A11104 0EE03A

NBS

PUBLICATIONS

NBSIR 79-1720

Mobile Home Fire Studies:

Summary and Recommendations

Edward K. Budnick

David P. Klein

Center for Fire Research

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, D.C. 20234

March 1979

•~QG

Prepared for: Division of Energy, Building Technology and Standards

ffice of Policy Development and Research

.S. Department of Housing and Urban Development

100 'ashington, D.C. 20410

. U56

79-1720

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ftarwM of StMdar

MAY 2 2 1979

NBSIR 79-1720

MOBILE HOME FIRE STUDIES:

SUMMARY AND RECOMMENDATIONS

Edward K. Budnick

David P. Klein

Center for Fire Research

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, D.C. 20234

March 1979

Prepared for: Division of Energy, Building Technology and Standards

Office of Policy Development and Research

U.S. Department of Housing and Urban Development

Washington, D.C. 20410

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES iv

EXECUTIVE SUMMARY . V

Abstract 1

1. INTRODUCTION 2 1.1. Background 2 1.2. Project Objective 5 1.3. Approach 5

2. SCENARIO DEFINITION 6

3. EXPERIMENTAL TEST PLANS 8

4. KEY EXPERIMENTAL FINDINGS 8

4.1. NBSIR 75-788, Evaluation of the Fire Hazard in a Mobile

Home Resulting from an Ignition on the Kitchen Range .... 9 4.2. NBSIR 7 6-1021, Fire Spread ?tlong a Mobile Home Corridor . . 10

4.3. NBSIR 78-1522, Characteristics of Incidental Fires in the

Living Room of a Mobile Home 10

4.4. NBSIR 78-1530, Mobile Home Living Room Fire Studies: The

Role of Interior Finish 11

4.5. NBSIR 78-1531, Mobile Home Bedroom Fire Studies: The

Role of Interior Finish 11

4.6. Supplemental Mobile Home Living Room Fire Studies: The

Role of Interior Finish (Appendix A of this Summary Report)

.

12

5. DESIGN STRATEGIES FOR LIMITING FIRE GROWTH AND SPREAD 12

5.1. Controlling Incidental Fires on the Kitchen Range 13

5.2. Controlling Incidental Room Fires 14

5.2.1. Development of Material Hazard Matrices 14

5.2.2. Review of Similar Work 18

5.2.3. Design Options for Improved Fire Safety 20

6. IMPACT ASSESSMENT 22

6.1. General 22

6.2. Classification of Data 22

6.3. Sorting of Data 24

6.4. Application of Data 2 5

7. RECOMMENDATIONS 27

7.1. Kitchen Area Protection 28

7.2. Interior Finish Flame Spread Requirements 29

7.2.1. Design Option 1 29

7.2.2. Design Option 2 30

7.2.3. Design Option 3 31

7.2.4. Discussion 31

8. ACKNOWLEDGMENTS 32

9. REFERENCES 33

iii
TABLE OF CONTENTS (continued)

Page

FIGURES 36

TABLES 39

APPENDIX A. SUPPLEMENTAL MOBILE HOME LIVING ROOM FIRE STUDIES:

THE ROLE OF INTERIOR FINISH A1

APPENDIX AA. PLOTTED DATA ILLUSTRATING KEY CHANGES IN MEASURED

CONDITIONS FROM APPENDIX A . . AAl

LIST OF FIGURES

Figure 1. Material Hazard Matrix for Low Intensity Exposure

Fire in the Living Room (Based on ASTM E-84 FSC) 36

Figure 2. Material Hazard Matrices for Moderate Intensity

Exposure Fires in the Living Room and Bedroom

(Based on ASTM E-84 FSC) 37

Figure 3. Expanded Material Hazard Matrix Based on SwRI and

UL Test Results (Based on ASTM E-84 FSC) 38

LIST OF TABLES

Table 1. Accumulated Mobile Home Fire Incident Statistics 39

Table 2. Probable Mobile Home Fire Scenarios 40

Table 3. States and Years of NFIRS Data Examined for

Analysis 41

Table 4. NFPA Classifications for Area of Fire Origin 42

Table 5. Areas of Fire Origin for Mobile Home Analysis

and Corresponding NFPA 901 Codes for Area of

Fire Origin 43

Table 6. NFPA Classifications for Form of Material Ignited 44

Table 7. Intensity of Exposure Fire and Corresponding NFPA 901

Codes for Form of Material Ignited 45

Table 8. Mobile Home Fires with Unknown Area of Origin 46

Table 9. Summary for Oregon 1977 of all Fires Which Spread

Beyond the Initial Room of Origin 47

Table 10. Impact Summary for 1977 Data 48

IV
EXECUTIVE SUMMARY

Title VI of the Housing and Community Development Act of 1974

provided for the development of a Federal mandatory standard for

mobile home construction and safety. Statutory responsibility for

development and promulgation of such a standard was delegated to the

Secretary of the Department of Housing and Urban Development (HUD)

.

Title VI explicitly authorized HUD to undertake mobile home safety

research and development in order to improve the mobile home con- struction and safety standards, particularly in those areas which

impact personal injuries and deaths and property damage in mobile

home s

.

A key area identified as a potential problem in mobile homes was

fire safety. Various statistical sources indicated that while the

incidence rate was approximately the same, the injury and life hazard

and the extent of property damage per incident were three to five

times greater than for conventional residences.

Most residential fires are initially localized and small in size,

but the design characteristics inherent in mobile homes such as fire

load density, room geometry, and combustible finishes may provide the

potential for rapid fire development, resulting in higher temperatures,

smoke, and toxic gas generation in a relatively short period of time.

While various design and structural features appear to be possible

contributors to this problem, interior finish materials used on walls

and ceilings have been suggested as one of the most important con- tributors to fire spread in mobile homes. No organized research

studies had been performed to evaluate this thesis. Therefore in

1975, within the statutory power under Title VI, the Office of Policy

Development and Research of HUD requested that the Center for Fire

Research at NBS expand and accelerate the activities of an ongoing

research project. The purpose of this ongoing project was to provide

experimental data on the potential growth and spread of fire in mobile

homes.

The Federal Mobile Home Construction and Safety Standard was promulgated, effective June 15, 1976. This mandatory standard adopted

many of the provisions contained in the existing Standard for Mobile

Homes (NFPA 501B, ANSI A119.1), a voluntary consensus standard previously utilized by many mobile home manufacturers and state and local

regulatory officials. Included in the provisions adopted from NFPA

v
501B was a surface flame spread rating for interior finish materials

of 200 or less, based on the ASTM E-84 Tunnel Test Method. In addition,

results from initial segments of the Mobile Home Fire Safety Project

(NBS) were evaluated and criteria based on this evaluation were

incorporated into the standard.

Work has continued at NBS in the area of fire safety in mobile

homes since promulgation of the standard. Results from a total of

five segments of the project have been published, addressing fire

growth and spread in the kitchen, corridor, living, and sleeping areas

of a mobile home, and the characterization of the ignition sources

used in these segments. This report provides a summary of the most

important findings from these previously reported segments of the

project. In addition, it includes the results and analysis of a segment of work not previously published. That final segment of work

encompassed eight full-scale fire tests conducted in a living room

under a controlled set of conditions, in which various combinations of

wall and ceiling interior finish materials were exposed to fires from

burning upholstered chairs and sofas.

The full-scale fire testing conducted for each of the segments of

the project, including the segment being reported herein, was conducted

in typical single-wide mobile homes constructed in accordance with the

NFPA 501B Standard for Mobile Homes in effect in 1972 (reference

figure A1 , Appendix A). These units had comparable structural, material

and spatial characteristics to mobile homes currently being constructed

to comply with the present Federal standard. Analyses of the tests were directed at evaluating the extent of the potential hazard to life

and/or property damage occurring in each of the tests.

The criteria used to evaluate the hazard to life were selected

based on available reference literature on human tenability, and

included high temperature, excessive carbon monoxide, and oxygen

deficiency. The criterion used to evaluate the extent of property

damage was the attainment of flashover in the room of fire origin.

Flashover is defined for this work as a fire phenomenon in which

thermal radiation from the upper walls and ceiling and from the hot

gases and smoke layer in the upper part of the room is sufficient to cause ignition amd rapid complete fire involvement of all combustible

materials in the room.

vi
This report describes the rationale upon which the overall

experimental approach was based, and provides a series of recommendations, some in the form of design options, for possible changes to

the standard. These recommendations are presented in the form of

specific material and design requirements for the kitchen range area

and in the form of a series of design options concerning ASTM E-84

flame spread requirements for interior finish in general. The design

options provide for increasing levels of fire safety and are based on

an overall analysis of the work performed at NBS, with consideration

given to applicable work conducted by other organizations. A limited

impact assessment is included to provide a relative measure of the

potential impact of each of three design options for flame spread

requirements for interior wall and ceiling materials. The impact is

based on the likely effect on fire severity, and does not include an economic analysis.

Vll

MOBILE HOME FIRE STUDIES: SUMMARY AND RECOMMENDATIONS 1

Edward K. Budnick and David P. Klein

Abstract

Since 1974, a major research project has been

ongoing at the National Bureau of Standards to investigate various aspects of fire growth and spread in

typical single-wide mobile homes. The objective of

this project is to provide recommendations for possible

changes to the Federal Mobile Home Construction and

Safety Standard promulgated in June, 1976 by the

Department of Housing and Urban Development. These

changes are intended to provide an improved level of

fire safety in mobile home construction.

This report provides a summary of the important

findings from previously reported parts of the project

which involved the conduct of full-scale fire tests in

the kitchen, corridor, living room and bedroom areas of

typical mobile homes. Also included in this summary

are the findings from a previously unreported series of

full-scale living room tests, which are discussed in some detail in Appendix A.

This report describes the rationale upon which the

overall experimental approach was based, and provides a series of recommendations, some in the form of design

options, for possible changes to the standard. A

limited impact assessment is included to provide a relative measure of the potential impact of each of

three design options for flame spread requirements for

interior wall and ceiling materials. This assessment

is based on the likely effect of each option on fire

severity, and does not include an economic analysis.

Key Words: ASTM E-84 Tunnel Test; construction standard;

fire growth; fire tests; flame spread; flashover;

impact assessment; interior finish; kitchen fires; life

safety; mobile homes; room fires.

Principal support for this project was provided by the Division of Energy,

Building Technology and Standards, Office of Policy Development and

Research, U.S. Department of Housing and Urban Development, Washington, D.C.

20410.

1
1 . INTRODUCTION

1.1. Background

Title VI of the Housing and Community Development Act of 1974

provided for the development of a Federal mandatory standard for

mobile home construction and safety. Statutory responsibility for

development and promulgation of such a standard was delegated to the

Secretary of the Department of Housing and Urban Development (HUD)

.

Title VI explicitly authorized HUD to undertake mobile home safety

research and development in order to improve the mobile home construction

and safety standards, particularly in those areas which impact personal

injuries and deaths and property damage in mobile homes.

A key area identified as a potential problem in mobile homes was

fire safety. Various statistical sources indicated that while the

incidence rate was approximately the same, the injury and life hazard

and the extent of property damage per incident were three to five

2 times greater than for conventional residences [1-9] .

Examination of fire loss statistics indicates that most residential

fires are initially localized and small in size [1]; that is, they do

not spread beyond the room of fire origin and by themselves do not

pose a serious problem. However, the design characteristics inherent

in mobile homes such as fire load density, room geometry, and combustible

finishes may provide the potential for rapid fire development, resulting

in higher temperatures, smoke and toxic gas generation in a relatively

short period of time. While various design and structural features

appear to be possible contributors to this problem, interior finish

materials used on walls and ceilings have been suggested as one of the

most important contributors to fire spread in mobile homes.

No organized research studies have been performed to evaluate

these characteristics. Therefore, in 1975, within the statutory power

under Title VI, the Office of Policy Development and Research of HUD

requested that the Center for Fire Research at NBS expand and accelerate

the activities of an ongoing research project which was initiated

in 1974. The purpose of this ongoing project was to provide experimental

data on the potential growth and spread of fire in mobile homes.

2 Numbers m brackets refer to the literature references listed at the end of

this paper.

2
The Federal Mobile Home Construction and Safety Standard was

promulgated, effective June 15, 1976. This mandatory standard adopted

many of the provisions contained in the existing Standard for Mobile

Homes (NFPA 501B, ANSI A119.1), a voluntary consensus standard previously

utilized by many mobile home manufacturers and state and local regulatory

officials. Included in the provisions adopted from NFPA 501B was a surface flame spread rating for interior finish materials of 200 or

less based on the ASTM E-84 Tunnel Test Method. In addition, results

from initial segments of the Mobile Home Fire Safety Project [10] were

evaluated and criteria based on this evaluation were incorporated into

the standard.

Work has continued at NBS in the area of fire safety in mobile

homes since promulgation of the standard. A total of ninety fullscale fire tests have been conducted in typically constructed 3.7 x

3 18.3 m (12 x 60 ft) single-wide mobile homes (reference figure Al in

Appendix A) . These mobile homes were constructed in accordance with

the NFPA 501B Standard for Mobile Homes in effect in 1972, and from a fire safety standpoint had comparable structural, material and spatial

characteristics to mobile homes presently constructed in accordance

with the current Federal standard. Analyses of these tests were

directed at evaluating the extent of potential hazard to life and

property damage under the experimental set-ups selected.

The criteria used to evaluate the hazard to life were selected

based on available reference literature on human tenability, and

included high temperature, excessive carbon monoxide, and oxygen

deficiency. The criterion used to evaluate the extent of property

damage was the attainment of flashover in the room of fire origin.

Flashover is defined for this work as a fire phenomenon in which the

radiation from the upper walls and ceiling and from the hot gases and

smoke layer in the upper part of the room is sufficient to cause ignition and rapid complete fire involvement of all combustible

materials in the room.

Five interim technical reports have been published, addressing

fire growth and spread in the kitchen, corridor, living, and sleeping

areas of a mobile home, as well as the characterization of the ignition

3 Values given in engineering units are actual; metric equivalent units may

be approximate.

3
sources used in these segments. These reports contain extensive

detail regarding the full-scale experimental approaches, the rationale

for selection of evaluation criteria, and the results. Reference may

be made to these reports for details not included in this summary

report. The five interim reports are:

(1) NBSIR 75-788, Evaluation of the Fire Hazard in a Mobile Home

Resulting from an Ignition on the Kitchen Range, Edward K.

Budnick and David P. Klein [10]

.

(2) NBSIR 76-1021, Fire Spread Along A Mobile Home Corridor,

Edward K. Budnick [11]

.

(3) NBSIR 78-1522, Characteristics of Incidental Fires in the

Living Room of a Mobile Home, David P. Klein [12]

.

(4) NBSIR 78-1530, Mobile Home Living Room Fire Studies: The

Role of Interior Finish, Edward K. Budnick [13]

.

(5) NBSIR 78-1531, Mobile Home Bedroom Fire Studies: The Role

of Interior Finish, Edward K. Budnick, David P. Klein and

Robert J. O'Laughlin [14].

This report provides a summary of the important findings from

these previously reported segments of the project. In addition, it

includes the results and analysis of a segment of work not previously

published. This final segment of work encompassed eight full-scale

fire tests conducted in a living room under a controlled set of

conditions, in which various combinations of wall and ceiling interior

finish materials were exposed to fires from upholstered chairs and

sofas. The work is similar to, and was designed to complement, the

series of sixteen tests conducted in the living room area the results

of which have been previously reported [13]

.

This report describes the rationale on which the overall experimental approach was based, and provides a series of recommendations,

some in the form of design options, for possible changes to the

standard. These recommendations are presented in the form of specific

material and design requirements for the kitchen area and in the form

of a series of design options concerning ASTM E-84 flame spread

requirements for interior finish in general. The design options

provide for increasing levels of fire safety and are based on an

4
overall analysis of the work performed at NBS, with consideration

given to applicable work conducted by other organizations. A limited

impact assessment is included to provide a relative measure of the

potential impact of each of three design options for flame spread

requirements for interior wall and ceiling materials. The impact is

based on the likely effect on fire severity, and does not include an economic analysis.

1.2. Project Objective

Mobile homes are currently constructed in compliance with the

Federal Mobile Home Construction and Safety Standard [15] , which was developed and promulgated by HUD in accordance with Title VI of the

Housing and Community Development Act of 1974 [16] . The long range

objective of this project is to provide recommendations for possible

changes to the standard with respect to material and design requirements

that would provide an improved level of fire safety in mobile home

construction. Recommendations previously published [10] , dealing with

the kitchen area included both material and design considerations.

The remaining recommendations included in this report involve additional

material requirements, relating specifically to flame spread ratings

of interior finish.

1.3. Approach

The general approach to this project can be described in terms of

four discrete but related steps. The first step was to define the

problem—that is, to isolate the aspects of particular significance in

mobile home fires which are within the rule-making jurisdiction of

HUD. This was accomplished by defining probable scenarios for fire

growth and spread based on a compilation of available mobile home fire

incidence data.

The second step was to design an experimental approach for several

series of full-scale fire tests in a typically constructed mobile home

in order to examine the characteristics of fire growth and spread for

the major scenarios. This step included the selection of evaluation

criteria for analysis of the test data.

5
The third step involved the actual conduct of the particular

series of full-scale tests to examine the effect of changing key

design parameters on fire development for each of the scenarios. This

step included the collection and analysis of experimental test data

from 90 fire tests in a fully-instrumented mobile home. While these

tests were performed under a set of environmental and end-use conditions

likely to be encountered in mobile home use, it was not possible to

investigate all conditions and variables. For example, the effects of

a wide range of interior and exterior ambient temperature and humidity,

of natural or forced ventilation, and of different levels of thermal

insulation were not examined. In addition, while many interior finish

materials having a wide range of flame spread values were tested, it was not possible to test every material which might be used in a mobile home, nor was it possible to examine all combinations of wall

and ceiling flame spread values presented by the representative

interior finish materials used.

The last step was an analysis of the experimental results of the

various segments of the project, an examination of the relative impact

of possible changes to the standard, and the preparation of recommendations to increase the level of fire safety in mobile homes.

2. SCENARIO DEFINITION

II A fire scenario can be defined as a postulated sequence of events

starting with ignition and including the subsequent chain of events

leading to a fire loss or injury [17] . The scenario plays a significant

role in the experimental design and in the interpretation of the data

collected during testing. Therefore, it has a distinct bearing on the

qualifications or limitations of the results. For example, the

significance of the contribution to fire growth of particular wall and

ceiling materials in a room may depend to a large degree on the

location and configuration of the furnishings and other movable contents

which may be the initial source of the fire and/or serve as a critical

link in fire spread. The size or location of the initial burning item

(the exposure fire) could be selected so that the influence of the

interior finish materials would be insignificant. That is, the

exposure fire may be very small or may be located such that the interior

finish is not exposed during initial fire buildup, or it may be very

large, thus masking the contribution of the interior finish. Considerable

attention was given to the development of plausible fire scenarios

upon which the experimental work was based in order to avoid such

extremes

.

6
If a fire cannot be prevented, a chain of events occurs (referred

to by some fire researchers as stages or "states" of fire growth)

This chain includes:

1. Ignition

2. Incipient burning (single item)

3. Spread to surrounding combustibles

4. Total room involvement (flashover)

5. Spread beyond room (post-f lashover

)

A survey of available mobile home fire incidence data [1-9, 18] provided

information which could be related to the concept of "stages" for fire

buildup (see table 1) . Key elements in the data which were identified

were

1. Area (location) of fire origin

2. Primary source of ignition

3. Primary means of fire spread beyond initial item

As shown in table 1, the data indicated that the three most common

areas of fire origin were:

1. Bedroom/living room

2. Kitchen

3. Heating equipment area

It was further indicated that the most common sources of ignition

were:

1. Fuel fired equipment

2. Electrical

3 . Smoking

And finally, the most common means of spread were:

1. Structural or interior finish

2. Power transfer equipment

Based on these findings, scenarios for fire incidents were developed.

A rank ordering of the scenarios in terms of probable occurrences

resulted in the three major scenarios illustrated in table 2.

7
Experimental plans were developed to conduct full-scale tests to

provide data on the first two scenarios. Interim reports NBSIR 76-

1021, NBSIR 78-1522, NBSIR 78-1530 and NBSIR 78-1531 all provide

experimental results and analysis of selected measurements of fire

4 . . growth and spread from incidental fires in the bedroom, living room

and corridor areas of a 3.7 x 18.3 m (12 x 60 ft) single-wide, three

bedroom mobile home. Interim report NBSIR 75-788 specifically addresses

the results of experimental testing to examine the impact of incidental

fires occurring on the kitchen range. The exposure fires used in the

kitchen tests consisted of cooking oil on a kitchen range. The exposure

fires used in the other tests included wastebaskets, standardized wood

cribs, upholstered chairs, and a mattress.

The third scenario, involving ignitions in heating equipment, was

not selected for study. Section 280.203(3) of the Federal Mobile Home

Construction and Safety Standard included requirements to increase the

fire resistance of the enclosures where the hot water heaters and

heating units were located. It was anticipated that these requirements

would have a significant impact on the potential spread of these types

of fires beyond the compartment. Therefore, this scenario was assigned

a low priority, and no experiments were planned.

3. EXPERIMENTAL TEST PLANS

Details of the experimental procedures, the facilities, and

rationale for selection of evaluation criteria are included in the

interim reports.

4. KEY EXPERIMENTAL FINDINGS

The following are conclusions, drawn from the various experimental

segments of the project, which are pertinent in considering recommendations to improve the fire safety in mobile home construction.

For this work an incidental fire is defined to be one which by itself does

not cause flashover in the room in which it is burning. Flashover is

defined to be a fire phenomenon in which the radiation from the upper walls

and ceiling and from the hot gases and smoke layer in the upper part of the

room is sufficient to cause ignition and rapid complete fire involvement of

all combustible materials in the room. The term is synonymous with the

phrase "total room involvement" [19].

8
4.1. NBSIR 75-788, Evaluation of the Fire Hazard in

a Mobile Home Resulting from an Ignition on the

Kitchen Range

1. A pan of cooking oil which burned freely for as little as 40

seconds on a range in a mobile home kitchen represented a potential

of fire spread and involvement of the cabinets and back wall in

the kitchen area.

2. For the range of vertical clearances studied, 57 to 79 cm (22.5

to 31 in) , the height to the bottom surface of the cabinet directly

above the range had a slight effect on the time it took to reach

sustained burning of the cabinet. Without a metal range hood,

sustained burning of the Class C cabinet underside occurred

within three minutes after ignition in the majority of tests with

a cooking oil fire. Class C refers to a flame spread classification

(FSC) within the range 76-200 according to ASTM E-84 [20]

3. Installation of a metal range hood of a design described in the

test report provided significantly improved resistance to sustained

burning of the underside of the cabinet directly above the range,

significantly reduced the rate of temperature rise and maximum

temperatures at the ceiling above the range, and increased the

time to ignition of the vertical surfaces of the cabinet assembly,

including doors and trim.

4. Installation of minimum 6 mm (0.25 in) inorganic board between

the underside of the cabinet and the metal range hood provided a significant reduction in temperatures transmitted to the cabinet

underside. However, due to direct exposure on other surfaces,

this did not prevent ignition of the cabinet in all cases.

5. The partition behind the kitchen range represented a critical

area for lateral flame spread and for fire penetration into the

adjacent room due to a cooking oil fire on a rear burner. The

presence of a range hood tended to increase this potential for

the typical ASTM E-84 Class C partition material.

6. With a range hood installed, the differences in performance of

the three types of cabinet door materials were less pronounced

than with a range hood not installed. However, in all of the

9
tests with polystyrene cabinet doors, there was a structural

collapse of the door.

7. Cabinets adjacent to the cabinet directly above the kitchen range

could be ignited from a cooking oil fire, but not as readily as the cabinet directly above.

4.2. NBSIR 76-1021, Fire Spread Along a Mobile Home Corridor

1. The tests showed that an incidental fire entering the corridor in

a mobile home, rather than venting itself by burning up through

the roof or out the windows located along with corridor or burning

through partitions into adjacent areas, initially progressed

directly down the length of the corridor, significantly limiting

egress

.

2. For fires starting in the corridor, the extent of fire spread and

the time to reach thresholds for limiting physiological conditions,

based on the various criteria provided, were significantly

influenced by the surface flame spread characteristics of the

wall and ceiling finish materials in the corridor.

3. Combustible corridor wall and ceiling linings with ASTM E-84

flame spread classifications in the vicinity of 200, produced

untenable temperature conditions in the corridor in less than

four minutes after ignition of a wood crib in the corridor.

4.3. NBSIR 78-1522, Characteristics of Incidental Fires

in the Living Room of a Mobile Home

1. Under the experimental conditions of this test series, including

noncombustible walls and ceiling and no additional furnishings,

an incidental fire resulting from the burning of a wood crib

weighing up to 13.6 kg (30 lb) or a medium size upholstered chair

by itself did not result in conditions conducive to full room

involvement (flashover)

.

10
4.4. NBSIR 78-1530, Mobile Home Living Room Fire Studies:

The Role of Interior Finish

1. Fire spread beyond the initial burning item occurred as a result

of involvement of the wall and ceiling interior finish materials

near the burning item. The rate of fire growth and spread, the

severity of the fire, and the resulting attainment of limiting

conditions selected for life safety depended on the thermophysical and fire properties of the wall and ceiling finish

materials.

2. Flashover, observed to have occurred as a result of radiative

heat transfer from the hot smoke layer and the surfaces in the

upper part of the room to the combustibles in the lower part of

the room, occurred in those tests in which the upper room temperature

exceeded 600°C. Lateral heat transfer and flame propagation from

the initial burning item were not of sufficient intensity prior

to the attainment of flashover to involve other combustibles

except those in close proximity to it.

3. A rapid rate of fire growth and the attainment of flashover

always resulted in exceeding all of the selected physiological

limits established for occupant incipient incapacitation at the

back exit door.

4. The use of the ASTM E-84 flame spread rating (FSC) provides an indication of the potential contribution of interior finish

materials when exposed to an incidental fire under the conditions

established irt this test series.

4.5. NBSIR 78-1531, Mobile Home Bedroom Fire Studies:

The Role of Interior Finish

1. Given an upholstered chair fire in the corner of the master

bedroom in a single-wide mobile home, in the absence of other

combustible furnishings near enough to be ignited by flame contact,

the attainment of flashover required the involvement of the

interior finish materials. Flashover occurred if the ASTM E-84

FSC of the wall lining material was greater than 60 regardless of

the FSC of the ceiling material. However, the time from flame

impingement on the wall to flashover increased with decreasing

FSC of the ceiling material.

11
2. Given a fire in bedding with a mattress susceptible to rapid

flaming combustion (e.g., a polyurethane mattress) in the corner

of the master bedroom of a single-wide mobile home, flashover is

likely to occur regardless of the FSC of the interior finish

materials. However, it should be noted that bedding fires involving

mattresses constructed of other materials such as cotton batting

or neoprene may not pose as serious a hazard as the polyurethane

mattress used in this series.

3. Limiting conditions adverse to life safety were reached in the

living room at the remote end of the mobile home from the bedroom

where the fire was started at approximately the same time that

flashover occurred in the bedroom. If flashover did not occur,

limiting conditions of carbon monoxide and oxygen were reached in

the living room only after an extended period of time, or not at

all.

4.6. Supplemental Mobile Home Living Room Fire Studies:

The Role of Interior Finish

(See Appendix A)

1. The test results provided the basis for extending the material

hazard matrix developed in NBSIR 78-1530 to a higher intensity

exposure fire. This supported the earlier finding that the use

of the ASTM E-84 flame spread rating (FSC) provided an indication

of the potential contribution of interior finish materials when

exposed to an incidental fire under the conditions established in

this test series.

2. The range of FSC for combinations of wall and ceiling materials

demonstrating no flashover was reduced significantly when the

exposure fire was increased from one of low intensity to one of

moderate intensity.

5. DESIGN STRATEGIES FOR LIMITING FIRE GROWTH AND SPREAD

Fire safety can be accomplished either through preventing the

ignition or by managing the impact of the fire. It is not realistic

to expect that design requirements for construction can effectively

prevent all hostile ignitions. Flaming ignitions are common in normal

12
activities (e.g., cooking on a gas range or striking a match for a cigarette) and any one of them could, under the proper circumstances,

become a hostile ignition. In addition, electrical appliances which

are malfunctioning or are improperly used could produce a spark or produce the heat to cause a hostile ignition.

Given the condition that a fire has occurred, it becomes necessary

to manage the fire impact. Referring back to the "chain" of events in

the typical fire growth process,

(1) Ignition

(2) Incipient burning (single item)

(3) Spread to surrounding combustibles (including walls and ceiling)

(4) Total room involvement (flashover)

(5) Spread beyond room (post-f lashover

)

it is necessary to identify where regulations could be imposed that

would make use of available engineering techniques to effectively

control the fire growth process. Furthermore, it is necessary to

define the criteria that can be used to measure the successful application of these techniques.

Intervention strategies involving control of the construction and

interior finish materials were developed to limit the impact of a fire

(1) resulting from an ignition on the kitchen range, and (2) from an item of burning furniture or other incidental fire. These strategies

were based on an analysis of the test results which indicated that

flashover was a critical stage in mobile home fire growth. The strategies

were designed to prevent a fire from reaching step 4 of the "chain"

Other strategies were not developed here.

5.1. Controlling Incidental Fires on the Kitchen Range

The effectiveness of several design features in preventing the

spread of an accidental fire occurring on the kitchen range to the

surrounding combustibles was examined. Design requirements were

i derived which, if implemented, would reduce the likelihood of rapid

fire spread to the combustible overhead cabinets, the back wall, and

other combustibles within close proximity to the kitchen range. The

recommended design requirements are:

13
1 . A steel range hood of minimum no. 2 6 U.S. Standard Gage thickness

should be installed above the kitchen range with a minimum vertical

clearance from the range top to the hood of 61 cm (24 in) . The

range hood should be designed such that a minimum 13 cm (5 in)

eyebrow is extended beyond the front vertical surface of the

overhead cabinets to prevent direct impingement of flames on the

vertical cabinet surfaces such as the doors. In cases where the

hood and overhead cabinet are recessed so that the bottoms of the

adjacent cabinets to the hood are lower than the hood, the exposed

sides of these adjacent cabinets should be protected by an extension

of the hood design. In all cases, a sheet of minimum 6 mm (0.25

in) thick inorganic board (or equivalent) should be provided

between the hood and the surfaces of the overhead and adjacent

cabinets. The underside of the adjacent overhead cabinets within

a horizontal distance of at least 46 cm (18 in) from the range

should be constructed of materials having a maximum flame spread

classification not greater than 50 when tested in accordance with

the Standard Test Method for Surface Burning Characteristics of

Building Materials, ASTM E-84 [20] , and a rating of limited

combustibility as defined in NFPA No. 220, Types of Building

Construction, 1975 edition [21]

.

2. The material comprising the exposed partition behind the range

should be limited to a flame spread classification of not greater

than 50 (under ASTM E-84) and a rating of limited combustibility

(under NFPA 220, 1975 ed.) to prevent fire penetration into

adjoining areas. It should be attached by mechanical means and

extend at least 46 cm (18 in) beyond the edge of the range.

5.2. Controlling Incidental Room Fires

5.2.1. Development of Material Hazard Matrices

A room fire may initially involve the ignition of a small piece

of furniture, a waste container filled with combustibles, or a small

appliance; or it may involve the ignition of an upholstered chair, a sofa, or a bed. Other parameters to be considered are the size of the room in which the fire occurs, the ventilation, and the interior

finish.

14
Tests were conducted in the living room, bedroom and corridor

areas to provide data on a range of enclosure sizes. In addition, a range of incidental exposure fires was selected to provide data on the

5 growth and spread of low and moderate intensity fires , which would

typically be expected to occur in a residence. Various combinations

of wall and ceiling materials were tested covering a wide range of

FSC. As a result of the variations in these parameters the examination

of the incidental room fire scenario for mobile homes required the

conduct of over sixty full-scale fire tests.

The role of fire growth and spread and the maximum fire size are strongly affected by the intensity of the exposure fire, the size of

the room, and the interior finish of the wall and ceiling materials.

It was found that the attainment of flashover in the room of fire

origin was of paramount significance not only in terms of the extent

of property damage but also in terms of attainment of limiting conditions

selected for occupant tenability. It was also found that the use of

limited flame spread interior finish materials on the walls and ceiling

could provide successful design options to prevent the attainment of

flashover from a low or moderate intensity incidental fire.

In order to illustrate the effect of various combinations of wall

and ceiling materials with different FSC values on fire growth to

flashover for a particular size room and particular intensity incidental

fire, material hazard matrices (flashover matrices) were developed.

Such matrices were used in NBSIR 78-1530 and NBSIR 78-1531, and are used with the supplemental living room test results in Appendix A.

The matrices illustrate, based on the results of the full-scale tests,

the range of FSC combinations for wall and ceiling materials which

would not be expected to result in room flashover from exposure to an incidental fire. They also illustrate the range of combinations in

which flashover would be expected to occur, as well as an intermediate

range in which flashover is uncertain due to the absence of test data

for some combinations of FSC. All flame spread values, referred to as

FSC, are based on the results of the ASTM E-84-77a Tunnel Test (see

table 1 of Appendix A in this report, table 2 of NBSIR 78-1530, and

table 1 of NBSIR 78-1531).

5 For purposes of this study, a low intensity fire is a fire resulting from

the ignition of a small piece of furniture, a waste container or a small

appliance. A moderate intensity fire is one resulting from the ignition

of a larger item such as an upholstered chair or sofa. Both the low and

moderate intensity fires are considered to be "incidental" as defined in

footnote 4.

15
Three matrices were constructed. The one in figure 1 illustrates

the range of wall and ceiling materials, as a function of the FSC, for

which flashover would or would not be expected when exposed to a low

intensity incidental fire in the corner of a mobile home living room. The two matrices in figure 2 provide similar illustrations for flashover

in the living room and the bedroom, depending on the FSC of the interior

finish materials, but from exposure to a moderate intensity incidental

fire in the corner.

These matrices represent the probable occurrence of flashover

based on the full-scale mobile home tests conducted at NBS and the

results of ASTM E-84 tests conducted at a single testing laboratory.

For these reasons the borders separating the "no flashover", "untested",

and "flashover" regions, while shown as well defined boundaries,

should not be assumed to be that precise. This is due to inherent

variations in ASTM E-84 results among laboratories, due to batch to

batch variations of the same generic material, and due to the effects

of different fire properties such as ignitability , heat release rate,

potential heat, etc., for the different generic materials with the

same FSC. In addition, more information could become available about

other combinations of wall and ceiling materials currently falling in

the "untested" region if such materials are used in future full-scale

fire tests.

Where appropriate, data from one test series are extrapolated

from one matrix to another. For example, in figure 1 the region where

flashover was not observed for the low intensity fires has been

increased slightly based on the results of the upholstered chair

series. The more severe chair fire did not result in flashover in

test MHLIV 24 which tested a wall material having higher FSC than wall

materials in similar tests in the series with the low intensity fire

exposure. It is assumed that for similar materials, if the larger

exposure fire did not result in flashover, then it is unlikely that

flashover would occur for a smaller exposure fire.

Similarly, the region defined as that where flashover was observed

for the moderate intensity exposure fire in the bedroom (fig. 2) has

been extended to include those material combinations which demonstrated

flashover for the moderate intensity exposure fire in the living room. This extrapolation was based on the understanding that if flashover

occurred in the living room with a given size exposure fire, then it

is likely that flashover will occur in the bedroom, which is significantly smaller, for a similar exposure fire.

16
In figure 2, the material hazard matrix covering moderate intensity

incidental fires in the living room shows a common region of intersection

between the regions of high and low flashover probability. The tests

which define that uncertain region (MHLIV 23 and 24) both used intumescent

treated lauan plywood walls (FSC of 36 and 45, respectively) . In

addition, both tests used ceiling materials with an FSC of 25. However,

in test MHLIV 23, where flashover was observed, the ceiling was a fireretardant treated finished wood fiberboard while in test MHLIV 24,

where flashover was not observed, the ceiling consisted of taped,

spackled, and painted gypsum board.

This result serves to highlight a limitation in the use of FSC

alone in determining the hazard of a material. It is important to

recognize that FSC alone is not a complete measure of the contribution

of a material to fire growth and spread. Consideration of other

properties such as ignitability , heat release rate, thermal conductivity,

density, potential heat, and specific heat would provide a more accurate

prediction of the contribution, particularly for materials having

widely divergent thermophysical properties while at the same time

having similar FSC values. The two ceiling materials tested in MHLIV

23 and 24 provide a case in point. While the FSC was similar for both

materials, the integrated heat release rate for a five minute period,

based on laboratory tests conducted in the NBS Rate of Heat Release

2 Calorimeter Model II at an exposure of 6 W/cm , was quite different

for the two materials. The fire retardant treated wood fiberboard had

an integrated heat release rate of 1324 J/cm2

; the value for the

2 gypsum board was 394 J/cm . (Further discussion of this is included

in section 5 of Appendix A.

)

In addition to the extrapolations mentioned above, the region

where "flashover was not observed" for the moderate intensity exposure

fire in the bedroom has been expanded to include ceiling materials

having FSC values up to 25. The gypsum board ceiling material tested

in the bedroom series had a measured FSC of 15. However, a gypsum

board ceiling material with similar material and fire properties

tested in the living room series had an incrementally higher FSC of

25. The results of the two test series indicate that there was no significant difference in performance under full-scale conditions for

the two similar ceiling materials having FSC values of 15 and 25

respectively when tested with a wall material having an FSC value of

25 or less. Therefore, the region in the matrix was extended for

ceilings up to FSC of 25, in lieu of the more restrictive limit of 15.

17
However, limitations on the use of FSC, as described above, and

the absence of comparative full-scale test data discourage a direct

extension of the non-f lashover region in the low intensity material

hazard matrix (fig. 1) to include ceiling materials having FSC values

up to 25. While such an extrapolation of the full-scale results was performed for the moderate intensity exposure fire in the bedroom,

some comparative full-scale test data were available, and the corresponding

FSC values for the wall materials in the non-f lashover region did not

exceed 25. In the case of the low intensity exposure fires in the

living room, wall materials having much higher FSC values (from 45 up

to 182) are involved. The results of tests MHLIV 23 and 24 provide at

least an indication that the use of some ceiling materials having FSC

values of 25, in conjunction with a wall material having an FSC value

as low as 36, can result in f lashover. As discussed in section 5 of

Appendix A, material properties other than surface flame spread are likely responsible for this. Therefore, in the absence of applicable

full-scale test data, an extension of the non-flashover region of the

matrix in figure 1 from ceiling materials with FSC values up to 15 to

ceiling materials with FSC values up to 25 (when combined with wall

materials ranging in FSC from 45 to 182) cannot be made without introducing additional requirements for the ceiling materials. That is, it

may be permissible to allow a ceiling material with an FSC value up to

25, provided that other key properties of the material such as potential

heat, ignitability , and heat release rate do not vary appreciably from

those of the material actually tested in the living room with the low

intensity incidental fire exposure.

5.2.2. Review of Similar Work

Discussions of the significance of previous experimental research

on related aspects of fire growth and spread are included in the

interim reports, and will not be repeated. However, it was desirable

to use the material hazard matrix to compare the results of other

experimental work of similar scope.

The results of the following three projects were analyzed for

this purpose:

1. Hardwood Plywood Manufacturers Association (HPMA) /Southwest

Research Institute (SwRI) , Fire Tests (1967-1968). [22,23]

18
2. Hardwood Plywood Manufacturers Association/Underwriters'

Laboratories, Inc. (UL) , Fire Tests (1977). [24]

3. Hardwood Plywood Manufacturers Association/Underwriters'

Laboratories, Inc., Fire Tests (1978). [25]

The first project involved the conduct of four full-scale fire

tests to examine the relative performance of wall materials having

different FSC when exposed to an upholstered chair fire. The tests

were conducted in a rectangular shaped three-room home which generally

resembled a mobile home in configuration.

The second project involved the conduct of two full-scale tests

in identically designed mobile homes. The only parameter which was varied was the interior wall finish which was 4 mm thick lauan plywood

in one test and 8 mm thick gypsum board in the other. The exposure

fire was an upholstered chair, positioned in a corner in the living

room.

In the third project an actual mobile home was not used, but the

test facility was representative of mobile home construction. The

spatial characteristics of the facility varied from those tested in

the second project. That is, the spatial dimensions of the living

room were reduced in scale. The bedrooms were eliminated and the

corridor was reduced in length and left open at the end, providing

different ventilation. The furniture was not scaled down although the rooms were, and the two tests were again performed by varying the wall

finish and exposing the room to an upholstered chair fire.

The following key observations were made from the HPMA tests:

(1) Attainment of flashover resulted in exceeding the thresholds

for limiting conditions for occupant safety of temperature,

carbon monoxide and oxygen (thresholds adopted by NBS) at

remote locations from the initial fire.

(2) In the one test in which flashover did not occur, thresholds

for limiting conditions were not reached (SwRI #1)

These key observations based on the results of these projects of

SwRI and UL, are in agreement with the results of the studies conducted

at NBS.

19
The material hazard matrix developed for the moderate intensity

exposure fires was extended to include the eight tests from these

projects. Figure 3 illustrates the resulting changes in the material

hazard matrix for the moderate intensity exposure fires in the living

room of the mobile home. In essence, the additional information from

these eight tests provided some limited reduction in the size of the

untested region, by expansion of the region where flashover was observed.

The combinations of materials in the "no flashover" region remained

the same.

The results of this analysis indicate that the material hazard

matrix can be extended to provide a framework for evaluation of results

from experiments conducted under similar conditions. However, it

should not be assumed that the material hazard matrix is independent

of geometric constraints. The actual effect on the validity of the

matrix of changes in the experimental configuration cannot be ascertained

from this limited exercise.

5.2.3. Design Options for Improved Fire Safety

The results of the full-scale testing clearly demonstrate the

significance of flashover in terms of both property damage and occupant

safety in mobile homes. While the absence of flashover does not

assure occupant safety under all possible fire conditions, in the

event that flashover occurs, conditions throughout the mobile home

deteriorate rapidly. The material hazard matrices provide tools for

identification, based on the limited number of full-scale tests conducted,

of combinations of interior finish materials which did not result in

flashover

.

The individual matrices in figures 1 and 2 are based essentially

on three different combinations of test conditions, reflecting variations

in room size, the intensity of the exposure fire, and the measured FSC

of the various interior finish materials tested. As a result of these

variations, three design options are identified, each reducing the

likelihood of flashover for a different set of conditions. This is

accomplished by limiting the FSC of the wall and ceiling interior

finish materials to those which fall in the region of the matrices

which is identified, as a result of the full-scale tests, as not

demonstrating flashover.

20
The design options are:

1. Any combination of wall and ceiling materials having FSC

values which place them in the "flashover not observed"

region of the material hazard matrix for low intensity

exposure fires in the living room (fig. 1)

2. Any combination of wall and ceiling materials having FSC

values which place them in the "flashover not observed"

region of the material hazard matrix for a moderate intensity

exposure fire in the living room (fig. 2)

3. Any combination of wall and ceiling materials having FSC

values which place them in the "flashover not observed"

region of the material hazard matrix for a moderate intensity

exposure fire in the bedroom (fig. 2)

It is intended that design option 1 limit the likelihood of

flashover from exposure of the interior finish materials to a low

intensity incidental fire in the living room. Design option 2 would

extend this limitation to include both low and moderate intensity

exposure fires in the living room.

As would be expected, the FSC limitations are more restrictive

for the moderate intensity exposure fires than for the low intensity

exposure fires.

Design option 3 is intended to limit the likelihood of flashover

for moderate intensity incidental fires in the bedroom. In addition,

because the bedroom is smaller than the living room, implementation of

this design option in the living room will also limit the likelihood

of flashover from a moderate intensity fire in that area. While a material hazard matrix was not developed for the corridor area, the

test results [11] indicate that design option 3 will limit flashover

from a low or moderate intensity exposure fire starting in, or near

the corridor.

The full-scale tests on which the flashover matrices and the

design options are based involved varying the interior finish materials

only in the room of fire origin and not the entire mobile home.

However, to provide the increased level of fire safety in areas where

fires could begin other than the specific locations which have been

21
investigated with full-scale fire testing, the FSC requirements for

each of the three design options are specified for the entire mobile

home. In addition, because of the configuration of the "flashover not

observed" regions in the matrices, separate flame spread limitations

must be specified for the wall material and the ceiling material.

6. IMPACT ASSESSMENT

6.1. General

It was necessary to quantify the effect of each of the three

design options for limiting the FSC of interior finish materials in

order to provide an assessment of their relative effectiveness.

Therefore, a limited analysis of data on actual fire incidents involving

g mobile homes was performed to assess the likely impact of each of the

three design options on the severity of these fires had the options

been implemented before the incidents occurred.

6.2. Classification of Data

The statistical data base chosen for this analysis was the National

Fire Incident Reporting System (NFIRS ) data base which is collected

and maintained by the U.S. Fire Administration (USFA) . This data base covers several states across the country, offers a breakdown of each

fire incident, and is computer based, permitting easy access. The

states from which mobile home fire incidents were examined are listed

in table 3.

NFIRS uses the coding system described in the National Fire

Protection Association (NFPA) publication. Fire Incident Data Coding

Guide [26], based on NFPA 901, Uniform Coding for Fire Protection

[27]

.

This system of coding provides classification of many aspects

of a fire incident, including a breakdown of the area of origin and

the form of material ignited. The NFPA classifications and related

code numbers for possible areas of origin are shown in table 4. . For

the purpose of examining mobile home fire incidents, these classifications were grouped together into nine general areas: Living Room

g Impact is defined here as the likelihood that the particular design

option under consideration would have prevented or significantly

reduced the potential for flashover for the fire incidents examined.

22
Area (living room, dining room, lounge and other larger volume rooms)

,

Sleeping Area (also closets, storage and laundry rooms, and other

smaller volume rooms) , Kitchen Area, Hallway or Corridor Area, Heating

Equipment Area, Structural Assembly, Chimney or Duct, Exterior, and

Multiple Use or Unknown. Table 5 lists the NFPA 901 code numbers for area of origin classifications which comprise each of the nine general

areas of a mobile home where a fire could originate. Since the NFPA

area of origin classifications were designed for general use with any

fire incident, many classifications are not directly applicable to

mobile homes and were either never referenced in any of the mobile

home fire incident data examined or were only referenced in a small

number of incidents. These area of origin classifications were not

included in the nine general areas and are designated in table 5 as being not applicable.

The NFPA classifications and related code numbers for the form of

material ignited (i.e., exposure fire) are shown in table 6. These

classifications have been separated into four groups of exposure

fires, including low, moderate, high, and unknown. These groups are based on the intensity of the fires. A 6.4 kg (14 lb) wood crib of

the type used as an exposure fire in the NBS fire tests conducted in

the mobile home living room, bedroom, and corridor is considered to be

of low intensity. A pan of 100% vegetable oil which is burning on the

kitchen range, as was used as the exposure fire for tests conducted in

the kitchen area, is also considered to be of low intensity. A 16 kg

(35 lb) polyurethane and cotton upholstered chair of the type used as

an exposure fire in tests conducted in the living room and bedroom is

considered a moderate exposure fire. And a 100% polyurethane mattress

with sheets and pillows, as was used as an exposure fire in a bedroom

test, is considered to be a high intensity exposure fire. The low and

moderate fires are not sufficiently intense to cause flashover by

themselves (i.e., they are incidental fires). The high intensity

fires are normally large enough to flash over a room without contributions from other combustible materials. The classification "unknown"

covers all fires of unknown intensity or fires which otherwise did not

fall into one of the groupings of low, moderate or high.

23
6.3. Sorting Of Data

The NFIRS data base was first sorted to separate and discard all

incidents not involving mobile homes. A mobile home was defined as:

Fixed Property Type = 411, Mobile Property Use = 17 (see line I of

NFPA Form 902 F [26]). The remaining incidents were then sorted again

by area of origin and examined.

Table 8 lists for each state and year, the total number of fire

incidents involving mobile homes and the number of fire incidents with

an unknown area of origin. This table is based on all reported fire

incidents involving mobile homes. However, in order to relate the

statistics to the experimental test results only those fire incidents

which resulted in fire spread beyond the room of fire origin and could

have involved interior finish were considered. This was achieved by

sorting the data again and retaining only those fires that spread

beyond the initial room of fire origin (i.e., the NFPA Form 902 F

entry for Extent of Flame Damage was 5, 6 or 7).

The data were already sorted by the intensity of the exposure

fire. Generally, a low or moderate intensity incidental fire by

itself will not cause flashover in a typical mobile home living room

or bedroom, and therefore, will not cause a fire severe enough to

spread beyond the room of origin [12,13,14]. It follows that a fire

which begins as a low or moderate intensity fire but eventually spreads

beyond the room of origin must have involved an additional source of

fuel. The results of the experimental studies demonstrated that

interior finish contributed to fire growth and spread and the attainment of flashover. Therefore, for purposes of this limited assessment,

it was assumed that in those fire incidents in which flashover and

subsequent fire spread beyond the room occurred, interior finish

provided the additional source of fuel.

Table 9 shows an example summary, for Oregon 1977, of all reported

fires which spread beyond the initial room of origin, classified by area of origin and intensity of exposure fire. Such a summary was

made for each of the eight states having 1977 incident data. The year

1977 was chosen because the number of mobile homes in each individual

state at the end of 1976 (i.e., the beginning of 1977) was readily

available [28]. Oregon was used in table 9 simply as an example.

24
A number of the categories of incidents listed in table 9 were

not included in the impact analysis. This resulted in a conservative

estimate. First, the requirements in the Federal Mobile Home Construction

and Safety Standards [15] concerning the ASTM E-84 flame spread rating

for interior finish in the heating equipment compartment and the

requirements for fire protection in the kitchen area around the range

are currently such that any additional future impact in these areas

would probably be marginal. Therefore, all fires which originated in

these areas were eliminated from consideration. Second, although

lower FSC interior finish materials could have an impact on fires

originating in the structural assembly, chimney, duct, or outside of

the mobile home, no experimental research was conducted to evaluate

this possibility. Therefore, these fires were eliminated from consideration

along with fires of unknown or multiple use areas of origin.

These exclusions leave only those fires originating in the living

room area, sleeping area, or corridor. In those areas high intensity

exposure fires were either not tested or were so severe that flashover

was reached independent of any contribution from the interior finish

material; although not all high intensity exposure fires would be

expected to cause flashover they were eliminated from consideration in

the impact analysis. The category of unknown exposure fires, which

also includes those special cases which did not fall into the other

categories, were also eliminated. Therefore, the only fires to be

considered in the analysis were those of low or moderate intensity,

occurring in the living room area, sleeping area, or corridor area.

6.4. Application of Data

The estimated impact of the design options, in terms of limiting

the occurrence of flashover, for the example data for Oregon for 1977

(table 9) , is as follows:

Design Option 1 : If the interior finish of the mobile homes

represented by the Oregon 1977 data had been restricted to combinations

having flame spread values which fall in the "flashover not

observed" region for the Living Room Low Intensity Fire Matrix

(fig. 1) , it is expected that 26 fires (all of the low intensity

fires in the living room area) could have been impacted; e.g.,

limiting the occurrence of flashover. Although many low intensity

fires in the sleeping area and corridor area would also have been

impacted, these fires are not included in the estimate.

25
Design Option 2 : If the interior finish in those mobile home

fire incidents tabulated in table 9 had been restricted to combinations having flame spread values which fall in the "flashover

not observed" region of the Living Room Moderate Intensity Fire

Matrix (fig. 2), it is expected that 34 fires (all of the low and

moderate intensity fires in the living room area) could have been

impacted. Again, although many fires in the sleeping area and

corridor area would also have been limited to a severity lower

than that associated with flashover, no estimate of these fires

is included.

Design Option 3 : If the interior finish in those mobile home fire

incidents (table 9) had been restricted to combinations having flame

spread values which fall in the "flashover not observed" region of

the Bedroom Moderate Intensity Fire Matrix (fig. 2) , it is expected

that 67 fires (all of the low and moderate intensity fires occurring

in the living room area, sleeping area, and corridor area) could have

been impacted.

Similar calculations for the other seven states with 1977 data resulted

in the values shown in table 10. From these numbers an average value for

the number of fires per thousand mobile homes which would have been

impacted had these design options been present in mobile homes was determined

as follows:

Impacted Fires

Reported Fires]

X Reported Fires ! Impacted Fires ! [Thousand Mobile HomesJ [Thousand Mobile HomesJ

For Design Option 1: 76 v 2890

2890 926.250 0.082

For Design Option 2: 115 „ 2890

2890 926.250 0.124

For Design Option 3: 250 v 2890 _ n 0 _ n 2890 926.250 U

If it is assumed that this sample of eight states is representative of

national fire incidence, then an estimate of the number of mobile home

fires which would have been impacted in the United States had the design

option been present in all mobile homes may be obtained as follows:

26
[

Impacted Fires ! „ [Number (in thousands) of Mobile Homes _ Thousand Mobile HomesJ [in United States

[

Number of Impacted Mobile Home Fires!

in United States

For Design Option 1: 0.082 x 4,308.391 = 353

For Design Option 2: 0.124 x 4,308.391 = 534

For Design Option 3: 0.270 x 4,308.391 = 1,163

These numbers represent estimates of the relative effectiveness of each

of the design options for a static population of mobile home fire incidents.

The accuracy of the assessment is dependent on the accuracy of the data

base. In order to assess the actual impact of each design option on mobile

home fire safety based on their future implementation in the manufacturing

of new mobile homes, a more comprehensive approach is necessary. This

approach should include consideration of the rate of influx of new mobile

homes with the selected option present into the mobile home population,

and the effect of other design criteria which could impact fire frequency

and severity in mobile homes.

7. RECOMMENDATIONS

Changes are recommended to the Federal Mobile Home Construction and

Safety Standards as a means of controlling the likelihood and extent of

fire spread in mobile homes. These changes are based on an extensive series

of full-scale fire tests performed under a prescribed set of environmental and

end-use conditions likely to be encountered in mobile home use. Details of

the testing, of the supporting rationale, criteria and analysis, and of the

limitations on its applicability are set out in the reports. The recommendations relate to protection in the kitchen range area, where cooking fires

are likely, and to flame spread limitations for the wall and ceiling finish

materials throughout the mobile home, since interior finish surfaces could

serve as means of rapid flame spread.

Based on an analysis of the results of experimental testing previously

referenced in this report, the following changes to the Federal Mobile

Home Construction and Safety Standards are recommended. Because of the

variability of FSC values, all FSC values have been rounded down to the

nearest 5. Limitations on FSC values are based strictly on the results of

the full-scale tests, and the logical extrapolations discussed in this

report.

27
7.1. Kitchen Area Protection

Intent of Kitchen Area Protection

The intent of the following two recommendations is to reduce the

likelihood of vertical or horizontal spread of a fire occurring on the

cooking range beyond the immediate area of the range, by restricting the

flammability of materials which are in close proximity to it.

Recommended Wording of Paragraph 280.204 (a) :

A steel hood of minimum No. 26 U.S. Standard Gage shall be installed

above the cooking range with a vertical clearance from the range top

to the hood of at least 61 cm (24 in) . The range hood shall be designed

such that a minimum 13 cm (5 in) eyebrow (measured horizontally) extends

beyond the front vertical surface of the overhead cabinets to prevent

direct impingement of flames on the cabinets. In cases where the hood

and overhead cabinet are recessed so that the bottoms of the cabinets

adjacent to the hood are lower than the hood, the exposed sides of

these adjacent cabinets shall be protected by an extension of the hood

design. In all cases, a sheet of minimum 6 mm (0.25 in) thick inorganic

board (or equivalent) shall be provided between the hood and the surfaces

of the overhead and adjacent cabinets. The underside of the adjacent

overhead cabinets shall be constructed, for a horizontal distance of

at least 46 cm (18 in) beyond the edge of the range, of materials

having a flame spread rating not exceeding 50 when tested in accordance

with the Standard Test Method for Surface Burning Characteristics of

Building Materials, ASTM E-84 , and a rating of limited combustibility

as defined in NFPA No. 220, Types of Building Construction, 1975 edition.

Recommended Wording of Paragraph 280.203 (a) (5);

The material comprising the exposed partition behind the cooking range

shall be limited to a flame spread rating not exceeding 50 (by ASTM E-84

and a rating of limited combustibility (as defined in NFPA 220, 1975 ed.

)

to prevent fire penetration into adjoining areas. This material shall be

attached by mechanical means and extend at least 46 cm (18 in) (measured

horizontally) beyond the edge of the range.

28
7.2. Interior Finish Flame Spread Requirements

7.2.1. Design Option 1 [For protection against the attainment of flashover from a low intensity

exposure fire in the Living Room Area]

Intent of recommendations of section 7.2.1.

The intent of the following two recommendations is to prevent a fire

of low intensity in a relatively large volume enclosure such as a living room from reaching the point of flashover. This is accomplished

by permitting only combinations of wall and ceiling interior finish

materials which have been shown not to contribute appreciably to rapid

fire growth and spread and the attainment of flashover under these

conditions.

Recommended Wording of Paragraph 280.203 (a) (1) :

The interior finish of all walls and partitions shall not have a flame spread rating exceeding 180 except as otherwise specified herein.

The flame spread limitation shall not apply to: molding, trim, windows,

doors or series of doors not exceeding 1.2m (4 ft) in width, and

permanently attached decorative items such as pictures or accent

panels constituting not more than 10 percent of the aggregate wall

surface in any room or space nor more than 3 square meters (32 square

feet) in surface area whichever is less.

Recommended Wording of Paragraph 280.203 (a) (2) :

Ceiling interior finish, excluding molding and trim 5 cm (2 in) or less

in width, shall not have a flame spread rating exceeding 15, with two

exceptions. Exception 1: Ceiling interior finish, excluding

molding and trim 5 cm (2 in) or less in width, shall not have a flame

spread rating exceeding 25 provided the interior finish of all walls

and partitions does not have a flame spread rating exceeding 45.

Exception 2: Ceiling interior finish, excluding molding and trim

5 cm (2 in) or less in width, shall not have a flame spread rating

exceeding 60 provided the interior finish of all walls and partitions

does not have a flame spread rating exceeding 25.

29
7.2.2. Design Option 2 [For protection against attainment of flashover from a low or moderate

intensity exposure fire in the Living Room Area]

Intent of recommendations of section 7.2.2.

The intent of the following two recommendations is to prevent a fire of low or moderate intensity in a relatively large volume

enclosure such as the living room from reaching the point of

flashover by permitting only combinations of wall and ceiling

interior finish materials which have been shown not to contribute

appreciably to rapid fire growth and spread and the attainment of

flashover under these conditions.

Recommended wording of Paragraph 280.203 (a)(1) :

The interior finish of all walls and partitions shall not have a flame spread rating exceeding 45 except as otherwise specified

herein. The flame spread limitation shall not apply to: molding,

trim, windows, doors or series of doors not exceeding 1.2 m (4 ft)

in width, and permanently attached decorative items such as pictures or accent panels constituting not more than 10 percent

of the aggregate wall surface in any room or space nor more than

3 square meters (32 square ft) in surface area whichever is less.

Recommended Wording of Paragraph 280.203 (a)(2) :

Ceiling interior finish, excluding molding and trim 5 cm (2 in) or less in width, shall not have a flame spread rating exceeding

25. Exception: Ceiling interior finish, excluding molding and

trim 5 cm (2 in) or less in width, shall not have a flame spread

rating exceeding 55 provided the interior finish of all walls and

partitions does not have a flame spread rating exceeding 25.

30
7.2.3. Design Option 3 [For protection against attainment of flashover from a low or moderate

intensity exposure fire in the Living Room Area, Sleeping Area or Corridor Area]

Intent of recommendations of section 7.2.3.

The intent of the following two recommendations is to prevent a fire of low or moderate intensity in either a small volume

enclosure such as a corridor or bedroom, or a larger volume

enclosure such as the living room from reaching the point of

flashover. This is accomplished by permitting only combinations

of wall and ceiling interior finish materials which have been

shown not to contribute appreciably to rapid fire growth and

spread and the attainment of flashover under these conditions.

Recommended Wording of Paragraph 280.203 (a)(1) :

The interior finish of all walls and partitions shall not have a flame spread rating exceeding 25 except as otherwise specified

herein. The flame spread limitation shall not apply to: molding,

trim, windows, doors or series of doors not exceeding 1.2 m (4 ft)

in width, and permanently attached decorative items such as pictures

or accent panels constituting not more than 10 percent of the

aggregate wall surface in any room or space nor more than 3 square

meters (32 square ft) in surface area whichever is less.

! Recommended Wording of Paragraph 280.203 (a) (2) :

Ceiling interior finish, excluding molding and trim 5 cm (2 in) or less in width, shall not have a flame spread rating exceeding

25.

7.2.4. Discussion

Sections 7.2.1., 7.2.2., and 7.2.3. present three alternate

design options for controlling the growth and spread of fires in

mobile homes through the use of interior finish. These options

represent different levels of safety and are based on the material

hazard matrices shown in figures 1 and 2. The material hazard matrices

are based on results of the ASTM E-84 Tunnel Test from a single

31
laboratory and therefore the borders separating the "no flashover,"

"untested," and "flashover" regions for the matrices may not be exact

due to inherent variations in ASTM E-84 results among laboratories and

from batch to batch of the same generic material. Certain combinations

of flame spread values which now fall in the "untested" region of a matrix may, if tested in a full-scale fire test, exhibit no flashover.

Therefore, it is recommended that HUD consider requests from mobile

home manufacturers to test such interior finish materials and to

provide complete data from full-scale tests which duplicate all the

conditions and instrumentation of the NBS test series as an alternate

basis for acceptability of a combination of wall and ceiling materials.

In addition, the use of the matrices should be restricted to

"conventional materials." A "conventional material" is one whose

history supports the applicability of flame spread values, as determined

by the ASTM E-84 Tunnel Test, as a prediction of relative fire hazard.

Materials with widely divergent properties such as low density foam

plastics or other exposed insulation materials would require fullscale testing in order to determine performance.

8 . ACKNOWLEDGMENTS

The authors wish to thank Mr. S. Leigh for development of a computer software package for data reduction and analysis, and the

other members of the Information and Hazard Analysis Group at the

Center for Fire Research who provided advice and assistance in data

analysis

.

This work was sponsored principally by the Division of Energy,

Building Technology and Standards, Office of Policy Development and

Research, U.S. Department of Housing and Urban Development.

32
9. REFERENCES

[1] Fires and Fire Losses Classified, 1975, Fire Journal, Vol. 70,

No. 6, pp. 17-19 (Nov. 1976).

[2] Fires and Fire Losses Classified, 1974, Fire Journal, Vol. 69,

No. 5, pp. 43-45 (Sept. 1975)

[3] U.S. Department of Health, Education and Welfare, Accidental Injury

Hazards in Mobile Homes: Fire and Carbon Monoxide, Report

No. FT 72-R2 , (Dec. 1971).

[4] U.S. Department of Health, Education and Welfare, Report on

the Risk of Fire in Mobile Homes, prepared by the Division

of Community Injury Control, Bureau of Community Environmental

Management (1974)

[5] Stickney, C.W. , The Mobile Home Fire Protection Problem, a talk presented to the Fire Marshals Association of North

America (Nov. 1971)

[6] Committee on Mobile Homes and Recreational Vehicles, National

Fire Protection Association; California Fire Loss Experience,

Mobile Homes/Travel Trailers vs 1 and 2 Family Dwellings,

Calendar Year 1974; MH/RV Document No. 75-14, Boston (May 1975).

[7] Klem, T.J., Preliminary Analysis of Fire Incidents in Mobile

Homes, National Fire Prevention and Control Administration,

unpublished transmittal.

[8] Tryon, G.H., A Talk on Mobile Homes and Fire Safety, a talk

presented to the 101st Annual Convention of the Fireman's

Association of the State of New York, MH/RV Document No. 73-8,

Boston (Sept. 1973)

[9] Center for Concerned Engineering and Center for Auto Safety,

Mobile Home Fires, prepared for presentation to the National

Commission on Fire Prevention and Control (Sept. 1972) .

33
[ 10 ]

[ 11 ]

[ 12 ]

[13]

[14]

[15]

[16]

[17]

[18]

[19]

[ 20 ]

Budnick, E.K., and Klein, D.P., Evaluation of the Fire Hazard

in a Mobile Home Resulting From an Ignition on the Kitchen

Range, Nat. Bur. Stand. (U.S.), NBSIR 75-788 (Feb. 1976).

Budnick, E.K., Fire Spread Along a Mobile Home Corridor,

Nat. Bur. Stand. (U.S.), NBSIR 76-1021 (July 1976).

Klein, D.P., Characteristics of Incidental Fires in the

Living Room of a Mobile Home, Nat. Bur. Stand. (U.S.),

NBSIR 78-1522 (Sept. 1978).

Budnick, E.K., Mobile Home Living Room Fire Studies: The

Role of Interior Finish, Nat. Bur. Stand. (U.S.), NBSIR

78-1530 (Sept. 1978).

Budnick, E.K., Klein, D.P., and O'Laughlin, R. J. , Mobile

Home Bedroom Fire Studies: The Role of Interior Finish,

Nat. Bur. Stand. (U.S.), NBSIR 78-1531 (Sept. 1978).

U.S. Department of Housing and Urban Development, Mobile

Home Construction and Safety Standards, Federal Register,

Vol. 40, No. 244, pp. 58752-58792 (December 18, 1975).

National Mobile Home Construction and Safety Standards Act

of 1974, Title VI of the Housing and Community Development

Act of 1974, Public Law 93-383, 93rd Congress (August 22, 1974).

Clarke, F.B., and Ottoson, J., Fire Death Scenarios and

Fire Safety Planning, Fire Journal, Vol. 70, No. 3, p. 20

(May 1976) .

Flash Facts: Pocket Reference to the Mobile Home Industry,

Mobile Homes Manufacturers Association (June 1973)

.

Parker, W.J., and Lee, B.T.

,

Fire Buildup in Reduced Size

Enclosures, Nat. Bur. Stand. (U.S.), Special Publication

411 (Nov. 1974).

1978 Annual Book of ASTM Standards, Part 18, American Society

for Testing and Materials, Philadelphia (1978) .

34
[21] 1978 National Fire Codes, Vol. 9, National Fire Protection

Association, Boston (1978)

[22] Pryor, A.J., Full-Scale Evaluation of the Fire Hazard of

Interior Wall Finishes, Final Report, SwRI Project No. 03-2167

Southwest Research Institute, San Antonio, Texas (Feb. 1968) .

[23] Pryor, A.J., Full-Scale Evaluation of the Fire Hazard of an Interior Wall Finish, SwRI Project No. 03-2363, Southwest

Research Institute, San Antonio, Texas (Dec. 1968)

[24] Fact-Finding Report on Comparative Fire Testing of Two Mobile

Home Units with Representative Interior Finish Materials

and Furnishings, for the Hardwood Plywood Manufacturers

Association, Arlington, VA; Project 76NK1062, Underwriters

Laboratories, Inc., Northbrook, IL (January 17, 1977).

[25] Fact-Finding Report on Comparative Fire Testing of Two Mobile

Home Living Room Sections with Representative Interior Finish

Materials and Furnishings, for the Hardwood Plywood Manufacturers Association, Arlington, VA; Project 77NK7202,

Underwriters Laboratories, Inc., Northbrook, IL (Jan. 6, 1978)

[26] Fire Incident Data Coding Guide, NFPA No. SPP-42, National Fire

Protection Association, Boston (1976)

[27] Uniform Coding for Fire Protection, NFPA No. 901-1976, National

Fire Protection Association, Boston (1976)

[28] Klem, T.J., Interim Report: The Mobile Home Fire Problem in

the United States, National Fire Prevention and Control

Administration, unpublished transmittal.

35
LIVING

ROOM

Low

Intensity

Exposure

Fire

(Standardized

wood

crib)

36

Figure

1.

Material

Hazard

Matrix

for

Low

Intensity

Exposure

Fire

in

Living

Room

(Based

on

ASTM

E-84

FSC)
LIVING

ROOM

BEDROOM

Moderate

Intensity

Exposure

Fire

Moderate

Intensity

Exposure

Fire

(Upholstered

chair

or

sofa]

(Upholstered

chair]

<DM3

ino u

acn X fa w

>lOO

r\i in

(U 0) 3 ^ -H 3 fa •H

fa

37

\////X

Expanded

region

for

"Flashover

not

observed’
Moderate

Intensity

Exposure

Fire

(Upholstered

chair

or

sofa)

38

Figure

3.

Expanded

Material

Hazard

Matrix

Based

on

SwRI

and

UL

Test

Results

(Based

on

ASTM

E-84

FSC)
rtf PO

-P

44O

4-1 C(1) O

1)C4

4.1 C

CU

co

cu

>40.

cu

14

to

14

cu0

S2

00I <T>

COU

•r4

4-> CO H

4-1

rtf -UUi

4-> C

CU T3•HOcH

01

14 •H

p4

CUeo

EE

cu I—

•H

XIo

T,

TS

CU

4-1

rtf I—

3eooc

cu i—

XI

rtf E4

39
Table

2.

Probable

Mobile

Home

Fire

Scenarios

CO Q

«x Ui

uu <r 2 QCO

>-

cr LU

cr

cr u- o. o

40
Table 3. States and Years of NFIRS Data Examined for Analysis

Alaska . . California

Maryland

Michigan

Minnesota

Missouri

New York

Ohio

Oregon . . . Rhode Island

South Dakota

1977

1975

1976

1977

1977

1978 -

1978 -

1977

1976

1977

1978 -

1976 -

1977

1978 -

1976

1977

1978 -

1977

1978

1978

1 /

1 /

2 /

2 /

2 /

—^First quarter only —

2 / Not included in analysis due to small sample size

3/ — Third and fourth quarters only

41
Table

4.

NFPA

Classifications

for

Area

of

Fire

Origin

(reproduced

from

reference

[26])

42
Table 5. Areas of Fire Origin for Mobile Home Analysis

and Corresponding NFPA 901 Codes for Area of Fire Origin

Areas of Fire Origin

for Mobile Home Analysis

LIVING ROOM AREA

Living room, lounge area Dining area Other larger volume rooms

SLEEPING AREA AND OTHER LESSER VOLUME ROOMS

Sleeping area for under 5 persons

Sleeping area for 5 or more persons

Bathroom

Laundry room

Closet, storage room

Other storage or function area

NFPA 901 Codes for Area of Fire Origin

(Line J on NFPA Form 902 F)

14

23

[ 11-13 ]*

21

2225

26

27, 42, 43, 49

[ 31, 32, 35, 39, 41, 46 ]

KITCHEN AREA

Kitchen, cooking area 24

HALLWAY CORRIDOR

Hallway, corridor

Interior stairway

Entrance way

Other egress area [

HEATING EQUIPMENT AREA

Heating equipment area, water heater area 62

Other service equipment area [ 61, 63-65, 68, 69 ]

01

t 03 ] 05

04 ], 09

STRUCTURAL ASSEMBLY

Ceiling/Floor assembly or concealed space 73

Ceiling/Roof assembly or concealed space 74

Wall assembly or concealed space 75

Other structural area 79

CHIMNEY, DUCT

Duct

Chimney

Other shaft or service facility

55

57

52, 59

EXTERIOR

Crawl space

Exterior wall surface

Exterior roof surface

Stairway, porch, awning, garage

Lawn, field, woods

Other exterior location

7176

77 02, 47, 72, 78, 93

17, 94, 95

91, 92

MULTIPLE USE, UNKNOWN, OTHER

Miscellaneous transportation related

Multiple location or use area

Not applicable or not classified above

Undetermined or not reported

[ 81-86, 89 ] 97

[ 98 ], 99

00

*Codes in brackets [ ] are not applicable.

Codes not listed were never referenced in the incident data.

43
t3

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tr>

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in a)u

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fdU 'O H 0) MM U

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m cm

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(LCm2

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<d

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u= v >

jy el

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c x *x 13 tJ rcc w. _ O 4J C

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c “

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2 £

-C cc c .V

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c Q. c

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0 ^ E.l s s s= 8 s S t si E 0^2(Xu(T3j3'T5 >T3',5 fl o _-,

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C ^1

S J j-O , o 9- c o

•C C J2 7 '

Q- o <T3 9 2 D/.0«T3

9 <X o, - „ 00

3 0 .9

j ^ 3

3 o IH-c .

2 « ^*5

2 15 c «-

3 .2 2

-£ -o

.si 3

8 " "I £

O •-,

-0 o.

be £ 3 3 J

C .2 .3 .3 d

c o. £ £

-£ P CL 3 3 t

1 I

1 I

5 4 i

12 Z 0.5 1 ill;

> Z 5 « I o -g-c-s s — It U l. t

c^Iq « Ji <tj a tf'g 8 g

u .9 o

* ~o ^-O O ^

3

•X "O C- c u

I .§

S.S s. - 2 2

Sc(X u 11

9.3

53 9

. Jx5*u 3 <r!

§§ |=-C tS|-

7; T 73 uu - 2^ 1 -O .<x ^ (X X X T3 (X > 73 Q-Q-cdv ^

a. a.— c *2 --J? q cxcxjz^^ -n 5 ^

to m - 2 ^ v 0 o _o s c £

c « m5q3

£

'= 2 -2 1 S.° JS TSSJ-S1

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44
Table

7.

Intensity

of

Exposure

Fire

and

Corresponding

•X3<U

4-1 •HC

CD

M-lOa£uo

M-l

05

0) T3OOO

CT> C

fa

faz

45
Table 8. Mobile Home Fires with Unknown Area of Origin

STATE AND YEAR

TOTAL

FIRES

NUMBER OF FIRES WITH

AREA OF ORIGIN UNDETERMINED

OR NOT REPORTED

PERCENT

NUMBER OF TOTAL

Oregon 1977 316 12 3.80

California 1977 1,045 56 5.36

Michigan 1978 136 9 6.62

Ohio 1978 161 11 6.83

California 1976 1,162 82 7.06

Maryland 1977 65 5 7.69

Ohio 1976 526 41 7.79

Alaska 1977 125 10 8.00

California 1975 1,022 92 9.00

Ohio 1977 619 66 10.66

Missouri 1978 112 13 11.61

Missouri 1977 204 25 12.25

New York 1978 134 21 15.67

Minnesota 1977 184 32 17.39

Missouri 1976 158 28 17.72

New York 1976 199 60 30.15

New York 1977 332 106 31.93

6500 669

Maryland 1978 i5 y

South Dakota 1978 12 -

Rhode Island 1978 2 -

—^Not included in analysis due to small sample size
Table 9. Summary for Oregon 1977 of all Fires Which Spread Beyond the

Initial Room of Origin

Area of Origin

Intensity of

Low Moderate

Exposure

High

Fire

Unknown Total

Living Room Area 26 8 0 8 b2

Sleeping Area,

Lesser Vol. Rooms

2b 3 11 7 b5

Kitchen Area 1

7 0 3 26

Hallway, Corridor 2 b 1 0 7

Heating Equip. Area 5 1 0 1 7

Structural Assembly 3 0 0 0 3

Chimney, Duct 0 0 0 0 0

Exterior 5 0 0 1 6

Multiple Use, Unknown 0 1 0 9 10

Not Applicable 0 0 0 1 1

Total 81 2b 12 30 1U7

47
Table

10.

Impact

Summary

for

1977

Data

CO 'a 4-1 a) (DOB* M O CO vO CO

m o ON sr nO o

cfl

M 33 00 00 ON CM 00

mm s a) on o ON o CM m oo NO CM CM

•H jQ d)r

—1

At * A AC #» •» A> At * vO 00 O nO CO ro rH vO NO

ID 3'H c co 04 CO rH

m o CO CM

W 3 Xl i-l CO rH rH rH ON os H CO CO <1) K (11 NO LO m m ON CM o

XI 4-1

X t-l rH <r nO CM rH o oo CO ON 0 O fl CO o rH NO CM rH co 00 3 2 <H 1—1

At z CM

<v CO U c « <u 3 HE > H o u o oo <! 3 4) Pt q C U pi -H u a) O •h a. u v£>

m NO rH o m o o

Cti 4J 2 co oo a) o nO rH rH r^* CO CM CM

m

CJ

a e a) T) CM

4-J £d 3 tH

H rl

a. 4J > C/i t-l

w

a 3 G -H

U

<D iH o i-l

X

O

M

•H

C

<U

x o

iw X> O a> 0) M > u c

0) «J C3 •H xi x; V4

If

01 Pt 00

c-i c B cd z o •H -H O D CM

m rH CO o NOm s CO > o n CO i—4 CO rH rH rH G X OfJ c rH j uQ 0) «-J 4J 3 G o M

XI

>. oo a 5 3 CO > B cd o G i-l o <U nO 00 CM CM rH nO NO

m NO

X 4-i axonod <j CM CM r-s a c M »H

P^j r^« •3w < >4 M < pr Q t-4 H

US s P^

O 2

13 o < z CO o cn

C

d o P-i ,_4 o2 o w >4

X

H

O

M >• CO o CO 3 < w < M CO pr. s H H P3 <1 X 3 M M w o

<73 o u * •3

O s s z H

48

Estimated

Number

of

Mobile

Homes

in

U.S.

in

1976

was

4,308,391*
APPENDIX A. SUPPLEMENTAL MOBILE HOME LIVING ROOM FIRE STUDIES:

THE ROLE OF INTERIOR FINISH

1 . INTRODUCTION

This appendix provides a summary of a series of eight full-scale

mobile home fire tests conducted by the Center for Fire Research (CFR) at

NBS over a period of six months, from April to September, 1978. These tests

were conducted in the living room of a typical single-wide mobile home and

were designed to provide experimental data to supplement a previous series

of sixteen full-scale fire tests. The results of that test series were

reported in an NBS technical report, NBSIR 78-1530, Mobile Home Living Room

Fire Studies: The Role of Interior Finish [13] ^ . As in the first series of

tests, the experiments were conducted in the living room area of a 3.7 x 18.3 m (12 x 60 foot) single-wide mobile home constructed in accordance with

the NFPA 501B, 1972 Edition, Standard for Mobile Homes. The structural,

material and spatial characteristics of the mobile home were comparable to

those in mobile homes constructed to the current Federal standard, promulgated

effective June 15, 1976 [15].

It should be noted that the same experimental approach was used in both

series of tests. Rationale for the experimental approach as well as the

basis for evaluation criteria were provided in the previous report. Therefore, NBSIR 78-1530 will be extensively referenced. As a result, this

appendix will provide an evaluation of the experimental results in a framework

similar to that utilized in NBSIR 78-1530, with detailed descriptions of the

experimental approach, results, and analysis included only when not adequately

covered in NBSIR 78-1530.

The primary purpose for this supplemental series of experimental tests was to provide data to expand the utility of the material hazard matrix

developed in NBSIR 78-1530. In particular, additional interior finish

materials were tested having flame spread classifications (FSC) in the

intermediate ranges in accordance with the ASTM E-84-77a Tunnel Test to

reduce the size of the untested region in the matrix. Further, for this

series of eight tests, upholstered chairs were used as the exposure fires in

order to supplement the data from the five upholstered chair tests conducted

in the first series. This provided the basis for expanding the material

hazard matrix for a moderate intensity exposure fire.

^"Numbers in brackets refer to the literature references at the end of the

summary report.

A1
1.1. Technical Objectives

The technical objectives of this particular segment of the project

were

:

(1) to provide quantitative technical data regarding the fire buildup

process resulting from an incidental fire in the living room of a typically designed single-wide mobile home, primarily as a function

of interior finish; and

(2) to provide an evaluation of the extent to which the results of the

presently required ASTM E-84 Tunnel Test can characterize the

hazard of these interior finish materials when installed on the

walls and ceiling in the living room of a mobile home.

1.2. Approach

The full-scale fire test procedure was designed based on the scenario

that an ignition might occur resulting in an incidental fire in the corner

of the room. For this case interior finish materials on the walls and

ceiling, having different surface flame spread characteristics, were evaluated

to determine if they significantly influenced the growth and spread of the

fire, and the resulting severity. Formulation of this scenario was based on

(1) statistical evidence that most fires occurring in residential occupancies

are initially small in size [1] ; and (2) in a significant number of mobile

home fires combustible interior finish materials on the walls and ceiling

provide the means for growth and spread of the fire beyond the initial

burning item [1-9] .

The results of the full-scale tests were examined from two viewpoints.

First, an assessment of fire growth and spread in the room of origin was

made, based on the various combinations of wall and ceiling materials tested.

This assessment was based on measurements of incident heat flux and gas

temperatures at strategic locations in the room of origin, and provided

information on the rate of fire buildup and extent of room involvement from

exposure of various lining materials to an exposure fire of moderate intensity.

Secondly, changes in the environment in adjacent areas outside the room of

origin as a result of fire buildup were examined. Specifically, the effect

of fire buildup on conditions in the corridor at the back exit door was

examined, based on changes in the levels of temperature, smoke density,

carbon monoxide concentrations and oxygen depletion.

A2
A qualitative evaluation of the relationship between the room fire

buildup process and the laboratory measured surface flame spread classification

of the wall and ceiling materials (ASTM E-84) is provided by incorporating

the supplemental test results along with the results of the initial series

into a matrix similar to that developed in NBSIR 78-1530.

2. EXPERIMENTAL PROGRAM

The test facility was a conventional single-wide mobile home approximately

3.7 x 18.3 m (12 x 60 ft) with a living/dining room, kitchen, bathroom, and

three bedrooms. Figure Al illustrates the spatial design of the mobile home

and location of the exposure fire. Reference NBSIR 78-1530 for detailed

descriptions of the mobile home, construction of the living room, and com- bustible furnishings. (For this test series, the living room was "sparsely"

furnished as in tests #1 through #9 of the first experimental series)

2.1. Initial Burning Items

In six of the eight tests the exposure fire resulted from the ignition

of a 16 kg (35 lb) upholstered chair positioned in the northwest corner of

the living room. The chairs were alike in construction and produced by the same manufacturer; constructed of wood, polyurethane foam and cotton materials

and covered by rayon fabric. The chairs were stored in a nearby test building

where temperature and humidity are nearly constant at 75 + 5°F and 25 + 10%

RH until the weight of the chair stabilized.

In two of the tests (MHLIV 18 and 19) a 35 kg (78 lb) sofa constructed

of wood, polyurethane foam and cotton materials and also covered in a rayon

fabric was used as the exposure fire. The sofas were also conditioned at

75 + 5°F and 35 + 10% RH until their weight stabilized.

2.2. Interior Finish Materials

Table Al lists the interior finish materials used in each of the eight

tests, their flame spread classification values (FSC) determined in accordance

. 2 with the ASTM E-84-77a, Tunnel Test Method , and the type of exposure fire.

2 FSC calculated based on the area of the flame distance versus time curve,

adopted by ASTM in April, 1976.

A3
2.3. Full-Scale Test Criteria

Criteria for evaluating the test results were based on two related

aspects of fire growth. First, the measurements of fire growth, and in

particular the attainment of flashover in the room of fire origin were

selected as the primary criterion for assessment of property damage. Generally,

flashover was assumed and reported to have occurred when radiant ignition of

the other combustibles located in the room was observed. The changes in

temperature, incident heat flux, carbon monoxide, carbon dioxide and oxygen

which occurred as the fire developed were recorded.

The second aspect of fire growth of importance in establishing fire

safety criteria upon which to evaluate the results of these full-scale tests

was the effect of the fire on the environment in adjacent areas outside the room of fire origin. By necessity, any approach to this must be pursued in

terms of an assessment of the impact of the changes in the environment on

the occupants.

Limiting criteria were selected to evaluate the principal factors

affecting the life safety of occupants of the mobile home in the event of a fire originating in the living room. Performance of the various combinations

of wall and ceiling materials installed in the living room was analyzed

based on the changes in the environmental conditions along the normal paths

of egress and in the bedrooms, in terms of the measured changes in temperature,

CO and 0 2

. In addition to monitoring these conditions which have a direct

impact on life safety, measurements were taken outside the living room to

monitor the amount of visible smoke being produced by the fire. These data

were collected to provide some information on the accumulation of smoke

along the corridor which was the principal path of egress.

Thresholds for limiting conditions of temperature, CO and 0 2 under a fire condition beyond which adverse physiological or psychological effects

would result have not been established. Difficulties in pursuing this have

arisen due primarily to the variation in 1) exposure times, 2) vertical and

horizontal distribution of gases, 3) the activity rate of the occupant, 4)

the general health of the occupant, and 5) the lack of clinical epidemiologic

data. However, for purposes of analysis there is sufficient information

available to tentatively establish levels at which adverse effects begin to occur. Therefore, based on this information, the following thresholds for

limiting conditions for life safety were adopted:

A4
Temperature 100 °C (212°F)

Oxygen Concentration 14% (by vol.)

1.036

Carbon Monoxide 41,800 [(ppm) x (min)] time-integrated CO; or

1.0% (10,000 ppm), short duration exposure level

In selecting these thresholds, no consideration has been given to

either the synergistic effects or additive effects resulting when limiting

conditions are reached for two or more of these measured conditions. Further,

the thresholds suggested here are based on the levels of these elements

which result in "incipient incapacitation" rather than death. Incipient

incapacitation is defined as that point at which physiological and psychological

effects are sufficient to impair thinking and influence physical efforts to

escape. The criteria are based upon the assumption that these critical

levels represent thresholds for human beings who are capable of normal

physiological and psychological behavior. The thresholds should not be

interpreted as precise boundaries but rather an approximation, based on the

literature and the unique characteristics of the occupancy type being assessed,

of the levels of conditions which would result in adverse effects. Reference

NBSIR 78-1530 (pp 8-15) for detailed discussion of rationale.

2.4. Measurements

2.4.1. Ambient Measurements

The moisture content of the wall and ceiling finish materials was measured and recorded for each test using an electrical moisture meter.

Outside and inside temperatures and relative humidity were also recorded, as were wind velocity, wind direction, and barometric pressure. Pertinent

measurements are tabulated in table A2.

2.4.2. Test Measurements

Test measurements were carried out in similar locations to those in the

test series reported in NBSIR 78-1530. Figure A2 illustrates the locations

of measurements and table A3 lists each channel and the type of measurement

taken.

3 . PROCEDURE

The procedures for installation of the interior finish materials, and

for conditioning of the interior environment of the mobile home were similar

to those in the previous test series.

A5
In the tests using the upholstered chair as the exposure fire, the

chairs, having an approximate weight of 16 kg (35 lbs) were positioned on

the load cell platform in the northwest corner of the living room with the

back of the chair approximately 25 mm (1 in) from the walls comprising the corner. The chairs were ignited by placing a commercially available 9 a (9.5 qt) capacity polyethylene waste container containing 225 gm (8 oz) of

crumbled newspaper adjacent to the left arm of the upholstered chair and

igniting the newsprint (figure A3)

.

In the two tests using the sofa as the exposure fire, the sofa was positioned on a load cell platform along the west wall in the northwest

corner. The sofa was approximately 10 cm (4 in) from the walls in both

tests which was the minimum permitted distance from the walls without interference with the weighing platform. The sofas were ignited by placing 400 gms

(0.9 lbs) of newsprint, folded once, on a stainless steel rack and igniting

the newsprint. The rack was designed to expose both the seat and back

cushion of the sofa to the burning newsprint (figure A4)

.

4. RESULTS

The fires developed in a similar sequence to those in the first series

of tests, and varied in length depending on the development of the exposure

fires and the extent of involvement of materials comprising the interior

finish. The tests ranged from just under eight minutes in test MHLIV 21 to

approximately 38 minutes in test MHLIV 19. The tests were terminated either

when there was a significant reduction in the intensity of the fire or, when

total room involvement occurred (flashover) . The determination that a significant reduction in the intensity of the fire had occurred was based on

1) a reduction in temperature levels at selected locations monitored continuously during the test, and 2) a noticeable reduction in the magnitude of the

fire and the area exposed.

Key measurements selected based on the extensive analysis of the initial

series of tests are tabulated in tables A4 and A5 . In addition, plotted

data based on the selected measurements are provided in Appendix AA

(pp. AAl-16)

.

5. ANALYSIS AND DISCUSSION

The primary objective of this series of tests was to extend the scope

of the flashover matrix developed in N3SIR 78-1530. Therefore the analysis

specifically addresses this objective. The results were also examined to

determine whether or not the contribution of different types of interior

finish materials when exposed to similar ignitions appreciably affected the

A6
change in environmental conditions considered necessary for continued safety

of the mobile home occupants, and whether or not this occurred at a significantly earlier point in time than flashover. Changes in temperature, CO and

0 2 at the back exit door which would serve as the primary means of egress in

the event that a fire occurs in the living room at the other end of the

mobile home were used in this determination.

As in the first series of tests, the results of these eight full-scale

tests indicated that in a typical single-wide mobile home, the rate of fire

growth and the maximum fire size directly affected whether or not limiting

conditions were reached. Flashover occurred in four of the six upholstered

chair tests (MHLIV 17, 20, 21, 23), and, as in the previous studies [13,14],

was accompanied by upper room temperatures in excess of 600 °C. Flashover

was not observed in tests MHLIV 22 and 24 where the respective maximum upper

room temperatures reached 556 and 536°C. For both tests the temperature

development in the upper room was characterized by a short period of rapid

increase up to the peak levels, followed by a decrease. The corresponding

plot for incident flux at the floor level was similar in shape to the temperature plot, with peak levels of incident heat flux occurring during the same time period as maximum temperature (reference data plots in Appendix AA)

Although flashover was not observed in test MHLIV 22, the thresholds

for limiting conditions of temperature, CO and 0 2 were either reached or exceeded. It should be noted however that these thresholds were marginally

exceeded, and after an extended period of time; on the order of 16 to 19

minutes when compared to those tests in which flashover occurred (reference

table A5)

In test MHLIV 24 the thresholds for temperature and CO were exceeded.

However, as in test MHLIV 22, the rate of change of these measured conditions

was not as high as that which occurred in tests where flashover was observed.

As illustrated by the data plots in Appendix AA the rates of change for the

measured conditions were lower, and so were the peak values. While flashover

was not observed, it would appear that the combinations of wall and ceiling

materials used in these two tests resulted in fire conditions which may

place these combinations very close to the boundary between flashover and no flashover in the material hazard matrix.

Flashover occurred prior to the attainment of thresholds for limiting

conditions of temperature, carbon monoxide and oxygen in all four chair

tests where flashover was observed. With the exception of test MHLIV 23

where the limiting threshold for 0 2 was not reached, the limiting thresholds

for temperature, CO and 0 2 were exceeded for all four tests. And, for the

A7
most part, as can be seen from the data tabulated in table A5, the thresholds

for limiting conditions occurred within a very short period after flashover

in these tests.

Flashover did not occur in either of the two sofa tests. In test MHLIV

18 the fire progressed along the sofa, eventually consuming most of the com- bustible materials. The flame envelope was somewhat larger in area than

that of the chair fires, and was of sufficient height to impinge on the

ceiling. However, there appeared to be no qualitative difference in the

severity of the sofa fire in MHLIV 18 and the upholstered chair fires. The

maximum upper room temperature was 453 °C which was only 9°C higher than the

maximum upper room temperature which occurred in test MHLIV 11 (NBSIR 78-1530)

under similar experimental conditions with an upholstered chair. In addition,

after reaching this peak of 453°C, temperatures in the upper room dropped

off rapidly, and fluctuated between approximately 150° and 250°C for the

duration of the test. This indicated that for this experimental configuration

the peak intensity of the exposure fires from the sofa and the upholstered

chairs were of similar magnitude, though the duration of burning was longer

for the sofa due to the additional fuel.

The initial fire buildup in the sofa in test MHLIV 18 occurred more

rapidly than in the chair fires due to the direct exposure of the polyurethane

seat and back cushions on the sofa to the burning newsprint. This buildup

of the exposure fire resulted in marginally exceeding the thresholds for

limiting conditions of temperature and oxygen at the back exit door, again

indicating a slightly more severe fire from the burning sofa. The oxygen

concentration dropped to a minimum concentration of 13.6% at 4 min 10 sec into the test, but then increased to approximately 18% where it remained for

the duration of the test. The temperature development was similar in that

it exceeded the 100 °C threshold, peaking at 119 °C during the same time that

the minimum 02 concentration was reached, and then decreased to approximately

a constant level of 100°C for the duration of the test. The peak 0 2 depletion

and temperature rise coincided with the rapid initial development of the

sofa fire.

In test MHLIV 19, the intensity of the exposure fire from the sofa was significantly lower than that of the upholstered chair tests or the other

sofa fire. The maximum upper room temperature was only slightly higher than

in the tests conducted in the first series with the wood crib exposure

fires. Fire spread along the surface of the sofa as well as the mass con- sumption rate was considerably slower than in test MHLIV 18, and during the

period of most intense burning the height of the flame envelope was not

sufficient to reach the ceiling.

A8
Why the sofa fire in test MHLIV 19 did not develop into a more severe exposure fire than the wood cribs as would be expected could not be determined. However, the results of the test indicated considerable deviation

from the remainder of the tests. Therefore, the results of test MHLIV 19 are included for information purposes but are not included in the discussion

regarding the material hazard matrix. Test MHLIV 20 provided information on

the exposure to an upholstered chair fire of the same interior finish

materials as in test MHLIV 19. The results of this test provided an evaluation of the performance of this combination of interior finish materials to an exposure fire of realistic intensity from an upholstered chair.

5.1. Comparison of Full-Scale Results

and ASTM E-84 FSC

Based on analysis of results a matrix was prepared to illustrate the

likelihood for flashover from exposure of interior finish materials to an upholstered chair fire. The matrix was based on the results of the five

upholstered chair fires conducted in the initial series of tests and seven

of the tests in the supplemental series. As previously discussed, analysis

indicated that in this test configuration the sofa fire (test MHLIV 18) was only slightly more severe than the upholstered chair fires and therefore was included in the analysis. The results of test MHLIV 19 were not included.

The material hazard matrix for the upholstered chair tests is provided

in figure A5 . For comparative purposes a modified form of the material

hazard matrix developed for the low intensity fire exposures is also provided.

The modification involved only a change in indexing of the FSC axes. In the

original matrix the categories specifically identified those FSC values

tested. In figure A5 , this was modified to provide a basis for comparing

performance of similar combinations of wall and ceiling materials to both

exposure fires. In addition, the traditional ASTM E-84 classification

ranges corresponding to Classes A (0-25), B (26-75) and C (76-200) were

adopted to provide a more conventional interpretation. These matrices,

while simplified for purposes of illustration, reflect the experimental

results similar to the matrix presented in NBSIR 78-1530.

The results of MHLIV 23 and 24, when incorporated into the material

hazard matrix, give rise to an interface between the flashover and non- flashover regions, at which the untested region is eliminated. This interface is itself an uncertain region. Flashover occurred in MHLIV 23 with a wall material having a measured FSC of 36, while it did not occur in MHLIV

24 with a wall material having a measured FSC of 45. Both ceiling materials

A9
had an approximate FSC of 25, though the one in MHLIV 23 was a wood fiberboard

having a higher potential heat than the material in MHLIV 24 which was gypsum board.

This result serves to highlight limitations in the use of FSC alone in

determining the hazard of a material. First, while FSC has been demonstrated

as a tool for providing some prediction of performance, material properties

such as ignitability , potential heat, rate of heat release, and rate of

flame spread, not adequately accounted for in FSC values, also influence

fire growth and spread. While the values for most of these properties for

the materials tested in this series have not been determined in time to be

included in this report, heat release rates were determined for the two

ceiling materials tested in MHLIV 23 and 24 . The integrated heat release

rates over a five minute interval were 1324 J/cm 2 and 394 J/cm2 for the

fiberboard and the gypsum board respectively. Therefore, while the FSC of

the two materials were similar, the higher heat release rate of the wood

fiberboard material could account for the more severe fire which occurred in

test MHLIV 23.

Furthermore, it should not be assumed that the boundaries drawn to

distinguish among the "flashover", "no flashover" and "untested" regions in

the matrix can be precisely defined. The method of determining the FSC does

not provide sufficient accuracy or repeatibility to enable such an interpretation. The boundaries in the matrices are constructed based strictly on

the reported FSC values of the materials tested. However, when considering

the accuracy of the values, it is more appropriate to interprete the boundaries

in terms of a range of FSC values (e.g., + 5).

A conservative approach would suggest that test MHLIV 24 having walls

with a FSC of 45 and ceiling with a FSC of 24 should be included in the non- flashover region of the matrix. This gives rise to an anomaly in the material

hazard matrix based on the results of test MHLIV 23. This anomaly cannot be

satisfactorily resolved in terms of FSC. And, the limited data regarding

other fire properties of the ceiling materials, while providing an explanation

for the anomaly, is not sufficient to permit adoption of an additional

criterion, based on a test method other than the ASTM E-84. Such an approach

would require additional analysis in order to establish the technical basis

for adoption of the additional test method.

3 Values for heat release rates for materials C9 (gypsum board) and CIO (wood

fiberboard) were determined from laboratory tests with NBS Rate of Heat

Release Calorimeter, Model II. Tests were conducted at 6 w/cm2 sample

exposure

.

A10
It should be noted that the area of the region in the matrix (figure

A5) where flashover was not observed for the low intensity fire has been

increased slightly. This increase reflects extrapolation of the results of

the upholstered chair fires. The more severe chair fire did not result in

flashover in test MHLIV 24 which tested a wall material having higher FSC

than wall materials in similar tests in the series with the low intensity

fire exposure. It is assumed that for similar materials, if the larger

exposure fire did not result in flashover, then it is unlikely that flashover

would occur for a smaller exposure fire. Therefore, the area of the non- flashover region was extended to reflect this.

In comparing the two matrices, the impact of increasing the intensity

of the exposure fire can be visualized. The area in the matrix where flashover was observed is somewhat larger for the upholstered chair fires.

However, a more significant difference is found in the size of the region

that includes those combinations of wall and ceiling materials which did not

result in flashover. In the upholstered chair tests this region was significantly reduced.

6 . SUMMARY

Eight full-scale fire tests were conducted in the living room of a typical single-wide mobile home. The experimental scenario established for

this series of tests involved the exposure of a number of combinations of

interior wall and ceiling finish materials to a moderate intensity fire from

the burning of a 16 kg (35 lb) upholstered chair or a 35 kg (78 lb) upholstered

sofa located in one corner of the room.

As in previous studies on mobile homes, [13,14] flashover was determined

to be a critical point in fire growth, after which property damage is

extensive and the thresholds for limiting conditions for life safety, including

temperature, carbon monoxide and oxygen, are significantly exceeded.

The contribution from the interior finish was found to significantly

affect the extent of fire growth and the subsequent attainment of limiting

conditions for life safety.

The following are specific conclusions based on the results of these

tests

1. The extent of fire spread beyond the initial burning item varied

depending on the extent of involvement of the wall and ceiling

materials near the burning item.

All
2. Rapid fire growth and the attainment of flashover resulted in

exceeding all of the selected limits established for occupant

incipient incapacitation at the back exit door.

3 . The test results provided the basis to extend the material hazard

matrix developed in NBSIR 78-1530 to a higher intensity exposure

fire. This supported the earlier finding that the use of the ASTM

E-84 flame spread classification (FSC) provided an indication of

the potential contribution of interior finish materials when

exposed to an incidental fire under the conditions established in

this test series.

4 . The range of FSC for combinations of wall and ceiling materials

which did not result in flashover was reduced significantly when

the exposure fire was increased from one of low intensity to one

of moderate intensity.

7 . ACKNOWLEDGMENTS

The authors would like to thank Mr. W. Bailey, Mr. T. Maher, Mr. 0. Owens,

Mr. B. Ramey, Mr. S. Steel, and Mr. C. Veirtz for their assistance in the

experimental work, and Mr. M. Womble for his assistance in preparation,

instrumentation, scheduling, and the conduct of the experimental work.

Some of the materials selected for this test series were provided by

the Armstrong Cork Company.

This work was sponsored principally by the Division of Energy, Building

Technology and Standards, Office of Policy Development and Research, U.S.

Department of Housing and Urban Development.

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Flame

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method,

adopted

by

ASTM

in

April,

1976.
Table

A2.

Test

Conditions

for

Full-Scale

Mobile

Home

Fire

Tests

(Supplemental

Series)

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A19
Table A3. Mobile Home Living Room Test Series: Instrumentation Locations

TC 1 TC - Living room, north wall 211 cm above floor

TC 2 TC - Living room, north wall 188 cm above floor

TC 3 TC - Living room, north wall 132 cm above floor

TC 4 TC - Living room, northwest corner 211 cm above floor

TC 5 TC - Living room, northwest corner 188 cm above floor

TC 6 TC - Living room, northwest corner 132 cm above floor

TC 7 TC - Living room, west wall 211 cm above floor

TC 8 TC - Living room, west wall 188 cm above floor

TC 9 TC - Living room, west wall 132 cm above floor

TC 10 TC - Living room, east wall 211 cm above floor

TC 11 TC - Living room, east wall 188 cm above floor

TC 12 TC - Living room, east wall 132 cm above floor

TC 13 TC - Living room, center 211 cm above floor

TC 14 TC - Living room, center 188 cm above floor

TC 15 TC - Living room, center 132 cm above floor

TC 16 TC - Living room, center 91 cm above floor

TC 17 TC - Living room, center 46 cm above floor

TC 18 TC - Living room, center 2.5 cm above floor

TC 19 TC - Living room, south wall 211 cm above floor

TC 20 TC - Living room, south wall 188 cm above floor

TC 21 TC - Living room, south wall 132 cm above floor

TC 22 TC - Living room, south wall 91 cm above floor

TC 23 TC - Corridor, north 211 cm above floor

TC 24 TC - Corridor, north 188 cm above floor

TC 25 TC - Corridor, north 132 cm above floor

TC 26 TC - Corridor, north 91 cm above floor

TC 27 TC - Corridor, north 46 cm above floor

TC 28 TC - Corridor, north 2.5 cm above floor

TC 29 TC - Corridor, center 211 cm above floor

TC 30 TC - Corridor, center 188 cm above floor

TC 31 TC - Corridor, center 132 cm above floor

TC 32 TC - Corridor, center 91 cm above floor

TC 33 TC - Corridor, center 46 cm above floor

TC 34 TC - Corridor, center 2.5 cm above floor

TC 35 TC - Corridor, south 211 cm above floor

TC 36 TC - Corridor, south 188 cm above floor

TC 37 TC - Corridor, south 132 cm above floor

TC 38 TC - Corridor, south 91 cm above floor

TC 39 TC - Corridor, south 46 cm above floor

TC 40 TC - Corridor, south 2.5 cm above floor

TC 41 TC - Bedroom 3, center 211 cm above floor

TC 42 TC - Bedroom 3, center 188 cm above floor

TC 43 TC - Bedroom 3, center 132 cm above floor

TC 44 TC - Bedroom 3, center 91 cm above floor

TC 45 TC - Bedroom 1, center 211 cm above floor

TC 46 TC - Bedroom 1, center 188 cm above floor

TC 47 TC - Bedroom 1, center 132 cm above floor

RAD 1 Incident heat flux transducer - Living room, center, floor level

RAD 2 RAD 3 RAD 18 RAD 19 RAD 20 HSM HSM

HSM VSM

HSM

HSM

HSM 10 VSM 11 CO 13 C02 14

02 15 CO

02

1617 L CELL

Incident heat flux transducer - Corridor, north, floor level

Incident heat flux transducer - Corridor, south, floor level

Incident heat flux transducer - North wall, 20cm from corner, .9 m above floor

Incident heat flux transducer - North wall, 20cm from corner, 1.8m above floor

Incident heat flux transducer - Living room, center, ceiling level

Horizontal smoke meter - corridor, north, .6 m above floor

Horizontal smoke meter - corridor, north, 1.2 m above floor

Horizontal smoke meter - corridor, north, 1.8 m above floor

corridor, north, upper, .46 m

- corridor, south, .6 m above floor

Horizontal smoke meter - corridor, south, 1.2 m above floor

Horizontal smoke meter - corridor, south, 1.8 m above floor

Vertical smoke meter - corridor, south, .46 m

CO - Center of living room at 1.5 m above floor

C02 - Center of living room at 1.5 m above floor

02 - Center of living room at 1.5 m above floor

CO - South corridor at 1.5 m above floor

02 - South corridor at 1.5m above floor

Load cell

Vertical smoke meter - Horizontal smoke meter

A20
Table

A4.

Selected

Results

of

Full-Scale

Mobile

Home

Living

Room

Tests

(Supplemental

Series)

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A22
APPENDIX AA. PLOTTED DATA ILLUSTRATING KEY CHANGES

IN MEASURED CONDITIONS FROM APPENDIX A.

JURE

(DEC

C)

TEMPERATURE

(DEC

C)

elapsed t«ie (seconds)

ELAPSED THE (SECONDS)

AA1

INCIDENT

FLUX

(R/CM

1)

INCIDENT

FLUX

(R/CM*)
TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)

ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

AA2

1

NO

DENT

FLUX

(W/CM*)

INCIDENT

FLUX

(W/CM*)
TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)

ELAPSED TME (SECONDS)

AA3

INCIDENT

FLUX

(W/CM*)

INCIDENT

FLUX

(*/

CM*)
TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)

ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

AA4
TtON

OR

DEPLETION

(PCT

BY

VOL)

CONCENTRATION

OR

DEPLETION

(PCT

BY

VOL)

ELAPSED TME (SECONDS)

too 200 300

ELAPSED TME (SECONDS) 400 S00 600 700 BOO 900 1000 1100 1200

AA5

TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)
ELAPSED TME (SECONDS)

ELAPSED TME (SECONDS)

AA6

temperature

(DEC

C)

temperature

(DEC 0
CONCENTRATION

OR

DEPLETION

(PCT

BY

VOL)

CONCENTRATION

OR

DEPLETION

(PCT

BY

VOL)

ELAPSED TIME (SECONDS)

0 100 200 300 400 SOO 600 700 900 900 1000 1100 1200

AA7

TEMPERATURE

(DEC

C)

TEMPERATURE

(DEG

C)
ELAPSED TIME (SECONDS)

ELAPSED TIME (SECONDS)

ELAPSED TIME (SECONDS)

AA8

TEMPERATURE

(DEC

C)

TEMPERATURE

(DEC

C)
ELAPSED TIME (SECONDS)

0 100 200 300 400 SOO 600 700 800 900 1000 1100 1200

ELAPSED TIME (SECONDS)

0 100 200 300 400 500 600 700 600 900 1000 1 100 1200

AA9

SMOKE

DENSITY

(OD/M)

SMOKE

DENSITY

(OD/M)
ELAPSED TIME (SECONDS)

0 2 00 200 300 400 SOO 600 700 BOO 900 1000 1100 1200

ELAPSED TWE (SECONDS)

ELAPSED TWC (SECONDS)

AA10

SMOKE

DENSITY

(OD/M)

SMOKE

DENSITY

(OD/M)
SMOKE

DENSITY

(OD/M)

SMOKE

DENSITY

(OD/M)

100 200 300 ELAPSED TIME (SECONDS) 400 500 600 700 BOO 900 1000 1100 1200

ELAPSED TIME (SECONDS)

ELAPSED TIME (SECONDS)

ELAPSED TIME (SECONDS)

AA11
SMOKE

DENSITY

(OD/M)

m

SM9

KE

DENSITY

(OO/M)

ELAPSED TWE (SECONDS)

ELAPSED TME (SECONDS)

ELAPSED TWE (SECONDS)

AA12

SMOKE

DENSITY

(OD/M)

SMOKE

DENSITY

(OD/M)
0 75000

60000 -

f

2

£45000 -

o

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Q 30000 -

UJ

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0 L

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100 200 300 400 600 600 700 800 900 1 000 1 100 1200

75000 r

60000 -

f

2

£45000 -

o

oQ 30000 -

o

i ? 15000 -

0

ELAPSED TIME (SECONDS)

0 100 200 300 400 600 600 700 800 900 1000 1 100 1200

AA13

TEMPERATURE

(DEG

C)

TEMPERATURE

(DEC

C)
75000 r

60000 -

55

£

45000 -

o

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z

i UJ| 15000 -

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ELAPSED TIME (SECONDS)

75000

60000 -

f

5

£ 45000 -

Z

5

O

oq 30000 r

i5o

I UJ| 15000 -

0

ELAPSED TIME (SECONDS)

AA14

TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)
75000

60000

£ 45000

oo

Q 30000 -

UJ

¥—2

O

I Ui2 15000 -

0

ELAPSED TIME (SECONDS)

75000 r

60000 -

f

2

£45000 -

o

o

UiQ 30000 h —

2OUJ—

z

UJ? 15000 h

0 L

ELAPSED TIME (SECONDS)

0 100 200 300 400 600 600 700 800 900 1000 1100 1200

AA15

TEMPERATURE

(DEG

C)

TEMPERATURE

(DEG

C)
75000 r

60000 -

r

g; 45000 -

o

o

q 30000 - £o

z

I LJ| 15000 -

0 L

ELAPSED TIME (SECONDS)

0 100 200 300 400 600 600 700 800 900 1000 1 100

75000 r

60000 -

f

5

^

45000 -

Z

5o

oq 30000 - £

O

1 LaJ |

15000 -

0 L

12001000

- 900

- 000

- 700

- 600

- 500

- 400

- 300

- 200

- 100

1200

1200

r— iooo

- 900

- 000

- 700

- 600

- 500

- 400

- 300

- 200

"~-i 100 —~ 1 -I

AA16

TEMPERATURE

(DEC

C)

TEMPERATURE

(DEG

C)
MBS-114A (REV. 0-78)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 79-1720

IWt feipstai No.

?'

*

4. TITLE AND SUBTITLE

MOBILE HOME FIRE STUDIES: SUMMARY AND RECOMMENDATIONS

5. Publication Date March 1979

Performing Organization Code

- 7. AUTHOR(S)

Edward K. Budnick and David P. Klein

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

19. Projad/Task/Work Unit No.

'

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, state, ZIP)

Division of Energy, Building Technology and Standards

Office of Policy Development and Research

U.S. Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period Covered

Code

'

15. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or leas factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.) Since 1974, a major research project has been ongoing at the National Bureau of

Standards to investigate various aspects of fire growth and spread in typical singlewide mobile homes. The objective of this project is to provide recommendations for

possible changes to the Federal Mobile Home Construction and Safety Standard promulgatec

in June, 1976 by the Department of Housing and Urban Development. These changes are intended to provide an improved level of fire safety in mobile home construction.

This report provides a summary of the important findings from previously reported

parts of the project which involved the conduct of full-scale fire tests in the kitchen,

corridor, living room and bedroom areas of typical mobile homes. Also included in this

summary are the findings from a previously unreported series of full-scale living room

tests, which are discussed in some detail in Appendix A. This report describes the rationale upon which the overall experimental approach

was based, and provides a series of recommendations, some in the form of design options,

for possible changes to the standard. A limited impact assessment is included to

provide a relative measure of the potential impact of each of three design options for

flame spread requirements for interior wall and ceiling materials. This assessment is

based on the likely effect of each option on fire severity, and does not include an economic analysis.

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)

ASTM E-84 Tunnel Test; construction standard; fire growth; fire tests; flame spread;

flashover; impact assessment; interior finish; kitchen

homes; room fires.

fires; life safety; mobile

18. AVAILABILITY gx} Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF

PRINTED PAGES

| | For Official Distribution. Do Not Release to NTIS UNCLASSIFIED 94

j | Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

20. SECURITY CLASS

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22. Price

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i isroMM.nc
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