CASE STUDY:

RESTORATION OF AN HISTORIC CLAY­TILE ROOF SYSTEM

BY CHRISTOPHER W. GIFFIN, AIA, AND JAMES M. BROWN, AIA WISS, JANNEY, ELSTNER AND ASSOCIATES, INC. 2915 Premiere Parkway, Suite 100, Duluth, GA 30097 P: 770­923­9822 • F: 770­232­9044 • E­mail: [email protected] and [email protected]

S YMPOSIUM ON B UILDING E NVELOPE T ECHNOLOGY • N OVEMBER 2 0 1 0 G IFFIN AND B ROWN • 6 7

ABSTRACT This case study discusses the restoration of a steep-slope, clay-tile roof assembly on an historic hotel structure built in 1912. In 2000, the original clay-tile roof was scheduled for replacement. Shortly after the replacement, problems with the clay tile began to manifest, ultimately requiring significant repairs to the roof. This case study will describe the inves- tigative techniques that were employed and the repair approach that was developed to allow the hotel to continue to operate and serve its guests while significant repairs were being made to the steep-slope roof and other key features of the roof system.

SPEAKERS

JAMES M. BROWN, AIA — WISS, JANNEY, ELSTNER AND ASSOCIATES, INC.

JAMES M. BROWN is a licensed architect who specializes in the assessment and repair of roofing, waterproofing, and building envelope problems. His experience includes condi- tion assessments, storm damage assessments, development of repair designs and con- struction documents, and construction administration and observation services for a vari- ety of historic and contemporary structures, including commercial buildings, residences, airports, convention centers, hotels, and stadiums. He also has experience with many dif- ferent types of materials, including marble, terra cotta, concrete, masonry, glass, exterior insulation and finish systems (EIFS), and stucco. Brown has performed several different types of field tests for quality control purposes and for diagnosis purposes in investigations, including water testing, adhesion testing, and wind uplift testing.

CHRISTOPHER W. GIFFIN, AIA — WISS, JANNEY, ELSTNER AND ASSOCIATES, INC.

CHRISTOPHER W. GIFFIN is a licensed architect specializing in the diagnosis and repair of building envelope problems. With approximately 20 years of experience, he has been involved with many roofing and waterproofing projects relating to both historic and con- temporary structures. Notable projects include the Candler Building, the Grove Park Inn Resort and Spa, Chicago Public Schools, U.S. Cellular Field, and Fenway Park. He has per- formed prepurchase surveys, design peer reviews, storm damage assessments, nondestruc- tive moisture surveys, and numerous roofing and waterproofing investigations. He has also managed the repair design and performed construction period services for the installation of numerous flat and steep-slope roofing systems.

6 8 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1

CASE STUDY:

RESTORATION OF AN HISTORIC CLAY­TILE ROOF SYSTEM

INTRODUCTION dormers varies from The Grove Park Inn dormer to dormer with the Resort and Spa is an his- average slope being toric hotel structure locat- approximately 2:12. ed on Sunset Mountain Throughout the five differ- overlooking the Blue Ridge ent roof areas, there are a Mountains, in the city of total combined number of Asheville, North Carolina 42 eyebrow dormers. (Figure 1). The hotel was During the course of our constructed in 1913 and work, we actually uncov- was listed on the National ered an abandoned Register of Historic Places dormer that was covered in 1973. Owner and local up when the kitchen area businessman E. W. Grove was expanded on the low- began construction on the est section of the hotel. It hotel in 1912. A promi- appears this addition was nent Asheville resident added in approximately and pharmacist, Grove 1916. The shape of the was the inventor of Figure 1 – The Grove Park Inn Resort and Spa, circa 1913. Photo eyebrow dormers and Grove’s Tasteless Chill courtesy of the Grove Park Inn Resort and Spa. flowing curving lines were Tonic, used to reduce heavily influenced by the fevers and chills associated with malaria. No. 5 at the top of the hill. The main thatch roofs found in Europe. The clay tile After several real estate adventures in entrance to the hotel is located in the sec- that was installed on the hotel mimicked the late 1890s and early 1900s, Grove tion with Roof Area No. 4 (Figure 2). The these older thatch roofs but also provided a wanted to build a hotel in Asheville. After structural roof deck consists of a reinforced fire-resistant roof coving. visiting Yellowstone National Park in cast-in-place concrete slab with multiple Over the cast-in-place concrete roof Wyoming, Grove wanted to build the hotel slopes and complex curving surfaces. The decks, an asphalt built-up roof was that embodied the character, rustic, and slope of the roof changes pitch from 16:12 installed, followed by bright red- and megalithic appearance of the Old Faithful around the eaves, to 10:12 in the middle orange-colored clay tiles to accentuate the Inn and Canyon Hotel. In the winter of section, to 7:12 near the ridges. Concrete surrounding landscape. The tiles were then 1912, an architectural competition was pours ran continuously until an entire roof nailed through the built-up membrane into held for the design of the inn. However, no area was complete in order to avoid seams the concrete roof deck. At the eyebrow entries fully captured the rustic feel Grove and construction joints within the complex dormers, an interlayment system was also desired, so no architect was selected. Fred roof structure. For the main section of the originally installed between the tile courses. L. Seely, Grove’s son-in-law, is credited with hotel, concrete placement continued for 24 The original red shingle tiles installed were drawing the sketch that influenced the hours straight. manufactured by the Murray Roofing building. Under the supervision of Seely, Large window openings were created in Company of Cloverport, Kentucky. Each tile construction began on the hotel. the concrete roof slabs to form curving eye- measured approximately 6 in wide, 12 in Massive granite boulders quarried from brow dormers. The top slope of the eyebrow long, and three-eighths of an inch thick. the nearby mountains were used to form the exterior of the resort. Some walls mea- sure more than four feet thick at the base and six stories tall. For construction of the walls, Grove required that only the native uncut stone remain visible. The inn was built in five sections that join end-to-end and step terrace-like along the mountain ridge. Each of the five sections contains its own separate steep-slope roof area. During our involvement on the project, the roof areas were identified as Roof Area No. 1 at the bottom, then stepping up to Roof Area Figure 2 – Grove Park Inn Resort and Spa roof plan. 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 G IFFIN AND B ROWN • 6 9 placed over the modified bitumen mem- brane to approximately match the thick- ness of the adjacent wood battens and counterbattens. The flat slab clay tiles were then mortar set onto the concrete setting bed. Shortly after the replacement of the clay-tile roof assembly, a number of prob- lems with the new clay-tile installation began to manifest. One of the initial indica- tors that problems were occurring was the formation of large efflorescence deposits around the sides and eaves of the dormer areas (Figure 3). A number of leaks also began to develop, primarily at the base of the dormers. In an attempt to reduce the amount of efflorescent staining and leaks that were occurring, a clear penetrating sealer was applied over several of the dorm- ers. This was found to be unsuccessful as the leaks and efflorescent staining contin- ued to worsen, in addition to voiding the clay-tile warranty. Figure 3 – Formations of large efflorescent deposits around the sides and eaves of In 2003, we were retained by the hotel the dormer areas. to perform an investigation to determine what was causing the efflorescent staining The construction of the hotel was complet- tive-treated counterbattens spaced at 5 and leakage problems. Our investigation ed in 11 months and 27 days and officially inches on center were then screwed into the revealed these findings: opened on July 1, 1913. battens. New, 6-in-wide by 13-in-long flat

In 1955, Charles Sammons purchased slab clay tiles similar to the original tiles INVESTIGATIVE FINDINGS the Grove Park Inn and immediately began were secured to the counter-battens. 1. Inspection openings revealed the a renovation of the 42-year-old structure. In On the roof dormers, hips, and ridge mortar-setting bed was often satu- 1982, Sammons built a new addition con- areas, in lieu of a wood batten and counter- rated with water and could easily nected to the hotel containing guest rooms batten system, a concrete setting bed was crumble. Where the tiles were mortar- and conference space. In 1987, another wing was constructed to provide more guest space and additional conference areas. This was followed by the construction of the underground spa between 1999 and the replacement of the original tile roof assem- bly in 2000.

ROOF REPLACEMENT In 1999, after 86 years of service, chron- ic leaks, and deteriorated roof conditions, the famous clay-tile roof was replaced. Many roof tiles were cracked, broken, and loose. The flashings had deteriorated, and even the concrete deck had become deterio- rated in places. From 1999 to 2000, a com- plete removal and replacement of the clay- tile roof was undertaken. The 2000 replace- ment consisted of placing a granular-sur- faced, modified-bitumen membrane over the concrete structural deck. Along the main flat field areas of the roof, preserva- tive-treated 2x2 wood battens were placed vertically approximately 24 inches on cen- ter and then anchored to the concrete deck. Figure 4 – Many of the tiles had debonded from the mortar­setting bed and were Over the battens, horizontal 1x4 preserva- loose. 7 0 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 set, many of the tiles had debonded the roof revealed several open laps into the existing adjacent field areas. Then from the mortar-setting bed and and seams in the granular-surfaced, a new wood batten and counterbatten sys- were loose and could easily be lifted modified-bitumen membrane. Once tem was installed over the membrane. To by hand. These conditions created a water bypassed the clay tiles, the effectively secure the clay tiles around the hazard, as the tiles could easily fall open laps and seams were vulnera- dormers, the counterbatten system needed from the roof (Figure 4). ble to water entry, resulting in the to be solid and not spaced like the field 2. During the investigation, we discov- water leakage observed on the inte- areas of the roof. ered that at the dormers and hip rior. The modified bitumen was To allow the dormer tiles to continuous- conditions, the 13-in-long tiles had adhered with a cold-applied adhe- ly flow around the dormers as they did in been cut in half and then installed sive. At some locations, the modi- the original, the individual clay tiles must on the mortar bed, maintaining the fied-bitumen membrane was not transition from their conventional hanging 5-in exposure. As a result, no head bonded to the adhesive, indicating position in the field area, with the fasteners lap was installed, and the mortar- the adhesive had set prior to the at the top of the tile, to hanging with the setting bed was exposed through the membrane’s application, or the fasteners positioned on their side as they joints between the clay tiles. At the membrane never made contact with roll up the vertical sides of the dormers. tops of the dormers where the slope the adhesive when installed. When this occurs, the tiles lose their ability is approximately 2:12, even if full- 6. Fastener pull tests found that the to properly shed water. An interlayment sized tiles were installed, the water- existing batten anchors were gener- system of ethylene propylene diene shedding principles of a shingle- ally well anchored into the existing monomer (EPDM) strips was then installed style tile system would be compro- concrete deck. Typical pull-out test to collect and divert any water back to the mised, and water would readily flow values ranged between 750 and exterior that might migrate through the tile through the tile joints and seep into 1700 lbs. joints. In addition, since the slope at the top the mortar-setting bed. 7. The clear penetrating sealer was of the dormer is approximately 2:12, the 3. Laboratory analysis indicated that completely ineffective in slowing the tiles would also not shed water. A self- the mortar on the dormers did not rate of water intrusion into the mor- adhering membrane was placed over the top meet any of the ASTM material spec- tar-setting bed and reducing the of the counterbatten system before the tiles ifications for mortar. The mortar efflorescent staining. were installed. contained vermiculite aggregate, a With the new modified-bitumen mem-

very porous and lightweight fill 2004 REPAIR MOCK­UP brane on the dormer and the new tile with material. We also found the mortar Shortly after the investigation was com- the interlayment flashing installed, the contained significant amounts of pleted, the process of determining how to water leakage problems into the dormer ettringite crystals, indicating a large repair the roof began. It became clear that were resolved, and a new method of amount of moisture has been pre- some form of repairs would be needed at mechanically attaching the tiles to the sent in the mortar samples. In those locations where the tiles were mortar- dormers was accomplished. The hotel then freeze-thaw environments, the set. We recommended that at the dormer, needed to evaluate how long such a repair expansive forces of the freezing hip, and ridge areas, where the tiles were would take over the entire roof and the water, along with the ettringite crys- mortar-set, they be completely removed and associated costs. Since the completion of tal formation, expands the mortar a new batten and counter-batten system be the 2000 replacement, the hotel was until the mortar eventually crum- installed so that the new clay tiles could be extremely busy and scheduled full with con- bles and falls apart. This condition secured with screws in a similar manner to ventions, guests, and other activities, mak- was responsible for the tiles’ losing the field areas of the roof. To address the ing another full-scale repair a burden on bond to the mortar-setting bed. The leakage problems experienced into many of operations. testing also revealed that no latex the guest rooms, and to repair the defects

additives or air entrainment were associated with the membrane, completely REPAIR MITIGATION:

added to the mortar; as a result, the removing the entire clay-tile roof assembly NETTING THE ROOF mortar could not withstand repeated to access the existing modified-bitumen Based on the deteriorated conditions freeze-thaw cycles. Due to these membrane might also be necessary. observed, our first priority was to address construction defects, over time, the To verify the extent of the repair and to the safety concerns regarding the potential mortar-set tile areas on the roof determine if a new batten and counterbat- of tiles’ falling from the roof. It was impera- would continue to decay and more ten system could effectively be installed on tive to implement safety measures around areas would become unstable. the complex shape of the eyebrow dormers the entire perimeter of the building as soon 4. The efflorescent staining was found at a location where leakage issues were also as possible. Although the hotel was prepar- to be calcite, which was produced occurring, the existing clay tiles and mor- ing to cordon off areas in front of the main from water passing through the tar-setting bed were completely removed entrances to the building by displaying cau- mortar dissolving the calcium from one of the eyebrow dormers. The exist- tion signage around the cordoned areas and hydroxide within the mortar, where ing granular-surfaced, modified-bitumen alerting staff to the issues so that they it then evaporated on the tile surface membrane was also removed, and a new could work with guests to avoid having peo- as calcite. modified-bitumen membrane was installed ple congregating in high-risk areas, addi- 5. Inspection openings in the field of on the concrete structural deck and tied tional steps were needed to protect the pub-

2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 G IFFIN AND B ROWN • 7 1 lic from possible falling tile. We suggested a ladders. Rock climbing equipment was also broken throughout the roof areas. Most of temporary solution to assist with the pre- used to access the soffits to attach the bot- the broken tiles are likely attributable to vention of falling tiles, which was to install tom of the net. accessing the roof to install the netting and protective netting from the top of the roof to maintenance-related work over the previous the underside of the eave. TILE AND NETTING ASSESSMENT few years. The condition of the tiles at the Given our unique application, selecting The netting was in place for approxi- dormers and underlying setting bed had an appropriate net was critical. After dis- mately two and a half years. During that significantly deteriorated, resulting in cussions with netting manufacturers, two time, numerous tiles became dislodged and numerous loose and detached tiles at the different types of netting were obtained. were caught in the net, and a few repairs to dormers and hips. Nearly all of the dormers One type was a lightweight net typically the net were implemented. In the spring of on Roof Area No. 4, and 50 percent of the used for bird control, and the other type 2008, the hotel requested that an assess- dormers on Roof Area No. 5 had tiles on the was a medium-weight net typically used for ment of the existing tiles and containment dormers either completely loose or missing sporting protection. To determine which netting be performed. We observed the net altogether. At locations where the tiles were type of net would work best on the roof, we had significantly shrunk, was tented across loose, they could easily be lifted by hand, as performed a mock-up of the net installation the dormers, was brittle, and did not lie there was no bond between the tile and the on the roof. The mock-up consisted of per- against the tiles. Since the net did not lie mortar-setting bed. The areas where roof forming a tile slide test on the net and drap- against the tiles at many areas, if a tile were tiles had fallen also increased significantly ing the net on the dormers. The lightweight to fall, it could slide unrestricted down to since the net was installed. net failed the tile slide test as the tile sliced the eave, and if there was enough force, it At a few dormer locations where the right through the net and landed on the roof could potentially go through the net (Figure mortar-setting bed was exposed due to fall- area below. The medium-weight net per- 5). en tile, the setting bed was cracked and formed very well in the test, as the tile only The netting had also become severely deteriorated. At one location at the top of a slid about 3 or 4 ft down-slope and was weathered from exposure to the sun and the dormer, a separation formed in the mortar- caught on the net. The medium-weight net ultraviolet rays. This was evident fromo the setting bed, and it appeared the entire mor- draped well in the dormer valleys and fairly discoloration and lightening of the net. tar bed on the top of the dormer slid down- well from the top of the dormer down to the When initially installed, the net was black; ward. At other locations, many tiles had eave below the windows. The net also and at areas where it had become weath- shifted and buckled, while being held extended out far enough to allow guests to ered, it was now gray. Where exposed to together with mortar. This gave us the indi- open the dormer windows. The lightweight direct sun, the netting also became stiffer cation that there was a high potential for net was found to be too stiff and did not and was more brittle than those areas larger sections of the dormer tiles and mor- drape well over the dormer surfaces. In late where the net was more protected. tar bed to become loose and fall from the 2005, the medium-weight net was then The amount of efflorescent staining on roof. Since the net was also severely weath- installed over the clay-tile roof areas. Access the tile had increased over the past few ered, there was a possibility that the con- to the roof was provided by boom lift and years. Also, several random field tiles were tainment netting would not be able to with- stand these conditions. Therefore, we rec- ommended complete removal of the mortar- set tiles at the dormers, hips, and ridges as soon as possible.

DEMOLITION Based on the condition of the tiles on selected dormers and the overall net deteri- oration, removal of the mortar-set tiles began in fall of 2008. Once the tiles and mortar were removed, the containment net- ting was to be repaired and repositioned on the roof. This eliminated the immediate hazards on the roof until the replacement of the tile-roof areas could be scheduled. This work would be performed on approximately half of the 42 dormers on the hotel. To access the dormers and provide safe- ty protection, scaffolding was installed on the building façade in a number of areas. Some dormers were also accessible from a boom lift. Many of the tiles could easily be removed by hand, but where tiles were still adhered, hammers and small chipping Figure 5 – Investigation showed that larger sections of the dormer tiles and hammers were often used. The mortar bed mortar bed had become loose and could fall from the roof. was also removed with small chipping ham- 7 2 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 mers and hand scrapers. Once the mortar mechanically attached. No other significant reduced, since we would be repairing only a bed was removed, the existing granular- repairs would be performed on the remain- portion of a currently aged system. We esti- surfaced, modified-bitumen membrane was ing modified-bitumen membrane or field mated the repair could perform well for cleaned with a wire brush and repaired with clay-tile areas, with the exception of local- approximately 50 to 60 years or more before liquid membrane. The amount of repairs ized broken-tile replacement. This second needing a major renovation. This repair became such that it was more practical to approach would rely on improving the approach would have a lower installation coat the entire area of exposed membrane. water-shedding characteristics of the steep- cost compared to the complete replacement Due to the exposure to ultraviolet rays, the slope tile assembly. by allowing the owner to realize the value liquid membrane was coated with an acrylic The complete roof replacement option previously spent to install the clay tiles in paint, which was tinted to closely match the would ensure that a primary water barrier the field areas of the roof. The repair could color of the existing tile. This was only a was achieved on the concrete deck. The clay be performed within eight to ten months, temporary solution to improve the appear- tiles applied to new battens and counter- depending on the qualifications of the con- ance of the hotel during the busy holiday battens would provide a new covering that tractor and available contractor personnel, season until permanent repairs could be maintains the historical appearance and thus reducing the impact and disruption to made. aesthetic appeal of the hotel. The clay tile the hotel operations. This repair was also During the demolition process, we met would have minimal maintenance needs dependent on providing new replacement with the owner to discuss the progress of over the life of the roof and, with the new tile that would closely match the existing the work and how the remaining dormer, membrane, be protected from the elements. field tile color to avoid a checkerboard hip, and ridge areas that were not identified We would expect the roof to perform for appearance to the roof. as needing to be immediately removed approximately 75 to 100 years before need- Based on our observations from the would ultimately need to be removed in the ing a major renovation. However, this demolition project and the performance future either to implement any roof repair approach would come with a higher initial seen from the previously repaired 2004 option or to remedy continued decay of the installation cost and could take 12 to 16 dormer mock-up, localized repair of the mortar-setting bed in those areas. To limit months or longer to implement, depending clay-tile roof at the dormers, hips, and the amount of disruption to hotel opera- on the qualifications of the contractor and ridges could be effective. This repair could tions with stopping and restarting the pro- available contractor personnel. This reestablish the water-shedding qualities of ject, the owner decided to continue with the approach would avoid potential tile color- the existing steep-slope roof system so that demolition of all of the remaining dormer, matching issues, as new tile can be fully the underlying water barrier or modified- hip, and ridge areas. Therefore, the remain- blended and integrated with the existing bitumen membrane does not become as der of the tile and mortar demolition contin- tile. The primary disadvantages to this critical. The following discussion outlines ued until February 2009. During the meet- repair solution involve a longer period of some of the steps that were undertaken to ing, we were also requested to develop a disruption to hotel operations and guests ensure a successful repair and the chal- summary of the possible repair options and during replacement, as well as removal of lenges that were faced along the way. provide our recommendation to restore the the current battens, counterbattens, and roof system and begin the development of clay tile in the field that were in generally REPAIR MOCK­UP AND repair plans and specifications for bidding sound condition. PRECONSTRUCTION SERVICES purposes. Localized repair of the roof at the dorm- In 2009, prior to the start of the repair ers, hips, and ridges with new clay tile project, we recommended completing a sec-

REPAIR SOLUTION would require that the water-shedding ond dormer mock-up in a fairly accessible Going forward to permanently repair the properties of a steep-slope roof system be location to allow for observation and docu- clay-tile roof, two repair options were pre- achieved so that only a minimal amount of mentation of the repair process without the sented and discussed with the owner. The water was allowed to reach the existing need for elaborate scaffolding. This ensured first repair option included the complete modified-bitumen membrane. From our the repairs would work and gave us the removal of the remaining existing clay tiles, previous investigation, we knew whether opportunity to refine the repair documents wood battens, wood counterbattens, and some defects exist with the membrane dur- as necessary. modified-bitumen membrane over all roof ing extreme events; however, we did not Prior to bidding, several qualified repair areas. This approach would allow for a new know to what extent. This would require contractor candidates were researched and roof membrane system to be installed on complete removal of the clay tile and coun- recommended. Once the field of contractors the concrete deck to serve as the primary terbatten system. In addition, since the was determined, they were invited to bid on water barrier for the roof system. New bat- mortar bed demolition and localized repair the project. By previously making the recent tens and counterbattens would be installed, of the existing membrane were complete, it 2009 repair mock-up, we were able to give followed by new or reused clay tiles. The appeared no significant leakage problems the bidding contractors an example of the second repair option included only the existed at that time. This repair option finished product, since by that time all of replacement of the clay tiles at the dormers, would maintain the historic appearance the existing mortar-set areas had been hips, and ridges, which were by then and aesthetic appeal of the hotel without removed. This was found extremely helpful exposed from the demolition. The existing complete removal of the remaining tile in the process, as they could see the assem- exposed modified-bitumen membrane areas. This repair would also result in min- bly, review how the tile would be laid so the would be removed and replaced, new bat- imal maintenance over the remaining ser- coursing lines flowed over the dormers, and tens and counterbattens installed similar to vice life; however, it was anticipated the then ask questions. the complete removal option, and clay tile remaining service life would be slightly Once the bids were received, the owner 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 G IFFIN AND B ROWN • 7 3 wanted to have a meeting with each of the When it became apparent that a roof ROOF VENTILATION bidders so they could have an understand- repair or replacement was inevitable, there When the 2000 roof replacement was ing of the bidders’ proposed schedule, how was much discussion about how to improve implemented, the batten and counterbatten they planned on staging the work, what on the operational issues from the lessons system provided a ventilation space measures or ideas they had to minimize the learned from the past roof construction and between the concrete roof deck and the disruption to the hotel, and lastly, to review to try to avoid these during this repair. underneath side of the clay tiles. While a their costs. Each of the bidders brought his Several of the ideas discussed and imple- good means of ventilation was provided own expertise and experience to the meeting mented during the repair process included along the eaves, there were no ridge vents and offered up a wide range of solutions for the following: provided, as these tiles were set in a mortar the owner to consider. In addition to inter- • Selectively scaffolding portions of bed. In addition, the ventilation was dis- viewing the bidders personally, each bid- the building at a time, rather than rupted at the eyebrow dormers. During the der’s references were verified, and in some the entire main inn at once. design, we felt increasing the ventilation cases, the owner arranged site visits of their • Erecting the scaffolding in a manner would help to prolong the service life of this referenced work product so that the quality so that it did not excessively block system. If excessive moisture and heat were of their work could be witnessed firsthand. the views from the guest room win- to develop in this cavity space, this could dows. The scaffold system used in have adversely affected the wood and

DISRUPTION OF HOTEL the 2000 repair often left many of resulted in early tile failures. Therefore, by

OPERATIONS the lower-floor guest rooms with sig- placing the eyebrow dormers on a batten When the roof was replaced in 2000, the nificantly obstructed views. and counterbatten system, we could tie this entire main inn was completely scaffolded • Scheduling the repair work on cer- system into the cavity space created in the up to the roof eaves. Work also continued tain sections of the hotel that would field areas to improve the ventilation. The over the entire structure at the same time. be away from other areas during cavity space at the eaves of the eyebrow Therefore, all of the eyebrow dormer rooms their peak holiday seasons. dormers was exposed, thereby increasing were only able to be rented for sporadic • Installing scaffold netting to mask the amount of soffit or eave ventilation. periods of time. In addition, one of the main the appearance of the scaffolding A method of providing ridge ventilation character features of the inn—the ability to and hide the general movement of was needed. A new ridge detail was devel- open the large wood casement windows and the work in highly visible areas. oped that involved securing a new curved enjoy the fresh mountain air and views from • Adjusting the contractors’ work ridge tile to a vertically anchored preserva- the guest rooms—was restricted. This ele- schedules with later daily start tive-treated wood ridge board. This allowed ment was sacrificed by all of the scaffolding times and occasional earlier daily for the cavity space to vent at the ridge. A due to the building façades. The 2000 roof finish times when special events sheet metal flashing was placed under the replacement took approximately 12 months such as weddings might be taking clay tiles to assist with creating the air to complete and had an overall negative place. space needed between the ridge board and impact on the hotel’s operations. the flashing. To protect from bee and wasp hive for- mation that might occur, should insects find their way into the cavity space and then become a nuisance should the guests’ room windows be open, a stainless steel insect screen, serving as an eave and ridge closure, was fabricated and installed.

CONCRETE REPAIRS During the demolition of the existing granular-surfaced, modified-bitumen mem- brane that was installed on the dormers, we discovered that the top concrete surfaces of some of the dormers were severely spalled. Rather than repairing the concrete with a new concrete patch, wood decking was mechanically attached to fill the void creat- ed by the spall and match the surrounding slab thickness. Faced with a decision to either remove the wood decking or leave the wood in place as is, an inspection of the wood decking found that it was well anchored into the existing concrete deck. The wood deck would be covered again with Figure 6 – View of wood and stainless steel battens and wood counterbattens a new roof membrane and would not be being installed. exposed. Removing the wood decking may 7 4 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 have actually compromised the concrete deck further, requiring a large, full-depth reconstruction of the dormers. During the course of the repairs, we did encounter some other smaller spalls and cracks in the existing structural concrete deck that required concrete repairs to be made. These were accomplished by remov- ing all of the unsound concrete and expos- ing the twisted reinforcing steel, which was generally found to be in good condition, then adding a new latex-modified concrete repair patch.

BATTEN AND COUNTERBATTEN

INSTALLATION The repair design included the installa- tion of stainless steel Z battens to the eaves and sides of the dormers and at the hips. Depending on whether the curve of the sub- strate was convex or concave, either the tops or the bottoms of the Z battens were slit to assist in molding the Z battens into Figure 7 – View of tile transition at corners of main roof area with bottom of tile the shape of the curve. The Z battens were cut and open joints allowing water to bypass tiles. prefabricated in ten-foot sections and slit by hand in the field with an angle grinder. The slits assisted in bending the Z battens so There were instances when the dormers courses of tile installed. As a result, to that each piece could be easily hand-molded may have been one or two courses off from match the coursing lines on one side of a into the shape of each irregular curve. The one dormer to the next. This created chal- dormer with those on the other side of the Z battens allowed for a more efficient instal- lenges in the field when trying to lay out the dormer, 97 courses had to transition into lation in lieu of wood battens that would flow of the tiles over the dormers and in 90 courses, resulting in seven courses of tile need to be cut in numerous small sections attempting to keep the appearance consis- being lost. To avoid being able to visually to form into the sharp curves of the dormer tent, as different rows often may have been see the tile courses merge together, we eaves and valleys. Once the Z battens were the dormer starter course. elected to hide these conditions where they formed, the bottom flange was set in a bed Once the position starter course was would not be noticeable from the ground. of liquid membrane and anchored into the determined, a half-size, flat starter tile was Often, we could effectively merge a course concrete deck with masonry anchors. The then installed around the opening of the or two where the dormer eave would inter- heads of the anchors were also sealed with dormer. Three courses of custom-curved, 6- sect the main roof area. Another location to liquid membrane. The preservative wood in-long tile on the eave of the dormer would hide the lost courses was at the top of the counterbattens were then attached to the Z form the bullnose radius of the eave. The dormers. battens with compatible self-tapping stain- following courses of tile all consisted of full- Another tile-coursing challenge was less steel screws (Figure 6). length tiles that were custom-cut in width faced at the front entrance canopies. The At some hip areas, the slope changed to accommodate the curvature of the dorm- hip conditions were mortar-set like those on and the concrete deck was irregularly ers. Often, due to the slope of the dormer the upper roof areas; however, as we start- formed, creating flat spots. The Z battens and orientation of the three courses of ed into the repair of these areas, we discov- often needed to be shimmed with preserva- curved tile, an additional short tile might ered issues with the tile installation in the tive-treated wood blocking. The blocking have been required to ensure that the prop- tile field areas. The field tile was cut so that created more curvature so the transition in er pitch of the full-length tiles was achieved. the tiles were only 8 in long and the expo- the slope changes did not become flat and For every dormer and each course and tile sure was stretched to 6-1/2 in. As such, a the hips would contain an even curve and installed, the dormer conditions needed to proper repair at the hips could not be imple- flow in the tiles. be fully analyzed and appropriate adjust- mented and integrated with the existing ments to the tile installation made. field tile. Therefore, all of the tiles on the

TILE COURSING LINES As the tile would be laid up the dormers, entire front entrance canopy needed to be By only doing a repair at the eyebrow the complex shape of the main center roof removed and reinstalled. dormers, hips, and ridge conditions, the area often presented additional challenges. At the four corners of the main roof coursing lines within the field of the roof For example, during the repair it was dis- area, Roof Area No. 4, the eave line extends had to then continue over the dormers. covered that along the corners where the downward for several courses. To accom- During the installation, we discovered that roof swoops downward, there were 97 plish this transition, we found the bottom of structures for the eyebrow dormers were courses of tile from eave to ridge, but in the the tile had been cut on the diagonal, with often not in alignment with each other. center of the roof area, there were only 90 the side joints perpendicular to the slope 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 G IFFIN AND B ROWN • 7 5 function as a water-shedding system. The repair had to reestablish the water-shed- ding qualities of the clay tile system so that the underlying granular-surfaced, modi- fied-bitumen membrane does not become as critical. The repairs also had to address the transition areas on the roof where water infiltration through the water-shedding portion of the roof was most vulnerable, essentially reducing the amount of water that would reach the existing membrane. The repairs began by reestablishing the watertightness of granular-surfaced, modi- fied-bitumen membrane by replacing it where exposed. We ran into some chal- lenges in getting the sheet membrane to roll down the sides of the dormers and into the valleys. We often had difficulty adhering the membrane to the substrate due to the slope of the sides. It eventually led to additional preparation work on the substrate, applica- tion of a primer, and rolling the membrane to ensure full contact of the adhesive on the Figure 8 – Overall view of dormers with interlayment and tile being installed. membrane to the substrate. This also required numerous cuts and laps in the (Figure 7). This resulted in many locations original tiles installed on the roof. membrane. The membrane was even more where the tile was then installed with an After several attempts to reproduce the problematic when forming the severe curve improper head lap. The side joints were tile colors in the plant, a sample was sent to of the eyebrows at the end of the dormers. often very wide, thus exposing the underly- the site. From this sample, two out of the Therefore, the membrane was terminated ing counterbattens and allowing an exces- four colors were found to be acceptable. The along the flatter portion of the dormer, and sive amount of water under the tiles. Over manufacturer then went back, reformulated the severe curve at the eyebrow was water- time, this would have resulted in premature several different colors, and then sent out a proofed with a liquid membrane. decay of the wood batten and counterbatten new set of samples with two of the accept- Over the counterbatten system, a self- system in this area. To remedy this situa- able colors and two new colors. In an inter- adhering underlayment was installed. At tion, all of the field tiles in these areas were esting turn of events, none of the colors the outer perimeter, the self-adhering mem- removed and new properly positioned and were found acceptable — even those that brane was turned up at the existing adja- cut tiles were installed. This involved plac- were previously acceptable. After some cent field tile, acting as an end dam and ing the tiles perpendicular to the diagonal investigation by the manufacturer, it was redirecting any water back out onto the slope so that the bottom of the tile was not determined that, depending on the colors of tiles. Our repair design also included an cut, and the sides of the tiles were then cut some of the other tiles within the kiln, this EPDM interlayment within the tile courses as necessary in a similar manner to the could adversely affect the outcome of the at the dormer eyebrows and valleys (Figure dormer tiles. tiles. Once this was determined, there were 8). Photographic research on the original eight new colors fabricated and approxi- 1913 tile installation indicates that an

TILE COLOR MATCHING mately 100 tiles of each color were sent to interlayment flashing was also employed at The flat-slab clay tile used on the hotel the site for a large-scale mock-up. Several the eyebrow dormers. The EPDM interlay- actually consists of four separate tile colors mock-up panels were constructed so that ment was utilized to shed water, bypassing blended together according to a specific different tile colors and proportions could the bottom edge of the tile at the low-sloped ratio. New flat-slab tile was then required to be evaluated. After careful study, a new set tops of the dormers and numerous tile be fabricated that would match the then- of colors and mix ratio was selected that joints in the eyebrows and valleys, back out nine-year-old tile. After working with the most closely matched the original tile col- onto the underlying tiles and preventing the tile manufacturer, we learned that the exist- ors. water from reaching the underlayment. ing tile colors could not be directly duplicat- WATER­SHEDDING ISSUES The EPDM interlayment was to be ori- ed, despite having the original color mix A clay-tile roof is to function primarily ented as perpendicular to the direction of designs. Since the tile had been fabricated as a water-shedding system, allowing little the water flow as possible to maximize its in 1999 - 2000, the manufacturer had its to no water to bypass to the underlying sub- water-shedding capabilities. Eventually firing process and the type of kiln used to strate. Under normal circumstances, in the during construction, the EPDM interlay- produce the tile. As a result, when new tiles field of the roof, the tiles shed water so that ment was installed parallel to the tile; and were manufactured with the original colors ultimately very little water reaches the mod- the width was extended, creating a head lap and sent through the firing process, they ified-bitumen membrane. However, at the in the interlayment. Water leakage testing did not match the range of colors from the eyebrow dormers, the clay tiles did not was performed on the mock-up dormer and 7 6 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 at other locations on the roof for quality culties with the implementation of ence to the table and can offer up a control, and it was found that water did not the repairs and allow for modifica- wide range of solutions for consider- bypass the level of the EPDM interlayment. tion and refining the repair design, if ation. The owner was open to cre- necessary. The mock-up also allows ative ideas and solutions to the

LESSONS LEARNED for testing of the repair design if nec- scheduling, sequencing, and staging The information gained and the lessons essary. We were able to perform of the work in the determination. learned during the investigation and repair water testing on a fully repaired Also, the recommended contractor process that can assist designers and con- dormer to ensure the repairs per- may not necessarily be the lowest tractors from avoiding similar problems in formed as designed prior to imple- bidder. There are many factors in the future are as follows: menting the repairs on the entire determining the best contractor for 1. Understand the client’s needs. Meet project. the client, including the repair with, discuss, and work closely with 4. Conduct meaningful prebid meet- schedule, staging and sequencing of the client to understand his or her ings. Research and select qualified the repairs, ability to adapt to and business and project needs. While potential contractors to attend the respond to client’s needs, and cost the roof repair project is important prebid meeting. The prebid meeting of the repairs. All of these factors to the architect and contractor, it is is extremely important to communi- need to be evaluated to give the a huge inconvenience for the owner cate the scope of work and project owner the best contractor for each and the day-to-day operations of the requirements. The meeting also sets project. hotel. There will be different circum- the stage for the expectations of the 7. Conduct appropriately scheduled stances and requirements for each quality of work and schedule for the project meetings. Project meetings client and project. However, if infor- project. By previously making the permit the team to review and dis- mation is obtained in the beginning, recent 2009 repair mock-up, we cuss the project schedule, field it can be used to effectively define were able to demonstrate to the bid- observations, problems encountered and develop the scope of work that ding contractors an example of the during the repairs, and unforeseen can be conveyed to the contractor to finished product. This allowed the conditions, and they allow for devel- avoid conflict and problems during contractors to observe a completed opment of corrective measures and the repairs. In our circumstance, the dormer assembly, review how the procedures and making decisions owner had issues from the past roof tile would be laid so the coursing affecting the project. Typically, these construction that he wanted to lines flowed over the dormers, and are scheduled weekly or biweekly improve on, and we were able to ask questions. and are dependent upon the project identify those issues with the con- 5. Completely review prospective con- schedule and amount of work being tractor in the beginning of the repair tractors. On a high-profile project performed. At the beginning of our process. such as this, we recommend inter- project, the meetings were sched- 2. Eliminate delays of material deliv- viewing the bidders, reviewing their uled weekly, as the work schedule ery. Get product manufacturers completed work product on other was very busy. During the winter involved as early as possible and projects, and interviewing their ref- months and the end of the project, prior to the start of the project to erences. The interview of the bidders the meetings were scheduled assist in reducing or eliminating will provide a better understanding biweekly and eventually every three scheduling delays due to fabrication of the bidders’ proposed schedule, weeks as the work schedule dimin- or procurement of the repair materi- staging of the work, repair pricing, ished. als. On our project, we ran into a few measures or ideas they have for 8. Work as a team. Work closely with delays with the procurement of the minimizing the disruption to the the contractor in an attempt to iden- netting materials, color matching of building, and review any issues the tify issues that may develop ahead of the tiles, and fabrication and deliv- client may have. We interviewed time, and have an open line of com- ery of the replacement clay tile each potential bidder and arranged munication. In our case, throughout units. The tile delays affected the site visits of referenced work for the the course of the work, we reviewed staging and repair schedule for the top two prospective bidders. The site the existing conditions in detail on project. visits were arranged with personnel each roof area after the work scaf- 3. Mock-ups, mock-ups, mock-ups. If familiar with their work and who folding was in place. We found exist- possible, perform mock-ups prior to had firsthand experience with the ing conditions, such as erroneous the start of the project. If not, the contractor on a project. This allowed tile orientation, missing coursing mock-ups should be performed us to get the most information pos- lines, and poor flashing conditions. prior to the installation of the sible and make the best recommen- Because we identified these issues repairs on the building. In addition, dation for awarding the contractor at the start of the repairs on each the mock-ups should be full-scale or the work on our project. roof area, appropriate repair details, as close to full-scale as possible and 6. Select the appropriate contractor. pricing of the repairs, and change include all of the products to be Pair the owner with the best possible orders could be implemented with used in the final repair. The mock- contractor for the project. Each of little or no adjustments in the work ups will assist the architect and the prospective contractors brings schedule. contractor to understand any diffi- his or her own expertise and experi- 9. Be open-minded. Be flexible and 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1 G IFFIN AND B ROWN • 7 7 our project, we have had experience with other similar projects and encountered different types of underlayment that are more perme- able than the underlayment in- stalled on this project. The under- layment used on our project will per- form well as designed, since in- creased ventilation is also added. However, a more permeable under- layment may help with the preven- tion of condensation if ventilation is limited. 11. The original tile installation on the concrete deck and eyebrow dormers was accomplished by fastening nails through the built-up membrane directly into the concrete deck. The replacement in 2000 utilized a mor- tar-setting bed installed over the eyebrow dormers in lieu of a nailed installation. Ultimately, the tiles and mortar-set areas had to be removed, Figure 9 – Overall view of nearly completed roof repairs from similar vantage and the 2009 repair essentially point as Figure 1. replicated the original installation on the roof with fastened tiles have the ability to change the design was extended to provide a head lap (Figure 9). As modern architects, if necessary throughout the project, and the interlayment was cut in consultants, and contractors, we especially during construction. Our smaller sheets to accommodate the can often lose sight of the crafts- original design was to install the multiple curves and shapes in the manship and knowledge that our interlayment oriented perpendicular valleys. The newly orientated EPDM forefathers had. This craftsmanship to the flow of water down the sides of interlayment was installed and and knowledge, in many instances, the dormers into the valleys. During water tested. The testing indicated it cannot be replaced with modern construction, the contractor performed well, and the interlay- materials or methods. changed the orientation of the ment was installed this way on the EPDM interlayment to be parallel remainder of the dormers. with the coursing of the tiles. 10. Alternative material products. Since However, the size of the interlayment the original design of the repairs for

7 8 • G IFFIN AND B ROWN 2 6 TH RCI I NTERNATIONAL C ONVENTION AND T RADE S HOW • A PRIL 7 ­ 1 2 , 2 0 1 1