RE I Interface — RCI OFFERS SPR1TECH 90 TICKETS AT A SAVINGS in this issue SPRITECH 90, page 1 19 Preservation Briefs, page 2 RCI member contest, page 11 Seminars, page 11 RCI Staff, pagell Region TV Director, page 12 New CRCs, page 12 DON’T MISS spntech 90 A one-day technical seminar and information exchange on single ply roofing produced by SPRI (The Single Ply Roofing Institute) and co-sponsored by RCI. For registration information, call RCI headquarters (919) 859-0742. For program information, call SPRI (708) 940-8800. MARK YOUR CALENDAR TODAY FOR SPRITECH ’90 November 5, 1990 at the Orlando Airport Marriott and December 6, 1990 at the Grand Kempinski, Dallas. RCI is participating as a sponsor in SPRITECH 90, SPRI’s technical and information exchange scheduled for November 5 in Orlando and December 6 in Dallas. As a savings to our members, we are offering tick¬ ets to each of the seminars for $60, a savings on $15. Earn .1 RCIEU credit for each hour of technical session. Please contact RCI Head¬ quarters to purchase your tickets. (919-859-0742). Newsletter of The Roof Consultants Institute2 19 PRESERVATION BRIEFS The Repair and Replacement of Historic Wooden Shingle Roofs Part I of II Reprint from: U.S. Department of the Interior, National Park Service, Preservation Assistance Division, Technical Preservation Reconstructed hospital at Colonial Williamsburg used fire retardant cypress shingles custom-made for project. Photo: Colonial Williamsburg The Secretary of the Interior’s “Standards for Rehabilitation” call for the repair or replacement of missing architectural features “based on ac¬ curate duplication of features, substantiated by historic, physical, or pic¬ torial evidence rather than on conjectural designs.” On a wooden shingle roof, it is important not only to match the size, shape, texture, and con¬ figuration of historic shingles, but also to match the craftsmanship and details that characterize the historic roof. Proper installation and main¬ tenance will extend the life of the new roof. Introduction Wooden shingle roofs are important elements of many historic build¬ ings. The special visual qualities imparted by both the historic shingles and the installation patterns should be preserved when a wooden shingle roof is replaced. This requires an understanding of the size, shape, and detailing of historic shingle and the method of fabrication and installation. These combined to create roofs expressive of particular ar¬ chitectural styles, which were often influenced by regional craft prac¬ tices. The use of wooden shingles from the early settlement days to the present illustrates in extraordinary range of styles (see illus. 1,2,3,4). Wooden shingle roofs need periodic replacement. They can last from 15 to over 60 years, but the shingles should be replaced before there is deterioration of other wooden components of the building. Appropriate replacement shingles are available, but careful research, design, Newsletter of The Roof Consultants Institute iff } t I » r M ‘■< lt “,’i 3 specifications, and the selection of a skilled roofer are necessary to as¬ sure a job that will both preserve the appearance of the historic building and extend the useful life of the replacement roof. Unfortunately, the wrong shingles are often selected or are installed in a manner incompatible with the appearance of the historic roof. There are a number of reasons why the wrong shingles are selected for replace¬ ment roofs. They include the failure to identify the appearance of the original shingles; unfamiliarity with available products; an inadequate budget; or a confusion in terminology. In any discussion about historic roofing materials and practices, it is important to understand the historic definitions of terms like “shingles,” as well as the modem definitions or use of those terms by craftsmen and the industry. Historically, from the first buildings in America, these wooden roofing products were called shingles, regardless of whether they were the earliest handsplit or the later machine-sawn type. The term shake is a relatively recent one, and today is used by the industry to distinguish the sawn products from the split products, but through most of our building history there has been no such distinction. Considering the confusion among architects and others regarding these terms as they relate to the appearance of early roofs, it should be stated that there is a considerable body of documentary information about historic roofing practices and materials in this country, and that many actual specimens of historic shingles from various periods and places have been collected and preserved so that their historic appearan¬ ces are well established. Essentially, the rustic looking shake that we see used so much today has little in common with the shingles that were used on most of our early buildings in America. Throughout this Brief, the term shingle will be used to refer to his¬ toric wooden roofs in general, whether split or sawn, and the term shake will be used only when it refers to a commercially available product. The variety and complexity of terminology used for currently available products will be seen in the accompanying chart entitled “Shingles and Shakes.” This Brief discusses what to look for in historic wooden shingle roofs and when to replace them. It discusses ways to select or modify modem products to duplicate the appearance of a historic roof, offers guidance on proper installation, and provides information on coatings and main¬ tenance procedures to help preserve the new roof. *Preservation Brief 4: Roofing for Historic Buildings discusses re¬ search meathods, analysis of deteration, and the general significance of historic roofs. Newsletter of The Roof Consultants Institute 4 Wooden Shingle Roofs in America Because trees were plentiful from the earliest settlement days, the use of wood for all aspects of construction is not surprising. Wooden shingles were lightweight, made with simple tools, and easily installed. Wooden shingle roofs were prevalent in the Colonies, while in Europe at the same time,thatch, slate and tile were the prevalent roofing materials. Distinc¬ tive roofing patterns exist in various regions of the country that were set¬ tled by the English, Dutch, Germans, and Scandinavians. These patterns 1. The Role-Warren House, a tidewater Virginia property, was restored to its 18thcentury appearance in 1933. The handsplit and dressed wooden shingles are typi¬ cal of the tidewater area with special features such as curved butts, projecting ridge comb and closed swept valleys at the dormer roof connections. Circa 1970 Photo: Association for the Preservation of Virginia Antiquities. 2. Handsplit and dressed shingles were also used on less elaborate buildings as seen the restoration of the circa 1940 kitchen at the Winedale Inn, Texas. The un¬ even surfaces of the handsplit shingles were generally dressed or smoothed with a draw-knife to keep the rainwater from collecting in the wood grain and to ensure that the shingles lay flat on the sub-roof. Photo: Thomas Taylor. Newsletter of The Roof Consultants Institute 5 and features include the size, shape and exposure length of shingles, spe¬ cial treatments such as swept valleys, combed ridges, and decorative butt end or long side-lapped beveled handsplit shingles. Such features impart a special character to each building, and prior to any restoration or rehabilitation project the physical and photographic evidence should be carefully researched in order to document the historic building as much as possible. Care should be taken not to assume that aged or deteriorated shingles in photographs represent the historic appearance. 3. Readily available and inexpensive sawn shingles were used not only for roofs, but also for gables and wall surfaces. The circa 1891 Chambers House, Eugene, Oregon used straight sawn butts for the majority of the roof and hexagonal butts for the lower portion of the comer tower. Decorative shingles in the gable ends and an attractive wooden roof cresting feature were also used. Photo: Lane Coun¬ ty Historical Society. 4. With the popularity of the revival of historic styles in the late 19th and early 20th centuries, a new technique was developed to imitate English thatch roofs. For the Tudor Revival thatch cottages, steaming and curving of sawn shingles provided an undulating pattern to this picturesque roof shape. Photo: Courtesy of C.H. Roofing. Newsletter of The Roof Consultants Institute 6 Shingle Fabrication Historically wooden shingles were usually thin (3/8″-3/4″), relatively narrow (3″-8″), of varying length (14″-36″), and almost always smooth. The traditional method for making wooden shingles in the 17th and 18th centuries was to handsplit them from log sections known as bolts (see illus. 5A). These bolts were quartered or split into wedges. A mallet and froe (or ax) were used to slit or rive out thin planks of wood along the grain. If a tapered shingle was desired, the bolt was flipped after each successive strike with the froe and mallet. The wood species varied ac¬ cording to available local woods, but only the heartwood, or inner sec¬ tion, of the log was usually used. The softer sapwood generally was not used because it deteriorated quickly. Because handsplit shingles were somewhat irregular along the split surface, it was necessary to dress or plane the shingles on a shavinghorse with a draw-knife or draw-shave (see illus. 5B) to make them fit evenly on the roof. This reworking was necessary to provide a tight-fitting roof over typically open shingles lath or sheathing boards. Dressing, or smoothing of shingles, was almost universal, no matter what wood was used or in what part of the country the building was located, except in those cases where a temporary or very utilitarian roof was needed. Shingle fabrication was revolutionized in the early 19th century by steam-powered saw mills. Shingle mills made possible the production of uniform shingles in mass quantities. The sawn shingle of uniform taper and smooth surface eliminated the need to hand dress. The supply of wooden shingles was therefore no longer limited by local factors. These changes coincided with (and in turn increased) the popularity of architec¬ tural styles such as Carpenter Gothic and Queen Anne that used shingles to great effect. 5. Custom Handsplit shingles are still made the traditional way with a mallet and a froe or ax. For these cypress shingles, a “bolt” section of log (photo A) the length of the shingle has been sawn and is ready to be split into wedge-shaped segments. Handsplit shingles are fabricated with the ax or froe cutting the wood along the grain and separating, or riving, the shingle away from the remaining wedge. The rough surfaces are dressed on a shavinghorse using a draw-knife as shown above (photo B). Note the long wooden shingles covering the work shed in Photo A. Photos: Al Honeycutt, North Carolina Division of Archives and History. Newsletter of The Roof Consultants Institute 7 Handsplit shingles continued to be used in many places well after the introduction of machine sawn shingles. There were, of course, other popular roofing materials, and some regions rich in slate had fewer ex¬ amples of wooden shingle roofs. Some western “boom” towns used sheet metal because it was light and easily shipped. Slate, terneplate, and clay tile were used on ornate buildings and in cities that limited the use of flammable wooden shingles. Wooden shingles, however, were never abandoned. Even in the 20th century, architectural styles such as the Colonial Revival and Tudor Revival, used wooden shingles. Modem wooden shingles, both sawn and split, continue to be made, but is important to understand how these new products differ from the historic ones and to know how they can be modified for use on historic buildings. Modem commercially available shakes are generally thicker than the historic handsplit counterpart and are usually left “undressed” with a rough, corrugated surface. The rough surface shake, furthermore, is often promoted as suitable for historic preservation projects because of its rustic appearance. It is an erroneous assumption that the more ir¬ regular the shingle, the more authentic or “historic” it will appear. While the size, shape and finish of the shingle determine the roof’s tex¬ ture and scale, the installation patterns and details give the roof its unique character. Many details reflect the craft practices of the builders and the architectural style prevalent at the time of construction. Other details had specific purposes for reducing moisture penetration to the structure. In addition to the most visible aspects of a shingle roof, the details at the rake boards, eaves, ridges, hips dormers, cupolas, gables, and chimneys should not be overlooked. The way the shingles were laid was often based on functional and practical needs. Because a roof is the most vulnerable element of a build¬ ing, many of the roofing details that have become distinctive features were first developed simply to keep water out. Roof combs on the windward side of a roof protect the ridge line. Wedges, or cant strips, at dormer cheeks roll the water away from the vertical wall. Swept valleys and fanned hips keep the grain of the wood in the shingle parallel to the angle of the building joint to aid water run-off. The slight projection of the shingles at the eaves directs the water run-off either into a gutter or off the roof away from the exterior wall. These details varied from region to region and from style to style. They can be duplicated even with the added protection of modem flashing. In order to have a weathertight roof, it was important to have adequate coverage, proper spacing of shingles, and straight grain shingles. Many roofs were laid on open shingle lath or open sheathing boards (see illus. 6). Roofers typically laid three layers of shingles with approximately 1/3 Historic Detailing and Installation Techniques. Newsletter of The Roof Consultants Institute 8 of each shingle exposed to the weather. Spaces between shingles (1/8″- 1/2″ depending on wood type) allowed the shingles to expand when wet. It was important to stagger each overlapping shingle by a mini¬ mum of 1 1/2″ to avoid a direct path for moisture to penetrate a joint. Doubling or tripling the starter course at the eave gave added protection to this exposed surface. In order for the roof to lay as flat as possible, the thickness, taper and surface of the shingles was relatively uniform; any unevenness on handsplit shingles had already been smoothed away with a drawknife. To keep shingles from curling or cupping, the shingle width was generally limited to less than 10″. Not all shingles were laid in evenly spaced, overlapping, horizontal rows. In various regions of the country, there were distinct installation patterns; for example, the biaxially-tapered long shingles occasionally found in areas settled by Germans (see ill. 7). These long shingles were overlapped on the side as well as on top. This formed a ventilation chan¬ nel under the shingles that aided drying. Because ventilation of shingles can prolong their life, roofers paid attention to these details (see illus. 8). Early roofers believed that applied coatings would protect the wood and prolong the life of the roof. In many cases they did; but in many cases, the shingles were left to weather-naturally and they, too, had a long life. Eighteenth-century coatings included a pine pitch coating not unlike turpentine, and boiled linseed oil or fish oil mixed with oxides, red lead, brick dust, or other minerals to produce colors such as yellow, Venetian red, Spanish brown, and slate grey. In the 19th century, in addi¬ tion to the earlier colors, shingles were stained or painted to comple¬ ment the building colors: Indian red, chocolate brown, or brown-green. 6. Reshingling of historic bam. Note open shingle lath to allow ventilation under shingles. Some deteriorated shingles lath has been replaced. Sawn red cedar shingles match historic shingles in length, width, thickness and exposure. Newsletter of The Roof Consultants Institute 9 During the Greek Revival and later in the 20th century with other revival styles, green was also used. Untreated shingles age to a silvergrey or soft brown depending on the wood species. The craft traditions of the builders often played an important role in the final appearance of the building. The Historic Details and Installation Patterns Chart (see illus. 9) identifies many of the features found on his¬ toric wooden roofs. These elements, different on each building, should be preserved in a re-roofing project. 7. The long biaxially tapered handsplit shingles on the Ephrata Cloisters in Pen¬ nsylvania were overlapped both vertically and horizontally. The insert sketch shows channels under the shingles that provided ventilation and drainage of any trapped moisture. The aged appearance of these handsplit and dressed shingles belies their original smoothness. Replacement shingles should match the original, not the aged appearance. Photo: National Park Service; Sketch Reed Engle. Sharon C. Park, AIA » Sharon C. Park, a registered architect, has worked for the National Park Service for the past 10 years. She is respon¬ sible for writing technical pub¬ lications on preservation. Prior to working for the Na¬ tional Park Service, she had 10 years experience in private practice doing restora¬ tion work. She earned a bachelor of architecture from Catholic University and a masters in historic preserva¬ tion from George Washington University. 8. This 1927 view of the reshingling of the French Castle at Old Fort Niagara, NY, shows the wooden sleepers being laid (see arrow) over solid sheathing in order to raise the shingles up slightly to allow under-shingle ventilation. Note that the horizontal strips are not continuous to allow airflow and trapped moisture to drain away. This cedar roof has lasted for over 60 years in a harsh moist environ¬ ment. Photo: Old Fort Niagara, Assoc. Inc. Newsletter of The Roof Consultants Institute 10 WOODEN SHINGLES—HISTORIC DETAILS AND INSTALLATION PATTERNS Shingle Patterns Long biaxiallytapered, sidelapped overlap Fancy butts (fishscales shown) Ridges Staggered overlap Steamed & bent “thatch” Hips Traditional alternating shingle hip Boston capped hip Rolled metal hip cover Fanned or swirled alternating shingle hip 9. The Historic Details and Installation Patterns Chart illustrates a number of special features found on wooden roofs. Documented example of these features, dif¬ ferent for every building and often reflecting regional variations, should be accurately reproduced when a replacement roof is installed. Chart: Sharon C. Park; delineation by Kaye Ellen Simonson. Newsletter of The Roof Consultants Institute 11 WHO IS ELIGIBLE: All RCI Members CONTEST PERIOD: October 1990 through February 1991 ’’ADD A NEW RCI MEMBER” CONTEST CONTEST RULES: Headquarters will keep a tally of the SPONSORS of all new member¬ ships that are submitted during the period from October 1990 through February 1991 . Please ask each person that you sign up to write YOUR name on the RCI Membership Application Form by the Line “RCI Member Sponsor (Referred by)” and to submit the completed RCI mem¬ bership application to RCI Headquarters by the end of February 1991. PRIZE: • LA FREE CONVENTION REGISTRATION to the 199 1 RCI Convention in Colorado Springs, CO, April 28-May 1, 1990. • 2. Formal recognition at the RCI President’s Banquet. RCI is pleased to announce co-sponsorship of two RIEI seminars. The two back-to-back seminars will be held in Raleigh, NC, May 13-16, 1991. Mark your calendars now to attend the Quality Assurance seminar and the Single Ply & Modified Bituminous Roofing Systems seminar. We will publish more information about these seminars in future edi¬ tions of INTERFACE. RIEI AND RCI CO-SPONSOR SEMINARS Paula Baker was named RCI Executive Manager effective September 1, 1990. Paula was employed in 1988 as RCI’s first full-time administra¬ tive assistant and convention coordinator. Paula has a B.A. degree from the University of North Carolina at Wilmington. She has a background in association management and meeting planning experience. Sheila Sheats was hired as administrative assistant for RCI effective September 1, 1990. Sheila has a B.S. degree from the University of Maryland. Her previous work experience includes assistant to the execu¬ tive director for the Gardner, MA Chamber of Commerce and program coordinator for the University of Southern California Center in Augsburg, West Germany. Curtis Liscum, CRC Roof Tech Inc P.O. Box 12103 Shawnee Mission KS 66212 913-894-4367 RCI STAFF NEW REGION IV DIRECTOR APPOINTED Newsletter of The Roof Consultants Institute 12 NEW Certified Roof Consultants (CRC) Wells T. Jackson CRC W. T. Jackson Consultant RO. Box 9628 Ft. Collins CO 80525 303-484-7950 OR 404-978-6337 David J. Laks CRC (First Canadian CRC) Tremco (Canada) Inc. 70 Cass Ave #187 Scarborough, Ontario, CANADA MIT 3P9 416-421-3300 Gary W. Ludden CRC U.S. Tesing Co. Inc 3467 Kurtz St. San Diego, CA 92110 619-225-9641 Luther C. Mock CRC Martin Riley Architects/Consultants 122 West Wayne Fort Wayne, IN 46802 219-422-7994 FIRESTONE SPONSORS INTERFACE ISSUE Firestone Building Products Company manufactures a complete line of single-ply EPDM and APP and SBS modified bitumen membrane sys¬ tems, insulations, fasteners, adhesives and many other accessories for in¬ stallations on commercial and industrial roofs. The “Interface Newsletter” is published by the Roof Consultants Institute. Copyright © 1988 Roof Consultants Institute. All rights reserved. Please address all submittals, subscription requests, advertising, etc. to the Roof Consultants Institute, 7424 Chapel Hill Road, Raleigh, NC 27607. Telephone 919/859-0742. The RCI logo, the name “Interface Newsletter” and the title “RCI Certified Roof Consultant” abbreviated “CRC” are the property of the Roof Consultants Institute and must not be used without permission. Disclaimer: The articles contained in this publication have been prepared for, and are intended to provide information that may be useful to members of the Roof Consultants Institute. RCI does not necessarily warrant this information. The reader must evaluate this information in light of the unique circumstances of any particular situation and must determine independently the applicability of this information thereto. Advertising in RCI publications does not constitute endorsement of any product or system by RCI or any of its roof consultant members. Newsletter of The Roof Consultants Institute
