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NBS TECHNICAL NOTE 1131

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U.S. DEPARTMENT OF COMMERCE/ National Bureau of Standards

Field Investigation of the

Performance of Residential

Retrofit Insulation
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities 2 — Radiation Research — Thermodynamics and

Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering2 — Mechanical

Engineering and Process Technology2 — Building Technology — Fire Research —

Consumer Product Technology — Field Methods.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection,

acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and

provides the technical foundation for computer-related policies of the Federal Government.

The Institute consists of the following centers:

Programming Science and Technology — Computer Systems Engineering.

'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234.

2 Some divisions within the center are located at Boulder, CO 80303.
for**, Of St»n*T*

OCT 2 4 1980

Field Investigation of the Performance of

Residential Retrofit Insulation

no. i I9So

John L. Weidt

Robert J. Saxler

John Weiclt Associates, Inc. Chaska, MN 55318

Walter J. Rossiter, Jr.

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

Sponsored by: Office of Weatherization Assistance U.S. Department of Energy

1000 Independence Ave., SW

Washington, DC 20585

^°f C*

'**.

«35

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U.S. DEPARTMENT OF COMMERCE, PHILIP M. KLUTZNICK, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity, Technology and Innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued September 1980

^
National Bureau of Standards Technical Note 1131

Nat. Bur. Stand. (U.S.), Tech. Note 1131, 67 pages '(Sept. 1980) mnFN CODEN: NRTNAP NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1980

For Sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. Price $3.75

(Add 25 percent for other than U.S. mailing.)
immjflcmTffmTtiBtffflnmffliwrffnrnHnniii

FIELD INVESTIGATION OF THE PERFORMANCE OF RESIDENTIAL

RETROFIT INSULATION

John L. Weidt*

Robert J. Saxler*

Walter J. Rossiter, Jr.

ABSTRACT

A study was conducted to obtain information on the performance of inservice insulations of the type commonly used in the United States to

retrofit side-walls of housing: urea-formaldehyde based foam, loose-fill

cellulose, and loose-fill mineral fiber.

In the field phase of the study, observations were made on performancerelated factors such as: the completeness of filling the cavity, the

condition of the insulation and wall components, and evidence of moisture

accumulation such as water stains on sheathing, studs and other wall components. Shrinkage was observed to have occurred for all urea-formaldehyde

based foam specimens. Where measurable, it was found to be within a range

of 4 to 9 percent. For the six test houses containing loose-fill insulation which were opened at the top of the wall cavity, only one with

cellulose contained a void of undetermined origin at that location.

Insulation specimens removed from the walls were tested to determine their

density, thermal resistivity and moisture content. The pH and moisture

absorption of the urea-formaldehyde based foam specimens were also determined. Results of the laboratory measurements are discussed and compared

with data from other studies. Relationships between the moisture contents

of the samples and their thermal resistivities were not found. Results

indicated that the retrofitting of the inspected sidewalls was for the

most part accomplished without adverse effect upon them.

Key words: Conservation; energy; field survey; insulation; moisture

content; residences; retrofit; thermal resistivity.

*John Weidt Associates Inc., Chaska, Minnesota.

iii

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TABLE OF CONTENTS

Page

ABSTRACT iii

LIST OF TABLES v LIST OF FIGURES vi

1.0 INTRODUCTION 1

1 .

1

Background 1 1.2 Objectives 3

1.3 Importance of Laboratory Tests 3

2.0 CONDUCT OF THE STUDY 4

2.1 Identification and Selection of the Test Houses 4

2.2 Field Examination of the Test Houses 7 2.3 Laboratory Tests of Insulation Samples 7

3.0 RESULTS AND DISCUSSION 10

3 .

1

Laboratory Tests 10

3.1.1 Density 10

3.1.2 Thermal Resistivity 17

3.1.3 Moisture Content 23

3.1.4 pH of Urea -Formaldehyde Based Foams 26

3.1.5 Water Absorption of Urea-Formaldehyde Based

Foams 2 C3 .

2

Field Examinations 30

3.2.1 Shrinkage of Urea-Formaldehyde Based Foams 30

3.2.2 Settling of Loose-Fill Insulations 34

3.2.3 Condition of Wall Components 37

3.2.4 Workmanship 38

3.2.5 The Presence of Membrane-Type Vapor Barriers 39

4.0 SUMMARY AND CONCLUSIONS 41

5.0 RECOMMENDATIONS 44

6.0 ACKNOWLEDGMENTS 45

7.0 REFERENCES 46

APPENDIX A NEWS RELEASE REQUESTING VOLUNTEERS FOR PARTICIPATION

IN THE STUDY A-l

APPENDIX B PROCEDURES USED IN THE FIELD EXAMINATIONS B-l

APPENDIX C LABORATORY TEST PROCEDURES C-l

APPENDIX D TABLE OF DEFINITIONS OF S.I. AND CUSTOMARY UNITS USED

IN THIS REPORT D-l

APPENDIX E LINEAR SHRINKAGE OF UREA-FORMALDEHYDE BASED FOAMS E-l

IV
LIST OF TABLES

Page

Table 1. Distribution of the Retrofit Insulations in the

Houses Volunteered for Inclusion in the Field

Inspection 5

Table 2. Insulation Sample Distribution by City, Date of Field

Inspection, Type of Material, and Number of Foam

Insulation Manufacturers and Loose-Fill Insulation

Installers 6

Table 3. Summary of the Tasks Performed during the Field

Inspections 9

Table 4. Age, Density, Thermal Resistivity, Moisture Content,

and Linear Shrinkage of the Urea-Formaldehyde Based

Foam Samples 12

Table 5. Age, Density, Thermal Resistivity, and Moisture

Content of the Loose-Fill Insulation Samples 13

Table 6. Range and Average of Thermal Resistivity Values for

Urea-Formaldehyde Based Foam Insulations by Geographic

Location 24

Table 7. Range and Average of Thermal Resistivity Values for

Cellulose Insulations by Geographic Location 24

Table 8. Range and Average of Thermal Resistivity Values for

Urea-Formaldehyde Based Foam Insulations by Manufacturer 25

Table 9. Range and Average of Thermal Resistivity Values for

Cellulose Insulations by Installer 25

Table 10. Values of pH at the Surfaces and Center of the

Urea-Formaldehyde Based Foam Samples 27

Table 11. Water Absorption of Urea-Formaldehyde Based Foams 29

Table 12. Range and Average Values of Linear Shrinkage for

Urea-Formaldehyde Based Foams by City, Manufacturer

and Installation Season 33

Table 13. A Comparison of Shrinkage Values from Cavity Width

and Cavity Depth Measurements 34

Table 14. Types and Locations of Vapor Barriers Found in WallCavities and Corresponding Moisture Contents of

Insulations 42
LIST OF FIGURES

Page

Figure 1 * Executing an Exterior Wall Opening 8

Figure 2. Photographing Mineral Wool Insulation in an Opened

Wall Cavity 8

Figure 3. Laboratory Apparatus for Determination of the

Thermal Resistivity of the Loose-Fill Insulations 11

Figure 4. Laboratory Apparatus for Determination of the Thermal

Resistivity of the Urea-Formaldehyde Based Foams 11

Figure 5. Range of Installed Densities of Urea-Formaldehyde

Based Foam Insulations from References and from this

Study 14

Figure 6. Range of Installed Densities for Cellulose Insulations

from References and from this Study 15

Figure 7. Range of Installed Densities of Loose-Fill Glass

Fiber Insulations from References and from this Study .... 16

Figure 8. Range of Installed Densities of Loose-Fill Rock/Slag

Wool Insulation from Reference and from this Study 17

Figure 9. The Relationship Between Density and Thermal

Resistivity for the Urea-Formaldehyde Based Foam

Insulation Samples 19

Figure 10. The Relationship Between Density and Thermal

Resistivity for the Loose-Fill Cellulose Insulation

Samples 20

Figure 11. The Relationship Between Density and Thermal

Resistivity for Glass Fiber Insulations, as Given in the

Literature [15] and from this Study 21

Figure 12. The Relationship Between Density and Thermal

Resistivity for Loose-Fill Rock/Slag Wool Fiber

Insulations, as Given in the Literature [2] and from

this Study 22

Figure 13. Plot of the Percent Linear Shrinkage of the

Urea-Formaldehyde Based Foam Specimens versus Density .... 31

Figure 14. Example of Urea-Formaldehyde Based Foam Sample Which

Cracked into Small Pieces 35

Figure 15. Examples of Urea-Formaldehyde Based Foam Sample

Which Contained Large Horizontal Cracks 36

vi
Page

Figure 16. The Void Observed at the Top of the Cavity

Insulated with Loose-Fill Cellulose Insulation 37

Figure 17. Incomplete Application of Urea-Formaldehyde Based

Foam Insulation 40

1 Figure 18. Electrical Outlet Box Filled with Urea-Formaldehyde

Based Foam Insulation 40

Figure 19. Existing Batt Insulation Compressed by the Retrofit

Insulation 41

vii

ma

1.0 INTRODUCTION

A result of the energy crisis has been the retrofitting of residences.

Effective retrofitting not only contributes to the nation's efforts to conserve energy, but provides a means for the individual homeowners to

reduce heating-and cooling-fuel consumption and save heating and cooling

costs. Shortly before the onset of the energy crisis in 1973, it was estimated that nearly 20 percent of the energy used for residential

heating and cooling could be conserved by effective retrofitting of

residences [1]*. Common techniques for the retrofitting of residences

include the addition of thermal insulation to walls, ceilings and floors,

the installation of storm windows and doors, and caulking and weatherstripping of windows, doors and cracks where air may infiltrate. Effective retrofitting not only requires that proper and durable materials

be used, but that the materials be correctly installed.

Of the common retrofit techniques mentioned above, that most generally

questioned is the addition of insulation to walls. This technique has

been open to question mainly because it involves the application of

insulation to an inaccessible cavity which may contain unknown and unseen

objects or obstructions. Moreover, the insulation usually cannot be

inspected after insulation, although infrared thermography may be used

for inspection of the insulated wall. Changes which may occur to reduce

the effectiveness of the insulation or deleterious effects on wall components due to retrofitting may go undetected or not be observed until

long after the insulation has been installed.

1.1 BACKGROUND

The thermal insulations commonly used to retrofit exterior walls of residences for energy conservation are loose-fill cellulose, loose-fill

mineral fiber, and urea-formaldehyde based foam. A considerable body of

information concerning the properties and performance of these insulations has been developed from laboratory studies. A review of this

information has recently been given [2] . Less is known about the properties and performance of these insulations after they have been installed

in walls of residences.

An economic basis for retrofitting sidewalls exists, since Petersen has

shown that blowing insulation into exterior walls may be cost-effective

in many areas of the United States [3]. It is noted that Petersen's

analyses incorporated laboratory measured thermal properties of the

insulation. Burch, Siu and Powell have indicated that the total thermal transmittance of retrofitted walls may be sometimes higher than the

predicted values, which are based on laboratory-determined thermal con- ductivity values [4]

.

* Numbers in brackets refer to references given in Section 7.

1
Factors such as the settling of loose-fill insulation, shrinkage of foam

insulation and the accumulation of moisture within insulations may reduce

their insulating effectiveness. Moreover, according to these authors [4],

if substantial moisture accumulation occurs, it may result in unwanted

effects such as paint failures, buckling and warping of wooden siding

and, in isolated cases, rotting of wood. Other factors which are important to the successful retrofitting of sidewalls include the completeness

of the installation and compatibility with components of the wall. For

example, the insulation should not contribute to accelerated corrosion

of metal objects in the wall.

In spite of concerns such as these, few field studies of the effects of

retrofitting exterior walls have been reported. As part of their comprehensive study to evaluate the energy conservation achieved in retrofitting a wood-frame residence, Burch and Hunt compared the thermal

performance of loose-fill cellulose, loose-fill mineral fiber and urea- formaldehyde based foam insulations which were used to retrofit the

exterior walls of a residence in suburban Washington, D.C. [5]. Among

their findings they reported that approximately 3 years after installation, no settling of the loose-fill materials was observed in the walls,

while approximately 2 years after application, the urea-formaldehyde

based foam had undergone a linear shrinkage of about 8 percent.

The most extensive field examination involving retrofitted residential

sidewalls, published to date, was conducted by Weidt [6]. As part of

the study performed in Minnesota, the sidewalls of twenty-two residences

were opened to examine the insulations and measure their properties.

Six of the houses contained loose-fill cellulose, four contained loosefill mineral fiber and twelve had urea-formaldehyde based foam. In

general, the thermal conductivities of the insulations removed from these

houses were relatively close to values referenced in the literature for

these types of insulations. Moisture contents of the insulations were

found to be low. In particular the moisture contents of the cellulose

specimens were lower than expected. It is noted that the investigation

was conducted during the summer time. Settling of loose-fill insulations

was not a parameter investigated in the Minnesota study. Linear shrinkage of urea-formaldehyde based foams ranged from 2.5 to 9 percent. The

average linear shrinkage of the foam specimens in the twelve houses

was reported to be 4.5 percent.

Another field survey, sponsored by the U.S. Department of Energy, the

Oregon State Department of Energy and others, was conducted in early

1979 in the state of Oregon. This study was intended to determine the

moisture contents of installed insulations and wooden wall components

Results of this study were recently presented at the ASHRAE/DOE Conference on the thermal performance of the exterior envelopes of buildings,

and it is anticipated that they will be published in the Conference

Proceedings

.

Grot has reported on a field survey involving the use of thermography

for the determination of the effectiveness of retrofit techniques [7].
Thermographic inspections of sixty-five homes located in eight cities

in the United States were conducted during the 1978-1979 heating season

after the residences had been retrofitted. The purpose of the

thermographic surveys was to assess the quality of workmanship, to

determine the percentage of wall area which was uninsulated after the

retrofit, and to observe the thermal defects which still existed in the

residences. A number of retrofit techniques was used including insulation of the walls of the residences with either urea-formaldehyde based

foam or cellulose insulation. Grot's findings included observations

concerning the completeness of filling the walls with insulation. Within

the limits of the thermographic technique for surveying houses for heat

loss, he found that two-thirds of the residences contained fissures in

the insulated wall and shrinkage of the urea-formaldehyde based foam.

In addition, some areas of the exterior walls of the residences were

not insulated: 20 percent of the residences had greater than 10 percent

of the total wall areas uninsulated; 30 percent of the residences showed

between 5 and 10 percent of the wall areas uninsulated; and 50 percent

of the residences had less than 5 percent of the wall areas uninsulated.

Inspite of the field studies many unanswered questions concerning the

properties and performance of insulations used to retrofit exterior

walls still remained. Thus, additional information from field studies was considered necessary to assist in formulating recommendations and

guidelines for the retrofitting of residences. If field studies indicated that retrofitting of sidewalls could be accomplished successfully

and without adverse effect, encouragement to install wall insulation

might be given to homeowners. This report presents the findings of a field and laboratory study to inspect and examine cavity walls of

residences which have been retrofitted with thermal insulation. A

summary report of the study has been presented [8].

1.2 OBJECTIVES

One objective of the study was to determine properties and performance

characteristics of the retrofitted insulations installed in cavity-walls.

Retrofit insulations included in the study were urea-formaldehyde based

foam, loose-fill cellulose and loose-fill mineral fiber. Values of the

properties of insulation specimens removed from the inspected houses

were to be compared to the properties of comparable insulation specimens

which had been tested in laboratory studies. The study was to provide

information concerning questions such as to what extent do loose-fill

materials settle and foam insulation shrink. A second objective was

to obtain information concerning the effects of the addition of insulation on the walls of existing residences. Data and information obtained

from the study may be used in formulating guidelines to assure the proper

and adequate retrofitting of sidewalls of residences to conserve energy.

1.3 IMPORTANCE OF LABORATORY TESTS

Laboratory tests to measure density, thermal resistivity and moisture

content were conducted on all insulation samples removed from the test
houses. The pH and water absorption were also determined for the urea- formaldehyde based foam samples. Values of density, thermal resistivity

and moisture content for the insulation samples from the test houses may

be compared to values of these properties reported in the literature or other sources.

The pH of the urea-formaldehyde based foam insulations was measured at

the center of the foam sample and at its surfaces corresponding to

the interior and exterior sides of the wall cavity. It was of interest

to determine whether the acid catalyst, present for foam production,

had accumulated at the surfaces. An accumulation of acid catylyst at

the surfaces might be expected to make the foam susceptible to acidcatalyzed hydrolytic decomposition at those locations. The water

absorption tests were conducted to determine whether foams which had

aged in service would absorb more water than freshly-prepared foams. It

had been suggested that surface deterioration of the foam specimens due

to aging might result in greater water absorption of the aged foams.

2.0 CONDUCT OF THE STUDY

Thirty-nine houses were included in this study. The side-walls of most

of these houses were of typical wood-frame construction, although one house consisted of masonry construction. The insulations were those

commonly used in the United States to retrofit sidewalls. Twenty-five

of the houses contained urea- formaldehyde based foam insulation, eight

contained loose-fill cellulose insulation, and six contained loose-fill

mineral fiber insulation. The field examinations were conducted between

late November, 1978, and early January, 1979.

2.1 IDENTIFICATION AND SELECTION OF THE TEST HOUSES

Volunteer homeowners were the source of test houses included in the

study. Many homeowners offered the use of their residences as test

houses in response to a widely-published news release which asked for

volunteers. The text of the news release is given in Appendix A. The

volunteered houses were considered as being eligible for inclusion in

the study according to the following set of criteria:

the insulations should have been installed as a retrofit

material and consist of loose-fill cellulose, loose-fill

mineral fiber or urea-formaldehyde based foam;

° the installation should in general have occurred at least

two years prior to examination;

each generic type of insulation examined should have been

produced by a number of different manufacturers and/or

applied by a number of different installers; and

;''.
° the test houses should have been located In certain

geographic areas including the northeast, mid-Atlantic,

mid-western, and southeast regions of the country.

More than 1100 responses were received from homeowners who volunteered

to participate, as shown in Table 1. Only about 25 percent of the volunteered houses met the above criteria. Although an adequate distribution of the loose-fill cellulose, loose-fill mineral fiber and urea- formaldehyde based foam insulations were volunteered, many of these

houses were widely-separated from each other and could not be conveniently

reached. It was interesting that almost 25 percent of the homeowners

who volunteered did not know the type of insulation within the cavity

walls of their houses. These houses could not be considered for examination. The thirty-nine test houses finally selected from among the 310

qualified residences were chosen to provide an efficient schedule for

the field examinations and to minimize travel costs.

TABLE 1.

DISTRIBUTION OF THE RETROFIT INSULATIONS IN THE

HOUSES VOLUNTEERED FOR INCLUSION IN THE FIELD INSPECTION

Type of Insulation in Total Qualified

The Volunteered House Responses Residence^ '

Cellulose 331 128

Mineral Fiber 111 54

Urea-Formaldehyde Foam 430 128

Unknown 252

TOTAL 1124 310

(1) A qualified residence was considered to meet the criteria for

determining the eligibility of a test house for inclusion in the

field study.

The selection criterion concerning the geographic area where the test

house was located was considered to be particularly important in the case of urea-formaldehyde based foam insulations. It was desired to

examine the foams in houses located in areas which experience prolonged

seasons of relatively high temperatures and high humidities such as the

lower Southeast. The durability of foam insulations exposed to combined

high temperatures and high humidities had been previously questioned and

considered to be suspect [9]. However, few houses containing ureaformaldehyde based foams were volunteered from the lower southeast region

of the country. The practical aspects concerning time and travel
prohibited the examinations of those few house containing foam volunteered

from the lower southeast region.

The houses selected for the study were located in Connecticut, Indiana,

Kentucky, Maryland, Minnesota, Ohio, Virginia, and the District of

Columbia. A two-person team consisting of a skilled carpenter and a project manager conducted each wall opening and field inspection of the

insulation. At times, National Bureau of Standards' research staff members were present at the field site. Table 2 lists the cities near which

the test houses were located, the date of the field examinations, the

total number of insulations examined, the number of each type of insulation examined, and the number of manufacturers of foam insulation and

installers of loose-fill insulation. The itinerary followed by the

inspection team is represented by the order of cities listed in Table 2.

TABLE 2. INSULATION SAMPLE DISTRIBUTION BY CITY, DATE OF THE FIELD

INSPECTION, TYPE OF MATERIAL, AND NUMBER OF FOAM INSULATION

MANUFACTURERS AND LOOSE-FILL INSULATION INSTALLERS

Cities Where

Inspection

Was Conducted

Date Total

Insulation Samples

UF (a) Cellulose

NO. MFR. ( b ) NO. INST/ C )

Mineral Fiber

NO. INST.

1. Minneapolis,

Minn. Nov. 78 4 4

2. Hartford/

New Haven,

Conn. Nov. 78 6 5

3. Washington,

D.C. Dec. 78 10 4 5 4

4. Richmond,

Va. Dec. 78 4 -

5. Louisville,

Ky. Jan. 79 7 7

6. Dayton,

Ohio Jan. 79 8 5

1 1

2 2

TOTALS 39 25 ; (d) ** (e) ** (e)

(a) UF indicates urea-formaldehyde based foam.

(b) MFR. indicates the number of foam manufacturers.

(c) INST, indicates the number of loose-fill insulation installers.

(d) The total number of different manufacturers was eight.

(e) The total number of different installers was six.
2.2 FIELD EXAMINATION OF THE TEST HOUSES

The general procedure for examining the retrofit insulations was as follows: a small section of the sidewall, about 0.4 to 0.6 m (4 to

6 ft ), was opened from the exterior by removing the siding and sheathing

(Figure 1), or less commonly, from the interior by removing the gypsum

board or other interior surface material; the insulation was inspected,

and appropriate measurements and observations recorded (Figure 2); wall

component materials were also observed to determine if they had been

affected by the presence of the insulation; a sample of the insulation

was removed and packaged for shipment to the testing laboratory; the mass (weight) of the insulation sample and the volume of the wall cavity

from which the insulation was removed were determined; the wall cavity

was re-insulated with glass fiber batt insulation; and, finally, the

wall was closed and restored to its original condition. A summary of

the general procedure is listed in Table 3 and a description is given

in Appendix B.

During the examination of the retrofitted sidewalls, visual observations

were made concerning the condition of the insulation and of the wall

components (Table 3). Observations included such parameters as the pre- sence of cracks and voids in the insulation, insulation color, the condition of the paint and/or siding, corrosion of metal wall objects such

as electrical boxes and accessories, and evidence of moisture accumulation, odor, wood rot, fungus or mold, and vermin. Other factors noted

were the completeness of the insulation application and the presence

of membrane-type vapor barriers (flow retarders) within the insulated

cavity. The sizes of voids due to settling or incomplete application

of loose-fill materials were measured and linear shrinkages of urea- formaldehyde based foam insulations were determined.

2.3 LABORATORY TESTS OF INSULATION SAMPLES

Insulation samples were removed from the walls of the houses, sealed in

polyethylene bags or jars, and sent to a commercial testing laboratory.

The laboratory was chosen because of its capability and experience in

testing thermal insulations. Laboratory measurements of density, thermal resistivity and moisture content were conducted on all samples.

The pH of the urea-formaldehyde based foams was also determined. In

addition, a few foams were sent to the National Bureau of Standards

laboratories for determination of moisture absorption.

Details of the test procedures used to measure the insulation properties

are given in Appendix C. In general, the density was calculated from

measurements of the mass and volume of the removed insulation specimens.

The thermal resistivity ( resistance per unit thickness) was determined

based on the test procedure given in ASTM C 518-76. The insulation

samples were intentionally not oven dried, and thermal resistivity

measurements were conducted on samples as they were received from the

nnmia
Figure 1. Executing an Exterior Wall Opening

Figure 2. Photographing Mineral Wool Insulation in an Opened Wall Cavity

8
TABLE 3

SUMMARY OF THE TASKS PERFORMED DURING THE

FIELD INSPECTIONS

Task Considerations

Select wall area for

examination

Area should be repairable

Area should contain electrical components, if possible

Area should be at the top of the cavity, if possible,

in the case of loose-fill insulations

Open the wall o Either from the interior or exterior

Observe the condition

of the insulation and

wall components

Cracks and voids in the insulation

Color of the insulation

Paint

Siding/sheathing/studs /other components

Moisture

Presence of membrane-type vapor barriers

Electrical components

Corrosion

Odor

Rot

Fungus /mold

Vermin

Record appropriate

information

Photographs

Sketches

Comments

Measurements Shrinkage (urea-formaldehyde based foam)

Settling (loose-fill materials)

Voids

Mass (weight)

Volume

Remove insulation

samples

In general seal in plastic bags for shipment to lab

Seal samples for moisture measurements in plastic jars

Restore wall Reinsulate with glass fiber batt

Close wall to original condition
field. This practice was adopted to make the laboratory measured thermal

resistivities more representative of the thermal resistivities of the

installed insulations, since laboratory tests are normally conducted on dried samples. Figures 3 and 4 show the laboratory apparatus used for

the determination of the thermal resistivities of loose-fill materials

and urea-formaldehyde based foams, respectively.

The percent volatile loss by mass upon heating to 105°C (221°F)* was determined according to the test method described in ASTM D 644-55

(1976). The percent volatile loss was taken to be the moisture content.

As noted in Table 3, insulation samples removed from the houses for the

determination of moisture content were immediately sealed in polyethylene

jars to prevent moisture loss or gain during shipment to the testing

laboratory. Mass determinations of the polyethylene jars containing

insulation conducted both in the field and upon arrival at the testing

laboratory indicated no significant changes during shipment.

Since no standard test procedure was available for measuring the pH of

the urea-formaldehyde based foam insulations, a test method developed in an industrial laboratory which had experience with foams was employed.

This procedure involved extracting a small quantity of the foam specimen

with water and measuring the pH of the resulting solution. The moisture

absorption of the foams was determined according to the test procedure

described in U.S. Department of Housing and Urban Development (HUD) Use

of Materials Bulletin No. 74.

3.0 RESULTS AND DISCUSSION

3.1 LABORATORY TESTS

The results of the density, thermal resistivity, and moisture content

determinations conducted on the urea-formaldehyde based foam and loosefill insulations are given in Tables 4 and 5, respectively. Discussions

of these results follow in Sections 3.1.1 to 3.1.3. The results and

discussions of the pH and water absorption tests for urea-formaldehyde

based foams are given in Sections 3.1.4 and 3.1.5.

3.1.1 Density

Density is an important property for characterizing retrofit insulations.

Manufacturers generally have insulation guidelines regarding the proper

density at which their materials should be applied. Application of the

retrofit insulations at densities other than recommended may result in

decreased thermal performance of an insulated wall. For example, loosefill insulation applied at too low a density may settle.

* Definitions of the S.I. (International System) units and customary units

are given in Appendix D.

10
Figure 3. Laboratory Apparatus for Determination of

the Thermal Resistivity of the Loose-Fill

Insulations.

Figure 4. Laboratory Apparatus for Determination of

the Thermal Resistivity of the Urea-Formaldehyde

Based Foams

.

11
TABLE 4

AGE, DENSITY, THERMAL RESISTIVITY, MOISTURE CONTENT, AND LINEAR SHRINKAGE

OF THE UREA-FORMALDEHYDE BASED FOAM SAMPLES

SAMPLE CITY (a) MFR.< b > AGE< b > DENSITY THERMAL RESISTIVITY MOISTURE CONTENT^

LINEAR

SHRINKAGE

No. yrs. kg/m3 lbm/ft 3 m'K/W h*ft 2-0 F/Btu*in percent by mass percent

.(e)

1 1 H 2.0 5.4 0.34 20.8 3.00 9.1 6.5

2 1 F 2.4 9.9 0.62 26.7 3.85 10.5 4.1

3 1 F 2.1 12.8 0.80 27.8 4.00 3.2 4.4.

4 1 B 2.1 7.8 0.49 26.4 3.80 12.5

5 2 C 1.9 9.6 0.60 26.7 3.85 6.5 7.4

6 2 C 2.3 9.1 0.57 28.1 4.05 17.5 9.0

7 2 C 2.6 9.0 0.56 26.0 3.75 11.5 5.7

8 2 A 3.3 8.8 0.55 26.7 3.85 11.7 6.2

9 2 D 3.4 11.5 0.72 < d > < d) 13.1 (f) 10 3 F 1.8 13.4 0.84 25.7 3.70 14.9 < e)

11 3 C 4.1 14.4 0.90 29.9 4.30 11.1 7.4

12 3 F 2.9 13.8 0.86 28.5 4.10 10.3 <*)

13 3 F 2.8 9.4 0.59 28.1 4.05 4.5

14 5 G 3.1 10.9 0.68 27.8 4.00 14.0 4.4

15 5 G 3.5 12.6 0.79 25.3 3.65 18.6 5.1.

16 5 G 2.8 14.4 0.90 31.6 4.55 14.8

17 5 C 2.0 13.9 0.87 29.5 4.25 7.8 6.7

18 5 G 2.5 11.2 0.70 31.3 4.50 15.1 6.6

19 5 C 3.3 13.4 0.84 30.6 4.40 10.9 5.6

20 5 G 2.1 12.2 0.76 29.2 4.20 13.0 4.9.

21 6 E 2.3 9.0 0.56 25.0 3.60 13.6

22 6 C 3.7 12.8 0.80 29.5 4.25 11.5

23 6 G 1.4 9.6 0.60 27.8 4.00 22.0 8.1

24 6 E 2.0 13.6 0.85 31.9 4.60 13.3 3.9

25 6 G 3.2 18.4 1.15 31.3 4.50 10.9 6.0

(a) Number corresponds to that given in Table 2. (b) MFR. indicates the manufacturer; letter designations are used to indicate different manufacturers.

(c) Moisture content was taken to be the same as the percent volatile loss upon heating to 105°C (221°F).

(d) A test specimen large enough for determination of the thermal resistance was not available.

(e) Shrinkage not determined because of the presence of batt insulation.

(f) Large gaps, cracks and voids precluded shrinkage determination.

-(f)

_(e)

-(f) (f)

12
TABLE 5

AGE, DENSITY, THERMAL RESISTIVITY, AND MOISTURE CONTENT OF

THE LOOSE-FILL INSULATION SAMPLES

SAMPLE CITY/ 8 ) lNST.< b ) AGE DENSITY THERMAL RESISTIVITY MOISTURE CONTENT^

No . Type yrs kg/m3 lbm/ft 3 m'K/W h'ft 2 -°F/Btu'in percent by mass

26 Cell.< d > 27 Cell.

28 Cell.

29 Cell.

30 Cell.

31 Cell.

32 Cell.

33 Cell.

34 MF-Gl.< e)

35 MF-G1.

36 MF-G1.

37 MF-R/S (f) 38 MF-R/S

39 MF-R/S

A 1.8 64.0 4.0

B 2.0 67.2 4.2

C 1.9 59.2 3.7

B 2.4 64.0 4.0

D 5.2 41.6 2.6

B 1.7 51.2 3.2

E 2.3 44.8 2.8

F 10.3 46.4 2.9

G 9.1 27.2 1.7 H 1.8 36.8 2.3

I 2.4 46.4 2.9

J 7.8 140.9 8.8 K 5.3 126.5 7.9 L 3.8 27.2<8> 1.7 (g)

2423

2524

24

25

2625

2528

2926

25

24

5040

60

55

50

60 3.75

3.70

3.65

0520

75

65 3.55

12.4 13.4

12.4

9.2

10.1 21.2

12.4 8.8

1.0

1.0 1.0

1.0

1.0 1.0

(a) Number corresponds to that given In Table 2. (b) INST. Indicates the installer.

(c) Moisture content was taken to be the same as the percent volatile loss upon heating to 105°C (221°F).

(d) Cell, indicates cellulose insulation.

(e) MF-G1. indicates mineral fiber insulation consisting of glass fiber.

(f) MF-R/S indicates mineral fiber insulation consisting of rock or slag fibers.

(g) Sample contained voids and the density measured in the field was 27.2 kg/nr (1.7 lbm/ft-3 ). No correction was made for the voids. This density was not duplicated in the laboratory for the thermal resistivity measurement which was conducted on a sample with a density of 41.6 kg/nr

(2.6 lbm/ft3

).

13

ii.«-ipiiHni| i||H | HHVJU| | ll| |l|<l
It may be seen from Table 4 that densities of the twenty-five urea- formaldehyde based foam insulations ranged from 5.4 to 18.4 kg/m (0.34

to 1.15 lbm/ft ). The range of densities for these foams is generally

reported to be about 10.0 to 14.0 kg/m3 (0.6 to 0.9 lbm/ft3

) [2,9].

Figure 5 compares the range of densities determined in this study with

those given in the literature. The average value of 11.5 kg/m (0.72

lbm/ft J

) is within the range cited in the literature, while the extremes

of the range of the test samples were much broader than those given

in the literature [2,9]. Seven samples (nos. 1, 4, 6, 7, 8, 13, and

21) had densities below the literature range. Sample 1 had a density

of 5.4 kg/m (0.34 lbm/ft ) which is considered unacceptably low for a urea-formaldehyde based foam insulation. Only one foam sample (no. 25)

had a density which was greater than the literature-cited maximum of

14.0 kg/m3 (0.9 lbm/ft3

).

The eight cellulose samples (Table 5) showed a density range of 41.6

to 67.2 kg/m3 (2.6 to 4.2 lbm/ft3

), with an average density of 54.8

kg/m (3.4 lbm/ft ). The density values for cellulose insulations

were considered to be close to values reported in other field studies

[4,6]. For example, in the Minnesota field study, Weidt found that

the density of cellulose insulations ranged from 52.9 to 67.5 kg/m

(3.3 to 3.9 lbm/ft3

) with an average density of 58.5 kg/m3 (3.7 lbm/

ft )[6l. Burch, Siu and Powell reported a density of 56.0 kg/m (3.5

lbm/ft ) for one specimen [4]. One reference [10] has indicated that

the installed density for loose-fill cellulose ranges from approxmately

48.0 to 64.0 kg/m3 (3.0 to 4.0 lbm/ft3

). The range of densities found

in this study were slightly broader than that cited in this reference

[10]. Figure 6 compares the range of densities of the cellulose samples

in this study with ranges given in the literature.

DATA SOURCE

Reference 2

Reference 9

This study

DENSITY, kg/m3

8 16 24 32

_i i i i_

f

0.0 0.5 1.0 1.5 2.0

DENSITY, lbm/ft*

40 48

2.5 3.0

Figure 5. Range of Installed Densities of Urea-Formaldehyde Based

Foam Insulations from References and from this Study.

14
DATA SOURCE 32

DENSITY, kg/m3

40 48 56 64

i i i i 72i 80i

Reference 4

Reference 6

Reference 10

This study

1 '////

'////////

y///////////.

2.0 2.5 3.0 3.5 4.0

DENSITY, Ibm/W

4.5 5.0

Figure 6. Range of Installed Densities for Cellulose

Insulations from References and from this

Study.

Of the six mineral fiber insulations in the study, three were glass fiber

and three were rock/ slag wool* samples. Densities of the glass fiber

samples varied considerably from those of the rock/slag wool (Table 5).

The range of densities of the glass fiber samples in the study was 27.2

to 46.4 kg/m3 (1.7 to 2.9 lbm/ft 3

). It has been reported that the

density for loose-fill glass fiber insulation, as recommended by the

3

industry for application in wall cavities, should be about 32.0 kg/m

(2.0 lbm/ft 3

) [10]. Burch, Siu and Powell reported that the density of

the glass fiber specimen in their study was 32.2 kg/m (2.1 lbm/ft ) [4],

The ASHRAE Handbook of Fundamentals indicates a density range of about

9.0 to 32.0 kg/m3 (0.6 to 2.0 lbm/ft 3

) [11]. This reference does not

distinguish between density of these insulations applied in open areas

such as attics and closed spaces such as wall cavities. Loose-fill glass

fiber installed in wall cavities has a higher density than that installed

in attics [10]. The upper limit of the ASHRAE density range applies to

* The term, rock/slag wool, indicates that the insulation consisted of

either rock or slag wool fibers. The specific type of insulation

could not be identified.

15

nfurnriitfw
DATA SOURCE

Reference 4

Reference 10

Reference 11

This study

DENSITY, kg/m*

8 16 24 32

• • i 40 48

i i

1

1 V////////

////////

0.0 0.5 1.0 1.5 2.0

DENSITY, lbm/ft'

2.5 3.0

Figure 7. Range of Installed Densities of Loose-Fill Glass Fiber

Insulations from References and from this Study.

cavity wall insulations. Figure 7 compares the densities from the literature and from this study. It may be seen that the literature values

of approximately 32.0 kg/m (2.0 lbm/ftJ

) lie within the range of values

found for the samples in the field survey. The density of 46.4 kg/nr* (2.9

lbm/ft ) for sample no. 36 was about 45 percent higher than the maximum

density value cited in the literature.

The density range of 27.2 to 140.9 kg/m3 (1.7 to 8.8 lbm/ft 3

) for the

three rock/slag wool samples in the study was found to be broader than

expected, based on a comparison with the minimum recommended value of

40 kg/m3 (2.5 lbm/ft3

) cited in the literature [10]. Figure 8 shows

this comparison. The densities of two samples (nos. 37 and 38) were

much beyond the literature density, with values of 140.9 and 126.5 kg/m

(8.8 and 7.9 lbm/ft ), respectively. These high densities may have been

due to factors such as fiber size, shot content among the fibers, and the

degree of packing of the insulations in the cavities. One rock/slag wool

sample (no. 39) contained a number of voids which were apparently created

by mice in the cavity. The density of this sample was not corrected to

account for the voids.

16
DATA SOURCE 16

> 24

i

DENSITY, kg/m3

32 40 120 128

Reference 10

This study

I V////////?/////

1.0 1.5 2.0 2.5 7.5 8.0

DENSITY, Ibm/ft*

Figure 8. Range of Installed Densities of Loose-Fill Rock/Slag Wool

Insulation from Reference and from this Study.

3.1.2 Thermal Resistivity

The primary function of retrofitted sidewall insulation is the reduction

of heat flow through the wall. Thermal resistance is a measure of a material's ability to resist heat flow. The thermal resistivities

(resistances per unit thickness) for the urea-formaldehyde based foam and

loose-fill insulation samples in the study are given in Tables 4 and 5,

respectively. As determined in the laboratory, the three types of retrofit

insulations had good thermal insulating properties. The thermal resistivity

values of the urea-formaldehyde based foam insulations were on the average

higher than those of the loose-fill insulations. This was in accord with

the findings of Burch, Siu and Powell [4], When discussing laboratory

measured values of thermal resistivity, it is important to note that the

thermal performance of an insulation in a wall may be less than indicated

from the laboratory measurements. In particular, the effect of shrinkage

of urea-formaldehyde based foam insulations on the insulating properties

of foam-filled walls has been reported to be important [9,12-14]. For

example, it may be calculated that if the foam shrinks 6 percent linearly,

its effective thermal resistivity in service in a wood-framed cavity wall

may be 28 percent less than its thermal resistivity measured in the laboratory, due to the air gaps created by the foam shrinkage [14]. It is

noted that examples of calculating the total thermal transmittance of

insulated walls may be found in the ASHRAE 1977 Handbook of Fundamentals.

The thermal resistivity was determined for twenty-four of the twenty-five

urea-formaldehyde based foam insulations examined in the field survey.

One foam sample (no. 9) as found in the wall was too cracked to serve

as a test specimen for the determination of the thermal resistivity. The

thermal resistivity range of the tested foam specimens was from 20.8 to

31.9 m'K/W (3.00 to 4.60 h'ft ,0 F/Btu*in), with an average value of 28.0

Ei'K/W (4.03 h

# ft 2, °F/Btu*in). The foam specimen (no. 1) which had the

unacceptably low density of 5.4 kg/m (0.34 lbm/ft ) had the lowest

thermal resistivity of any of the insulations tested in the study.

17
The thermal resistivities of the eight cellulose samples ranged from 23.6

to 26.0 m'K/W (3.40 to 3.75 h* f

t

2 * °F/Btu* in) , with an average value of

24.9 m'K/W (3.58 h' f

t

2 * °F/Btu* in) . The range of thermal resistivity

values for the loose-fill mineral fiber insulations was 24.7 to 29.2 m'K/W

(3.55 to 4.20 h'ft 2

* °F/Btu*in), with an average value of 26.4 m'K/W (3.8

h'ft •°F/Btu*in). The two loose-fill mineral fiber samples (nos. 37 and

38) having relatively high densities of 140.9 and 126.5 kg/m (8.8 and

7.9 lbm/ft 3

) had thermal resistivities of 26.0 and 25.3 m'K/W (3.75 and

3.65 h'ft 2 * °F/Btu*in), respectively.

3.2.1.1 Relationship between Thermal Resistivity with Density

Figure 9 is a plot of the thermal resistivity of the urea-formaldehyde

based foam samples versus density for the data in Table 4. It can be seen that as the density of the foam sample increased, the thermal

resistivity tended to increase. The solid line in Figure 9 was obtained

from a linear regression analysis relating the the density versus the

thermal resistivity. The equation in S.I. units for this relationship

was y = 0.66 x + 20.4 (Customary Units, y = 1.51 x + 2.95) where y and

x were the thermal resistivity and density, respectively. The correlation

coefficient for this relationship was 0.73. The solid line may be compared

with the dashed line which represents data from Weidt's field study [6].

The comparison shows that the lines are in close agreement over the

thermal resistivity range for which data are available from both studies.

Using the data in Table 5, the thermal resistivity of the cellulose

samples was plotted as a function of density. Figure 10 shows that as

the density of the cellulose samples increased, the thermal resistivity

tended to decrease. The solid line in Figure 10 was generated from

the data in Table 5 by linear regression analysis which related the

thermal resistance to the density. The equation in S.I. Units for this

relationship was y = - 0.047 x + 27.42 (Customary Units, y = - 0.11 x + 3.96) where y and x represent the values for thermal resistivity

and density, respectively. The correlation coefficient was - 0.62.

This solid line in Figure 10 lies slightly above the dashed line which

represents data from Weidt's field study [6].

18
0.0

32

30 -

28

E

i= 26 -

£2

CO

?. 24 -

22 -

20

DENSITY, lbm/ft3

0.5 1.0 1.5 2.0

Data line from

reference 6

Line representing

data from this study

8 16

DENSITY, kg/nv*

24

4.4

4.0

GO

o

CM

3.6 £CO

CO

LU

3.2

32

Figure 9. The Relationship Between Density and Thermal Resistivity for

for the Urea-Formaldehyde Based Foam Insulation Samples.

19
28

26 -

coCO

24 -

22

32

DENSITY, Ibm/ft3

3 4 5

- 4.0 t

Line representing data

from this study

Data line from

reference 6

i 48 64

DENSITY, kg/m3

80

OQ

o

CM

3.6 £

co

CO

zl 3.2

96

Figure 10. The Relationship Between Density and Thermal Resistivity for

the Loose-Fill Cellulose Insulation Samples.

20
In seeking a relationship between the density of a loose-fill mineral

fiber insulation and its thermal resistivity the type of fiber such as glass, rock or slag should be considered. Since this study only

evaluated three glass fiber and three rock and/or slag wool samples,

establishment of relationships between denity and thermal resistivity for

these mineral fiber materials was not attempted. Figure 11 shows five

curves drawn from data in the ASHRAE Handbook of Fundamentals relating

the thermal conductivity to density for loose-fill glass fiber insulations consisting of fibers with different diameter thicknesses [15].

The points in Figure 11 represent the data points from the present field

study (Table 5). These three data points are seen to lie within the

range of curves generated from the ASHRAE data.

DENSITY, Ibm/ft3

2 3

I

30

P 25

CO

CO

DC

20 -

15 -

i r t

1 1 r

4.5 Mm (0.00018 in 5.6 /um (0.00022 in)

/// • -"^ \. 10 - 2 ^m (0.00040

///***>. M Mm (0.00050 in]

'/I ^7.1 Mm (0.00028 in)

in

-I 5.0 t

=3

+•> CO

Uo

• CM H 4.0 %

3.0 <3

NOTE: Curve values represent the

thicknesses of the diameters

of the fibers pi 5li » '

I L

i J i 1 L 16 32 48

DENSITY, kg/m3

64 80

2.0

Figure 11. The Relationship Between Density and Thermal Resistivity for

Glass Fiber Insulations, as given in the Literature [15],

and from this Study.

21
Figure 12 contains a curve plotted from data given in the literature [2],

which relate thermal conductivity and density for loose-fill rock/slag,

wool samples. The data points from this study (Table 5) are also

included in Figure 12. The data points for the two samples (nos. 37

and 38) with the high densities lie well beyond the range of the curve given in the literature [2].

E 29 : £^ 27 - CO ^

d E

DENSITY, Ibm/ft*

2 3 4 5 6 7 8 10

-Ref. 2

40 •— =

3.5

3.0

16 32 48 64 80 96 112 128 144 160

DENSITY, kg/itf

o

CM

Figure 12. The Relationship Between Density and Thermal Resistivity for

Loose-Fill Rock/Slag Wool Fiber Insulations as given in the

Literature [2] and from this Study.

3.1.2.2 Effect of Age on Thermal Resistivity

An insulating material is expected to remain effective in reducing heat

flow for many years. The thermal resistivities of the urea-formaldehyde

based foam and loose-fill cellulose samples were analyzed in relation to

their age. It was obviously not possible to observe whether any changes

in thermal resistivity occurred in time, since the materials were tested

at one point in time only.

The urea-formaldehyde based foam samples for which the thermal resistivities

were determined ranged in age from 1.4 to 4.1 years (Table 4), with an average of 2.7 years. The age of the cellulose samples ranged from 1.7 to

10.3 years (Table 5), with an average of 3.5 years. Analysis of these

data indicated no correlation between thermal resistivity and age of the

samples. It is noted that the oldest cellulose sample with 10.3 years of

age had a thermal resistivity of 25.7 m

# K/W (3.70 h'f

t

2, °F/Btu»in) , which

was among the highest value of all cellulose samples. Establishment of

relationships between thermal resistivity and age for the glass fiber

and rock/slag wool insulations was not attempted because of the small

number of samples of each type of material.

22
3.1.2.3 Relationship Between Thermal Resistivity and Geographic Location

The climatic environment to which an insulation is subjected may affect its

performance. It was thus of interest to tabulate the thermal resistivities

of the insulations according to the geographic location of the test house

from which each insulation was removed. Tables 6 and 7 list the ranges

and average thermal resistivity values for the urea-formaldehyde based foam

and loose-fill cellulose samples, respectively, according to geographic

location. These tables did not show any important trends.

Although the average thermal resistivity for the four urea-formaldehyde

based foam samples from Minneapolis was the lowest of the five geographic

locations, this average included the value for sample no. 1 which was quite

low and not typical of foam insulations [9]. No further analysis of the

tabulated data was performed, since the number of samples in any city

was limited.

3.1.2.4 Relationships Between Thermal Resistivity with Manufacturer or Installer

The thermal resistivities of the urea-formaldehyde based foam insulations

are listed in Table 8 along a letter designating the manufacturer of the

component materials. Table 9 presents the thermal resistivities and the

numerical designations of the installers of the cellulose insulations.

It was of interest to compare the thermal resistivities with the manufacturer

or installer, since these variables may contribute to differences in material performance. Although the tables show slight variations in thermal

resistivities as related to foam manufacturers or cellulose installers,

the differences were not considered to be important. The number of

the test samples per manufacturer or installer was very limited.

3.1.3 Moisture Content

As previously mentioned, moisture accumulation within insulation or wall

components may adversely affect the thermal performance of the insulated

wall or result in deterioration of the wall component materials. Table 4

gives the moisture contents of the urea-formaldehyde based foam samples.

The moisture contents of the foams exhibited the widest range among all

of the retrofit insulations and varied from 3.2 to 22.0 percent. The

average value was 12.1 percent. The reasons for this wide variation

were not determined, but may be influenced by differences between foam

samples. Factors such as differences in chemical formulation, cell size,

and open cell content may influence the moisture absorption properties

of foams. Also some foam samples may lose other volatiles upon heating

in addition to moisture. In at least one case on odor was detected

while the foam was heated during drying. Previous data summarized by

Rossiter et al. indicated that the moisture content of foams may be in

the range of 8 to 18 percent by weight, depending upon the temperature

and humidity conditions [9]. It is of interest to note that no correlation

was found between moisture content and thermal resistivity for the foam

samples

.

23
TABLE 6. RANGE AND AVERAGE OF THERMAL RESISTIVITY VALUES FOR UREA-FORMALDEHYDE

BASED FOAM INSULATIONS BY GEOGRAPHIC LOCATION

Geographic

Location

Number

of

Samples

Range of

Thermal Resistivity

Average

Thermal Resistivity

m'K/W h'ft 2 '°F/Btu'in m'K/W h'ft 2 '°F/Btu'in

Minneapolis

Hartford/New Haven

Washington, D.C.

Louisville

Dayton

5(a)

4

75

20.8 to 27.8

26.0 to 28.1

25.7 to 29.9

25.3 to 31.6

25.0 to 31.9

3.00 to 4.00 25.4 3.66

3.75 to 4.05 26.9 3.88 u;

3.70 to 4.30 28.1 4.04

3.65 to 4.55 29.3 4.22

3.60 to 4.60 29.1 4.19

(a) Although five samples were examined in the Hartford/New Haven location, the thermal

resistivity of one sample (no. 9) was not determined, since an adequate test specimen

was not available. Therefore, the average value of thermal resistivity is for four

specimens

.

TABLE 7. RANGE AND AVERAGE OF THERMAL RESISTIVITY VALUES FOR CELLULOSE INSULATIONS

BY GEOGRAPHIC LOCATION

Average

Thermal Resistivity

Number

Geographic of Range of

Location Samples Thermal Resistivity

m'K/W h«ft 2 «F/Btu»in m'K/W h'f

t

2 ' °F/Btu'in

Washington, D.C. 5 Richmond 1 Dayton 223.6 to 25.0

(a)

25.7 to 26.0

3.40 to 3.60

(a)

3.70 to 3.75

24.4 3.51

25.0 3.60

25.9 3.73

No range is given since only one sample was examined in the Richmond location.

24
TABLE 8. RANGE AND AVERAGE OF THERMAL RESISTIVITY VALUES FOR UREA-FORMALDEHYDE

BASED FOAM INSULATIONS BY MANUFACTURER

Numbe r of Range of Average

Manufacturer Samples Thermal Resistivity Thermal Re sis tivity

nTK/W h'ft 2 ' F/Btu'in m'K/W h" ft 2, °F/Btu'in

A 1 „(a)

__(a)

..(a)

_.(a)

26.7 3.85

B 1 26.4 3.80

CD l(b)

26 •0_t

?bJ0.6

3.75 tp 4.40

__(b)

28,6

!:H)

E 2 25 .0 to 31.9 3.60 to 4.60 28.5 4.10

F 5 25 .7 to 28.5 3.70 to 4.10 27.4 3.94

G 7 25 .3 to 31.6

__(a)

3.65 to 4.55

__(a)

29.2 4.20

H 1 20.8 3.00

fa) v No range is given since only one sample from this manufacturer was examined.

(b) The thermal resistivity of this sample was not determined, since an adequate test

specimen was not available.

TABLE 9. RANGE AND AVERAGE OF THERMAL RESISTIVITY VALUES FOR CELLULOSE INSULATIONS

BY INSTALLER

Installer

Number

of

Samples

Range of

Thermal Resistivity

m'K/W h'ft 2 *°F/Btu*in

Average

Thermal Resistivity

m'K/W h-ftz *°F/Btu'in

1 1 --K*)

233

1 23.6 to 25.0

__(a$

4 1 „(a)

5 1 __(a)

6 1 __(a)

_.(a)

3.40 to 3.60

__(a)

__(a)

__(a)

..(a)

24.3

24.4

25.0

24.3

26.4

25.7

3.50

3.52

3.60

3.50

3.75

3.70

^ a ' No range is given since only one sample applied by this installer was examined.

25
The cellulose samples showed a moisture content range of 8.8 to 13.4

percent, with the exception of one (no. 31) which had a moisture content

of 21.2 percent (Table 5). This sample was removed from a wall area in the

vicinity of a window frame which leaked rain water. The higher moisture

content measured for this house was attributed to the leaks. Excluding

the value for this sample (no. 31), the average moisture content of the

other seven cellulose insulations was about 11 percent. The average value

is close to the ten percent value reported by Burch, Siu and Powell for

a loose-fill cellulose sample conditioned to constant mass at 23.9°C (75°F)

and 40 percent relative humidity [5] . The average value of 11 percent may

also be compared with values of the equilibrium moisture content of wood,

as reported by Nottage [16]. According to him, the equilibrium moisture

content of wood determined at temperatures of about 21 to 27°C (70 to

80°F) and at relative humidities of about 40 to 60 percent ranged from

approximately 7 to 11 percent by weight. No correlation was found between

moisture content and thermal resistivity for the cellulose samples.

The data in Table 5 show that the loose-fill mineral fiber samples had

moisture contents of less than 1 percent. This was the lowest percentage

for the three types of retrofit insulations, and is identical with the

value reported by Burch, Siu and Powell for a glass fiber sample conditioned to constant mass at 23.9°C (75°F) and 40 percent relative humidity

[4] . The moisture contents of the mineral fiber samples showed no relationship to their thermal resistivities. The samples exhibited a range of

resistivities, while the moisture contents were constant at less than 1 percent, as shown in Table 5.

3.1.4 pH of Urea-Formaldehyde Based Foams

Urea-formaldehyde based foam insulations are in general produced at the

job-site through an acid-catalyzed chemical reaction. It may be be hypothesized that the acid catalyst may migrate to the foam surface along with

the water present during foam formation, as the freshly-prepared foam

dries. Migration of the acid catalyst might be expected to result in its

accumulation at the surfaces of the foam, provided that no other reactions

take place within the foam to neutralize the acid-catalyst or that the

acid is not absorbed into other building materials in contact with the

foam such as sheathing or gypsum wall-board. If the surfaces of the foam

were to accumulate the acid-catalyst, the insulation might be rendered

susceptible to acid-catalyzed hydrolytic decomposition at those locations.

Measurements which might provide evidence of this phenomenon were included

in this study.

The pH of the foam insulations was determined for three sections of each

test specimen removed from each house: at the interior and exterior sur- faces of the foam and at the middle. The pH values are given in Table 10

for the three sections of the foam samples. The results indicated that

the average pH of the foam surface next to the interior side of the wallcavity was slightly lower than that of the foam surface at the exterior,

which had approximately the same average pH as the middle sections of the

test specimens. The average pH values of the interior, exterior, and

middle sections of the test specimens were determined to be 3.9, 4.9, and

26
4.7, respectively. Only eight samples (nos. 1, 5, 11, 15, 20, 21, 22, and

24) showed the middle sections to have pH values which were greater than

those of both surfaces.

TABLE 10. VALUES OF pH AT THE SURFACES AND CENTER OF THE UREA-FORMALDEHYDE

BASED FOAM SAMPLES

Sample

Number

pH Value

Interior' 3 ' Middle Exterior (a)

6.0 6.5 6.3

5.8 6.0 6.0

3.3 3.4 6.1

5.8 5.5 6.5

3.6 6.6 4.5

3.1 3.3 3.5

3.2 3.4 4.0

3.8 3.1 3.6

4.6 4.9 6.0

3.0 4.7 5.1

3.8 6.4 4.8

4.0 6.2 6.4

3.6 3.8 5.2

2.9 4.6 5.1

3.3 6.0 4.0

3.1 3.2 3.3

3.1 3.8 5.8

3.3 4.6 4.7

5.1 4.0 3.3

2.8 4.2 3.9

3.6 5.4 5.1

2.9 3.4 3.0

4.2 3.9 4.8

5.6 6.5 5.7

2.7 4.2 4.7

123

4

5

6

78

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Average 3.9 4.7 4.9

^ a

^ Surface of the foam which faced the exterior side of the wall cavity.

^ ' Surface of the foam which faced the interior side of the wall cavity.

27
3.1.5 Water Absorption of Urea-Formaldehyde Based Foams

The Canadian Standard [13] developed by the Canadian Government Specifications Board (CGSB) and the Use of Materials Bulletin No. 74 [14] issued by

the U.S. Department of Housing and Urban Development for urea-formaldehyde

based foam insulations both require a water absorption test (Appendix C)

.

The test is performed on samples which have been conditioned at about

23°C (73°F) and 50 percent relative humidity for 28 days. The procedure

involves floating the specimen on water and determining the quantity of

water which is absorbed after 7 days. In order to meet the requirement of

the standards, the water absorption of the foam sample should not exceed

15 percent by volume. It is noted that, as specified in the standards,

the test is normally conducted on freshly-prepared dried foam samples and

not on aged samples.

Although foam samples may meet the water absorption requirement 28 days

after preparation, data were not available which describe the performance

of aged foams in the test. It has been suggested that foam deterioration

due to aging might result in an increase in the amount of water absorbed

by foams [17]. Thus, it was of interest to determine the water absorption

of some of the urea-formaldehyde based foam samples from the field study,

since they were in general more than 2 years old and had been exposed

to various environmental conditions. The water absorption test was not

conducted on all foams because of a lack of test samples.

The results of the water absorption tests are given in Table 11, along

with comments pertaining to the pre -test condition of the foam surface

which was in contact with the water during the float test. Whenever

sufficient test samples were available, duplicate tests were conducted

on each surface of the foam. In other cases, only one test was performed

on each surface, and for some samples, a single test was conducted on one surface only. The foam surface in contact with the water during the test

had been oriented towards either the interior or exterior side of the

cavity wall of the test house. No distinction was made as to whether the

tested surface of the foam faced the interior side or the exterior side

of the cavity wall.

As can be seen from Table 11, only one sample (no. 24) of the thirteen

foams included in the test had a water absorption which exceeded the maximum value of 15 percent by volume stated in the Canadian Standard [13] and

the HUD Use of Materials Bulletin [14]. This sample (no. 24) had a value

of about 18-19 percent for three determinations and 11 percent in a fourth determination. The majority of the foams exhibited water absorptions which were less than 5 percent by volume, even though the conditions

of the foam surfaces varied between samples. Sample no. 24 which had the

highest water absorption was described as having surfaces which would be

expected of foam in normal condition. This sample showed no signs of

surface deterioration. On the other hand surface B of sample no. 11 was powdery and slightly friable, indicating some deterioration. However,

the water absorption of this surface was only 1.2 percent by volume.

28
TABLE 11. WATER ABSORPTION OF UREA-FORMALDEHYDE BASED FOAMS

Sample^ N , vx Water Absorption Comment on the Cond^t^on

Number

Le Water Absorption Comment on the Condltic

' a ^ Surface^ ' Percent by Volume of the Foam Surface^ 3 '

6 A 0.5 Both surfaces were soft and A 0.7 somewhat spongy.

B 0.5

B 0.6

A 0.7 Surface was soft and somewhat

spongy.

8 A 1.2 Surface A was soft, while surface A 1.1 B was firm.

B 0.4

B 0.5

11 A 7.5 Both surfaces were powdery and

B 1.2 slightly friable to the touch.

14 A 2.8 Surface A was slightly yellow. A 3.1

B 1.9

15 A 1.6 Both surfaces were considered A 2.1 normal.

B 1.0

B 0.6

17 A 1.2 Both surfaces were very firm.

A 1.4

B 3.2

B 2.2

18 A 1.2 Both surfaces were very firm. A 1.3

B 2.1

B 2.0

19 A 7.6 Both surfaces were yellow and

B 6.8 not smooth.

21 A 1.1 Surface was soft and spongy.

23 A 1.6 Both surfaces were soft and

B 1.9 spongy.

24 A 19.0 Both surfaces were considered A 19.2 normal.

B 18.0

B 11.2

25 A 15.0 Surface was yellow and contained

a few small cracks and voids

(a)

(b)

Test was not conducted on all samples because sufficient Insulation was

not available for all samples.

Surface refers to the surface of the foam which was in contact with the water during the float test. Letter designations A and B were used only

to distinguish one surface of the foam from the opposite surface.

29
These results do not appear consistent with the suggestion that the water

absorption properties for foams may increase if the surfaces deteriorate

with age. It is noted that the data in this study are limited, and because

of the nature of the field survey, they do not include water absorption

values for the freshly-prepared foams. A laboratory study or extended field

survey would be needed to determine changes in water absorption properties

of foam specimens as a function of time. Until such a study is conducted,

it may be assumed that water absorption may not be used as an indication

of foam deterioration due to aging.

3.2 Field Examinations

3.2.1 Shrinkage of Urea-Formaldehyde Based Foams

Shrinkage of urea-formaldehyde based foam insulations is an important

performance factor, since gaps, cracks, and splits resulting from shrinkage

are void spaces in which air may circulate and thus reduce the thermal

.

efficiency of the foamed wall [9,12]. The Canadian Standard indicates

that because of shrinkage, when installed in cavity walls, the effective

thermal resistance of foam insulations may be 40 percent less than the

laboratory-measured values of thermal resistance [13]. In a similar

manner, the HUD Use of Materials Bulletin No. 74 states that the effective

thermal resistance may be 28 percent less than the laboratory-measured

value, provided that the foam shrinks 6 percent linearly [14]. The HUD

Bulletin also presents a curve relating shrinkage to effective thermal

resistance. Based on the results of the field inspections of twenty-five

houses which were retrofitted with foam insulations, and for the performance factors for which information or data were recorded, foam shrinkage

was considered to be of most concern.

Shrinkage had occurred in all inspected sidewalls containing ureaformaldehyde based foam insulation. Table 4 presents the percent linear

shrinkage values. The procedure for calculating the percent shrinkage is

given in Appendix E. For those test houses where more than one wall cavity

was opened, shrinkage values were determined for each separate cavity and

an average value was calculated. It can be seen in Table 4 that shrinkage

values were obtained for seventeen of the twenty-five houses inspected.

The linear shrinkage values ranged from about 4 to 9 percent, with an

average value of 6.0 percent. The average value of 6.0 percent was slightly greater than the 4.5 percent previously reported by Weidt in the

Minnesota study [6] and considerably higher than the 1 to 3 percent range

quoted in many sources [9]. The percent linear shrinkage could not be

measured for eight of the twenty-five houses for two reasons. In four

of the eight houses, gaps, cracks, and voids in the foam specimens were

too numerous to allow a shrinkage determination. In the other four cases,

the presence of batt insulation within the cavities precluded the

shrinkage measurements.

Plots of the percent linear shrinkage with foam density and age indicated

little relationship between the variables. As one example, Figure 13 is

a plot of the density of the foam specimens versus percent linear shrinkage.

30
MMMHU'wimwh

DENSITY, Ibm / ft3

0.2 0.4 0.6 0.8 1.0 1.2 1.4

10 15

DENSITY, kg/nv*

20 25

Figure 13. Plot of the Percent Shrinkage of the Urea-Formaldehyde Based

Foam Specimens Versus Density.

31

iiMIBMI(l»llHIMHHimillllHii7y
Table 12 summarizes the percent linear shrinkage data by geographic location

(city), component material manufacturer and installation season. No important differences in shrinkage values were found. As has been mentioned

previously, the number of samples was limited and in some cases only one sample comprised a specific category. For example, only one house was inspected in which the foam was installed in the spring. Statistical

analysis of the data in Table 12 was not attempted to determine whether

the differences in the shrinkage values between categories were significant,

since it could not be established that the houses included in the survey

comprised a random sample.

In observing the foam in various houses, it was seen that the shrinkage

patterns were not identical for all samples. In some cases, the foam

was undistorted which indicated that the rear, center and front areas of

the foam had shrunk uniformly. In other cases, the foam samples had warped

and the shrinkage was more pronounced towards the exterior side of the

cavity wall. Reasons for these different patterns of shrinkage were not

determined.

In comparing the shrinkage of a single foam in two cavities of the same

test house, it was found that shrinkage might vary considerably in the

two cavities. In some cases, the difference in foam shrinkage between two

cavities was over two percent. In one case, the foam shrinkage between

cavities differed by about one-fourth of a percent.

As previously mentioned, foam shrinkage was generally measured across the

cavity width. For four test houses, the percent shrinkage was determined

from measurements of the cavity wall depths and foam thicknesses. These

results are presented in Table 13 along with the shrinkage values based on measurements of the cavity wall and insulation widths. Table 13 shows

that the shrinkage values using cavity depth measurements were greater than

those from cavity width measurements for three of the four houses.

In addition to the formation of gaps and air spaces between wall studs

and sheathing and the foam, shrinkage of urea-formaldehyde based foam insulations sometimes results in cracks or fissures, and voids within the

sample. Cracking from shrinkage in general followed one of two patterns:

the foam sample contained many small cracks which broke it into many small

pieces (Figure 14); and the foam sample contained a few large cracks,

generally horizontally oriented, which split it into several distinct

pieces (Figure 15). The width of some of these large cracks ranged from

10 to 40 mm (0.4 to 1.6 in). In many cases, the foam samples contained

many small fissures which did not penetrate completely through the insulation. Although all foams had undergone shrinkage to varying degrees, the

surfaces of the foams were generally in good condition. One sample (no.

11) had surfaces described as powdery and slightly friable to the touch.

32
TABLE 12. RANGE AND AVERAGE VALUES OF LINEAR SHRINKAGE FOR

UREA-FORMALDEHYDE BASED FOAMS BY CITY, MANUFACTURER AND

INSTALLATION SEASON

Variables

No. of

Samples

Range of

Shrinkage

percent

Average

Shrinkage

percent

City

Minneapolis 3 4.1 to 6.5 5.0

Hartford/New Haven 4 5.7 to 9.0

__(a)

7.1

Washington, Ei.C. 1 7.4

Louisville 6 4.4 to 6.7 5.6

Dayton 3 3.9 to 8.1 6.0

° Manufacturer

A

B

1 __(b) —(a)

—(b)

6.2

__(b)

C

D

6

—(b)

5.7 to 9.0

—(b)

7.0 —(b)

E 1 „(a) 3.9

F 2 4.1 to 4.4 4.3

G

H

6

1 4.4_t

?a5

.l 5.9

6.5

Installation

Season

Summer

Fall

Winter

Spring

4.1 to 9.1

4.4 to 7.4

3.9 to 7.4

„(a)

6.5

5.7

5.8

5.7

(a)

(b)

No range is given since only one sample was in this category,

Shrinkage values were not determined for this manufacturer's

insulation.

33
TABLE 13. A COMPARISON OF SHRINKAGE VALUES FROM CAVITY WIDTH AND

CAVITY DEPTH MEASUREMENTS

Sample

No.

Shrinkage Value from

Cavity Width Measurements

Percent

Shrinkage Value for

Cavity Depth Measurement

Percent

5 7.4 8.2

8 6.2 6.7

17 6.7 5.1

18 6.6 8.1

3.2.2 Settling of Loose-Fill Insulations

Settling of loose-fill insulations is a phenomenon which may result in

decreased thermal performance of the insulated wall. The tops of the

wall cavities in six of the fourteen houses retrofitted with loose-fill

insulation were inspected to determine the completeness of the application or the presence of voids at these locations. Three of these houses

contained cellulose and three had mineral fiber insulations. It was the

intent of the study to examine the tops of the wall cavities in all

houses containing loose-fill insulations. Unfortunately, factors such

as the type of construction, ease of siding and sheathing removal without

damage to the residence, and restrictions set by homeowners concerning

wall areas available for examination limited the number of test houses

which could be opened at the top of the cavity.

For the six houses inspected at the top of the wall cavity, five were

found to be filled completely with the loose-fill insulation and no voids

were evident. One loose-fill cellulose insulation was seen to have voids

at the top of the opened cavities, as shown in Figure 16. It could not be

determined whether the voids were attributable to settling of the insulation or initial incomplete fill of the cavities. The voids in the cavities

ranged in height from about 30 to 130 mm (1.2 to 5.1 in).

34
Figure 14. Example of Urea-Formaldehyde Based Foam Sample Which

Cracked into Small Pieces

35

.
Figure 15. Examples of Urea-Formaldehyde Based Foam

Samples Which Contained Large Horizontal

Cracks.

36
>*

Figure 16. The Void Observed at the Top of the Cavity

Insulated with Loose-Fill Cellulose Insulation.

3.2.3 Condition of Wall Components

Voluminous notes concerning the general condition of the insulations and

wall components were assembled during the field examinations. It may be

generally summarized that no observations were recorded for the thirtynine houses which indicated that the retrofitting of the sidewalls had

adversely affected the conditions of the wall components at the location

where the sidewalls were opened. No visible evidence of moisture

accumulation and condensation or damage was found, except in the case

of one house (no. 31). However, in this case, the moisture was attributed

to a leak around a window frame which caused wood rot of the framing

studs and a high moisture content in the cellulose insulation within

the cavity.

It should not be construed that all walls and components examined were free

of problems. However, observed problems were minor and could not in general

be directly attributed to the retrofit. For example, fourteen of the twentynine painted houses were described as having paint problems including cracking, blistering, peeling and mold growth. In all these cases, the problems were observed on both insulated and uninsulated painted walls (for example,

the walls of garages and gables). The few electrical junction boxes or other metal components found in five of the houses were in good condition

and corrosion, if any, was minimal. Non-galvanized common nails were

present in most wall cavities and, as would be anticipated, they showed

some rust.

37
Very minor fungus or mold growth was visible in the cavities of three houses.

None of the walls was examined with a magnifying lens. An unusual case of

fungus growth was found for one urea-formaldehyde based foam installation.

The fungus was growing on the exterior painted surface of the plugs which

sealed the insulation application holes. Dark round spots were quite

visible on many sections of the walls, even when viewed at some distance

from the house. These spots reduced the attractiveness of a well maintained

home. No fungus was seen within the open wall cavities of this house.

It is interesting to note that a homeowner who had installed a urea- formaldehyde based foam stated that a formaldehyde odor had lingered in

the house (no. 10) several months after completion of the retrofit, but

the odor had stopped before the field investigation. The field investigators did not detect any formaldehyde odor within the residence. However, upon opening the sidewall from the exterior, an odor described

as that of formaldehyde was detected within the cavity by the investigators. Formaldehyde odors were not reported by homeowners nor detected

by the investigators in the cavities of the other twenty-four houses

surveyed in which foam had been applied. In one house, a urea-formaldehyde

based foam had been installed from the interior of the residence and

many application holes were left free and not sealed for many months

after the foam was installed. In this case, it might be assumed that

if excess formaldehyde was liberated from the foam, it would have readily

been detected by the occupants of the house. It is emphasized that

these findings concerning formaldehyde release from foams are subjective.

This field survey was not intended to address directly the subject

of formaldehyde release and no measurements of the concentration of

air-borne formaldehyde were made in the test houses.

Evidence of vermin activity in the retrofitted sidewalls was seen in the case of a rock/slag fiber installation. The insulation contained voids

or tunnels which were apparently made by mice. In another case, a mouse

nest which was probably present before the application of the insulation

was found within the urea-formaldehyde based foam.

3.2.4 Workmanship

Workmanship during retrofitting is an important parameter influencing the

thermal performance of a retrofitted sidewall, and poor workmanship may

result in insulated walls with less than expected thermal resistances.

Factors associated with poor workmanship include incomplete application of

the insulation, installation of an inferior quality material (which, for

example, may settle or shrink excessively), and damage to the wall or wall components. Wall cavities which are incompletely filled may be less

thermally efficient than those which are completely filled [4, 12-14, 18].

Observations relating to workmanship were noted where possible during

the field survey.

For the thirty-nine houses inspected, workmanship was in general found to

be satisfactory, although the inspected houses were not free of workmanship

problems. The survey produced no evidence to indicate wide-spread problems

due to poor workmanship. Nevertheless, sufficient isolated problems were

seen to serve as a warning that acceptable practice should be diligently

38
followed during the retrofitting of sidewalls. Some of the observed problems which may be associated with the quality of workmanship included:

the previously-mentioned house containing cellulose insulation which may

have settled in the cavity or which may have been incompletely installed;

one cellulose installation in which a cavity contained no insulation; four

urea-formaldehyde based foam insulations in which the cavities were not

completely filled (Figure 17); and two cases (one foam and the other mineral fiber) wherein excessive pressure was applied during application

which resulted in cracking and bowing of the interior wall surfaces.

The observation that some houses had cavities which were not completely

filled with insulation is consistent with the findings from Grot's field

survey using thermographic techniques [7].

Qualitative comparisons of foam samples of the same brand name indicated

that quality varied within a brand. Some of the foams were considered

to be relatively good, while others with the same brand name were described

as relatively poor. The relatively good foams had undergone a lesser

amount of shrinkage and contained fewer cracks, gaps and voids then those

described as relatively poor. The question may be asked whether these

observed differences between the quality of foams with the same brand

names were due to differences in workmanship during application.

Electrical outlet and switch boxes in a few houses were inspected for the

presence of insulation. Each type of material was found to some degree

in some boxes. Figure 18 shows an urea-formaldehyde based foam which had

completely filled one outlet box. In one case each, a cellulose and a mineral fiber sample were found in electrical boxes, and filled about 25 percent

of the volume of the boxes. In other cases, the inspected electrical boxes were seen to be free of insulation. Reasons why insulation was found in some electrical boxes and not others were not determined. It was not known

whether any installers had removed insulation from electrical boxes.

It is interesting to note that for seven of the test houses, a retrofit

insulation (six urea-formaldehyde based foams and one cellulose) was applied to wall cavities which contained batt insulation. For the wall

cavities inspected in these seven cases, the presence of the batt insulation did not adversely affect the installation of the retrofit insulation.

The wall cavities in the areas of inspection were completely filled, since

the retrofit insulation compressed the batt to one side of the cavity

(Figure 19). In two of the seven cases, the urea-formaldehyde based foam

was seen both to have compressed the batt and intermingled with it. Even

in these cases, the inspected wall cavities were filled with insulation.

This was in accord with Weidt's previous finding that presence of

insulation within the wall cavity did not necessarily preclude the

successful application of the retrofit insulation [6].

3.2.5 The Presence of Membrane-Type Vapor Barriers

Accepted practice is to place a vapor barrier on the warm side (during

the winter) of a wall to prevent moisture accumulation within the wall

due to vapor transmission. Improperly placed vapor barriers may result

39
*«m0mtik

Figure 17. Incomplete Application of Urea-Formaldehyde

Based Foam Insulation.

Figure 18. Electrical Outlet Box Filled With

Urea-Formaldehyde Based Foam Insulation.

40
Figure 19. Existing Batt Insulation Compressed by the

Retrofit Insulation.

in excessive accumulation of moisture within the wall. Membrane-type

vapor barriers were found in the wall cavities of ten of the surveyed

houses. The scope of this study did not include a determination of

the permeance of the interior facing of the cavities. Table 14 gives

the types and locations of the membrane vapor barriers found in the

study, and the moisture contents of the insulations in the cavities.

The moisture contents for the insulations installed in cavities with

vapor barriers were close to the average values of moisture content for

each of the three types of retrofit insulations. As presented in Section

3.1.3 the average moisture contents of urea -formaldehyde based foam,

loose-fill cellulose and loose-fill mineral fiber insulations were 12,

11, and < 1 percent, respectively. Although the observation may have

little significance, it is interesting to note from Table 14 that the

urea-formaldehyde based foam samples in cavities with the vapor barriers

on the exterior side had on the average lower moisture contents than

foams in cavities with interior side vapor barriers.

4.0 SUMMARY AND CONCLUSIONS

The study was intended to obtain information concerning the properties

and performance of retrofit insulations, as they are found in place in

the walls. This study involved the opening of sidewalls of residences

which had been retrofitted with loose-fill cellulose, loose-fill mineral

fiber and urea-formaldehyde based foam insulations. A major reason for

conducting the study was the lack of data on retrofit insulations in

place. Another reason was the concerns which have been associated with

the process of retrofitting sidewalls since it generally involves the

addition of an insulation to an inaccessible space which cannot be

inspected before or after the job is finished. Thus, the quality of

the end product is difficult to evaluate.

41
TABLE 14. TYPE AND LOCATION OF VAPOR BARRIERS FOUND IN WALL-CAVITIES

AND CORRESPONDING MOISTURE CONTENTS OF INSULATIONS

Sample Retrofit

Insulation

Vapor Barr ier Moisture Content

No. Type Location Percent by Mass

2 UF Foam Foil Exterior^ 3 ' 10.5

5 UF Foam Foil Exterior 6.5

19 UF Foam Foil Exterior 10.9

21 UF Foam Foil Exterior 13.6

4 UF Foam Batt Facing Interior^ 12.5

8 UF Foam Foil Interior 11.7

10 UF Foam Foil Interior 14.9

16 UF Foam Batt Facing Interior 14.8

26 Cellulose Batt Facing Middle (c) 12.4

35 Glass Fiber Foil Exterior < 1.0

AVERAGEUF Foam with exterior vapor ba rriers 10.5

AVERAGEUF Foam with interior vapor barriers 13.5

(a)

(b)

(c)

Exterior indicates that the vapor barrier was located on the exterior

side of the wall cavity.

Interior indicates that the vapor barrier was located on the interior

side of the wall cavity.

Insulation was on both sides of the vapor barrier.

In the field survey which was conducted in late fall, 1978, and early

winter, 1979, observations were made regarding factors which affect the

performance of the insulated wall. These factors included the condition

of the insulation and wall components, moisture accumulation, settling of

loose-fill insulations, shrinkage of urea-formaldehyde based foams, and

workmanship during application. In general, for the thirty-nine houses

surveyed, the observations showed no evidence of major problems associated with the retrofitting, although minor problems were evident for some houses. To investigate settling of loose-fill insulation, the walls of

six houses containing these types of materials were opened at the tops

of the cavity. Only one of these six houses was found to contain a void

in the insulation at that location. It could not be determined whether

the void was due to settling or initial incomplete fill of the cavity.

Shrinkage had occurred for all urea-formaldehyde based foam insulations. Linear shrinkage values ranged from about 4 to 9 percent and

42
averaged 6.0 percent for the seventeen houses in which it was measured.

Shrinkage could not be related to any observed variable including density,

age, geographic location, component material manufacturer, and season

of installation. Concerning workmanship, the results of the survey were generally favorable. However, sufficient minor problems were seen to

reinforce the general guideline that quality workmanship is important to

the successful retrofitting of sidewalls.

As part of the study, insulation specimens were removed from the

inspected sidewalls and sent to a testing laboratory for the determination of density, thermal resistivity and moisture content. The average

densities for the loose-fill cellulose and urea-formaldehyde based foam

insulation samples were 54.8 kg/m3 (3.4 lbm/ft 3

) and 11.5 kg/m3 (0.72

lbm/ft ), respectively. These values were in agreement with values

reported in the literature. No average value of density was calculated

for the loose-fill mineral fiber samples because of the wide range. In

general, the densities were higher than some values cited in the

literature. In the case of two rock/slag wool insulation samples, the

densities were much higher than expected, based on a comparison of literature values. However, the values of thermal resistivity for the two

samples were comparable to those found for the other mineral fiber

insulations included in the survey. In addition, the density of one urea-formaldehyde based foam sample was unacceptably low and, in this

case, its thermal resistivity was quite low.

The average values of thermal resistivity of the loose-fill cellulose,

loose-fill mineral fiber and urea-formaldehyde based foam insulation were

24.9, 26.4 and 28.0 m*K/W (3.58, 3.80 and 4.03 h'f

t

2 ,0 F/Btu*in) , respectively, and their respective average moisture contents were about 11, 1 and 12 percent by mass. In general, values of these properties were found to agree favorably with other values for these properties cited in

the literature. For each type of retrofit insulation, no correlation

was found between thermal resistivity and moisture content.

Relationships between density and thermal resistivity were found for the

loose-fill cellulose and urea-formaldehyde based foam insulations. In

the case of cellulose, the thermal resistivity decreased as the density

increased. For the foam insulations, the thermal resistivity increased

with an increase in density.

Laboratory measurements were also conducted to determine the pH of the

foam insulation samples at the surfaces and in the center. The average

pH value of the sample surfaces at the interior of the wall was slightly

lower than those of the sample surfaces at the exterior of the wall or center sections of the foams. The average values at these latter two

locations were approximately the same.

A laboratory test to determine the percent (by volume) water absorbed by

urea-formaldehyde based foam insulations after floating on water for 7 days was conducted on some samples. With one exception, these samples

absorbed less than 15 percent by volume. One sample which showed no signs

43
of surface deterioration had an average water absorption of about 17

percent by volume. This test should not be used to indicate deterioration

of foam insulations, unless further data are developed to relate water

absorption and surface condition.

In the strictest sense, the information obtained in this study applies

only to the thirty-nine houses surveyed. The sample size was limited

and only small sections of the walls of the houses were opened for inspection. Nevertheless, some conclusions may be made which may have broader

implications.

The results of the survey were encouraging in so far as they indicated

that the retrofitting of the sidewalls was in general accomplished without causing adverse effects. One of the houses surveyed contained a mineral fiber insulation which was about 10 years old. In this case, no problems were observed by the field investigators nor indicated by the

homeowner in an interview. For the survey in general, damage to wall

components which could be attributed to the retrofitted insulation was

not found. Although the few metal electrical components in the walls

of some houses showed little, if any, signs of corrosion, the number of

observations was extremely limited. Furthermore, the electrical components were not examined microscopically for the presence of oxide coatings. Electrical connections in junction boxes found to contain insulation were not inspected for corrosion. Further information is needed to

answer the important question concerning the effect of insulation on the

corrosion of metals in service.

From laboratory tests conducted on insulation samples removed from the

houses, it was concluded that the installed insulations had good thermal

insulating properties. However, from the field observations, it was concluded that the wall cavities were not always completely filled either

because of workmanship problems during application or settling and

shrinkage of the installed insulation. The observation that some walls

with loose-fill insulations contained no voids at the top of the cavities

indicated that settling may not always occur with these materials. On the

other hand, it was concluded that all urea-formaldehyde based foam samples

had undergone linear shrinkage much greater than the 1 to 3 percent often

quoted in the literature. This factor was of most concern, since

shrinkage may result in insulated walls with reduced thermal performance.

5.0 RECOMMENDATIONS

This study consisted of a field phase to observe retrofit insulations

installed in the cavity walls of houses and a laboratory phase to measure

some performance properties of the insulations after removal from the

walls. Based upon the field observations and results of the laboratory

tests, the following recommendations are made:

Voluntary consensus standard practices for the application of

retrofit insulations should be developed. Application of the

44
insulations according to standard practices should reduce the

possibility of workmanship problems during installation. Standard practices have been developed for the DoE Residential

Conservation Service Program. The development of these DoE practices as voluntary consensus practices should be encouraged to

broaden their application.

If urea-formaldehyde based foam insulations are to be commonly

used for retrofitting walls of residences, criteria should be

developed to establish the maximum allowable shrinkage which

foams may undergo in-service. Factors affecting shrinkage of

foams should be understood so that shrinkage may be minimized.

The foam insulations examined in the field survey were found to

have shrunk greater than about 4 percent, with the maximum shrinkage

being 9 percent. It is noted that some foam manufacturers have

indicated that newly-developed foam insulations shrink to a lesser

extent that their earlier-available products. Data are not

available from field studies to determine the extent of shrinkage

which these newly-developed foams undergo in service.

° The development of voluntary consensus standard practices for

re -insulating sidewalls containing batt insulation which does

not completely fill the cavity should be undertaken. This would

assure that the addition of retrofit insulation to existing

insulation is performed adequately. Observations from this study

indicated that wall cavities with existing batt insulation may be

completely filled during retrofitting.

° A performance criterion should be established concerning the

effect of retrofit insulations on the corrosion of metals in

walls. Little information was obtained during this study on the

important question regarding corrosion.

6 . ACKNOWLEDGMENTS

This study was sponsored by the Department of Energy (DoE), Office of

Weatherization Assistance. Ms. Sandra S. Monje and Mr. Heinz R. Trechsel

provided liaison between DoE and the Center for Building Technology,

NBS, respectively. The authors wish to express their appreciation to

those homeowners who extended their hospitality to the field investigators

and allowed their residences to be used as test houses. The response of

many hundreds of individuals to our news release in volunteering their

residences for inspection was also appreciated.

Thanks are given to those Dynatech R/D Company staff members who conducted

the laboratory tests: Stu Spinney, former Manager, Measurements Laboratory; Bill Terranova, Project Technician; and Ann Bersani, Technician.

The authors also thank Ms. Madeleine Jacobs, formerly of NBS, for her

effort in preparing the news release which attracted the helpful responses

from homeowners, and Mr. Robert G. Mathey, NBS, for providing many useful

comments and technical suggestions concerning the field inspection and

45
this report. Discussions with Dr. Geoffrey Frohnsdorff , NBS, concerning

this report also provided many useful suggestions and were appreciated.

Thanks are also given to the staff members of John Weidt Associates,

Kathy Thorstensen, Linda Heinman and Jenny Weidt, for their efforts in

corresponding with the volunteer homeowners and coordinating the itinerary

for the field inspections.

Finally, special mention should be made to the contributions of Mr. Dave

Benoy. Mr. Benoy was the carpenter with the responsibility to open the

sidewalls of. the houses and close them to the satisfaction of the homeowners. As judged by the comments of the homeowners, he completed his

task very successfully.

7.0 REFERENCES

1. Seidel, Marquis R. , Plotkin, Steve E., and Reck, Robert 0., "Energy

Conservation Strategies," Environmental Protection Agency Report

EPA-R5 -73-021, July 1973, p. 7.

2. "An Assessment of Thermal Insulation Materials and Systems for Building

Applications," prepared by Brookhaven National Laboratory with the

Assistance of Dynatech R/D Company, U.S. Department of Energy,

BNL-50862, UC-95d, June 1978.

3. Petersen, Stephen R., "Retrofitting Existing Housing for Energy

Conservation: An Economic Analysis," National Bureau of Standards

(U.S.), Building Science Series 64, 76 pages, December 1974.

4. Burch, D. M. , Siu, C.I. , and Powell, F. J., "Comparison of the Thermal

Performance of Three Insulating Materials Commonly Used to Retrofit

Exterior Frame Walls in Existing Residences," Proceedings, International Institute of Refrigeration, - Commission Bl , Washington,

D.C., 1976, pp. 151-162.

5. Burch, D. M., and Hunt, C. M. , "Retrofitting an Existing Wood Frame

Residence for Energy Conservation - An Experimental Study," National

Bureau of Standards (U.S.), Building Science Series 105, 82 pages,

July 1978.

6. "Minnesota Retrofit Insulation In-Situ Test Program," prepared by the

Minnesota Energy Agency with the Assistance of Dynatech R/D Company

and John Weidt Associates, U.S. Department of Energy, HCP/W2843-01

,

June 1978.

7. Grot, Richard A., "An Assessment of the Application of Thermography

for the Quality Control of Weatherization Retrofits," Proceedings of

the Conference, "Thermal Sense II," American Society of Photometry

(in preparation).

46
8. Rossiter, Walter J., Jr., Weidt, John L., and Saxler, Robert J.,

"A Field Survey of the Performance Properties of Insulation Used to

Retrofit Cavity Walls of Residences," Proceedings of the Conference,

"Thermal Performance of the Exterior Envelopes of Buildings,"

Orlando, Florida, December 3-5, 1979 (in preparation).

9. Rossiter, Walter J., Jr., Mathey, Robert G. , Burch, Douglas M. , and

Pierce, E. Thomas, "Urea-Formaldehyde Based Foam Insulation: An

Assessment of Their Properties and Performance," National Bureau of

Standards (U.S.), Technical Note 946, 92 pages, July 1977.

10. Rossiter, Walter J., Jr., and Mathey, Robert G. , "Criteria for

Retrofit Materials and Products for Weatherization of Residences,"

National Bureau of Standards (U.S.), Technical Note 982, September

1978, p. 34.

11. ASHRAE Handbook and Product Directory, 1977 Fundamentals, American

Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.,

Table 3A, p. 22-15.

12. Tye, R. P., Desjarlais, A. 0., Bourne, J. G. , and Spinney, S. C,

"The Effective Thermal Performance of an Insulated Standard Stud Wall

Containing Air Gaps," Proceedings of the Conference, "Thermal Performance of the Exterior Envelopes of Buildings," Orlando, Florida,

December 3-5, 1979 (in preparation).

13. Standard for: Thermal Insulation, Urea Based, Foamed in Situ,

51-GP-24M, Canadian Government Specifications Board, Ottawa,

Ontario, December 1977.

14. Thermal Insulation, Urea-Based, Foamed-in-Place, Use of Materials

Bulletin No. 74, U. S. Department of Housing and Urban Development,

Washington, D.C., October 13, 1977.

15. ASHRAE Handbook and Product Directory, 1977 Fundamentals, American

Society of Heating, Refrigerating and Air-Conditioning Engineers,

Inc., Figure 1, p. 19.3.

16. Nottage, H. B., "Thermal .Properties of Building Materials Used in

Heat Flow Calculations," Transactions of the American Society of

Heating and Ventilating Engineers, Vol. 53, 1947, p. 218.

17. Alan M. Bowles, Canadian Government Specifications Board, Personal

Communication.

18. Verschoor, J.D., "Effectiveness of Building Insulation Applications,"

Sponsored by Naval Facilities Engineering Command, Civil Engineering

Laboratory, CR 78.006, 134 pages, November 1977.

47

Appendix A. NEWS RELEASE REQUESTING VOLUNTEERS

FOR PARTICIPATION IN THE STUDY

This Appendix presents the news release published to seek homeowners who

would volunteer their residences as test houses in the field study. The news release contained a telephone number which is deleted herein.

HOMEOWNERS SOUGHT TO PARTICIPATE

IN STUDY OF WALL INSULATION

The Federal government is seeking homeowners to participate in a study

aimed at developing better information about the performance and use of

thermal wall insulation.

The study is being carried out by architect John Weidt of Minnesota under

contract to the Commerce Department's National Bureau of Standards (NBS).

The project is sponsored by the Department of Energy Office of Weatherization Assistance. Weidt recently completed a similar study of insulation

in Minnesota houses.

Homeowners who have had thermal insulation installed in the walls of their

houses at least two years ago are eligible to participate. The three

types of insulation that will be studied are urea-formaldehyde foams,

cellulosic loose-fill, and mineral fiber loose-fill.

Weidt is looking for homeowners in these different climatic regions of the

country:

--Northern (Minnesota, New England) —Middle Atlantic (Maryland, Virginia, District of Columbia)

--Southern (North and South Carolina, Georgia, Alabama, Louisiana,

Florida)

--Midwest (Ohio, Kentucky).

In the study small portions of the wall will be removed either from the

outside or inside of the house. The insulation will be inspected and

observations noted on such factors as corrosion of metal objects, moisture accumulation, odor, fungus or mold growth, and workmanship during

installation. Weidt will also be studying settling of loose-fill

insulations and shrinkage of foam insulations.

Small samples of the insulation will be removed and sent to the laboratories for testing their thermal conductivity, density, and moisture

content.

Homeowners will also be interviewed by Weidt to determine their satisfaction with the results obtained from insulating the walls of their

houses and to determine the effects on their fuel consumption.

Weidt has indicated that the walls of the homes will be repaired and

restored to the homeowner's satisfaction. For participating in the study,

A-l
homeowners will receive a clock thermostat, an energy saving device that

automatically controls the temperature of the house according to an adjustable time schedule.

Wall insulations are of particular concern to the federal government since

there is insufficient information about the performance of these materials

once they are installed. Although unseen, wall insulation must continue

to retain its insulating properties and remain compatible with the structural and other materials with which it is in contact.

"The government is sponsoring the study because substantial energy savings

as well as the health and safety of the occupants depend on the quality and

performance of these largely unseen insulations," says NBS Project Leader

Dr. Walter J. Rossiter, Jr. "In addition, millions of dollars will be spent

by homeowners installing insulation in their houses."

The results of the study, he notes, will be used to develop needed information on the performance of insulations in order to update guidelines

and standards for their application and use.

To participate, homeowners should know the type of insulation in their

homes and approximately when it was installed. Only retrofitted houses,

i.e., houses with insulation installed after the completion of constuction

and being occupied, will be considered for the study; houses originally

built with wall insulation are not included. Interested persons should

contact:

John Weidt Associates Inc.

Jonathan Lake Village Center

Post Office Box 401

Chaska, Minnesota 55318, or call Weidt collect at .

Deadline for participation in this study is December 1, 1978.

A-2
APPENDIX B

PROCEDURES USED IN THE FIELD EXAMINATIONS

B.l Selection of Sample Area

The residence was surveyed to locate an area for sampling that could be

repaired to the homeowner's satisfaction and would be likely to contain

electrical wiring or outlet boxes. The presence of electrical wiring or other metallic objects in the cavity could not always be ascertained

prior to the opening.

The procedure was designed to remove loose-fill insulation from the top of

a cavity; however, in certain cases, taking samples from the top of the

cavity was impossible because of structural framing of older homes, access

to the top of the cavity with the portable equipment or specific requirements of individual homeowners restricting the test location. In these

instances, if the sample area was close to the top of a cavity, the area above the sample was probed manually to ascertain whether the cavity was filled completely.

B.2 Opening of Cavity

After a suitable test area had been identified, an opening of approximately

0.4 to 0.6 m

2 (4 to 6 ft2

) was made in either the exterior or interior sur- face of the wall. Where an exterior opening was made, the siding was first

removed; any other subsiding or concealed material was next removed; the

building paper, if present, was cut away; and finally the sheathing was

cut and removed to expose the insulated cavity. The types of exterior

siding removed included wood clapboard, wood shingles, wood ship-lap, plywood, asbestos shingles, composite wood products and aluminum siding. No

masonry or stucco homes were opened from the exterior. Where an interior

opening was made, the interior surface was cut away to expose the insulated

cavity. Interior openings included paneling, gypsum wallboard, rock-lath

and plaster, and wood-lath and plaster materials.

B.3 Observations

Field observations were noted of the following: the condition of the outside and inside paint surfaces, siding, sheathing, structure, wiring; the

presence and location of physical vapor barriers; evidence of moisture, odor,

rot, fungus, mold, vermin and corrosion; presence of cracks or voids in

the insulation; and the insulation color.

B.4 Sampling

After observations concerning the condition of the installed insulation

were noted and field measurements of factors such as settling or shrinkage

age were recorded, a number of insulation samples were taken from each

sidewall cavity as follows:

B-l
Thermal Resistivity and Density Samples - The primary sample was a large

section of insulation that was used for the determination of thermal resistivity and density. This sample was removed from the cavity and placed in

tared double polyethylene bags which were labeled, weighed, sealed and sent

to the laboratory.

Moisture Content Samples - A sample to be used for the determination of

moisture content was taken across the total depth of the cavity. A measurement conducted on this sample would yield an average moisture content

from interior to exterior face. The sample was placed in a pre-labeled,

tared, one liter polyethylene jar which was sealed to prevent loss or gain of moisture, weighed and sent to the laboratory.

pH Samples - For those sidewalls which contained urea-formaldehyde foam

retrofit insulations, additional insulation samples were taken of the

interior surface, the exterior surface and the middle of the foam material. These samples were placed in individual pre-labelled polyethylene

containers and sent to the laboratory for pH measurements.

Absorption Samples - Samples of some urea-formaldehyde foam insulations were

sent to the National Bureau of Standards for moisture absorption testing.

B.5 Observations

Several methods were used on site to note the observations and record the

measurements made on the insulation of each test site. Color photographs

of each step of the work were taken to record specific conditions encountered on each site and close-up detail photographs were made wherever

any anomalies were found in specific cavities. Photographs of each test

site were coded directly on the film with a data-back number relating to

the specific test site. Figures in the text may show this number visible

in one corner of the frame.

A field worksheet was prepared which included a variety of comments, data

points and a sketch of the observed cavity. General comments on each test

site were made and recorded on a field comments worksheet. These comments

included notes on observations, the comments of the homeowner relative

to his opinion of the retrofit application and the impact on his fuel

consumption and personal comfort. The comments of the homeowners were not

discussed in this report, since the opinions were considered subjective.

In most cases, homeowners did not have documentation supporting opinions.

B.6 Data

Data taken in the field included: measurements of the dimensions of the

cavity after removal of the insulating material to determine volume;

measurements of shrinkage (urea-formaldehyde foam insulation); and mass

of all samples. Depth measurements were made with a probe caliper and

dimension measurements made with a steel rule, both graduated in millimeters. Masses of samples less than 1.5 kg (3.3 lbm) were obtained on a triple-beam balance which was calibrated prior to each test using weights

of known mass. Tare masses of containers determined made prior to.

B-2
filling them with insulation. Samples over 1.5 kg (3.3 lbm) were weighed

on a spring scale. These sample masses were compared with laboratory

measured values.

B.7 Closing of the Cavity

Upon completion of the observations, measurements and sampling, the

opened wall cavity was repaired to the satisfaction of the homeowner.

Exterior openings normally involved replacing all materials previously

removed, caulking, sealing and touch-up painting if required. Interior

openings required resurfacing of the opening with gypsum wall board and

taping as required. Both interior and exterior openings were reinsulated

with a glass fiber batt.

B-3

APPENDIX C

LABORATORY TEST PROCEDURES

A commercial laboratory received the samples of urea-formaldehyde based

foam, loose-fill cellulose, and loose-fill mineral fiber insulations to

measure density, thermal resistivity and moisture content. In addition,

the pH and moisture absorption of the urea -formaldehyde foam specimens were determined.

C.l Density

Upon arrival of the loose-fill insulation test specimen at the testing

laboratory, its mass was determined to compare it with the mass measured

in the field. Its density was then calculated from the mass and the

volume of the cavity from which the insulation was removed as follows: m

D =

(1) (w) (d)

where D = density

m = mass of material measured in the field

1 = length of selected cavity section w = width of cavity

d = depth of insulation

In the case of the urea-formaldehyde based foam samples, it was desired

to prepare with a mill 50 x 300 x 300 mm (2 x 12 x 12 in) test specimens

in the laboratory from larger sized samples received from the field.

However, the milled specimens were less than 50 x 300 x 300 mm (2 x 12 x

12 in), since the field samples were not large enough to obtain specimens

of the desired size. The dimensions of the urea-formaldehyde based foam

samples used for the density and thermal resistivity tests are presented

in Table C.l. The density of the foam samples was determined from;

D = m

where D = density of prepared sample

m = mass of prepared sample v = volume of prepared sample

C.2 Thermal Resistivity

C.2.1 Urea-Formaldehyde Based Foam Insulation

The thermal resistivity of the urea-formaldehyde based foam samples would

have been determined using specimens with dimensions of 50 x 300 x 300 mm

(2 x 12 x 12 in), if large enough pieces of foam had been available.

Since samples from the field with these dimensions were not available,

the test specimen for the determination of thermal resistance was cut

as large as possible (Table C.l). The thickness of the urea-formaldehyde

C-l
TABLE C.l DIMENSIONS OF THE UREA-FORMALDEHYDE BASED FOAM SAMPLES

USED IN THE DETERMINATION OF THEIR DENSITIES AND

THERMAL RESISTIVITIES

SAMPLE DIMENSIONS

Thickness mm inLength mm inWidth

No. mm in

1 41 1.6 119 4.7 112 4.4

2 51 2.0 145 5.7 107 4.2

3 56 2.2 297 11.7 277 10.9

4 51 2.0 236 9.3 206 8.1

5 58 2.3 300 11.8 249 9.8

6 64 2.5 254 10.0 234 9.2

7 53 2.1 221 8.7 188 7.4

8, , 51 2.0 302 11.9 231 9.1

9 (a) 48 1.9 124 4.9 74 2.9

10 56 2.2 150 5.9 145 5.7

11 51 2.0 216 8.5 201 7.9

12 48 1.9 119 4.7 71 2.8

13 36 1.4 119 4.7 119 4.7

14 53 2.1 287 11.3 236 9.3

15 56 2.2 292 11.5 269 10.6

16 43 1.7 239 9.4 188 7.4

17 53 2.1 257 10.1 213 8.4

18 56 2.2 254 10.0 196 7.7

19 56 2.2 272 10.7 231 9.1

20 53 2.1 297 11.7 269 10.6

21 46 1.8 208 8.2 185 7.3

22 58 2.3 188 7.4 168 6.6

23 53 2.1 272 10.7 268 10.5

24 64 2.5 246 9.7 216 8.5

25 53 2.1 208 8.2 188 7.4

(a) Sample was only used for the determination of density.

C-2
based foam test sample was measured and a 300 x 300 mm (12 x 12 in) piece

of extruded polystyrene foam was cut to the same thickness as the test

sample. An outline of the test sample was traced on the center of

extruded polystyrene and cut out. The urea-formaldehyde based foam test

sample was then inserted into this hole and its thermal resistivity was measured. As the actual heat flow transducer size was 100 x 100 mm (4x4 in), accurate measurements could be made on test samples at least

this size. The resistance was measured based on the procedure given in

ASTM C 518-76, "Steady-State Thermal Transmission Properties by Means

of the Heat Flow Meter", using a commercially available apparatus. The

upper and lower plates of the instrument with dimensions of 300 x 300 mm

(12 x 12 in) were blackened aluminum sinks containing heaters which were temperature controlled with proportional/reset temperature controllers.

Both plates were instrumented with Type T (copper/constantan) thermocouples.

The bottom plate, or cold face, was instrumented with a calibrated heat

flux transducer. The temperatures of the upper and lower plates were controlled at 34 and 14 °C (93 and 57 °F), respectively.

C.2.2 Loose-Fill Insulation

The thermal resistivities of the loose-fill cellulose and mineral fiber

insulations were determined in accordance with ASTM C 518-76, using a commercially available heat flow meter apparatus except that the samples were not dried. The upper and lower plates of the instrument with dimensions of 600 x 600 mm (24 x 24 in) were blackened aluminum sinks containing

heaters which were temperature controlled with proportional/reset

temperature controllers. Both plates were instrumented with a calibrated

integrating heat flow transducer. The temperatures of the upper and lower

plates were controlled at 10 and 38 °C (50 and 100 °F) respectively. The

thickness of the samples was 90 mm (3.5 in) and it was maintained by use

of a sample containment ring.

C.2.3 Thermal Resistivity Calculation

At equilibrium, the thermal resistivity for urea-formaldehyde based foam

and loose-fill insulations was calculated as follows:

R = (q/A)

-1

[(T. - T„)/x]

Where q/A = heat flux as measured by the heat flow

transducer

T, = temperature of upper hot face

T = temperature of lower cold face

x = specimen thickness

C.3 Moisture Content

The moisture content or total volatile content was determined in accor- dance with the procedure given in ASTM D 644-55 (1976), "Moisture Content

of Paper and Paperboard by Oven Drying". In the laboratory, the insulation specimens were removed from the sealed polyethylene jars and

immediately weighed. The nominal sample masses of the loose-fill and

urea-formaldehyde based foam samples were 5 g and 1 g (0.18 oz and 0.04 oz),

C-3
respectively. The samples were placed in tared evaporating dishes which

were weighed, placed in an air-circulating oven at 105 °C (221 °F) for

48 hours, removed, cooled to room temperature in a desiccator and

reweighed. Any loss in mass was recorded as moisture content. The

percent volatiles was taken to be the moisture content was calculated

from:

% Moisture Content =

10° ( wl ~ w2> w

2

where W, = original sample mass

W~ = mass of sample after oven drying

C.4 pH of Urea-Formaldehyde Based Foam Insulations

Since no standard test procedure for the determination of the pH of ureaformaldehyde based foam insulations was available, the following procedure,

used by the testing and quality control laboratories of a manufacturer of

urea-formaldehyde based foam, was employed.

The pH of the urea-formaldehyde based foams was determined by removing a small amount of the foam from each of three places during sample removal.

Material was removed from the surface facing the interior of the residence,

the middle of the foam and the surface facing the exterior of the residence,

Each sample was sent to the laboratory in a small plastic container. The

samples were removed from the containers and 1 g (0.04 oz) was crushed

into a 250 ml (8.5 fl oz) beaker. To the beaker was added 100 ml (3.4/

fl oz) of distilled water. The beaker was covered with a watchglass,

and the solution was boiled for 5 minutes. The solution was cooled to room temperature, the beaker sides rinsed with distilled water and the

volume of water was made up to 100 ml (3.4 oz). The pH of the solution

was measured with a standard pH meter which was calibrated with standard

buffered solutions of pH 4 and pH 7.

C.5 Moisture Absorption of Urea-Formaldehyde Based Foam Insulations

The moisture absorption of the urea-formaldehyde based foam insulation

samples was determined according to a test procedure which was essentially

the same as that given in Section 6.2.9.1 of HUD Use of Materials Bulletin

74 [14]. Foam specimens with dimensions of 100 x 100 mm (4 x 4 in) were

cut from larger pieces of foam which were removed from the walls of the

test houses. The thicknesses of the specimens were as found in the wall

cavities. However, all specimens had comparable thichnesses of 88 mm

(3.5 in) + 6 mm (0.25 in). The volume of the specimens were determined

using a rule graduated in millimeters. The specimens were weighed to

the nearest 0.1 g on a laboratory balance to determine their mass.

The specimens were placed on the surface of distilled water in a plastic

pan. The surfaces of the specimens placed on the distilled water were

those obtained from foaming during the retrofitting of the test houses

and corresponded to the exterior and interior sides of the wall cavities.

After 7 days at 23 + 2°C (73 ± 4°F) and 50+5 percent relative humidity,

the specimens were removed from the water and any water visible on their

C-4
surfaces was blotted with a paper towel. The blotted specimens were

reweighed on the laboratory balance. The water absorbed was calculated

as a percent of the volume of the original foam specimen.

C-5

APPENDIX D

TABLE D.l DEFINITIONS OF S.I. AND CUSTOMARY UNITS USED IN THIS REPORT

Property

Units

S.I.

(Customary)

Definition

S.I.

(Customary)

Density

Temperature

Thermal

Resistivity

kg/m3

Ubm/ftJ

)

°C

(°F)

m»K/W

(h«ft2 »°F/Btu«in)

kilogram/meter cubed

(pound-mass/foot cubed)

degree Celsius

(degree Fahrenheit)

meter • degree Kelvin/Watt

(hour • foot squared • degree

Fahrenheit/British Thermal

Unit • inch)

D-l

^u

APPENDIX E

LINEAR SHRINKAGE OF UREA-FORMALDEHYDE BASED FOAMS

Linear shrinkage was calculated as a percent of original specimen width.

The measured width of the cavity was taken as the original width of the

urea-formaldehyde based foam specimen.

All measurements were made at a clean horizontal section through the

insulation where the foam had not cracked, as described in Section B.6.

Mi

M2

M:

Mi + Mo + Mo

Material Width = -± -* s

3

Measurement of Foam Width In-Situ

YZZZZZZZZZZZTZZZZZZZ*/S777_

Cavity Width =

Ci + C 2 + C3

Measurement of Cavity Width

Cavity Width - Foam Width

Percent Shrinkage = —— x luu/° Cavity Width

E-l
NBS-U4A (REV. 9-76)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS TN 1131

Eg5 Vj^y II I

4. TITLE AND SUBTITLE

Field Investigation of the Performance of Residential

Retrofit Insulation

7. AUTHOR(S)

John L. Weidt, Robert J. Saxler & Walter Rossiter, Jr.

5. Publication Date September 1980

6. Performing Organ* :fcJ3

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10. Project/Task/Wor* Unit No.

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, city, state, zip)

Office of Weatherization Assistance

U.S. Dept. of Energy, 1000 Independence Ave., SW

Washington, D.C. 20585

13. Type of Report & Period Covered Final

ii

15. SUPPLEMENTARY NOTES

I | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

S!

Of

16. ABSTRACT (A 200-word or leas tactual summary of most significant information. It document includes a significant bibliography or

literature survey, mention it here.) A study was conducted to obtain information on the performance of in-service

insulations of the type commonly used in the United States to retrofit sidewalls of

housing: urea-formaldehyde based foam, loose-fill cellulose, and loose-fill mineral

fiber.

In the field phase of the study, observations were made on performance-related

factors such as; the completeness of filling the cavity, the condition of the

insulation and wall components, and evidence of moisture accumulation such as water

stains on sheathing, studs and other wall components. Shrinkage was observed to have

occurred for all urea-formaldehyde based foam specimens. Where measurable, it was

found to be within a range of 4 to 9 percent. For the six test houses containing

loose-fill Insulation which were opened at the top of the wall cavity, only one with |ti; cellulose contained a void of undetermined origin at the location.

Insulation specimens removed from the walls were tested to determine their

density, thermal resistivity and moisture content. The pH and moisture absorption oi the urea- formaldehyde based foam specimens were also determined. Results of the

laboratory measurements are discussed and compared with data from other studies.

Relationships between the moisture contents of the samples and their thermal

resistivities were hot found. Results indicated that the retrofitting of the inspecl

sidewalls was for the most part accomplished without adverse effect upon them.

hi

ii\

1°

sis

fro

pec

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Conservation; energy; field survey; insulation; moisture content; residences;

retrofit; thermal resistivity

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