This article appeared in Western Roofing January/February 2016.
Replicating Historical Tile
Reroof at Hearst Castle in San Simeon, California
by Marcus Dodson, publisher
Casa Grande was the private residence of William Randolph Hearst and the main house at Hearst Castle. Located on the Central Coast of California, nestled in the hills at San Simeon, on Highway 1, and about halfway between San Francisco and Los Angeles, Hearst Castle is a National and State Historical Landmark and working state park that shuts down only for a few select holidays. Casa Grande is made of poured concrete reinforced with steel and has approximately 68,500 sq.ft. of living space. It contains 115 rooms including 38 bedrooms, a library, movie theater, kitchen, and living quarters for the household staff. The reroof of Casa Grande seemed fairly simple on paper with approximately 150 squares of tile and 25 squares of builtup roofing. The project began in November 2014, and it became more complicated day by day. Additionally, with the building being almost 100 years old and having limited records, Casa Grande had plenty of surprises in store for the contractors.
The challenge of working efficiently, but also safely to protect the public, was a main concern. First, there was a bat population living under the existing tiles. California State Parks and Recreation brought in HT Harvey and Associates, Los Gatos, California, to observe the bat population and come up with a plan to safely deter the bats from the areas where the reroofing was to occur. The plan was to set up ultra-sonic devices to deter the bats from returning to their roost so tile could be removed.
Once California Access Scaffold of Carson, California, had erected scaffolding, the ultra-sonic devices were installed and left to run for three days in each location; and then tile was removed. After the scaffolding was up and bats had been deterred, the architects, Page and Turnbull, San Francisco, California, along with Best Contracting Services, Inc. (BCSI), and the State of California Parks and Recreation got their first real look at the roof at Casa Grande. Investigation of the site had been limited previously due to the 60’-80’ tall roof that had no fall protection.
The next challenge was creating access to the roof to remove debris and to load both materials and workers. BCSI brought in 60’ scissor lifts to provide access more efficiently than stair towers. California Access Scaffold devised free standing loading platforms to stack tile and eliminate the need for bringing the existing tile down from the roof. This step reduced breakage of existing tiles, allowing for the re-use of good tiles. American Services Group, San Dimas, California, provided tear-off and abatement as needed. One of the first discoveries was the condition of the concrete deck beneath the tiles.
When the tile and underlayment were removed, the concrete was found to be rough with voids in multiple areas. The original spec for the project called for a peel and stick underlayment system, but upon uncovering the condition of the deck, BCSI proposed a change to a Sopralene Flam® 25 FR GR (torched down) underlayment by Soprema®.
Once the underlayment issue was resolved, the next challenge arose with the anchoring system for the tile. The original spec called for 1⁄4” anchor bolts set into the concrete. BCSI began installing these anchors on the first section of roof; then brought out the deputy inspector to test the bolts. During testing it was determined that the concrete was rough as well as too soft to meet the requirements of the anchor bolts and wire tie system. A new anchor system was formulated which used 1⁄4” stainless steel allthread with Simpson AT_XP anchor adhesive.
Due to the delay with the underlayment change and anchor failure, construction now ran into the problem of bat maternity season, which runs from mid-April to late August. Originally, the scaffold plan was three phases to help minimize the amount of scaffolding up at any one time. Since BCSI only had access to roofs with scaffolding, a new plan for scaffolding had to be designed. Together with the California State Parks and Recreation and California Access Scaffold, BCSI was able to mobilize rapidly and get scaffolding erected around the entire castle in less than two weeks, install the ultrasonic devices to deter the bats, and remove and stack all the tile before the bat maternity deadline that would have shut down the project until September.
As the scaffold continued to be erected and more areas of the roof were accessible to exploration, it was discovered that there were additional tile sizes that were not previously known to exist on the roof. Casa Grande had been reroofed two times since it was originally completed and it was unknown which tiles were the original designs. The roof was found to have up to five different groups of tile from the various reroofs and repairs. California State Parks and Recreation, along with the architects, decided to replicate all tiles found on the roof, as they could not determine which tiles were original and which were the repair tiles.
Charlie Minshew, project manager, BCSI, Gardena, California, stated, “The Hearst Castle reroof was a unique and challenging project, being not only a historical site but also a site that averages between 2,000 and 6,000 visitors daily and only shuts down three to four days a year. We navigated many logistical, environmental (birds, bats, and lichen, etc.), and historical roadblocks during the project with the help of a great team from California State Parks, BCSI, and MCA Tile, who not only made amazing replica tiles but were able to expedite the tile-making process to keep the project going even after multiple new tiles were discovered in the reroof process.” Because of all the hard work by everyone involved and MCA’s historical replica tiles, the beauty of Casa Grande lives on and the roof should last for many years to come.