its drab yellowbrown colour.’ These views were widely shared by a generation reacting to the architecture of the previous generation.” In both the United States and United Kingdom, renders have also been misidentified as “a sacrificial coating” and removed to reveal underlying materials, such as stone, brick or logs, that were always intended to be covered (Grimmer, 1). While stucco can be successfully removed, before undertaking such a project, research should be conducted to determine the home’s original design. Removing any sort of wall finish is a tedious task that often damages the substrate, so caution is advised. Asheville Specifications. Because of the importance of pebbledash to the character of Asheville’s built environment, the Historic Resources Commission of Asheville & Buncombe County (HRC) is diligent about its use and upkeep in the city’s historic districts. The HRC includes information on the maintenance and repair of pebbledash and roughcast renders in design guidelines for neighborhoods where the style is prominent, like Montford and Biltmore Village. These common-sense suggestions—such as regular inspections for water and vegetation damage, structural cracks, and deterioration—reflect the Secretary of the Interior’s Standards for Rehabilitation and Bernard Feilden’s Ethics of Architectural Conservation. The HRC encourages owners to “use the gentlest means possible” when cleaning masonry (64). High pressure washing of pebbledash is not allowed, as this causes the aggregate to break off and allows moisture to permeate the substrate. Repairs or replacement of damaged materials must comply with “recognized preservation methods for piecing-in, consolidating, or patching damaged or deteriorated masonry” (65). The guidelines mandate that replacement materials should “match the visual and physical properties of the original” and “new pebbledash should match original in texture and application” (65-6). To maintain the visual character of the historic districts, HRC often requires owners to incorporate pebbledash in renovations and additions. For example, when James and Susan Murray applied for a certificate of appropriateness for the expansion of their Montford neighborhood bed and breakfast (a Richard Sharp Smith-designed home clad in painted pebbledash, as seen in Fig. 8), the HRC requested they cover one of the walls with roughcast rather than the proposed wood-shake siding (a material also common in the district). Conclusion While renders like roughcast and pebbledash are not always popular with homeowners, they represent a rich historic building material and technique that should be preserved through regular upkeep and repair when needed. In Asheville, in particular, its prominent role in the region’s history and vernacular architectural style enhances its significance. Given its natural resistance to moisture and longevity, pebbledash and roughcast require a relatively small amount of effort and should be able to be effectively preserved by Fig. 14: To match the historic render (right foreground), the first layer must be set back to allow for the thickness of the roughcast layer. Figs. 12 (l) and 13 (r): To match the historic render (right foreground), the first layer must be set back to allow for the thickness of the roughcast layer. UNCG The Historic Dimension Series: 7 following the Secretary’s Standards of Rehabilitation and the well-documented procedures for maintenance and restoration. When repairs or new application is needed, experts encourage the use of a professional in its application, as achieving the right balance of materials and perfecting the application is more difficult than it might seem. Bibliography Asheville-Buncombe Historic Resources Commission [HRC]. (2010) “Montford Historic District Design Review Guidelines.” Bennett, Bob. (n.d.) “The Development of Portland Cement.” Retrieved 5 March 2013 from http://www.buildingconservation.com/articles/prtlndcmnt/prtlndcmnt.htm. Bishir, Catherine W., Michael T. Southern, and Jennifer F. Martin. (1999) A Guide to the Historic Architecture of Western North Carolina. Chapel Hill: The University of North Carolina Press. Carlisle, Daloni. (10 February 2001) “Pebbledash is rendered trendy.” The (London) Times, 19. Howell, Jeff. “Property: Get really plastered with lime-and-hair.” The (London) Independent. Retrieved 11 April from http://www.independent.co.uk/news/business/property-get-really-plastered-with-limeandhair-1291626.html. Gibson, Scott. (n.d.) “How to Repair Sagging Plaster Ceilings.” Retrieved 5 March 2013, from http://www.oldhouseweb.com/how-to-advice/how-to-repair-sagging-plaster-ceilings.shtml. Grimmer, Anne. (n.d.) “The Preservation and Repair of Historic Stucco.” National Park Service Preservation Brief #22. Gurley, Robert M. (1994) Richard Sharp Smith. Thesis, University of South Carolina. MacDonald, Mary Lee. “Repairing Historic Flat Plaster Walls and Ceilings.” National Park Service Preservation Brief #22. Marshall, Alli. (September 24, 2008). “Working on a Building.” Mountain Xpress. Retrieved from http://www.mountainx.com/article/19782/Working-on-a-building. Millar, William. (1905) Plastering: Plain and Decorative. London: B.T. Batsford. Murray, Susan. (March 24, 2012) “Pebble Dash at the Carolina Bed & Breakfast.” Retrieved from http://www.carolinabb.com/2012/03/pebble-dash-at-the-carolina-bed-breakfast/. “Pebbledashing Trade Application Guide.” (n.d.) Retrieved 5 March 2013, from http://www.exterior housepainters.com/painting.pebbledash.php. Southern, Michael T., ed. Asheville’s Historic Montford. (1985) Asheville: The Preservation Society of Asheville & Buncombe County. Taylor, Jonathan. (n.d.) “Edwardian Pebbledash and Roughcast.” Retrieved 5 March 2013, from http://www.buildingconservation.com/articles/pebbledash/pebbledash.htm. _____. (n.d.) “Tools of the Trade.” Retrieved 5 March 2013, from http://www.building conservation.com/articles/toolsoftrade/toolsoftrade.htm. Image Credits Figs. 1, 8, 9, 10, and 11: Courtesy of Carolina Bed and Breakfast. Fig. 2: Photo by “Anguskirk” via Flickr Creative Commons < http://www.flickr.com/photos/anguskirk/7164173075/> Fig. 3: Photo by “bluekdesigns” via Flickr Creative Commons < http://www.flickr.com/photos/bluekdesign/3929984207/> Fig. 4: Photo by Jonathan Taylor < http://www.flickr.com/photos/12624116@N03/6966547730/> Fig. 5: add user name, (Flickr Creative Commons, www.flickr.com) Fig. 6: Richard Sharp Smith; “Cottage - Chestnut St. - For Miss Annie West--Front Elevation;” Richard Sharp Smith Collection (aam_RS); item no. aam_RS0316_0001; NCSU Libraries’ Digital Collections: Rare and Unique Materials; Retrieved 10 April 2013 from http://d.lib.ncsu.edu/collections/catalog/aam_RS0316_0001 Fig. 7: Photo by “Teemu008” (Flickr Creative Commons, www.flickr.com) Figs. 12-14: Photos from Pegasus Plastering <http://www.pegasusplasterers.co.uk/> Special Thanks To James and Susan Murray, Carolina Bed and Breakfast, Asheville, North Carolina (www.carolinabb.com) Stacy Merten, Director, Historic Resources Commission of Asheville & Buncombe Co. Pegasus Plastering, London, England (www.pegasusplasterers.co.uk) Jack Thomson, Preservation Society of Asheville and Buncombe County The Historic Dimension Series is a collection of briefs prepared by UNCG students under the direction of Professor Jo Ramsay Leimenstoll. For information on other topics in the series please visit the website at go.uncg.edu/hds
Click tabs to swap between content that is broken into logical sections.
Title | A stone's throw: Asheville's legacy of Pebbledash & Roughcast |
Date | 2013 |
Time period (decade) | 2010-2019 |
Creator (individual) | Stewart, Sunny Townes |
Creator (group/organization) | UNCG Department of Interior Architecture |
Subject headings | Historic preservation;Architecture;Architecture--History |
Topics | Architecture; Buildings; History |
Subtopics | pebbledash;roughcast;stucco;Richard Sharp Smith;Asheville NC;Biltmore Village;vernacular architecture;skilled trades |
Place | Greensboro (N.C.) |
Description | Pebbledash and roughcast are two types of stucco application that have their roots in ancient building history. Brought to Asheville, NC in the late 19th century by Richard Sharp Smith, the architect tasked with designing Biltmore Village, these render types can be found throughout the city's historic residential neighbhorhoods. This brief discusses the history of pebbledash and roughcast stucco, techniques for application and repair, and maintenance considerations related to preservation efforts. Key concepts include pebbledash, roughcast, stucco, Richard Sharp Smith, Asheville NC, Biltmore Village, vernacular architecture, and skilled building trades. |
Type | text |
Original format | reports |
Original publisher | Greensboro, N.C. : UNCG Department of Interior Architecture |
Language | en |
Contributing institution | UNCG Department of Interior Architecture |
Source collection | CC066 The Historic Dimension Series |
Rights statement | http://rightsstatements.org/vocab/InC/1.0/ |
Additional rights information | IN COPYRIGHT. This item is subject to copyright. Contact the contributing institution for permission to reuse. |
Object ID | CC066.2013.Spring.003 |
Digital access format | Application/pdf |
Digital publisher | The University of North Carolina at Greensboro, University Libraries, PO Box 26170, Greensboro NC 27402-6170, 336.334.5305 -- http://library.uncg.edu/ |
Full text | The Historic Dimension Series A student publication series by the UNCG Department of Interior Architecture A Stone’s Throw: Asheville’s Legacy of Pebbledash & Roughcast by Sunny Townes Stewart Spring 2013 While the Appalachian Mountains may be known for their quintessential log cabins, the dominant architectural style of Asheville, North Carolina—located in the southwestern corner of the state near the Tennessee border—does not fit the traditional stereotype. Instead, the hilly streets of the city’s suburbs are dotted with quaint, picturesque homes reminiscent of English cottages, clad in false half-timbering, wooden shake siding, exposed stone, and a coarse stucco that many in Asheville call pebbledash (though most examples in the city are more accurately a related rendering style called roughcast). Introduced to the region by English architect Richard Sharp Smith (1852-1924), pebbledash is abundant in neighborhoods that were built at the turn of the twentieth century, such as Biltmore Village (see Figs. 6 and 7) and Montford (see Figs. 8 and 9). Smith is regarded as Asheville’s most influential architect during the late nineteenth and early twentieth centuries—a period marked by rapid population growth and construction—and other designers and builders quickly adopted his distinctive styles. By the 1930s, the “earthy, richly textured pebbledash” had become a defining characteristic of Asheville’s residential districts (Asheville-Buncombe HRC). History of Pebbledash Pebbledash and roughcast are heavily textured and durable forms of stucco, a plastering technique used by builders in ancient Egypt, Greece, and Rome (Millar, 2). While most interior and artistic plaster is smoothed flat, stucco—often used for outdoor surfaces—includes a sandy substance to provide a “sugary texture” (see Fig. 3). Pebbledash and roughcast (see Figs. 4 and 5) feature a more prominent aggregate like gravel or pebbles, glass, shells, broken pottery, or mineral shards, depending on what was locally available in the region (Taylor). The technique was common in England, particularly in coastal regions and other areas with harsh weather. According to Anne Grimmer, author of the National Park Service (NPS) Preservation Brief on historic stucco, render of all types was a weather-repellent coating that offered a layer of insulation and protected the building from wind and rain penetration, as well as fire. As such, stucco as an architectural feature “probably has a history as old as lime mortar itself” (Taylor). Roughcast render was often used during the Middle Ages to cover the panels between buildings’ timber framing (see Fig. 2). In his 1897 treatise Plastering: Plain and Decorative, craftsman William Millar noted that roughcast was “one of the oldest forms of external plastering” because of its durability (210). Though it was often shunned during the Victorian era, the roughcasting tradition was renewed with the cottage ornée (or decorated cottage), Tudor revival, and Arts and Crafts movements of the nineteenth century (Taylor). According to architectural “Roughcast, as conservationists prefer to call the earliest material, probably has a history as old as lime mortar itself.” -Jonathan Taylor, conservator “Plastering is one of the earliest instances of man’s power of inductive reasoning, for when men built they plastered: at first, like the birds and the beavers, with mud, but they soon found a more lasting and comfortable method, and the earliest efforts of civilisation were directed to plastering.” -William Millar, nineteenth-century craftsman UNCG The Historic Dimension Series: 2 Fig. 2: A seventeenth-century cottage featuring half-timbering and roughcast render in Hampshire, England. conservator Jonathan Taylor, however, it was Richard Norman Shaw’s popular Queen Anne style that was likely most responsible for roughcasting’s popularity. Its “asymmetric composition of steeply pitched roofs, jettied floors, small-paned windows and rough textures evoke an atmosphere of cosy cottage comforts with roaring log fires” (Taylor). All of these late nineteenth and early twentieth century styles tend to combine a variety of textures, including brick, tile, wooden shingles, exposed wood timbers, native stone, and roughcast renders. It is obvious that Richard Sharp Smith was influenced by the popularity of these styles before immigrating to the United States, as he often mixed their motifs into his designs (see Figs. 6-9). He moved to Asheville in 1888 (from England via New York) to supervise the construction of Biltmore, George Washington Vanderbilt’s sprawling French chateau retreat that was designed by Smith’s employer, Richard Morris Hunt. After its completion, Vanderbilt commissioned Hunt and Smith to design a village that would support the operation of the mansion. Embracing its role as a manorial village, of sorts, the architects utilized designs reminiscent of medieval England. They blended arts and crafts, Tudor revival, and cottage ornée styles featuring steeply pitched, gambrel roofs; false half-timbering; decorative bracketing; and roughcast siding (see Figs. 6 and 7). After Hunt’s death, Smith settled permanently in the mountains, continuing to utilize similar motifs in the hundreds of homes that he designed throughout the late nineteenth and early twentieth centuries. The rough, rustic nature of the technique of roughcasting and or pebbledash complemented the natural surroundings and the other decorative elements. By the turn of the century, the technique had been adopted by other architects in the region, entering into the “building vocabulary” of Asheville (Bishir et al., 429). Techniques for Mixing and Application The techniques for pebbledash and roughcast renders are very similar, and in fact during the Arts and Crafts era were often used interchangeably, though there were regional variations (for example, Millar notes that harling was the term of choice in Scotland). Like other forms of plaster, both require multiple coats. When the pebbledash is used to cover textured masonry like brick, stone, or concrete block, the first layer is applied directly to the wall. In other instances, like when it is being used to cover log construction or smooth panels, lath—either small wood slats or, especially in the late-nineteenth and early-twentieth centuries, metal meshing (see Fig. 11)— is necessary to encourage the render to form a strong bond, or key (Grimmer). Millar called the makeup of the first layer coarse-stuff because it included sand and horse or ox hair to encourage the plaster to form a stronger key. Before it dried, the craftsman usually scratched the surface in order to encourage the second coat to key (Millar, 210). During the application, it is necessary to keep the surface being covered—be it wood lath, masonry, or a layer of cured render—damp to “ensure a good bond ... [and] prevent them from pulling moisture out of the stucco too rapidly, which results in cracking, loss of bond, and generally poor quality stuccowork” (Grimmer, 7). The difference between the application of stucco, roughcast, and pebbledash comes with the next step. With regular stucco, a more refined mixture would be used to form the third and final, skillfully textured layer (Fig. 3). For traditional roughcast or pebbledash applications, however, the aggregate was thrown forcefully onto the still-soft second coat of stucco, as the names (pebbledash and roughcast suggest). Millar instructed that the material to be dashed should be no Fig. 3: Traditional stucco Fig. 5: Roughcast Fig. 4: Pebbledash UNCG The Historic Dimension Series: 3 more than ¼- and ½-inch in size, which he said should be placed in a tub of hot lime and water in a “semi-fluid state” (210). The craftsman should retrieve the material as needed, Millar continued, and then “quickly and evenly throw or dash [it] on with a ‘scoop’ or hollow trowel, then brush [it] with liquid to give a uniform tint. A good craftsman can dash the shingle very regularly, and leave the face of the work with a uniform, though rough surface. The dashing should be begun at the top, gradually working down, taking in all angles and sides of panels” (210). Today, though some craftsmen continue the tradition of dashing, it is more common for the aggregate to be added to the mixture before application and painted after it dries (see Fig. 10). Though weatherproof by nature, renders were often made even more protective with coats of wax or oil (Grimmer). Millar provided instructions for different tints to add to the dash, if desired. For a buff color, for example, he suggested craftsmen add copperas and fresh cow manure, noting that adding an alum solution “will give brilliancy and permanency to the colours” (558). Though the terms were (and still are) often used interchangeably, when textured render is left natural or tinted, it is generally called pebbledash (Fig. 4) and when it is painted it is called roughcast (Fig. 5). Evolution of Binders Millar notes that the Egyptians, Greeks, and Romans all used plaster “of most exquisite composition” (4). Ancient builders used plasters bound with either burnt gypsum, a naturally occurring, crystallized mineral mined from ancient lake and sea beds, or lime, a chemical compound formed by grinding and heating limestone (4). Quicklime—or ground and heated lime ready to be mixed for plaster—is highly reactive and must not be allowed contact with the air before it is time to mix it with water (a process called slaking the lime), and the resulting plaster takes several months to dry completely. On the other hand, natural gypsum-based cements, like plaster of Paris, cure quickly, set in minutes, dry completely in two to three weeks, and make a more rigid plaster. However, there were downsides to gypsum-based plaster, including vulnerability to water damage and a less-adhesive nature. Whereas lime plasters “could survive occasional wind-driven moisture or water wicking up from the ground. Gypsum plaster needed protection from water. Furring strips had to be used against masonry walls to create a dead air space, [preventing] moisture transfer” (MacDonald, 4). As such, lime, which Millar called “one of the most important materials in the building trades,” would continue to be the main ingredient in renders of all types throughout the nineteenth century (38). In Millar’s manual—which has provided modern-day scholars and practitioners insight into traditional Victorian methods for mixing and applying various kinds of renders (as well as their histories and relative strengths)—he noted that “100 yards superficial of rough-casting (two coat on lath),” called for “25 cubic feet of lime, 50 cubic feet of sand, 16 lbs. of hair, and ¾ yard of prepared gravel for the dash coat. A quarter tub of lime putty should be mixed with every tub of gravel for the dash” (558). The development of portland cement, however, quickly made builders less dependant on lime renders. Developed by a bricklayer and plasterer in Leeds, England in 1824, it was first manufactured in the United States in 1871 (Millar, 55). When Millar published Plastering: Plain and Decorative in 1897, he noted that portland cement could be substituted for the first layer of coarse stuff (210). By the twentieth century, craftsmen Fig. 6: A front elevation drawn by Smith c. 1900 for a Montford home featuring a roughcast render (see detail). Fig. 7: A Biltmore Village cottage featuring the signature Richard Sharp Smith roughcast exterior. UNCG The Historic Dimension Series: 4 had transitioned to stucco composed of mostly portland cement bases mixed with a small quantity of lime (Grimmer). Millar notes that the advantages of portland cement were “its hydraulic properties [i.e., its ability to harden when combined with water], great strength at comparatively early dates, its continually increasing strength, and its power of carrying very large proportions of sand or other aggregate when made into mortar or concrete” (55). Grimmer also highlights the ways in which renders improved after the introduction of portland cement: “No longer used just as a coating for a substantial material like masonry or log, stucco could now be applied over wood or metal lath attached to a light wood frame. With this increased strength, stucco ceased to be just a veneer and became a more integral part of the building structure” (Grimmer, 3). Ultimately, the more coarse stuccos were “ideal for a portland cement render” (Taylor). More finely finished stuccos made with cement often cracked quickly after application because the heavy troweling needed to achieve the smooth finish pulled the aggregate and the moisture to the surface. According to British conservator Jonathan Taylor, pebbledash and roughcasting mixed with cement are less likely to crack because the mixture does not require much troweling and the stone aggregate actually strengthens the binding. Assessment of Damage and Deterioration Like other kinds of render, pebbledash and roughcast are assumed to be more resilient and weatherproof than plain stucco, but they suffer from many of the same issues as its less-textured cousin. According to Grimmer, “age and lack of maintenance hasten the deterioration of many historic stucco buildings. Like most historic building materials, stucco is at the mercy of the elements, and even though it is a protective coating, it is particularly susceptible to water damage” (1). Most often the water infiltrates the building from joints and seams in its construction— such as the roof, around chimneys, and windows and doors—or rising damp. Underlying issues should be taken care of before addressing the necessary stucco repairs. When assessing historic stucco of any variety, it is important to determine what kind of base was used in the original mixture. Lime renders are rarely used today; however, using gypsum plaster to repair work originally done with lime can be problematic. Experts caution that binders behave differently, and if two different binders are mixed (using gypsum plaster to repair historic lime-based render, for example), the surface will soon crack where the two come together (Howell). Grimmer notes that it is important to watch out for deterioration caused by previous badly done repairs “particularly if executed in portland cement, which tends to be very rigid, and therefore incompatible with early, mostly soft lime-based stucco that is more ‘flexible’” (7-8). It is also important to be aware of vibrations caused by nearby traffic or construction, as well as foundation shifts and settlement. All of these factors can contribute to failure of the material. Once the stucco begins to crack, water accumulates and can cause further damage from freeze-and-thaw cycles, especially in harsh climates like Asheville. Taylor warns that this can “cause render to fall away in sheets” or allow salt crystals (left behind from evaporated water) to grow in the substrate. To determine how extensive the damage is, gently tapping the surface with a wooden handle will identify unsound areas (Taylor). Maintenance and Repair Because of the general resilience of the material, general preventative maintenance and monitoring for deteriorating should keep textured renders sturdily in Fig. 9: Small batches of concrete and aggregate are mixed for application. If patching historic roughcast, modern materials are acceptable, but care must be used. Fig. 8: The Carolina Bed and Breakfast, located in Montford Historic District in Asheville, which used pebbledash in a recent renovation (Figs. 8-13). UNCG The Historic Dimension Series: 5 tact. Harsh chemicals and pressure washers should be avoided; if cleaning is absolutely required, the gentlest means possible should be employed. Harsh methods can cause the aggregate to break apart, causing the potential for further damage. Because stucco is often applied on top of masonry or wood, it is possible that it is hiding deterioration that can cause water to penetrate the structure. A close inspection at the point of water entry should reveal underlying problems. The render may have to be removed (as gently as possible) in order for the issue to be resolved and then re-applied. Repair. Finding the materials for and/or the craftsmen who are familiar with historic rendering techniques, however, can be challenging. When repairing pebbledash and roughcast renders, the heavy texture is far more forgiving than stucco, and therefore, less likely to show imperfections arising from mismatched materials. Grimmer addresses the difficulty in accessing historically accurate components in the NPS brief on historic stucco. She encourages the use of substitute materials, noting that “it may not be worthwhile, nor in many instances possible, to attempt to duplicate all of the ingredients,” unless authentic reproduction is absolutely necessary (Grimmar, 8). As noted, it is important to match the strength and flexibility of the binder used in the historic material. Research on the structure’s history might provide some insight, though Grimmar warns that the timing of the switch from lime to portland cement is imprecise. A more accurate method is to analyze the historic stucco to provide useful information on its basic ingredients. For example, “a dilute solution of hydrochloric (muriatic) acid will dissolve lime-based stucco, but not portland cement” (8). Products to avoid. Modern caulking products should be avoided, as they tend to attract more dirt, making them “highly visible and unsightly,” though a commercial bonding agent can be used to fill hairline cracks. (Grimmer, 9). Small cracks can be filled with a “thin slurry coat consisting of the finish coat ingredients, or even paint or whitewash” (Grimmer, 9). Larger cracks will have to be cut out. Rarely does an entire wall need to be recast. Whatever the case, the heavy texture of roughcast and pebbledash requires slightly less precision, though the difficult nature of the technique is best executed by a skilled professional. When modifying an existing structure (like the window being resized in Figs. 13-15) or a new addition constructed, the plasterers should be diligent in matching materials and colors of the historic materials. Patching. When patching is necessary, the area to be repaired is often squared off; however, clearing off an irregular-shaped section cut on an angle can sometimes make the patch less obvious and encourage a stronger bond between the historic and replacement render. Grimmer stresses the need to use sharp tools (such as a cold chisel, hatchet, diamond blade saw, or masonry bit) when cutting away and clearing damaged stucco, lest oversounding, or “breaking keys of surrounding good stucco,” occur (Grimmer, 9). A bristle brush should be used to clean the damaged area, clearing away the loose render and aggregate down to the lath or bare masonry. To ensure that the patch forms a strong key, the area to be patched should be cleared of all dirt, loose paint, and other contaminants Fig. 10: The first layer of stucco is applied in small sec-tions to mesh lath. Scratching the surface allows the second, roughcast layer to form a key, or strong bond. Fig. 11: Though it seems like it would be forgiving, the messy job (see Fig. 1) of dashing the roughcast is dif-ficult to master. UNCG The Historic Dimension Series: 6 and, if the substrate is brick or stone, the mortar joints should be scraped back approximately half an inch. Deteriorated lath should be either repaired or replaced with wire mesh. Grimmer instructs that the patch and the old stucco must not overlap. Removal. Homeowners not enamoured with the effect of the textured stucco may wish to remove it. Though revered in places like Asheville as a nostalgic, rustic material, in some places—particularly the United Kingdom—it has earned the reputation as a tacky, drab cover-up for shoddy construction. According to Taylor, one architectural critic wrote in 1962 that “‘one often recoils with acute distaste from [pebbledash’s] coarse and lumpy texture and its drab yellowbrown colour.’ These views were widely shared by a generation reacting to the architecture of the previous generation.” In both the United States and United Kingdom, renders have also been misidentified as “a sacrificial coating” and removed to reveal underlying materials, such as stone, brick or logs, that were always intended to be covered (Grimmer, 1). While stucco can be successfully removed, before undertaking such a project, research should be conducted to determine the home’s original design. Removing any sort of wall finish is a tedious task that often damages the substrate, so caution is advised. Asheville Specifications. Because of the importance of pebbledash to the character of Asheville’s built environment, the Historic Resources Commission of Asheville & Buncombe County (HRC) is diligent about its use and upkeep in the city’s historic districts. The HRC includes information on the maintenance and repair of pebbledash and roughcast renders in design guidelines for neighborhoods where the style is prominent, like Montford and Biltmore Village. These common-sense suggestions—such as regular inspections for water and vegetation damage, structural cracks, and deterioration—reflect the Secretary of the Interior’s Standards for Rehabilitation and Bernard Feilden’s Ethics of Architectural Conservation. The HRC encourages owners to “use the gentlest means possible” when cleaning masonry (64). High pressure washing of pebbledash is not allowed, as this causes the aggregate to break off and allows moisture to permeate the substrate. Repairs or replacement of damaged materials must comply with “recognized preservation methods for piecing-in, consolidating, or patching damaged or deteriorated masonry” (65). The guidelines mandate that replacement materials should “match the visual and physical properties of the original” and “new pebbledash should match original in texture and application” (65-6). To maintain the visual character of the historic districts, HRC often requires owners to incorporate pebbledash in renovations and additions. For example, when James and Susan Murray applied for a certificate of appropriateness for the expansion of their Montford neighborhood bed and breakfast (a Richard Sharp Smith-designed home clad in painted pebbledash, as seen in Fig. 8), the HRC requested they cover one of the walls with roughcast rather than the proposed wood-shake siding (a material also common in the district). Conclusion While renders like roughcast and pebbledash are not always popular with homeowners, they represent a rich historic building material and technique that should be preserved through regular upkeep and repair when needed. In Asheville, in particular, its prominent role in the region’s history and vernacular architectural style enhances its significance. Given its natural resistance to moisture and longevity, pebbledash and roughcast require a relatively small amount of effort and should be able to be effectively preserved by Fig. 14: To match the historic render (right foreground), the first layer must be set back to allow for the thickness of the roughcast layer. Figs. 12 (l) and 13 (r): To match the historic render (right foreground), the first layer must be set back to allow for the thickness of the roughcast layer. UNCG The Historic Dimension Series: 7 following the Secretary’s Standards of Rehabilitation and the well-documented procedures for maintenance and restoration. When repairs or new application is needed, experts encourage the use of a professional in its application, as achieving the right balance of materials and perfecting the application is more difficult than it might seem. Bibliography Asheville-Buncombe Historic Resources Commission [HRC]. (2010) “Montford Historic District Design Review Guidelines.” Bennett, Bob. (n.d.) “The Development of Portland Cement.” Retrieved 5 March 2013 from http://www.buildingconservation.com/articles/prtlndcmnt/prtlndcmnt.htm. Bishir, Catherine W., Michael T. Southern, and Jennifer F. Martin. (1999) A Guide to the Historic Architecture of Western North Carolina. Chapel Hill: The University of North Carolina Press. Carlisle, Daloni. (10 February 2001) “Pebbledash is rendered trendy.” The (London) Times, 19. Howell, Jeff. “Property: Get really plastered with lime-and-hair.” The (London) Independent. Retrieved 11 April from http://www.independent.co.uk/news/business/property-get-really-plastered-with-limeandhair-1291626.html. Gibson, Scott. (n.d.) “How to Repair Sagging Plaster Ceilings.” Retrieved 5 March 2013, from http://www.oldhouseweb.com/how-to-advice/how-to-repair-sagging-plaster-ceilings.shtml. Grimmer, Anne. (n.d.) “The Preservation and Repair of Historic Stucco.” National Park Service Preservation Brief #22. Gurley, Robert M. (1994) Richard Sharp Smith. Thesis, University of South Carolina. MacDonald, Mary Lee. “Repairing Historic Flat Plaster Walls and Ceilings.” National Park Service Preservation Brief #22. Marshall, Alli. (September 24, 2008). “Working on a Building.” Mountain Xpress. Retrieved from http://www.mountainx.com/article/19782/Working-on-a-building. Millar, William. (1905) Plastering: Plain and Decorative. London: B.T. Batsford. Murray, Susan. (March 24, 2012) “Pebble Dash at the Carolina Bed & Breakfast.” Retrieved from http://www.carolinabb.com/2012/03/pebble-dash-at-the-carolina-bed-breakfast/. “Pebbledashing Trade Application Guide.” (n.d.) Retrieved 5 March 2013, from http://www.exterior housepainters.com/painting.pebbledash.php. Southern, Michael T., ed. Asheville’s Historic Montford. (1985) Asheville: The Preservation Society of Asheville & Buncombe County. Taylor, Jonathan. (n.d.) “Edwardian Pebbledash and Roughcast.” Retrieved 5 March 2013, from http://www.buildingconservation.com/articles/pebbledash/pebbledash.htm. _____. (n.d.) “Tools of the Trade.” Retrieved 5 March 2013, from http://www.building conservation.com/articles/toolsoftrade/toolsoftrade.htm. Image Credits Figs. 1, 8, 9, 10, and 11: Courtesy of Carolina Bed and Breakfast. Fig. 2: Photo by “Anguskirk” via Flickr Creative Commons < http://www.flickr.com/photos/anguskirk/7164173075/> Fig. 3: Photo by “bluekdesigns” via Flickr Creative Commons < http://www.flickr.com/photos/bluekdesign/3929984207/> Fig. 4: Photo by Jonathan Taylor < http://www.flickr.com/photos/12624116@N03/6966547730/> Fig. 5: add user name, (Flickr Creative Commons, www.flickr.com) Fig. 6: Richard Sharp Smith; “Cottage - Chestnut St. - For Miss Annie West--Front Elevation;” Richard Sharp Smith Collection (aam_RS); item no. aam_RS0316_0001; NCSU Libraries’ Digital Collections: Rare and Unique Materials; Retrieved 10 April 2013 from http://d.lib.ncsu.edu/collections/catalog/aam_RS0316_0001 Fig. 7: Photo by “Teemu008” (Flickr Creative Commons, www.flickr.com) Figs. 12-14: Photos from Pegasus Plastering <http://www.pegasusplasterers.co.uk/> Special Thanks To James and Susan Murray, Carolina Bed and Breakfast, Asheville, North Carolina (www.carolinabb.com) Stacy Merten, Director, Historic Resources Commission of Asheville & Buncombe Co. Pegasus Plastering, London, England (www.pegasusplasterers.co.uk) Jack Thomson, Preservation Society of Asheville and Buncombe County The Historic Dimension Series is a collection of briefs prepared by UNCG students under the direction of Professor Jo Ramsay Leimenstoll. For information on other topics in the series please visit the website at go.uncg.edu/hds |
|
|
|
A |
|
C |
|
G |
|
H |
|
N |
|
P |
|
U |
|
W |
|
|
|