Astm stp 1498 2011

Journal of Testing and Evaluation

Selected Technical Papers

STP 1498

Condensation

in Exterior

Building Wall

Systems

JTE Guest Editors:

Bruce Kaskel

Robert J. Kudder

Journal of Testing and Evaluation

Selected Technical Papers STP1498

Condensation in Exterior Building

Wall Systems

JTE Guest Editors:

Bruce S. Kaskel

Robert J. Kudder

ASTM International

100 Barr Harbor Drive

PO Box C700

West Conshohocken, PA 19428-2959

Printed in the U.S.A.

ASTM Stock #: STP1498

Library of Congress Cataloging-in-Publication Data

Condensation in exterior building wall systems / JAI guest editors, Bruce S. Kaskel,

Robert J. Kudder.

p. cm. -- (Journal of testing and evaluation selected technical papers; STP1498)

Includes bibliographical reference and index.

ISBN: 978-0-8031-4471-2 (alk. paper)

1. Dampness in buildings. 2. Exterior walls--Protection. 3. Waterproofing. I. Kaskel,

Bruce S. II. Kudder, Robert J., 1945-

TH9031.C663 2001

693.8’93--dc22 2011006935

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Foreword

THIS COMPILATION OF THE JOURNAL of TESTING and EVALUATION

(JTE), STP1498, on Condensation in Exterior Building Wall Systems

contains only the papers published in JTE that were presented at a

symposium in San Antonio, TX, October 10–11, 2010 and sponsored by

ASTM Committee E06 on Performance of Buildings.

The Symposium Co-Chairmen and JTE Guest Editors are Bruce S.

Kaskel, Wiss, Janney, Elstner, Associates, Inc., Chicago, IL and Robert J.

Kudder, Raths, Raths & Johnson, Inc., Willowbrook, IL.

Contents

Overview ........................................................................ vii

Insulation Draws Water

W. B. Rose........................................................... 1

Testing/Analysis

Laboratory Tests of Window-Wall Interface Details to Evaluate the Risk of Condensation

on Windows

W. Maref, N. Van De Bossche, M. Armstrong, M. A. Lacasse,

H. Elmahdy, and R. Glazer............................................... 31

Drying Characteristics of Spray-Applied Cellulose Fiber Insulation

M. Pazera and M. Salonvaara............................................. 59

Moisture Damage in Vented Air Space of Exterior Walls of Wooden Houses

T. Umeno and S. Hokoi.................................................. 80

Moisture Measurements and Condensation Potential in Wood Frame Walls in a

Hot-Humid Climate

T. A. Weston and L. C. Minnich........................................... 94

A Review of ASHRAE Standard 160—Criteria for Moisture Control Design Analysis in

Buildings

A. TenWolde.......................................................... 119

Moisture Response of Sheathing Board in Conventional and Rain-Screen Wall Systems

with Shiplap Cladding

F. Tariku and H. Ge..................................................... 131

Investigation of the Condensation Potential Between Wood Windows and Sill Pans in a

Warm, Humid Climate

G. P. Stamatiades, III................................................... 148

Case Studies

Interior Metal Components and the Thermal Performance of Window Frames

S. K. Flock and G. D. Hall................................................ 169

Controlling Condensation Through the Use of Active and Passive Glazing Systems

A. A. Dunlap, P. G. Johnson, and C. A. Songer................................ 187

Case Study of Mechanical Control of Condensation in Exterior Walls

C. M. Morgan, L. M. McGowan, and L. D. Flick............................... 226

Considerations for Controlling Condensation in High-Humidity Buildings: Lessons

Learned

S. M. O’Brien and A. K. Patel............................................. 247

Fenestration Condensation Resistance: Computer Simulation and In Situ

Performance

E. Ordner............................................................ 269

Improving the Condensation Resistance of Fenestration by Considering Total Building

Enclosure and Mechanical System Interaction

P. E. Nelson and P. E. Totten............................................. 286

Condensation Problems in Precast Concrete Cladding Systems in Cold Climates

T. A. Gorrell.......................................................... 299

Author Index ..................................................................... 315

Subject Index .................................................................... 317

Overview

This STP represents the peer-reviewed papers first presented at the October

10–11, 2010 symposium on Condensation in Exterior Wall Systems in San

Antonio, Texas, sponsored by ASTM E06 Building Performance, Subcom￾mittee E06.55 Exterior Wall Systems. The symposium and this STP repre￾sent the continued efforts of this subcommittee to exchange state-of-the-art

knowledge through symposia on topics related to the performance of exte￾rior wall systems. Past symposia of this subcommittee include water leak￾age, repair and retrofit, façade inspection and maintenance, and perfor￾mance of exterior wall systems. Condensation in walls is a timely topic for

ASTM E06 to address. Advancements in building sustainability, energy ef￾ficiency, and new wall systems have progressed significantly in recent years,

while the consequential changes in wall moisture behavior resulting from

these advancements are less well understood.

Although the topic of condensation, per se, is not addressed in this sub￾committees prior symposia, it has been a related topic in much of the work of

this subcommittee and the ASTM E06 committee at large. Numerous previ￾ous papers, available through ASTM, have addressed this topic. Seminal

manuals and prior symposia presented by ASTM E06, and ASTM committee

C16 on Thermal Insulation, chaired solely or in part by Heinz Treschel,

serve as background to our current work. A sampling of those volumes in￾cludes:

MNL 40 Moisture Analysis & Condensation Control in Building Enve￾lopes - Treschel, ed. 2001;

MNL 18 Moisture Control in Buildings - Treschel, ed. 1994; and

STP 1039 Water Vapor Transmission Through building Materials and

Systems Treschel and Bomberg, eds. 1987.

Manual MNL 40 described some of the now-established computer simu￾lations for condensation control such as WUFI (ORNL/IBP). Given the now

nine years time since that work was published, E06 believed that the state￾of-the-art had advanced and that practical experiences have been gained

from the use of analytical products that were presented in the 2001 manual.

This symposium provided the opportunity for leading scientists and practi￾tioners to again advance the body of knowledge on the topic of condensation

in exterior wall systems.

Beyond ASTM, organizations such as ASHRAE have offered longstand￾ing input on the issue of condensation control. Other organizations have

grown more recently, such as BETEC; and USGBC along with their LEED

certification system. These organizations are interested, directly or periph￾erally, in the issue of condensation. They too have offered recent workshops

on the topic of condensation. Code writing organizations such as IBC, in

their energy code IECC, as well as their under-development green code,

vii

IgCC, are actively codifying issues related to condensation control, which

were brought to light in prior ASTM publications and in the work of these

other organizations. E06 believed in presenting this symposium, that these

current papers on condensation could have a similar impact in future build￾ing codes.

This STP is organized, in the same presentation as the October 2010 sym￾posium, into two parts:

Testing/Analysis 7 papers that concentrate on testing/analysis of materi￾als and mock-ups to predict and prevent condensation in common exterior

wall systems and

Case Studies 7 papers that document condensation problems found in the

real-world and their solutions.

In addition, there is one keynote paper by William Rose, which presents

the history that has lead to the present state-of-the-art and some of the er￾roneous concepts that have advanced to today. This paper sets the tone that

common-place thinking does not well serve the industry, and when it comes

to the on-going discussion of condensation control, new ideas, and concepts,

the consistent application of the principles of physics and the use of appro￾priate analytical techniques need to be embraced.

Although not included in this STP, the symposium attendees also ben￾efited from a first-day tutorial session offered by Wagdy Anis and Robert

Kudder on condensation. This primer provided the science of condensation

formation and present technologies used to control its formation. For those

without this background, this tutorial served as necessary background for

the technical presentations.

An ASTM symposium and STP are a team-effort, which warrants the rec￾ognition of those who spend much time and energy in their success. First,

recognition goes to the many unnamed reviewers who, solely to better the

industry, spent many hours reviewing and re-reviewing the submitted pa￾pers. ASTM and JTE efforts were spearheaded by Dorothy Fitzpatrick and

Susan Reilly, respectively, with able assistance by Hannah Sparks and

Christine Urso. Upon Dorothy’s retirement, Mary Mikolajewski ably

stepped in. Finally, special recognition goes to WJE staffer, Amber Stokes,

who assisted the Editors keep to the ambitious review and symposium

schedule, and the numerous email correspondences necessary to pull this all

together.

Bruce S. Kaskel

Wiss, Janney, Elstner Associates, Inc.

10 S. LaSalle Street, Chicago, IL

Robert J. Kudder

Raths, Raths & Johnson, Inc.

835 Midway Drive, Willowbrook, IL

viii

William B. Rose1

Insulation Draws Water

ABSTRACT: In the late 1930s, an architect and two researchers created a

version of hygrothermal building science for the United States that focused

on moisture conditions in exterior materials during cold weather. The version

they created was partial, and it was biased: It highlighted the importance of

vapor transport, while it obscured the importance of temperature impact.

They based their argument on the prevention of “condensation,” yet they

failed to provide a definition of condensation sufficient for use as a perfor￾mance measure or criterion. They produced prescriptive recommendations

that later became code requirements, and these prescriptions embodied the

incomplete and biased nature of their analysis. They supported their argu￾ment with a flawed and misleading analogy. They and their followers left a

legacy of consumer fear of ill-defined moisture effects in buildings and of

designers assigning excessive importance to prescriptive measures. Their

version provides inadequate preparation for the anticipated re-insulation of

millions of U.S. buildings in the years to come. This paper will provide a short

description of the hygrothermal issues involved. It will trace the development

of the condensation version by Rogers, Teesdale, and Rowley and the efforts

that followed up to 1952. It will explain the legacy and impact of this ap￾proach related to existing building re-insulation and professional practice in

design and architecture. It will propose a framework for reviewing the link

between moisture control prescriptive requirements and performance out￾comes.

KEYWORDS: condensation, moisture control, insulation

Condensation

In 1901, in the course of the design of the Minnesota State Capitol Building, the

architect Cass Gilbert was in discussion with Mr. Guastavino, a highly regarded

supplier of ceiling tiles, and a Mr. Butler, the contractor. Gilbert’s notes indicate

Manuscript received January 21, 2010; accepted for publication June 14, 2010; published

online August 2010.

1 Research Architect, Univ. of Illinois at Urbana-Champaign, Champaign, IL 61820.

Cite as: Rose, W. B., ‘‘Insulation Draws Water,’’ J. Test. Eval., Vol. 39, No. 1. doi:10.1520/

JTE102972.

Reprinted from JTE, Vol. 39, No. 1

doi:10.1520/JTE102972

Available online at www.astm.org/JTE

Copyright © 2011 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West

Conshohocken, PA 19428-2959.

1

I urged that great difficulty might be encountered in condensation, in

which Mr. Butler agreed, and that this condensation would drip and in￾jure the work below it or form as ice and cause the upper work to heave.

Mr. Guastavino said he had considered this. I had several times, during

the conversation, mentioned the danger from condensation. I then pro￾posed that…we should abandon the idea of an opening in the center of

this inner bell with a canopy over it, and should make it a continuous

vault of Mr. Guastavino’s material, and asked Mr. Butler if he were willing

to go forward on this basis, and if he had any doubts as to Mr. Guastavi￾no’s material for the inner bell. He said he had no doubts about it and was

willing to go forward with it 1.

This architectural conversation occurred more than 3 decades prior to the

appearance of building condensation as an issue of concern in the technical

engineering literature. Mr. Gilbert grasped, in a general sense, the conditions

under which frosting, melting, and paint peeling might occur and how these

conditions are associated with air flow through openings and with chilled sur￾faces. Condensation, in the sense of this discussion, was a visceral concern for

the architect, and it represented a range of possible phenomena rather than a

specific phenomenon. Mr. Gilbert did not need a scientific understanding of

condensation; he had a practical problem, which was resolved by practical

assurance from experienced collaborators. The appearance of “condensation”

as a vaguely defined worry about buildings predates by several decades the

appearance of technical studies related to condensation.

Insulation Draws Water

When insulation was introduced into wood frame houses in the late 1920s and

early 1930s, the paint began to peel. House painters often refused to paint

insulated houses 2. The painters developed a pithy expression to describe

what happens: “Insulation draws moisture.” The residential paint-peeling prob￾lem was assigned in 1929 to F. L. Browne, a chemist with the U.S. Forest

Products Laboratory in Madison, Wisconsin. He recognized that the paint￾peeling problem was occasional and was associated with two types of “abnor￾mal conditions.”

1 Type A—Rainwater seeping through leaky joints left by poor carpentry

work or faulty design

2 Type B—Moisture originating within the building and carried by air

circulating within the hollow outside walls. When moisture laden air

comes in contact with surfaces at sufficiently lower temperature, water

condenses 3.

Browne’s finding that bulk water effects were the cause of most problems

Type A bears repeating in every discussion of the subject. Regarding Type B

conditions, he notes that “sufficiently low temperature” is a precondition for

condensation. He suggests that the source of the moisture was from the interior

and air circulation was the transport mechanism.

Does insulation draw water? The Forest Products Laboratory 4 had devel￾oped the wood sorption isotherm several years earlier see Fig. 1. It shows a

2 JTE • STP 1498 ON EXTERIOR BUILDING WALL SYSTEMS

somewhat-linear relationship between the equilibrium moisture content in

wood and relative humidity RH of air that surrounds the wood for tempera￾tures above freezing. Figure 2 shows the same data as in Fig. 2 but plotted as

lines of constant wood moisture content on a psychrometric chart. This repre￾sentation allows temperature control and vapor control to be viewed indepen￾dently.

RH ratio vp/svp of vapor pressure, vp, to saturation vapor pressure, svp

can be raised in two ways of course—by increasing the vapor pressure nu￾merator or by lowering the temperature denominator. So at the same vapor

pressure, a cold piece of wood will be wetter than a warm piece of wood. We

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FIG. 2—Lines of constant wood moisture content plotted on a psychrometric chart.

Horizontal arrows show the impact of change in temperature; vertical arrows show the

impact of change in vapor.

ROSE, doi:10.1520/JTE102972 3

may expect that upon adding insulation to a wall, the exterior materials during

Winter will get cold, and by virtue of being cold, they will get wet. How wet is

a matter for analysis of course. Also, freezing events in exterior materials will

be more common and more severe. Insulation “draws” cold, and cold draws

wetness. So one cannot quarrel with the painters’ claim that insulation draws

moisture, at least on physical grounds. Insulated buildings in cold climates

have wetter cladding and sheathing materials than similar uninsulated build￾ings.

Tyler Stewart Rogers

Rogers was an architect and one of the founders of the reference work Time￾saver Standards for Architects. He wrote a seminal article on garages, as Ameri￾cans were turning from carriage houses toward the use of the automobile. In a

1936 article 5, he held the title of Director of Technical Service, though the

organization is not identified. In 1938, he was Director of Technical Publica￾tions for Owens Corning Fiberglass.

In November 1936, the opening salvo of the condensation paradigm was

provided in American Architect and Architecture, “Insulation: What we know

and ought to know about it,” by Rogers. His main intent was to present heat

transmission factors for building materials, which constituted “new informa￾tion, never before presented to the architectural profession.” He cited the need

for better knowledge regarding properties, installation techniques, testing

methods, rating methods, and amounts needed. Then he began a discussion of

moisture.

The advent of air conditioning2 is opening up still another field for con￾structive research. Technicians know that when indoor relative humidities

are artificially controlled as they should be for comfort and health there

is a theoretical dew point temperature somewhere within the exposed

walls or roof at which point air-borne moisture is condensed into water….

It is further known that vapor pressures tend to move this internal mois￾ture toward the cold side of the wall.

These facts set up a number of speculations that cannot be answered

without further research. It seems important to know how much air￾borne moisture permeates building sections of different types…. It would

appear also that plaster, building paper or any other impervious curtain

on the warm side might be a sufficient barrier to prevent any measurable

accumulation of dampness…. Much research is being undertaken, more is

planned for 1937…. Progress is being made 5.

Rogers was setting the stage for decades of understandings—and

distortions—to come, so his words should be reviewed carefully. The following

represent distortions contained in his writing.

• Although insulation was introduced about the same time as humidifica￾2

This includes Wintertime humidification.

4 JTE • STP 1498 ON EXTERIOR BUILDING WALL SYSTEMS

tion “air conditioning”, here Rogers associated wetness with humidifi￾cation rather than with insulation. The moisture increase associated

with insulation itself was not discussed.

• “Dewpoints” have locations within the wall.

• The terms “condensed” and condensation can be applied in the absence

of definition. Rogers saw no need to distinguish condensation phenom￾ena on sorptive and non-sorptive materials.

• Wetness on the outside requires a humidified interior as the moisture

source.

• Prescriptions “sufficient barrier to prevent measurable accumulation of

dampness” may be suggested or offered prior to the completion, publi￾cation, and discussion of research.

Rogers then wrote “Preventing Condensation in Insulated Structures” for

the first issue of Architectural Record, March 1938 6. It began

Architects, owners and research technicians have observed, in recent

years, a small but growing number of buildings in which dampness or

frost has developed in walls, roofs or attic spaces. Most of these were

insulated houses, a few were winter air-conditioned. The erroneous im￾pression has spread that insulation “draws” water into the walls and

roofs….

Obviously, insulation is not at fault—at least not alone. Nor could winter

air-conditioning, creating comparatively high and sustained relative hu￾midities for health, be charged with sole responsibility, for not all struc￾tures reporting dampness were equipped with humidifiers. The need for

research became apparent.

Rogers attributed the new problems to new conditions, including “humidi￾fication, reduced infiltration, weathertight construction, and efficient insula￾tion,” and he stated that all four “are highly desirable in terms of health, com￾fort, and economy.” This framing of the problem meant that other means of

moisture control needed to be adopted.

In this article Rogers, provided no operational definition of condensation.

He stated, in fact, that the problem of condensation had been fully solved; this

was even before it was ever satisfactorily defined. His position was that these

new measures must and will be adopted. He proceeded to discuss measures

necessary to mitigate the wetness associated with adoption of the new ele￾ments. The measures he proposed were the vapor barrier and attic ventilation.

Rogers stated

Architects may avoid all technicalities in explaining this new vapor bar￾rier principle by using some parallel situation such as that shown in figure

13

. Here are two basins into which water is running at the same rate. The

basin at the left has an outlet larger than the supply. In this no water

3

Figure 3 in this paper.

ROSE, doi:10.1520/JTE102972 5

accumulates. The one on the right has an outlet restricted in size to less

that that of the inflow. Here water accumulates until it spills over the

sides.

So with the wall sections shown below these basins. The room between is

indicated as being warm and humid. In the wall at the left there is a vapor

barrier not completely perfect in its stoppage of vapor movement. How￾ever, it checks most of the vapor, and what little remains can pass out

through the colder side of the wall with little difficulty. This wall shows no

accumulation of vapor.

This description is fundamentally flawed. The funnel and faucet analogy

describes a dynamic system where the faucet water feeds all of the materials

along its path. In kinetic moisture diffusion, the entire surrounding air and

materials provide moisture to the materials, not just a high source at a dis￾tance. Rogers said that by checking interior moisture at the warm side, the

“wall shows no accumulation of vapor.” However, vapor will accumulate in

materials that move to low temperature, and the capacity for barriers to miti￾gate that accumulation is limited. Rogers’ analogy is captivating—and mislead￾ing. Arguing that under diffusion “all of the water comes from the high vapor

pressure side” is equivalent to claiming that “all of the heat comes from the

high temperature side” under heat conduction.

The remainder of the article dealt with practical matters of placing vapor

barriers and providing attic ventilation. These included two pages from Time￾saver Standards on Heat Transmission, listing coefficients of heat transmission

of common building materials, and two pages on Preventing Condensation in

Insulated Structures. These figures were widely reproduced in guidance litera￾ture that followed.

FIG. 3—Flawed analogy comparing diffusion transport kinetic to bulk flow dynamic

from Ref 6.

6 JTE • STP 1498 ON EXTERIOR BUILDING WALL SYSTEMS