scope:

Introduction

THIS MANUAL strives to provide the major needed information and data to design and maintain moisture-resistant buildings and to investigate and correct moisture problems in existing buildings. It contains individual chapters devoted to the primary disciplines and mechanisms that promote and resist moisture-induced damage. To be responsive to the perceived need, it was essential to include in the manual many disciplines, types of investigators, theoreticians, and practitioners. Because these individuals do not currently agree in all aspects with one another, there are some conflicts and inconsistencies between the individual chapters.

As mentioned in the Preface, the main concern of building design is the development of structures for human habitation that are safe, provide a healthy and pleasant environment, and maintain these functions over a long service life. Since moisture affects all three, concerns for effective moisture control must be an integral part of the design process. This manual attempts to bring together in one volume the current state of the art relating to moisture control in buildings (good design practices), diagnosis and prevention of moisture-originated damage, and guidelines for rehabilitation of the structures. The manual addresses residential, commercial, and institutional buildings in all North American climatic zones. In all jurisdictions, design professionals are required to follow accepted standards of practice, but for many issues on moisture, accepted standards and practices are few or missing altogether and others are outdated by the development of new materials, new combinations of old materials into new systems, and new insights into the behavior of materials and structures.

The publication of this manual responds not only to the increasing awareness of the long-known potential structural and maintenance problems resulting from inadequate moisture control, but also to the more recently recognized and potentially even more serious health hazards of rot, mold, and other organisms which flourish in buildings with excessive moisture, or in localized areas with a conducive combination of moisture and temperature. The manual also recognizes the various interactions of materials, construction, equipment, and habitation, and the balance between the indoor environment, the building envelope, and the outdoor environment with its constantly changing temperature, humidity, and radiation.

The manual consists of four parts. Part 1, "Fundamentals," provides fundamental information and data relating to moisture control and the effects of moisture on buildings. Part 2, "Applications," discusses the application of related technologies to prevent or solve moisture problems in buildings. Part 3, "Construction Principles and Recommendations," gives guidelines and recommendations for designing and constructing new buildings and for increasing the moisture resistance of existing buildings. Part 4, "Implementation," provides insights into the various mechanisms for implementing moisture control strategies.

In Part 1, "Fundamentals," the theoretical basis of moisture control and applicable data is provided. Chapter 1 discusses the fundamentals of moisture transfer, condensation, and evaporation, and the appendix to the chapter is directed toward those with little or no knowledge of moisture transport mechanisms; the main body of Chapter 1 will be more useful to those with a good general understanding of the physical phenomena involved. Closely related to the first chapter is Chapter 2, which discusses the state of the art in computer programs for modeling the mechanisms discussed in Chapter 1. Chapters 3, 4, and 5 provide needed information and data on moisture-related properties of building materials and how their performance is affected by moisture. These chapters discuss building materials in general (Chapter 3), thermal insulations (Chapter 4), wood and wood products (Chapter 5). The last three chapters in Part I discuss: molds and other organisms in buildings and related health effects (Chapter 6); considerations of climate (Chapter 7), which includes needed tabular data for the United States, Canada, and other countries required for identifying climate zones and for use in calculations discussed in Chapters I and 11; and Moisture Sources (Chapter 8), which describes in both quantitative and qualitative form the major possible sources of moisture in buildings.

Part 2, "Applications," discusses the technologies that affect the moisture balance in buildings and the techniques used to determine the adequacy of materials, components, systems, and structures. Chapter 9 discusses the effect of ventilation and ventilation strategies both in cold and in warm and humid climates. Chapter 10 is devoted to issues of heating and cooling equipment and how they can be used to control moisture in buildings. In Chapter 11, several design tools for determining potential moisture effects on building components are discussed and their use demonstrated. Chapters 12 and 13 discuss the myriad of tests and measurement methods that can be used to determine material or component properties both in the field and in the laboratory (Chapter 12) and the techniques and methods used by investigators of moisture problems, including examples to demonstrate the use of test and evaluation methods (Chapter 13). An appendix to Chapter 13 also discusses statistical issues relating to the number of tests to perform and the degree of confidence a certain number of tests provides. The last chapter in Part 2, Chapter 14, provides a valuable compilation and discussion of many case studies conducted in this country and in Canada for determining the effect of moisture on constructions of actual buildings and to test various proposed standards designed to increase energy efficiency and moisture resistance. This chapter is useful in understanding the effect of climate on different building systems, components, and materials. The chapter will also be particularly helpful to those planning their own large-scale field studies. Because of a lack of major field studies and data on commercial and high-rise buildings, the chapter discusses only residential constructions.

Part 3, "Construction Principles and Recommendations," provides eight authors' recommendations for the design and construction of new moisture-resistant buildings and for upgrading existing buildings for greater moisture resistance or tolerance. The authors were carefully selected to provide a broad spectrum of the current state of the art, approaches, and solutions. Because of this, and because moisture control in buildings is still an immature science, still largely an art, the authors of these chapters do not necessarily agree with one another. Also, the guidelines are not ASTM recommendations, but present the authors' own understanding of the subject. Chapter 15 discusses the general concepts of moisture-resistant buildings. The chapter provides the traditional, generally accepted principles which apply to all buildings. Chapter 16 is devoted to roofing. Although it is recognized that roofing is the most important building component with regard to moisture control in buildings, roofing is discussed only in this chapter as it is recognized that roofing technology is well advanced and has its own broad and generally accessible literature. Chapter 17 discusses new residential construction. Chapters 18, 19, and 20 discuss new commercial and high-rise buildings (Chapter 18); existing residential buildings (Chapter 19), and existing commercial and high-rise buildings (Chapter 20). Because manufactured homes and historic buildings have unique moisture-related concerns, Chapters 21 and 22 were included to discuss these special building types.

Part 4 discusses implementation mechanisms. This section is organized along a simple concel~t: First, the building should be designed, built, and repaired according to contract documents which contain the principles outlined in the earlier sections and chapters. Second, codes and standards provide a firm basis for selecting products, systems, and construction features, and third, when all else fails, there are arbitration and court proceedings to resolve conflicts. The first three chapters of Part 4 follow these three phases. Chapter 23 explains the role of contract documents--specifications and drawings-- in implementing moisture control strategies and provides guidelines for those not familiar with architectural design and production. Chapter 24 provides a useful compilation of standards and codes relevant to moisture control in buildings. Chapter 25 discusses legal aspects, illustrated by a real life case study. It was suggested above that moisture control in buildings is not currently treated as a separate design discipline and that it is the hope of the editor and the authors that this manual will contribute to the establishment of such a discipline. The last chapter of Part 4, Chapter 26, suggests, as a start towards such a discipline, a methodology for the design of moisture-resistant buildings modeled after the well-established methods used for structural design and analysis.

It is the policy of ASTM to require SI (metric) measurements in all its publications. Accordingly, all chapters use SI units in the text, and most chapters also provide common units in the text. Most tabular data are provided in only one measurement system. As a convenience to the reader, a metric conversion table is printed at the back of this book.

ASTM, the editor, and the individual chapter authors request comments on the usefulness, technical content, format, and any other issues related to the manual in its current form. We will strive to respond to all comments and to incorporate useful suggestions in any upcoming editions.