Building Codes for Existing and Historic Buildings E-Book

Melvyn Green

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 380

Veröffentlichungsjahr: 2011

Beschreibung

Learn to apply the International Building Code and InternationalExisting Building Code to historic buildings Written for architects, engineers, preservation, and codeenforcement professionals, this is the only comprehensive book thatexamines how the International Building Code (IBC) and theInternational Existing Building Code (IEBC) can be applied tohistoric and existing buildings. For ease of use, the book isorganized to parallel the structure of the IEBC itself, and theapproach is cumulative, with the objective of promoting anunderstanding of the art of applying building regulations to theenvironment of existing buildings. Building Codes for Existing and Historic Buildings begins with adiscussion of the history of building regulations in the UnitedStates and the events and conditions that created them. Next, itprovides thorough coverage of: * The rationale behind code provisions and historic preservationprinciples * Major building code requirements: occupancy and use, types ofconstruction, and heights and areas * Building performance characteristics: fire and life safety,structural safety, health and hygiene, accident prevention,accessibility, and energy conservation * Case study projects that reinforce the material covered Additionally, the book includes building analysisworksheets--both blank and filled-in versions withexamples--that illustrate how to develop a code approach for anindividual building. If you are a professional at any level who isworking on creating a plan that meets the intent of the code forhistoric or existing buildings, Building Codes for Existing andHistoric Buildings gives you everything that you need tosucceed.

Leseprobe

CONTENTS

Preface

Acknowledgments

About Melvyn Green

Part 1: Introduction

Chapter 1: Introduction

How Are Building Codes Developed?

How Are Building Codes Applied?

Building Code Updates and Compliance

Chapter 2: How Codes Regulate Buildings

Understanding Code Approach

Part 2: Development of Codes and Standards in the United States

Chapter 3: Development of Building Codes in the United States

Local Codes

Early Model Codes

Comprehensive Model Codes

Chapter 4: Development of Model Code Provisions for Existing Buildings

Regional Model Codes

International Building Code

Change of Occupancy Classification or Group

International Existing Building Code

Chapter 5: Development of Code Provisions for Historic Buildings

Regional Model Codes

International Building Code Provisions for Historic Buildings

International Existing Building Code Provisions for Historic Buildings

State Building Codes for Historic Buildings

Federal Activities

Conclusion

Part 3: The Rationale Behind Code Provisions

Chapter 6: Occupancy

Factors Influenced or Determined by Occupancy

Occupancy Classifications

Occupancy Classifications in Previous Building Codes

Chapter 7: Planning and Construction Factors

Siting

Type of Construction and Materials

Building and Component Size

Part 4: How Codes Regulate Existing Buildings

Chapter 8: Principles of Regulating Existing Buildings

What Do You Need to Know about Your Building?

Building Rehabilitation and Regulation

Nonconforming Rights

Change of Occupancy

Chapter 9: International Existing Building Code Compliance Methods

Why Use the International Existing Building Code?

How Is the IEBC Organized?

Prescriptive Compliance Method

Work Area Compliance Method

Performance Compliance Method

Example Buildings

Chapter 10: International Existing Building Code—Prescriptive Compliance Method

General

Additions, Alterations, and Repairs

Change of Occupancy Classification

Evaluating the Prescriptive Compliance Method for a Project

Prescriptive Compliance Method—Examples

Chapter 11: International Existing Building Code-Work Area Compliance Method: Repairs and Alterations

Repairs

Alterations

Work Area Compliance Method Alteration Examples

Chapter 12: International Existing Building Code-Work Area Compliance Method: Special Conditions

Additions

Change of Occupancy

Historic Structures

Work Area Compliance Method Examples

Chapter 13: International Existing Building Code Performance Compliance Method

Scope

Additional Code Requirements

Performance Compliance Procedure

Performance Compliance Method Examples

Conclusion

Chapter 14: Summary of the Compliance Methodologies

Low-rise Building

High-rise Building

Summary

Part 5: Historic Preservation Regulations

Chapter 15: The Legal Basis for Historic Preservation Regulations

Federal Level

State Laws and Regulations

Model Code Provisions

Local Laws

Chapter 16: The Rationale Behind Historic Preservation Regulations

Underlying Philosophy of the Standards

Accuracy versus Subjectivity

Reproduction versus Original

Reversibility

Continuity of History

Examples

Chapter 17: The IEBC and the Secretary of the Interior’s Standards

Preservation

Rehabilitation

Restoration

Reconstruction

Chapter 18: Resources

Historic Buildings

Natural Hazards Information

Fire Safety

Index

Copyright © 2012 by John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

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Portions of this publication reproduce excerpts from the 2012 International Building Code, 2012 International Existing Building Code, 2009 International Building Code, 2009 International Existing Building Code, 2006 International Building Code, 2006 International Existing Building Code, 1987 BOCA National Building Code, 1988 Standard Building Code, 1979 Uniform Building Code, and the 1976 Uniform Building Code, International Code Council, Inc., Washington, D.C. Reproduced with permission. All Rights Reserved. See the International Code Council’s website at www.iccsafe.org for downloadable products and services.

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Library of Congress Cataloging-in-Publication Data:

Green, Melvyn.

Building codes for existing and historic buildings / Melvyn Green.

p. cm.

Includes index.

ISBN 978-0-470-19591-8 (cloth); ISBN 978-0-0470-94650-3 (ebk); ISBN 978-0-470-94652-7 (ebk); ISBN 978-0-470-94653-4 (ebk); ISBN 978-0-470-95023-4 (ebk); ISBN 978-0-470-95046-3 (ebk)

1. Historic buildings—Standards—United States. 2. Standards, Engineering—United States. 3. Building laws—United States. I. Title.

TH420.G74 2011

363.6'90973—dc22

2010033337

PREFACE

HOW TO USE THIS BOOK

The book’s approach is cumulative, with an objective of helping the user to develop judgment about code issues and existing buildings. Rather than offer reference material that can easily be used in a piecemeal fashion, the book is intended to promote an understanding of the art of applying building regulations to the environment of existing buildings. In using this approach, a reader can learn to evaluate the reasons for code requirements and apply them in such a way as to produce an acceptable level of safety.

This book can be used as a tool for practicing architects, engineers, and construction regulatory officials who deal with historic and other existing buildings. Its emphasis is on the formation of sound professional judgment concerning application of code provisions and exceptions to actual projects.

The book begins with an overview of the history of building regulations in the United States, with an emphasis on events and conditions behind the development of regulations. Development of code provisions for existing and historic buildings is also detailed. Following these sections is an exploration of the rationale behind code provisions. Two kinds of factors influence this rationale: changeable and permanent.

The changeable factor is occupancy, the use to which the building is put. Occupancy is important because it affects potential hazards within a building as well as the number and density of people at risk. Not every building is suitable for every occupancy. A particular occupancy may prove to be uneconomic in some buildings due to code restrictions; in the case of historic buildings, a particular occupancy choice may dictate an unacceptable level of alteration.

Permanent factors include the building’s position on the property, type of construction and materials, and building and component size. They may, however, be altered in minor ways. For example, if an existing building’s windows are too close to a property line, fire sprinkler heads may be permitted to reduce the risk of transmission of fire to adjacent buildings, even though a new building would not be allowed to have windows in those locations. However, the expense of modifying permanent factors may make a project infeasible.

The principles of regulating existing buildings are discussed. Basic building information, nonconforming rights, and the code’s approach to change of occupancy are included. The prescriptive, work area, and performance compliance methods of the International Existing Building Code are analyzed. Each method of compliance is described with regard to its application to particular situations, such as repairs, alterations, and change of occupancy. Examples are provided to show significant code issues.

Finally, there is a discussion of regulations that specifically affect the practice of historic preservation, such as the Secretary of the Interior’s Standards for Treatment of Historic Structures, model code provisions, and state and local laws. The rationale behind sometimes-mystifying historic preservation principles is discussed as well, as is the relationship between these laws and the International Existing Building Code.

ACKNOWLEDGMENTS

I would like to thank and acknowledge the many people who assisted in the development and preparation of this book. Much of the credit for preparing the text and developing the approach goes to Anne L. Watson, my associate for over twenty-five years. Loretta H. Duvall developed the case studies in the performance approach with hard work and dedication to details. Erwin R. Pascua prepared most of the graphics.

On the International Code Council side, thanks to Mark Johnson for his support and Hamid Naderi for offering comments and edits. And Lis Valdemarsen and Sandra Hyde, who are on the staff of ICC and worked on this project.

ABOUT MELVYN GREEN

Melvyn Green is a structural engineer who has been in private practice for almost forty years. He specializes in historic and existing buildings.

He was involved in the development of several model codes for existing buildings, including the Uniform Code for Building Conservation (UCBC), HUD’s Nationally Applicable Recommended Rehabilitation Provisions (NARRP), and the International Existing Building Code.

Prior to establishing his own firm, he was Director of Building and Safety for the City of El Segundo, California.

He is a past President of the Structural Engineers Association of California and a Fellow of ASCE, SEAOC, and ATPI.

He is an adjunct professor at Goucher College Master’s program in historic preservation and also an adjunct professor at the University of Arizona, where he teaches design of timber and masonry buildings. He is a lecturer in the University of Southern California—Historic Preservation Certificate Program.

ABOUT THE INTERNATIONAL CODE COUNCIL

The International Code Council (ICC), a membership association dedicated to building safety, fire prevention, and energy efficiency, develops the codes and standards used to construct residential and commercial buildings, including homes and schools. The mission of ICC is to provide the highest quality codes, standards, products, and services for all concerned with the safety and performance of the built environment. Most U.S. cities, counties, and states choose the International Codes, building safety codes developed by the International Code Council. The International Codes also serve as the basis for construction of federal properties around the world and as a reference for many nations outside the United States. The Code Council is also dedicated to innovation and sustainability, and Code Council subsidiary, ICC Evaluation Service, issues Evaluation Reports for innovative products and reports of Sustainable Attributes Verification and Evaluation (SAVE).

Headquarters:

500 New Jersey Avenue, NW, 6th Floor,

Washington, DC 20001-2070

District Offices:

Birmingham, AL; Chicago. IL; Los Angeles, CA

1-888-422-7233

www.iccsafe.org

PART 1

INTRODUCTION

CHAPTER 1

Introduction

For many years, building codes were considered to be something of an enemy of historic preservation. And the converse was also true: the general public and some code officials regarded old buildings as hazardous. Stories of disasters in dangerous old firetraps vied with accounts of landmarks lost to overzealous code enforcement. Two worthy objectives—public safety and heritage conservation—were on a perpetual collision course. Figures 1.1 and 1.2 show two examples of historic buildings, which are in current use through the effective implementation of building codes.

Figure 1.1 Mission San Gabriel, founded in 1771, illustrates the preservation issues of building codes and historic buildings. The Mission has a large number of visitors, and so requires a safe exit system, fire safety measures, and earthquake protection. © Melvyn Green

Figure 1.2 A high-rise building, constructed in the 1920–1930 period. Similar buildings may be found in the business districts of most cities. © Melvyn Green

In an effort to resolve this conflict, the National Trust for Historic Preservation sponsored a conference in 1972, inviting representatives from both sides of the issue. The idea took root, and codes began to be changed to encourage preservation of old buildings rather than demolition. Research on performance of archaic materials began, giving a background and rationale to code efforts.

By the time the first International Existing Building Code (IEBC) was published in 2000, much of the conflict had been resolved. The IEBC provided technically competent methods for evaluating old buildings and rehabilitating them to meet safety requirements. This book is an aid to understanding those methods.

Even as the 2006 or 2009 editions of the IEBC (seen in Figures 1.3 and 1.4) are most likely being used to varying degrees throughout the country, the 2012 IEBC is being drafted.

Figure 1.3 The 2006 International Existing Building Code (IEBC). The IEBC is a member of the International Codes family. The IEBC describes the compliance methods for work in existing buildings and how to effectively utilize them. © International Code Council

Figure 1.4 The 2009 IEBC. Codes are always being revised based upon experience. The 2009 edition is an update to the 2006 code. It is the result of code change submittals to the International Code Council. © International Code Council

To use the IEBC effectively, it is essential to understand not only its provisions but also the intent behind those provisions. Building rehabilitation requires judgment concerning risks and hazards in buildings and the code’s role in limiting them. This, in turn, requires a comprehensive understanding of building codes, their development, and intent, and knowledge of issues of code compliance and noncompliance and the development of code alternatives.

HOW ARE BUILDING CODES DEVELOPED?

Building regulations derive from different sources, and these sources must be coordinated and understood in context for regulations to be efficiently used.

Health and safety is a basic responsibility of state government, and many states and localities have adopted building regulations to meet the specific needs and practices of their communities. This is particularly true for historic buildings.Model codes, traditionally developed by private entities, also contain provisions for historic structures.A recent code developed by the International Code Council (ICC) is the International Existing Building Code (IEBC). Because this code is being adopted by many states and local jurisdictions and is updated on a regular basis, it is discussed in detail in this book.Historic preservation is also regulated at the federal level by the Secretary of the Interior’s Standards for Treatment of Historic Properties. These standards, and accompanying guidelines, have evolved to produce sophisticated guidance for good practice.

In the past few years, codes have been modified and new codes have been written to address these issues, but little has been written to help designers and code officials understand and apply these new regulations, especially as they pertain to historic preservation.

HOW ARE BUILDING CODES APPLIED?

New code editions apply

In their entirety to new construction, including new additions to existing buildings, foundations of moved buildings, and reconstructions of historic buildingsIn specified ways to rehabilitation and remodeling of existing buildings, subject to the reasoned development of alternatives that meet the intent of the codeRetroactively in rare cases when new requirements are judged to be of overriding importance to building safety

BUILDING CODE UPDATES AND COMPLIANCE

Building codes are typically revised on a three-year cycle. A building may be “not in conformance with current code” by the time it is completed—even though it conforms to the code in effect at the time the permit was issued. For a 50- or 100-year-old structure, the deviation from current code is likely to be much more significant. While preservation of historic structures is generally recognized as important, the question of code compliance can be a disturbing one.

What does it mean for a building to “not meet code”? Does it mean the building is unsafe? If not, why are codes updated? These questions can be puzzling to laymen, who often believe

That a building that conforms to code requirements is “fireproof” or “earthquake proof”That noncomplying buildings are suspect at best and should be made to comply as a matter of public safetyThat, since compliance with current code produces a safe building, any building failure must be preventable and unreasonable

None of these popular beliefs are true, of course. Compliance with current code does not mean that a building has no vulnerabilities. Nor does noncompliance necessarily mean that significant hazards exist.

Reasons for updating codes vary from including new materials to incorporating wisdom learned from recent disasters. Only rarely is new information considered to be so important that it triggers retroactive requirements.

In most cases, code innovations describe construction details or techniques that are arguably an improvement over existing practice but are not essential to safety. For example, under the 1982 Uniform Building Code, the maximum stair riser height was 7½ inches; the minimum tread width was 10 inches. With the 1985 update, the maximum permitted riser was 7 inches, and the minimum tread was 11 inches.

Whether the changes caused a marginal increase in stair safety is debatable. What they did do is to render most existing buildings nonconforming. To change these nonconforming stairways would require complete reconstruction of the stairwells. In a high-rise building, it would necessitate major structural work, as well as a loss of leasable space—to correct a “deficiency” that is not associated with any particular hazard or harm.

Thus, an element of judgment enters calculations about code conformance. When a code is used as an absolute standard, then a building either conforms or does not. In the case of existing buildings, that is often not the most effective or intelligent way to use the code. Instead, designers and code officials must consider means of achieving the code’s significant goals without necessarily meeting its specific details.

CHAPTER 2

How Codes Regulate Buildings

For millennia, human beings have constructed buildings to provide safety, health, and comfort. Like many solutions, construction of shelter generates its own set of problems. Though providing protection from weather and predators, buildings may collapse, catch fire and burn, or provide an unhealthful or unsafe interior environment. Building regulations have developed in response to these problems.

UNDERSTANDING CODE APPROACH

Under the U.S. Constitution, the responsibility for public safety is left up to the states. Thus, the power to regulate buildings is derived from “police power,” the right of each state to enact and enforce laws to regulate health, safety, and public welfare. Limiting hazards posed by buildings is an important part of each state’s responsibility.

A key concept in building code development is that of acceptable level of risk. No activity, including that of enjoying shelter, is risk-free. Society decides what level of risk is appropriate for specific kinds of buildings and revises this decision periodically. Codes represent expert opinion, usually fairly accurate, concerning what physical characteristics are needed to achieve a level of building performance that produces acceptable risk.

Historically, codes have regulated four overall risk sets:

Life and property loss in fires. Codes originated partly to prevent fire from spreading from one building to another. In later years, provisions were tightened to attempt to prevent casualties outside the room of fire origin. Today’s codes are beginning to address preventing casualties even within the room of ignition.Speed of exiting. A major concern in the protection of building occupants’ lives is the speed of possible exiting. Exiting can be pictured as a race between the occupants and the fire and combustion products. The outcome of the race can be improved by decreasing the fire’s head start, hastening the occupants’ escape, and reducing the fire’s speed.Partial or total structural collapse under foreseeable conditions. This concern addresses natural hazards such as snow, wind, and earthquake forces, as well as normal gravity loads from construction and occupancy of the building.General health and safety. This category includes habitability requirements such as ventilation and sanitation, accessibility, and accident prevention features, such as guardrails, steepness of stairs, and safety glazing. In recent years, energy conservation and accessibility improvements have been added to this category of regulation.

To control these risks, building codes address the following attributes of buildings and their parts:

Occupancy—The uses permitted for a particular building or building areaSiting—Relationship of the building to the land on which it is built, to property lines, and to the streets and alleys around itMaterials of constructionBuilding and component size, including overall plan dimensions, height, number of stories (called “heights and areas” in building codes), size of individual compartments, ceiling heights, widths of exits, and dimensions of stair risers and treads

Each of these factors influences all the others. When a new building is designed, the occupancy and overall desired size may be the only known elements. All other characteristics emerge during the design process. In rehabilitation, however, the only completely flexible factor is occupancy. Apart from appropriate occupancy choice, rehabilitation design relies on understanding the reasons for controls on siting, materials, and sizes so that effective alternates to the letter of the code can be developed if necessary.

PART 2

DEVELOPMENT OF CODES AND STANDARDS IN THE UNITED STATES

CHAPTER 3

Development of Building Codes in the United States

This chapter traces the evolution of local and model building regulations and of other standards that have affected building rehabilitation in the United States. Building regulations have typically followed, and have been partly inspired by, high-profile disasters. While such events have often provided final impetus for change, other factors have also promoted reform. A single event is less likely to cause widespread change than to act as a catalyst for reforms that might have come gradually in any case.

Major City and Building Fires in the United States

This list does not include fires that occurred as a result of acts of war. All listed fires caused major life and property loss.

DateDisasterCode Action1788 and 1794New Orleans Conflagrations1805Detroit Conflagration1811Richmond Theater Fire1813Portsmouth, New Hampshire ConflagrationThe Portsmouth, New Hampshire, Brick Act of 18141820, 1854, and 1862Troy, New York Conflagrations1835Great Fire of New YorkRebuilding with masonry and construction of new water system1849St. Louis FireLocal requirements for masonry construction and new water system1866Great Fire of Portland, Maine1871Great Chicago FireChicago Building Code (1875)1871Peshtigo, Wisconsin Fire1871Great Boston Fire1871Port Huron Conflagration1876Conway’s Theater Fire, New York1889Great Seattle FireLocal zoning to create fire district1901Great Fire of 1901, Jacksonville, Florida1903Iroquois Theater Fire1904Great Baltimore FireNational Building Code recommended by the National Board of Fire Underwriters (1905)1906San Francisco Earthquake and FireCodes were relaxed to permit quick reconstruction1908Rhodes Opera House Fire, Boyertown, Pennsylvania1911Triangle Shirtwaist Fire1917Great Atlanta FireLocal ordinance prohibiting wood shingles1923Berkeley, California Conflagration1942Coconut Grove Fire1944Hartford Circus FireLocal laws banning circus tents1946LaSalle Hotel FireLocal requirements for hotel safety1958Our Lady of Angels Fire, ChicagoNationwide changes in school safety procedures. Local fire code changes. New amendments to Illinois state fire code.1982Dorothy Mae Apartments, Los AngelesRetroactive ordinance requiring automatic sprinklers in common areas, inside entry doors into each residential unit, and fire alarm systems in buildings 3 stories and greater.

The table illustrates a number of major fires that have occurred in the United States. Many of these have resulted in building and fire code changes. Besides disasters, influences may include a series of smaller events, scientific and engineering advances that make problems more open to solution, publications by reformers, economic forces, and historical or cultural factors.

Although regulation of buildings may be traced to ancient times, tension always remains between the needs of society and the rights of the property owner. This tension may result in codes evolving through clear necessity, for example, to prevent recurrence of a disaster. Simultaneously, pressure in favor of regulation may come from social reformers, civic leaders, or affected industries, such as the insurance industry.

LOCAL CODES

Housing and building laws in the United States began at the level of local government and developed alongside public health regulations. The first comprehensive building law in the United States was the Tenement House Act passed by the City of New York in 1867. That may be put into context with the then-nascent science of epidemiology, which is generally agreed to have begun with John Snow’s 1854 discovery that a cholera outbreak in London could be traced to a polluted well, thus establishing an indisputable scientific connection between environment and health.

In the decade prior to the Tenement House Act, New York had seen wave after wave of immigration. Vast numbers of the newcomers were poor; many could not speak fluent English. Profit-minded landlords developed minimal housing in response to this demand. Health and safety conditions in these tenements were unspeakable.

Spurred by both idealism and fear of contagion, the Tenement House Act addressed minimal safety and health improvements; revisions in 1879 and 1901 increased the standards to include detailed provisions for lighting, sanitation, ventilation, room size, and other characteristics.

A similar alliance of reform and self-interest spurred the growth of local building regulations. Losses of life and property in several fires led to widespread support for development and enforcement of building standards. The earliest building controls were enacted at the local level, notably the Portsmouth, New Hampshire, Brick Act of 1814 and the Chicago Building Code of 1875. These reforms were urged by insurance companies as a way of controlling financial loss, and were generally supported by public outrage over the conditions that had produced the disasters.

EARLY MODEL CODES

A model code is a document prepared by a group of experts who have no legislative authority. It is not written for a specific jurisdiction and is not law until it is adopted by a jurisdiction, often with modifications. Model codes make it possible for jurisdictions to benefit from professional expertise without having to maintain a staff capable of writing a code. In addition, adoption of a model code produces coordinated requirements that are more or less uniform over a wide area. This, in turn, stimulates building by removing legal complexities from the process.

The earliest model code in the United States was the National Building Code recommended by the National Board of Fire Underwriters, published in 1905 in response to fire insurance losses in the Great Baltimore Fire of 1904 (Figure 3.1). The purpose of this code was to limit fire spread from the building of fire origin. Provisions included requirements for fire walls on property lines, control of roofing material, limitations on windows in fire-resistant walls, and other measures.

Figure 3.1 The cover of the National Board of Fire Underwriters Building Code published in 1905. It was widely adopted by local jurisdictions and became the basis for many local codes. From University of California library, as scanned by Google

Adopted in toto by many larger cities across the United States, the National Building Code also served as the basis for locally written codes. Because it was promulgated by an industry that was not organized for the purpose of writing codes, the document had no specified update procedure and little, if any, opportunity for public involvement in changes.

In 1913, standards for fire safety in schools and factories and for building exiting were published by the National Fire Protection Association (NFPA). The standards were expanded and published in 1927 as the Building Exits Code. Intentionally limited in scope to adequate egress, this document addressed the conditions that had led to several disasters, including the Iroquois Theater Fire in 1903 and the 1911 Triangle Shirtwaist Fire. Though promulgated by a professional code-writing organization rather than by the insurance industry, the Building Exits Code did not meet the need for a professional comprehensive code because of its restricted scope. The current NFPA publication that corresponds to the Building Exits Code is the Life Safety Code, commonly called NFPA 101.

COMPREHENSIVE MODEL CODES

Regional Model Codes

In 1927, the Pacific Coast Building Officials promulgated the Pacific Coast Building Code, which later became the Uniform Building Code (Figure 3.2). The organization of this code differed from that of the National Building Code in that it ranked occupancies by life risk and linked fire safety criteria to specific occupancies. The code included provisions for exiting and control of material finishes. In addition, this code contained numerous structural provisions organized by building material type. The Uniform Building Code was widely used west of the Mississippi River until the adoption of the International Building Code in 2000. The National Building Code was promulgated by the insurance industry. It was the basis for most local and state codes until late in the last century.

Figure 3.2 A reprint of the cover of the first Uniform Building Code in 1927. This code is different in its organization than previous codes. It is organized by occupancy and construction requirements, structural material design, egress, and other requirements. Its organization became the basis for most later building codes. © International Code Council

The Southern Building Code, later the Southern Standard Building Code (SBC), was first published by the Southern Building Code Congress in 1945. In the southern states, hurricanes were a major issue, so design for wind was an important consideration in the code.

The Basic Building Code, published by the Building Officials of America (now the Building Officials and Code Administrators International) (BOCA), was first published in 1950. It served the Midwest and New England regions. BOCA later obtained the right to use the title National Building Code. Some editions of the code are called the BOCA/National Building Code.

These organizations that published the three model codes were membership organizations with members from the building industry, the building regulatory community, and the public. Originally, only building officials could vote on code changes. However, the code change process was an open process involving submittals, hearings with industry and public involvement, and open advisory voting by the membership. The model building codes were updated on a three-year cycle.

International Building Code

Beginning in the late 1980s, efforts were made to improve consistency and uniformity among the three model codes. By 1990, agreement was reached on consistent chapter organization in the codes, reasonably consistent occupancy definitions, and construction types. The three model codes agreed to form the International Code Council and to publish one national model code. This resulted in the publication of the 2000 edition of the International Building Code. The International Building Code is updated on a three-year cycle.

CHAPTER 4

Development of Model Code Provisions for Existing Buildings

REGIONAL MODEL CODES

As soon as a building code is written or modified, a class of nonconforming buildings is created. Since adherence to code minimums produces the most inadequate building that may legally be constructed, it could be argued that nonconforming existing buildings should be raised to at least that standard.

But the question of whether, how, and when existing buildings should be brought into conformance with the code is one without an easy answer. It is clearly infeasible for owners to remodel with every code change. In addition, retroactive application of laws is difficult and subject to legal challenge; the need for such action would have to be compelling.

Traditionally, building codes have addressed this problem with a threefold approach.

1. The building code establishes, or refers to a code that establishes, a level of health and safety below which a building may not legally be maintained. Such codes may be called “abatement codes,” “housing codes,” “property maintenance codes,” or a similar title. Provisions of abatement codes are retroactively applied through a citation process, regardless of whether any building work had been contemplated by the owner. Failure to comply can lead to building condemnation and demolition. Abatement codes were written by each of the model code organizations and were coordinated with the building codes.

2. In cases of demonstrated need, specific code provisions may be applied retroactively to otherwise acceptable building types. An example would be the widespread retroactive requirement for smoke detectors in residences and enclosure of stairways in schools and apartment buildings.

3. Buildings that do not fall under abatement codes may be required to be upgraded as part of an approvals process for remodeling or change of use. Here the code is not being applied retroactively, because the building has previously been approved for conditions different from those proposed.

Efforts for safety in structures have gone on for years. Figures 4.1 and 4.2 show an added stair that was probably added in response to a retroactive provision in high-rise structures that had only a single stairway. This alteration was done in the 1950s, when there was much concern over safety in high-rise structures.

Figure 4.1 A high-rise urban building. Such buildings often had a single stairway with a fire escape. After a series of high-rise building fires with loss of life, cities implemented retroactive stairway requirements. © Melvyn Green

Figure 4.2 The same building as in Figure 4.1 showing an exterior stairway constructed in the 1950s on the building’s exterior to resolve fire safety issues. © Melvyn Green

An inconsistency may be noted between the minimum level of health and safety permitted in new construction and the minimum level required, under abatement codes, for a building to continue to exist. In reality, much of the work of rehabilitating buildings takes place between these two poles, in the area where a building is technically nonconforming but is not considered unsafe.

As codes have developed, different methods for dealing with building rehabilitation have been tried. One attempt was the “25–50 percent rule,” under which

Only the new work would be required to conform to the current code if the value of the rehabilitation was less than 25 percent of the assessed value of the building.The entire building would be required to conform to the code for new construction if the value of the rehabilitation work exceeded 50 percent of the building’s assessed value.In cases in which the value of the rehabilitation work was between 25 and 50 percent of the building’s value, the judgment of the building official would determine the degree of compliance appropriate.

Uniform Building Code 1976 Edition

SECTION 104 APPLICATION TO EXISTING BUILDINGS

(a) General. Buildings or structures to which additions, alterations, or repairs are made shall comply with all the requirements for new buildings or structures except as specifically provided in this section.

(b) Additions, Alterations and Repairs: More than 50 Percent. When additions, alterations, or repairs within any 12 month period exceed 50 percent of the value of an existing building or structure, such building or structure shall be made to conform to the requirements for new buildings or structures.

(c) Additions, Alterations and Repairs: 25 to 50 Percent. Additions, alterations, or repairs exceeding 25 percent but not exceeding 50 percent of the value of an existing building or structure and complying with the requirements for new buildings or structures may be made to such building or structure within any 12-month period without making the entire building or structure comply. The new construction shall conform to the requirements of this Code for new building of like area, height, and occupancy. Such building or structure, including new additions, shall not exceed the areas and heights specified in this Code.

(d) Additions, Alterations and Repairs: 25 Percent or Less. Structural additions, alterations, or repairs to any portion of an existing building or structure, within any 12-month period, not exceeding 25 percent of the value of the building or structure shall comply with all of the requirements for new buildings or structures, except that minor structural additions, alterations, or repairs, when approved by the Building Official, may be made with the same material of which the building or structure is constructed. Such building or structure, including new additions, shall not exceed the areas and heights specified in this Code.

(e) Nonstructural, Alterations and Repairs: 25 Percent or Less. Alterations, or repairs, not exceeding 25 percent of the value of an existing building or structure, which are nonstructural and do not affect any member or part of the building or structure having required fire resistance, may be made with the same materials of which the building or structure is constructed.

(g) Existing Occupancy. Buildings in existence at the time of the passage of this Code may have their existing use or occupancy continued, if such use or occupancy was legal at the time of the passage of this Code, provided such continued use is not dangerous to life.

Any change in the use or occupancy of any existing building or structure shall comply with the provisions of Sections 306 and 502.

Whether by design or accident, the 25–50 percent approach erects barriers to rehabilitation of seriously deteriorated buildings or buildings in neighborhoods where property values are low. Beyond a certain point, the rule assumes, improvements to the building are uneconomical, and, therefore, the building should be razed and replaced with a structure that conforms to the code for new construction.

In practice, the 25–50 percent rule worked poorly. Property owners in economically depressed neighborhoods could not improve their buildings, because the assessed value was low compared to the cost of repairs. In addition, the necessarily slow pace of the building condemnation process left many seriously deficient structures in use.

Further difficulties were caused if rehabilitation involved a change of use. Early approaches simply said that moving up in risk required compliance. For example, exterior walls of a dwelling that is 3 feet or more from a property line were not required to be fire resistant. In practice, this means that they could be constructed of wood with wood siding. Windows were not required to be rated either and most wood dwellings used simple wood sash windows. However, requirements for fire resistance of exterior walls and windows of an office are quite different, and these characteristics are quite difficult to change. As a result, conversion of a Victorian house to legal offices would have been nearly impossible. This approach resulted in the destruction of many historic buildings because literal compliance with requirements for a workable occupancy was not possible.

During the mid-1970s through the mid-1980s, the model code groups made successive changes in their provisions for existing buildings. All dropped the 25–50 percent rule from the published model codes, though some local jurisdictions and states chose to retain it. Again, language and details differed, though the objective was the same. A look at the relevant provisions of the three codes during that era shows how the approach to existing buildings was changing. Overall, the direction was to avoid restrictive provisions that would prevent rehabilitation, while retaining specific safety measures for fire resistance, structural integrity, and change of occupancy.

The following excerpts from codes of that era show a variety of approaches to modification of provisions for existing buildings.

Uniform Building Code 1979 Edition

SECTION 104 APPLICATION TO EXISTING BUILDINGS

(a) General. Buildings or structures to which additions, alterations, or repairs are made shall comply with all the requirements for new buildings or structures except as specifically provided in this section.

(b) Additions, Alterations and Repairs. Additions, alterations or repairs may be made to any building or structure without requiring the existing building or structure to comply with all the requirements of this code provided the addition, alteration or repair conforms to that required for a new building or structure. Additions, alterations or repairs shall not cause an existing building or structure to become unsafe or overloaded. Any building so altered, which involves a change in use or occupancy, shall not exceed the height, number of stories or area permitted for new buildings. Any building plus new additions shall not exceed the height, number of stories and area specified for new buildings.

Alterations or repairs to an existing building or structure which are nonstructural and do not adversely affect any structural member or any part of the building or structure having required fire resistance may be made with the same materials of which the building or structure is constructed.

BOCA National Building Code 1987 Edition

SECTION 103.0 EXISTING STRUCTURES

103.1 Continuation of existing use: The legal use and occupancy of any structure existing on the date of adoption of this code, or for which it has been heretofore approved, shall be permitted to continue without change, except as specifically covered in this code, the existing structures or fire prevention codes listed in Appendix A, or as is deemed necessary by the code official for the general safety and welfare of the occupants and the public.

103.2 Change in use: It shall be unlawful to make any change in the use or occupancy of any structure or portion thereof which would subject it to any special provisions of this code with approval of the code official, and the code official’s certification that such structure meets the intent of the provisions of law governing building construction for the proposed new use and occupancy, and that such change does not result in any greater hazard to public safety or welfare.

103.3 Additions, alterations or repairs: Additions, alterations or repairs to any structure shall conform to that required of a new structure without requiring the existing structure to comply with all the requirements of this code. Additions, alterations or repairs shall not cause an existing structure to become unsafe or adversely affect the performance of the building. Any building plus new additions shall not exceed height, number of stories and area specified for new buildings.

Alterations or repairs to an existing structure which are structural or adversely affect any structural member or any part of the fire resistance rating shall be made with materials required for a new structure.

Standard Building Code 1988 Edition

SECTION 101.5 EXISTING BUILDINGS

101.5.1 General. Alterations, repairs or rehabilitation work may be made to any existing building without requiring the building to comply with all the requirements of this Code provided that the alteration, repair or rehabilitation work conforms to the requirements of this Code for new construction. The Building Official shall determine the extent to which the existing system shall be made to conform to the requirements of this Code for new construction.

101.5.2 Change of Occupancy. If the occupancy classification of an existing building is changed, the building shall be made to conform to the intent of this Code as required by the Building Official.

In practice, this subjective approach to building rehabilitation worked well in sophisticated, well-staffed building departments, but was less effective in departments with fewer resources.

As this limitation became apparent, all three model code groups developed separate codes and provisions for building rehabilitation. The BOCA Basic/National Existing Structures Code was published in 1984, followed by the Uniform Code for Building Conservation in 1985 and the Standard Existing Building Code in 1988. The three codes varied in scope, but all addressed the problems of existing buildings. All required that new work meet the code for new construction but relied on the judgment of the building official to determine extent of compliance required for existing building fabric.

For change of occupancy, the Uniform Code for Building Conservation (UCBC) used an approach that considered the specific building features that affected life safety, spread of fire, and seismic safety. This was accomplished by the use of hazard tables that clarified the life and fire risk as well as building height and area limitations and seismic strengthening. Moving up in hazard category required code compliance, but maintaining or reducing a building’s risk level allowed acceptance of existing exits, exterior fire protection, and other systems.

In the previous example of the Victorian house, an exterior wall table would have defined a business occupancy at the same risk level as a single-family dwelling. So the UCBC developed the hazard-ranking tables based on fire records and the experience of building and fire officials. For historic buildings, the impact was a major reduction in the loss of historic fabric.

INTERNATIONAL BUILDING CODE

The International Building Code was first published in 2000. Regulations for existing buildings were similar to those contained in the three model codes but more extensive. The 2009 IBC uses the basic concepts of previous editions, but continues to evolve. The major change in both the 2009 IBC and IEBC is the division of the regulations for additions, alterations, and repairs into individual sections. Selected provisions of the 2009 IBC are shown below.

2009 International Building Code

3403.1 General. Additions to any building or structure shall comply with the requirements of this code for new construction. Alterations to the existing building or structure shall be made to ensure that the existing building or structure together with the addition are no less conforming with the provisions of this code than the existing building or structure was prior to the addition. An existing building together with its additions shall comply with the height and area provisions of Chapter 5.

3404.2 Flood hazard areas. For buildings and structures in flood hazard areas established in Section 1612.3, any alteration that constitutes substantial improvement of the existing structure, as defined in Section 1612.2, shall comply with the flood design requirements for new construction, and all aspects of the existing structure