Design Principles for Tower and Steeple Restoration
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Design Principles for Tower and Steeple Restoration Robert Fulmer Fulmer Associates LLC P.O. Box 434, North Conway, NH 03860 Phone: 603-828-2458 • E-mail: [email protected] S Y M P O S I U M O N B U I L D I N G E N V E L O P E T E C H N O L O G Y • O C T O B E R 2 0 1 6 F U L M E R • 5 7 Abstract The contemporary tectonics of analyzing and designing the restoration or construction of architectural towers and steeples can both inspire and confound contemporary design professionals. The effective design of steeples, bell towers, spires, and clock towers requires a multidisciplinary synthesis of technical, aesthetic, and engineering requirements that are unique to tower architecture. In this presentation, the speaker will discuss construction con siderations and design problems inherent to tower projects by reviewing recent restoration case histories. The information shared will help designers to produce effective and thorough design processes for architectural tower and steeple projects. Speaker Robert Fulmer — Fulmer Associates LLC ROBERT FUlmER specializes in the analysis and diagnosis of building envelope issues for both historical and contemporary structures. He provides inspection, design, specifica tion, and project management services for building envelope projects involving institutional, academic, and ecclesiastical structures. Fulmer is a published author and has lectured on historical preservation and contemporary building envelope topics. He is past president of the New England Chapter of RCi, inc. and currently serves on the board of directors of the National Slate Association and is chair of its Education Committee. 5 8 • F U L M E R S Y M P O S I U M O N B U I L D I N G E N V E L O P E T E C H N O L O G Y • O C T O B E R 2 0 1 6 Design Principles for Tower and Steeple Restoration INTRODUCTION 301 A.D. as the first cathedral in the (then) Campanile: An early Italian architec The contemporary tectonics of analyzing Kingdom of Armenia. The inclusion of tow tural term for a (usually) freestanding bell and designing the restoration or construc ers on ancient religious structures was tower, derived from “campa” (meaning bell). tion of architectural towers and steeples can actually predated by and adapted from their The earliest campaniles, dating from the both inspire and confound contemporary original purpose as military towers as early sixth to tenth centuries AD, were plain design professionals. The effective design as 3500 BC. round towers with minimal ornamentation of steeples, bell towers, spires, and clock Clock towers were not an architectur near the top. Square campaniles began to towers requires a multidisciplinary synthe al component of Christian churches until appear at the end of the tenth century. In sis of technical, aesthetic, and engineer approximately 600 AD, when their use was the 19th century, that design inspired the ing requirements that are unique to tower also adapted from military watchtowers. See tower at Westminster Cathedral (by J.F. architecture. While the design requirements Figure 1. Bentley, 1897). The revival of the campanile for tower and steeple restoration can be as At that time, towers were fairly modest in the 19th and 20th centuries included diverse as the structures themselves, there and were constructed separately from the installations at factories, country houses, is a commonality and standard principles principal church building. blocks of buildings, markets, and academic that need to be addressed within the design Some contemporary discussions use the structures as a bell or a clock tower. (See process for each project. architectural terminology associated with Figure 2.) towers and steeples interchange BRIEF HIS TORY AND ably. For the purpose of clarifica NOMENCLATURE tion, some basic tower terminology Throughout history, towers and steeples is defined below. have been an integral part of our architec Bell Tower: A tower that con tural landscape. There are numerous docu tains one or more bells or is designed mented third- and fourth-century church to hold bells, even if it currently structures with towers located principally has none. A bell tower may be in what is now know as the Middle East, integrated into a church building or such as Etchmiadzin Cathedral, built in serve as a freestanding structure. Figure 2 – Campanile, Cathedral of Pordenone, Italy. Figure 1 – Salisbury Cathedral, England, during a lead roof replacement. S Y M P O S I U M O N B U I L D I N G E N V E L O P E T E C H N O L O G Y • O C T O B E R 2 0 1 6 F U L M E R • 5 9 Tower Access Once the scope and focus of the inspec tion have been determined, access to all levels of the tower must be planned. Whether in the schematic design phase or the construction phase, the logistics of tower access can be challenging. Unlike the construction phase, the requirements for OSHA compliance are less onerous for design inspections. However, personal safety planning is obviously essential. The need to access the full height of a tower for inspection and actual construction signifi cantly impacts both the cost and the sched ule of all tower projects. The trade aphorism “everything costs more and takes longer when working at height” is a basic principle to be kept in mind (Figure 3). While interior access is normally avail able to the belfry or clock level on most towers, accessing the interior space above the belfry level to evaluate cupola, spire, weathervane mast, etc. can be problematic. In certain circumstances, mechanical lifts Figure 3 – Baker Tower industrial rope access inspection. or cranes can be utilized to access the tower exterior. Occasionally, however, “mechani Belfry: Defined as an integrated tower “tower” shall be used generically to describe cal access” is not adequate or feasible. component designed to house bells. It is not complete bell tower, clock tower, and steeple For example, recently Dartmouth a freestanding structure. assemblies. College requested a forensic building con Steeple: A tall ornamental structure, usually surmounting a tower and ending TOWER SCHEMATIC in a spire. Common on Christian churches DESIGN PHASE and cathedrals, the term generally connotes Just as in the architectural a religious structure. design of each building project, Spire: Defined as a tapering conical or the schematic design phase is the pyramidal structure commonly found on top first step in developing the contem of a church tower or skyscraper. The spire porary tower design process. It is originated in the 12th century as a simple, a logical sequence that differs in four-sided pyramidal roof, capping a church some respects from other building tower. Nineteenth-century architects uti projects. lized spires prolifically, particularly during Whether the purpose for the the Gothic Revival period of the mid-1800s. tower/steeple restoration is a result Pinnacle: An architectural, vertical of a discovery of water infiltra ornament of pyramidal or conical shape, tion, structural damage, a planned crowning a buttress, spire, or other archi change in use, or the expiration of tectural member. A pinnacle is distin the service lives of structural or enve guished from a finial by its greater size and lope materials, this phase begins complexity and from a tower or spire by its with preliminary client discussions smaller size and subordinate architectural to determine the proposed purpose, role. A tower may be decorated with pin goals, and budget for the restoration. nacles, each one capped by a finial. The data gathering process in Cupola: A secondary dome-like struc this phase is essential and begins ture on top of a building, used to admit light with the building conditions sur or provide ventilation, or as ornamentation. vey. The information obtained dur This basic glossary of architectural ing the survey is then utilized to tower terminology will assist in clarifying form the initial basis of design the design process in subsequent sections. (BOD) document early in the design Figure 4 – Rope access enables forensic analysis For the purpose of this discussion, the term development phase. and materials sampling. 6 0 • F U L M E R S Y M P O S I U M O N B U I L D I N G E N V E L O P E T E C H N O L O G Y • O C T O B E R 2 0 1 6 dition survey and structural evaluation of their iconic Baker Library tower as a pre cursor to restoration. The square-planned brick tower base is integral to the attached building on three elevations, with one tower elevation extending to grade and housing the main building entrance. The inspection requirements of the 200-ft.-tall tower precluded the use of a crane for access due to the heavy volume of pedestrian traffic at the tower base entrance, as well as landscaping consider ations. While inspection of the full tower height is always important to determine existing conditions, document load con cerns, inspect weathervane substructure, etc., full tower access was essential in this case. Without a mechanical access option and with the prohibitive cost of staging erection for our inspection, the author utilized our “industrial rope access” option to access the tower (Figure 4). Figure 5 – Baker Tower building conditions survey. Although the use of ropes to access structures has been employed for centuries, forensic inspections due to potential liabili content, and other conditions of use. These older techniques were encumbered with lim ties, it is important to clarify your forensic data are then utilized in timber-stress grad ited lateral mobility and safety issues.