Topical Fire Report Series July 2021 | Volume 21, Issue 6

One- and Two-Family Residential 

Building Fires (2017-2019)

These topical reports are 

designed to explore facets 

of the U.S. fire problem as 

depicted through data 

collected in the U.S. Fire 

Administration’s (USFA’s) 

National Fire Incident 

Reporting System (NFIRS). 

Each topical report briefly 

addresses the nature of 

the specific fire or firerelated topic, highlights 

important findings from 

the data, and may suggest 

other resources to consider 

for further information. 

Also included are recent 

examples of fire incidents 

that demonstrate some 

of the issues addressed in 

the report or that put the 

report topic in context.

Findings

ĵ Each year, from 2017 to 2019, an estimated average of 230,500 one- and two-family 

residential building fires were reported to fire departments in the United States. 

These fires caused an estimated annual average of 2,220 deaths, 7,250 injuries and 

$6 billion in property loss.

ĵ Deaths in one- and two-family residential building fires accounted for far more 

deaths in most years than all natural disasters combined.

ĵ One- and two-family residential building fires accounted for 63% of all residential 

building fires, representing the largest subgroup of residential building fires.

ĵ Cooking, at 37%, was the leading cause of one- and two-family residential building 

fires. Of these cooking fires, 90% were small, confined fires with limited damage.

ĵ One- and two-family residential building fires occurred more often in the cooler 

months, peaking in January at 11%.

ĵ In 54% of nonconfined one- and two-family residential building fires, the fire extended 

beyond the room of fire origin. The leading causes of these larger fires were other 

unintentional, careless actions (21%); electrical malfunctions (15%); open flames 

(10%); and intentional actions (9%).

ĵ Smoke alarms were not present in 23% of nonconfined fires in occupied one- and 

two-family residential buildings. 

ĵ Automatic extinguishing systems (AESs), including residential sprinklers, were present 

in only 1% of nonconfined fires in occupied one- and two-family residential buildings.

From 2017 to 2019, fire departments responded to an estimated average of 230,500 fires in one- and two-family 

residences each year across the nation.1, 2 These fires resulted in an estimated annual average of 2,220 deaths, 

7,250 injuries and $6 billion in property loss. One- and two-family residential building fires accounted for 63% 

of all residential building fires and dominated the overall residential building fire profile.3 One- and two-family 

residential buildings include detached dwellings, manufactured homes, mobile homes not in transit, and duplexes.

From 2017 to 2019, 62% of all fire deaths in the nation occurred in one- and two-family dwellings.4 Because these 

fatalities occurred throughout the year and all over the country, they often did not make national headlines. 

Nevertheless, fire deaths in one- and two-family dwellings accounted for far more deaths in most years than all 

natural disasters combined.5

Most one- and two-family residential building fires (60%) were larger, nonconfined fires; they were not contained in 

pots, garbage containers or other types of noncombustible containers that confine them (Table 1). Fires in all other 

types of residential buildings, by contrast, were mostly small and confined to noncombustible containers (69%).

One- and two-family residential building fires also differed from all other residential building fires in their cause 

profiles. While cooking, at 37%, was the leading cause of all one- and two-family residential building fires, it 

accounted for 71% of all other types of residential building fires. However, heating and electrical malfunction 

causes, such as short circuits, arcing and the like, accounted for larger percentages of one- and two-family 

residential building fires than for all other types of residential building fires.

National Fire Data Center

16825 S. Seton Ave.

Emmitsburg, MD 21727

usfa.fema.gov
TFRS Volume 21, Issue 6 | One- and Two-Family Residential Building Fires (2017-2019)

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This topical report is an update to the “One- and Two-Family Residential Building Fires (2013-2015)” (Volume 18, 

Issue 2) report, which was released in June 2017. As part of a series of topical reports that address fires in the major 

residential building types, the remainder of this report addresses the characteristics of one- and two-family residential 

building fires as reported to NFIRS. This data is useful by itself and as a point of comparison with other residential 

building categories. Comparisons to multifamily residential building fires noted throughout the report are based on 

analyses from the “Multifamily Residential Building Fires (2017-2019)” (Volume 21, Issue 7) topical report.6

The focus is on fires reported from 2017 to 2019, the most current data available at the time of the analysis.7 Complete 

or full years of data are required for statistical analyses presented in these topical reports. Although the NFIRS data 

for a calendar year are often reported to the USFA throughout the year, fire departments and or states have until 

the official cutoff date as set forth by the National Fire Data Center to submit their data to the USFA. Typically, this 

cutoff date is July 1 after the end of the previous calendar year. This provides states with ample time to perform data 

quality checks and correct questionable incidents before they are set to released status in the national production 

database and Enterprise Data Warehouse. Once the data are released to the USFA, additional data quality reviews 

are completed before the data are prepared for public release.

For this report, the terms “residential fires” and “one- and two-family fires” are synonymous with “residential building 

fires” and “one- and two-family residential building fires,” respectively. “one- and two-family fires” is used throughout 

the body of this report; the findings, tables, figures, headings and endnotes reflect the full category, “one- and 

two-family residential building fires.”

Type of fire

Building fires are divided into 2 classes of severity in the NFIRS: confined fires and nonconfined fires. Confined building 

fires are small fire incidents that are limited in extent to specific types of equipment or objects, staying within pots, 

fireplaces or certain other noncombustible containers.8 Confined fires rarely result in serious injury or large content 

loss and are expected to have no significant accompanying property loss due to flame damage.9 Nonconfined fires 

extend beyond certain types of equipment or objects. They are generally larger fires resulting in more serious injury 

and larger losses of property and content.

Of the 2 classes of severity, nonconfined fires accounted for 60% of one- and two-family fires. The smaller, confined 

fires accounted for the remaining 40% of one- and two-family fires. Cooking fires were the predominant type of 

confined fires in one- and two-family dwellings, as they were in most residential occupancies (Table 1).

Table 1. One- and two-family residential building fires by type of incident (2017-2019)

Incident type Percent

Nonconfined fires 60.2

Confined fires 39.8

Cooking fire, confined to container 26.4

Chimney or flue fire, confined to chimney or flue 5.5

Incinerator overload or malfunction, fire confined 0.1

Fuel burner/boiler malfunction, fire confined 2.2

Commercial compactor fire, confined to rubbish 0.0

Trash or rubbish fire, contained 5.6

Total 100.0

Source: NFIRS 5.0.
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Loss measures

Table 2 presents losses, averaged over the 3-year period from 2017 to 2019, of reported one- and two-family fires 

and all other residential fires.10 The average number of fatalities per 1,000 fires and average dollar loss per fire for 

one- and two-family fires were about 2 times as high as the same loss measures for all other residential building fires. 

In addition, all the average loss measures associated with nonconfined one- and two-family fires were notably higher 

than the same loss measures for confined one- and two-family fires. This can be expected, however, as nonconfined 

fires are generally larger fires that often result in serious injuries and more content loss.

Table 2. Loss measures for one- and two-family residential building fires (3-year average, 2017-2019)

Measure

One- and 

two-family 

residential building 

fires

Confined oneand two-family 

residential building 

fires

Nonconfined oneand two-family 

residential building 

fires

Residential 

building fires 

(excluding one- and 

two-family)

Average Loss

Fatalities/1,000 fires 7.9 0.0 13.2 3.3

Injuries/1,000 fires 25.3 5.5 38.4 25.7

Dollar loss/fire $22,030 $290 $36,390 $13,190

Source: NFIRS 5.0.

Notes:	 1.	Average loss for fatalities and injuries is computed per 1,000 fires; average dollar loss is computed per fire and rounded to the nearest $10.

2. The 2017 and 2018 dollar-loss values were adjusted to 2019 dollars.

When one- and two-family residential building fires occur

As shown in Figure 1, one- and two-family fires occurred most frequently in the early evening hours, peaking during 

dinner from 5 to 8 p.m., when cooking fire incidence was high.11,12 Cooking fires, discussed later in the “Causes of 

one- and two-family residential building fires” section, accounted for 37% of one- and two-family fires. Fires then 

declined throughout the night, reaching the lowest point during the early morning hours from 4 to 6 a.m.

Figure 1. One- and two-family residential building fires by time of alarm (2017-2019)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

11 p.m. - Mid

10 - 11 p.m.

9 - 10 p.m.

1 - 2 p.m.2 - 3 p.m.3 - 4 p.m.4 - 5 p.m.5 - 6 p.m.6 - 7 p.m.7 - 8 p.m.8 - 9 p.m.

12 - 1 p.m.

11 a.m. - 12 p.m.

10 - 11 a.m.

9 - 10 a.m.

1 - 2 a.m.2 - 3 a.m.3 - 4 a.m.4 - 5 a.m.5 - 6 a.m.6 - 7 a.m.7 - 8 a.m.8 - 9 a.m.

Mid - 1 a.m.

3.0 2.7 2.4 2.6

3.1

3.5

4.1

4.5

5.0 5.1 5.3

5.7

6.2

6.9 7.2

6.5

5.7

4.6

3.9

3.3

2.3 2.1 2.1 2.3

Percent of one- and two-family 

residential building fires

Time of alarm

Source: NFIRS 5.0.

Note: Total does not add up to 100% due to rounding.
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Figure 2 illustrates that one- and two-family fire incidence was higher in the cooler months, peaking in January at 11%. 

Winter peaks are often explained by the increase in heating fires. The increase in fires in the cooler months may also 

be the result of more indoor activities in general, as well as more indoor seasonal and holiday activities. During the 

spring and summer months, the fire incidence generally declined, reaching a low in September.

Figure 2. One- and two-family residential building fires by month (2017-2019)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

November

December

October

September

August

July

April

May

June

March

February

January

10.7

8.4

7.8 7.4 7.9

7.1 6.9

7.6

8.9

9.4 9.4

8.3

Percent of one- and two-family 

residential building fires

Month of year

Source: NFIRS 5.0.

Note: Total does not add up to 100% due to rounding.

Causes of one- and two-family residential building fires

Cooking was the leading cause of one- and two-family fires and accounted for 37% of all one- and two-family fires, 

as shown in Table 3.13 Of these cooking fires, 90% were small, confined fires with limited damage.

Heating, at 12%, was the second leading cause of one- and two-family fires. The next 4 causes combined accounted 

for 30% of one- and two-family fires: other unintentional, careless actions, a miscellaneous group (10%); fires caused 

by electrical malfunctions, such as short circuits and wiring problems (9%); open flames that resulted from candles, 

matches and the like (6%); and intentional actions (5%).14

Table 3. Leading causes of one- and two-family residential building fires (2017-2019)

Cause Percent

(unknowns apportioned)

Cooking 37.3

Heating 12.4

Other unintentional, careless 9.6

Electrical malfunction 9.2

Open flame 5.5

Intentional 5.4

Source: NFIRS 5.0.
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There was a striking difference between one- and two-family and all other residential occupancies in the prevalence 

of cooking as a fire cause. While cooking accounted for 37% of one- and two-family fires, it accounted for 74% of 

multifamily residential building fires and 58% of other residential building fires.15 The most persuasive explanation 

for this difference may be that the smaller, confined fires in one- and two-family dwellings are not reported as often 

to fire departments. They are small and contained, and they often do not cause much damage. In addition, if it is 

activated, only the residents hear the smoke alarm. However, these same confined fires in multifamily residences may 

be reported if someone else in the complex hears the alarm or smells the smoke. Alternatively, if it is a newer complex, 

the alarms may be connected to the building alarm system, and the fire department may automatically be called.

Heating and electrical malfunction causes accounted for larger percentages of one- and two-family fires than of 

multifamily fires. One reason for this may be that many one- and two-family residential buildings have fireplaces, 

chimneys and fireplace-related equipment that most other types of residential properties do not have.16

A strong relationship between housing age and the rate of electrical fires has been observed, with housing over 40 

years old having the strongest association with electrical distribution fires.17, 18 As of 2019, the median age of one- and 

two-family housing was over 40 years. With more than half of the housing stock older than 40 years, electrical fires 

will continue to be an issue in residential buildings.19 In addition, a 2008 study concluded that there are 3 major 

areas in older properties that contribute to compromised electrical systems: the effects of aging on the wiring itself, 

misuse and abuse of the electrical components, and non-code-compliant installations.20 Codes, including the National 

Electrical Code®, are comprehensive and standard in nearly every community. “Non-code” improvements or changes, 

however, are difficult to track and, therefore, difficult to enforce.

Fire spread in one- and two-family residential building fires

In 46% of one- and two-family fires, the fire was limited to the object of origin (Figure 3). Included in these fires are 

those coded as confined fires in the NFIRS. Additionally, 33% of the fires extended beyond the room of origin.

Figure 3. Extent of fire spread in one- and two-family residential building fires (2017-2019)

8.3

Fire spread

Percent of one- and two-family residential building fires

0.0 10.0 20.0 30.0 40.0 50.0 60.0

Beyond building of origin

Limited to building of origin

Limited to floor of origin

Limited to room of origin

Limited to object of origin 46.0

21.3

5.9

22.6

4.1

Source: NFIRS 5.0. 

Note: Total does not add up to 100% due to rounding.

Confined fires

The NFIRS allows abbreviated reporting for confined fires, and many reporting details of these fires are not required, 

nor are they reported. (Not all fires limited to the object of origin are counted as confined fires.21) For example, a fire 

contained to a chair or clothes dryer is not defined as a confined fire in the NFIRS because of the greater potential 

for spread. Unlike fires in pots or chimneys, there is no container to stop the fire, even though the fire did not spread 

beyond the object of origin.
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As previously discussed, however, it is known that confined fires accounted for 40% of all one- and two-family fires. 

Cooking fires — those fires confined to pots or pans, for example — accounted for 66% of these confined fires (Table 1).

In addition, the number of confined one- and two-family fires was greatest from 5 to 8 p.m.; these fires accounted 

for 53% of the one- and two-family fires in this time period. Moreover, confined cooking fires accounted for 71% of 

the confined fires and 38% of all fires that occurred from 5 to 8 p.m. in one- and two-family buildings.

Confined one- and two-family fires peaked in January, then declined through the spring and reached the lowest 

incidence in August.

Nonconfined fires

The next sections of this topical report address nonconfined residential fires — the larger and more serious fires — 

where more detailed fire data are available, as they are required to be reported in the NFIRS.

Causes of nonconfined one- and two-family residential building fires

While cooking was the leading cause of one- and two-family fires overall, it was the sixth leading cause of all nonconfined 

one- and two-family fires, and it only accounted for 7% of these fires (Figure 4). At 18%, other unintentional, careless 

actions was the leading cause of nonconfined one- and two-family fires, followed by electrical malfunctions (17%).

Figure 4. Causes of nonconfined one- and two-family residential building fires (2017-2019) Causes

Percent of nonconfined one- and two-family residential building fires

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0

Unknown

Cause under investigation

Other unintentional, careless

Equipment misoperation, failure

Exposure

Natural

Other equipment

Other heat

Open flame

Appliances

Electrical malfunction

Cooking

Heating

Smoking

Playing with heat source

Intentional

Percent of nonconfined one- and 

two-family residential building fires 

with cause determined

Percent of all nonconfined oneand two-family residential building fires

7.1

4.9

0.8

0.5

3.7

2.6

5.1

6.7

4.7

17.0

11.8

6.4

4.5

9.7

6.8

7.2

5.0

2.1

1.5

4.2

2.9

4.4

3.0

5.0

3.5

17.6

12.3

3.2

2.2

30.1

3.6

Source: NFIRS 5.0.

Notes:	 1.	Causes are listed in order of the U.S. Fire Administration (USFA) Structure Fire Cause Hierarchy for ease of comparison of fire causes across different aspects of

the fire problem. Fires are assigned to 1 of 16 cause groupings using a hierarchy of definitions, as shown in this figure. A fire is included in the highest category

into which it fits. If it does not fit the top category, then the second one is considered, and if not that one, the third, and so on. For example, if the fire is judged

to be intentionally set and a match was used to ignite it, it is classified as intentional and not open flame because intentional is higher in the hierarchy.

2. Total percentages do not add up to 100% due to rounding.
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Where nonconfined one- and two-family residential building fires start (area of fire origin)

Nonconfined one- and two-family fires most often started in cooking areas and kitchens (18%) as shown in Table 4. 

Bedrooms (12%) and family rooms or living rooms (7%) were the next most common areas of fire origin in the home. 

Smaller but not minor percentages of fires started in vehicle storage areas, such as garages and carports (6%); exterior 

wall surfaces (6%); attics and vacant spaces (6%); and laundry areas (5%).

These areas of origin do not include areas associated with confined fires. Cooking was the leading cause of all 

one- and two-family fires at 37%, and it is not surprising that kitchens were the leading area of fire origin. However, 

the percentages were not identical between cooking and kitchen fires because some cooking fires started outside 

the kitchen, some areas of origin for cooking fires were not reported (as in most confined cooking fires), and some 

kitchen fires were not due to cooking. In fact, only 35% of nonconfined one- and two-family fires that started in the 

kitchen were cooking fires. Other unintentional, careless actions accounted for 19% and equipment misoperation or 

failure accounted for an additional 11% of nonconfined one- and two-family fires that started in the kitchen.

Table 4. Leading areas of fire origin in nonconfined one- and two-family residential building fires (2017-2019)

Areas of fire origin Percent

(unknowns apportioned)

Cooking area, kitchen 17.9

Bedrooms 12.2

Common room, den, family room, living room, lounge 6.6

Vehicle storage area: garage, carport 6.1

Exterior wall surface 5.7

Attic, vacant spaces 5.6

Laundry area 4.5

Source: NFIRS 5.0.

How nonconfined one- and two-family residential building fires start (heat source)

Figure 5 shows sources of heat categories for nonconfined one- and two-family fires. Heat from powered equipment 

accounted for 49% of nonconfined one- and two-family fires. This category includes electrical arcing (19%); radiated 

or conducted heat from operating equipment (13%); heat from other powered equipment (12%); and spark, ember 

or flame from operating equipment (5%).

Heat from hot or smoldering objects accounted for 16% of nonconfined one- and two-family fires. This category 

includes miscellaneous hot or smoldering objects (7%) and hot embers or ashes (7%).

The third largest category pertained to open flame or smoking materials (15%). This category includes items such 

as cigarettes (4%), miscellaneous open flame or smoking materials (4%), lighters and matches (combined, 3%), and 

candles (3%).
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Figure 5. Sources of heat in nonconfined one- and two-family residential building fires by major category 

(2017-2019)

Percent of nonconfined one- and two-family residential building fires

Heat source

0.0 10.0 20.0 30.0 40.0 50.0 60.0

Undetermined

Multiple heat sources including

 multiple ignitions

Explosives, fireworks

Chemical, natural heat source

Other heat source

Heat spread from another fire

Heat from open flame or

 smoking material

Hot or smoldering objects

Heat from powered equipment

41.5

0.4

0.7

0.6

1.0

2.1

3.6

3.6

6.2

5.3

9.0

8.8

15.0

9.1

15.5

28.6

48.9

Percent of all nonconfined one- and 

two-family residential building fires

Percent of nonconfined one- and 

two-family residential building fires 

with heat source determined

Source: NFIRS 5.0.

Note:	 Total percentage for nonconfined one- and two-family residential building fires with heat source determined does not add up to 100% due to rounding.

Fire spread in nonconfined one- and two-family residential building fires

Figure 6 shows the extent of fire spread in nonconfined one- and two-family fires. In 46% of the nonconfined fires, 

the fire was limited to the object or room of fire origin; in 34% of nonconfined fires, the fire was limited to the room 

of origin; and in another 12% of fires, the fire was limited to the object of origin.

In 54% of nonconfined one- and two-family fires, the fire extended beyond the room of origin. The leading causes of 

these larger fires were other unintentional, careless actions (21%); electrical malfunctions (15%); open flames (10%); 

and intentional actions (9%).

Figure 6. Extent of fire spread in nonconfined one- and two-family residential building fires (2017-2019)

8.3

Fire spread

Percent of nonconfined one- and two-family residential building fires

0.0 10.0 20.0 30.0 40.0

Beyond building of origin

Limited to building of origin

Limited to floor of origin

Limited to room of origin

Limited to object of origin 12.1

33.9

9.7

37.4

6.9

Source: NFIRS 5.0. 
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Factors contributing to ignition in nonconfined one- and two-family residential building fires

Table 5 shows the categories of factors contributing to ignition in nonconfined one- and two-family fires. The leading 

category was the misuse of material or product (35%). In this category, the leading specific factors contributing to 

ignition were a heat source too close to combustible materials (13% of all nonconfined one- and two-family fires) and 

abandoned or discarded materials, such as matches or cigarettes (10% of all nonconfined one- and two-family fires).

Electrical failures and malfunctions contributed to 26% of nonconfined one- and two-family fires. Operational 

deficiency was the third leading category at 13%. Unattended equipment was the leading factor in the operational 

deficiency category and accounted for 6% of all nonconfined one- and two-family fires.

Table 5. Factors contributing to ignition for nonconfined one- and two-family residential building fires by 

major category (where factors contributing to ignition were specified, 2017-2019)

Factors contributing to ignition category

Percent of nonconfined one- and two-family 

residential building fires 

(unknowns apportioned)

Misuse of material or product 34.5

Electrical failure, malfunction 25.7

Operational deficiency 12.8

Fire spread or control 11.8

Mechanical failure, malfunction 7.5

Other factors contributing to ignition 5.8

Natural condition 4.5

Design, manufacture, installation deficiency 1.8

Source: NFIRS 5.0.

Notes:	 1.	Includes only incidents where factors that contributed to the ignition of the fire were specified.

	 2.	Multiple factors contributing to fire ignition may be noted for each incident; the total will exceed 100%.

Alerting/suppression systems in one- and two-family residential building fires

Fire fatalities and injuries have declined over the last 40 years, partly due to new technologies to detect and extinguish 

fires. Residential sprinklers have gained support from the fire service and many residential communities.

Smoke alarm data are available for both confined and nonconfined fires, although for confined fires, the data are 

very limited in scope. Since different levels of data are reported on smoke alarms in confined and nonconfined fires, 

the analyses are performed separately. The data presented in Tables 7 and 8 show the raw counts from the NFIRS 

dataset and are not scaled to national estimates of smoke alarms in one- and two-family fires. In addition, the NFIRS 

does not allow for the determination of the type of smoke alarm — that is, if the smoke alarm was photoelectric or 

ionization — or the location of the smoke alarm with respect to the area of fire origin.

Smoke alarms in nonconfined fires

Overall, smoke alarms were reported as present in 39% of nonconfined one- and two-family fires (Table 6). In 28% of 

nonconfined one- and two-family fires, there were no smoke alarms present. In another 34% of these fires, firefighters 

were unable to determine if a smoke alarm was present.22 Therefore, smoke alarms were potentially missing in 28% 

to 62% of fires with the ability to spread and possibly result in fatalities.
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Table 6. Presence of smoke alarms in nonconfined one- and two-family residential building fires (2017-2019)

Presence of smoke alarms Percent

Present 38.6

None present 27.8

Undetermined 33.6

Total 100.0

Source: NFIRS 5.0.

While 18% of all nonconfined one- and two-family fires occurred in residential buildings that are not currently or 

routinely occupied, these occupancies — which are under construction, undergoing major renovation, vacant and the 

like — are unlikely to have alerting and suppression systems that are in place and, if in place, that are operational. In 

fact, only 7% of nonconfined fires in unoccupied one- and two-family residential buildings were reported as having 

smoke alarms that operated. As a result, the detailed smoke alarm analyses in the next section focus on nonconfined 

fires in occupied one- and two-family residential buildings only.

Smoke alarms in nonconfined fires in occupied one- and two-family residential buildings

Smoke alarms were reported as present in 44% of nonconfined fires in occupied one- and two-family residential 

buildings (Table 7). In 23% of nonconfined fires in occupied one- and two-family residential buildings, there were no 

smoke alarms present. In another 33% of these fires, firefighters were unable to determine if a smoke alarm was 

present. Unfortunately, in over half (52%) of the fires where the presence of a smoke alarm was undetermined, either 

the flames involved the building of origin or spread beyond it. These fires were so large and destructive that it is 

unlikely the presence of a smoke alarm could be determined. 

When smoke alarms were present (44%) and the alarm operational status is considered, the percentage of smoke 

alarms reported as present consisted of:

ĵ Present and operated — 26%.

ĵ Present, but did not operate — 11% (fire too small, 6%; alarm failed to operate, 5%).

ĵ Present, but operational status unknown — 7%.

When the subset of incidents where smoke alarms were reported as present was analyzed separately as a whole, 

smoke alarms were reported to have operated in 59% of these incidents. The alarms failed to operate in 10% of these 

incidents, and the fire was too small to activate the alarm in another 14%. The operational status of the alarm was 

undetermined in an additional 17% of these incidents.

At least 23% of nonconfined fires in occupied one- and two-family residential buildings had no smoke alarms 

present — and perhaps more if fires without information on smoke alarms were also considered.23 A large proportion 

of reported fires without smoke alarms may reflect the effectiveness of the alarms themselves; smoke alarms do 

not prevent fires, but they may prevent a fire from being reported if it is detected at an early stage and extinguished 

before the fire department becomes involved. Alternatively, fires in homes without smoke alarms may not be 

detected at an early stage, causing them to grow large, require fire department intervention, and thus be reported.24

Properly installed and maintained smoke alarms provide an early warning signal to everyone in a home if a fire occurs. 

Smoke alarms help save lives and property. The USFA continues to partner with other government agencies and fire 

service organizations to improve and develop new smoke alarm technologies. More information on smoke alarm 

technologies, performance, training bulletins, and public education and outreach materials can be found at http://

www.usfa.fema.gov/prevention/technology/smoke_fire_alarms.html. Additionally, the USFA’s position statement on 

home smoke alarms is available at https://www.usfa.fema.gov/about/smoke_alarms_position.html.
TFRS Volume 21, Issue 6 | One- and Two-Family Residential Building Fires (2017-2019)

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Table 7. NFIRS smoke alarm data for nonconfined fires in occupied one- and two-family residential 

buildings (2017-2019)

Presence of 

smoke alarms

Smoke alarm 

operational status Smoke alarm effectiveness Count Percent

Present

Fire too small to activate 

smoke alarm 14,948 6.2

Smoke alarm operated

Smoke alarm alerted occupants, 

occupants responded 43,856 18.3

Smoke alarm alerted occupants, 

occupants failed to respond 1,585 0.7

No occupants 8,694 3.6

Smoke alarm failed to alert occupants 1,546 0.6

Undetermined 7,022 2.9

Smoke alarm failed to operate 10,878 4.5

Undetermined 17,831 7.4

None present 54,812 22.8

Undetermined 79,040 32.9

Total reported 

incidents 240,212 100.0

Source: NFIRS 5.0.

Notes:	 1.	 The data presented in this table are raw data counts from the NFIRS dataset summed (not averaged) from 2017 to 2019. They do not represent national

estimates of smoke alarms in nonconfined fires in occupied one- and two-family residential buildings. They are presented for informational purposes.

2. Total does not add up to 100% due to rounding.

Smoke alarms in confined fires

Less information about smoke alarm status is collected for confined fires, but the data still give important insights about 

the effectiveness of alerting occupants in these types of fires. The analyses presented here do not differentiate between 

occupied and unoccupied one- and two-family residential buildings, as this data detail is not required when reporting 

confined fires in the NFIRS. However, an assumption may be made that confined fires are fires in occupied housing, 

as these types of fires are unlikely to be reported in one- and two-family residential buildings that are not occupied.

Smoke alarms alerted occupants in 34% of the reported confined one- and two-family fires (Table 8). In other words, in 

about one-third of fires in these types of homes, residents received a warning from a smoke alarm. The data suggest 

that smoke alarms may alert residents to confined fires, as the early alerting allowed the occupants to extinguish 

the fires, or the fires self-extinguished. If this is the case, it is an example of the contribution to overall safety and the 

ability to rapidly respond to fires in early stages that smoke alarms afford. Details on smoke alarm effectiveness for 

confined fires are needed to pursue this analysis further.

Occupants were not alerted by smoke alarms in 20% of confined one- and two-family fires.25 In 46% of these confined 

fires, the smoke alarm effectiveness was unknown.
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Table 8. NFIRS smoke alarm data for confined one- and two-family residential building fires (2017-2019)

Smoke alarm effectiveness Count Percent

Smoke alarm alerted occupants 66,269 34.4

Smoke alarm did not alert occupants 37,588 19.5

Unknown 88,725 46.1

Total reported incidents 192,582 100.0

Source: NFIRS 5.0.

Note:	 The data presented in this table are raw data counts from the NFIRS dataset summed (not averaged) from 2017 to 2019. They do not represent national estimates

of smoke alarms in confined one- and two-family residential building fires. They are presented for informational purposes.

Automatic extinguishing systems in nonconfined fires in occupied one- and two-family residential buildings

AES data are available for both confined and nonconfined fires, although for confined fires, the data are also very 

limited in scope. In confined one- and two-family residential building fires, an AES was present in less than 1% 

of reported incidents.26 In addition, the following AES analyses focus on nonconfined fires in occupied one- and 

two-family buildings only, as even fewer AESs are present in unoccupied housing.

Residential sprinklers are the primary AES in one- and two-family residences but are not yet widely installed. In fact, 

full or partial AESs were reported as present in only 1% of nonconfined fires in occupied one- and two-family buildings 

(Table 9). This was the lowest reported presence of sprinklers in nonconfined fires in any occupied residential occupancy. 

Residential sprinkler systems help to reduce the risk of deaths and injuries, homeowners insurance premiums, and 

uninsured property losses. Despite these advantages, many homes do not have AESs, although they are often found 

in hotels and businesses. Sprinklers are required by code in hotels and many multifamily residences. There are major 

movements in the U.S. fire service to require sprinklers in all new homes. At present, however, they are largely absent 

in residences nationwide.27

The USFA and fire service officials across the nation are working to promote and advance residential fire sprinklers. 

More information on costs and benefits, performance, training bulletins, and public education and outreach materials 

regarding residential sprinklers is available at http://www.usfa.fema.gov/prevention/technology/home_fire_sprinklers.

html. Additionally, the USFA’s position statement on residential sprinklers is available at http://www.usfa.fema.gov/

about/sprinklers_position.html.

Table 9. NFIRS automatic extinguishing system data for nonconfined fires in occupied one- and two-family 

residential buildings (2017-2019)

Automatic extinguishing system presence Count Percent

Automatic extinguishing system present 3,155 1.3

Partial system present 121 0.1

Automatic extinguishing system not present 215,357 89.7

Unknown 21,579 9.0

Total reported incidents 240,212 100.0

Source: NFIRS 5.0.

Notes:	 1.	 The data presented in this table are raw data counts from the NFIRS dataset summed (not averaged) from 2017 to 2019. They do not represent national

estimates of AESs in nonconfined fires in occupied one- and two-family residential buildings. They are presented for informational purposes.

2. Total does not add up to 100% due to rounding.
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Examples

The following are recent examples of one- and two-family fires reported by the media:

ĵ February 2021: A Cadiz, Kentucky, duplex was destroyed after a Monday afternoon fire. Firefighters reported that 

the fire started because of unattended cooking and quickly spread throughout the structure. No injuries were 

reported, but both families living in the duplex were displaced due to damage caused by the fire.28

ĵ April 2021: A single-story house fire in Milwaukee, Wisconsin, resulted in the death of a 10-year-old boy. When 

firefighters arrived on scene, the boy was trapped in the house where he, his 14-year-old sister and his mother 

lived. While searching, firefighters found the boy unconscious in the home’s kitchen near a locked back door 

where he reportedly was trying to escape. Despite all efforts, firefighters were unable to revive him. The boy’s 

sister and mother were able to escape, but the mother was treated at a local hospital and released. The family 

also had 3 dogs, 2 of which escaped and 1 of which died. The fire reportedly started after a lit candle on top 

of a living room ottoman ignited the furniture. Most of the fire damage was contained to the living room area. 

Firefighters reported that the home had a working smoke alarm.29

ĵ May 2021: A single-family home in Ashburn, Virginia, was damaged in a Wednesday night fire. Upon arrival shortly 

after 8 p.m., firefighters found heavy fire and smoke coming from the second floor and roof area of the home. Two 

residents of the home were located outside, and firefighters were able to quickly control the fire. The fire started 

in the attic and was caused by a mechanical malfunction in the air handler system. Although the fire resulted in 

over $759,000 in damage, there were no reported injuries.30

NFIRS data specifications for one- and two-family residential building fires

Data for this report were extracted from the NFIRS annual Public Data Release files for 2017, 2018 and 2019. Only 

Version 5.0 data were extracted.

One- and two-family residential building fires were defined using the following criteria:

ĵ Incidents with Aid Types 3 (mutual aid given) and 4 (automatic aid given) were excluded to avoid counting a single 

incident more than once.

ĵ Incident Types 111 to 123 (excluding Incident Type 112):

Incident Type Description

111 Building fire

113 Cooking fire, confined to container

114 Chimney or flue fire, confined to chimney or flue

115 Incinerator overload or malfunction, fire confined

116 Fuel burner/boiler malfunction, fire confined

117 Commercial compactor fire, confined to rubbish

118 Trash or rubbish fire, contained

120 Fire in mobile property used as a fixed structure, other

121 Fire in mobile home used as fixed residence

122 Fire in motor home, camper, recreational vehicle

123 Fire in portable building, fixed location

Note: Incident Types 113 to 118 do not specify if the structure is a building.
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ĵ Property Use 419:

Property Use Description

419 One- or two-family dwelling, detached, manufactured home, mobile home not in transit, duplex

ĵ Structure Type:

Ý For Incident Types 113 to 118:

f 1 — Enclosed building, or

f 2 — Fixed portable or mobile structure, or

f Structure Type not specified (null entry).

Ý For Incident Types 111 and 120 to 123:

f 1 — Enclosed building, or

f 2 — Fixed portable or mobile structure.

The analyses contained in this report reflect the current methodologies used by the USFA. The USFA is committed 

to providing the best and most current information on the U.S. fire problem and continually examines its data and 

methodology to fulfill this goal. Because of this commitment, data collection strategies and methodological changes 

are possible and do occur. As a result, analyses and estimates of the fire problem may change slightly over time. 

Previous analyses and estimates on specific issues (or similar issues) may have used different methodologies or data 

definitions and may not be directly comparable to the current ones.

Information regarding the USFA’s national estimates for residential building fires, as well as the data sources used to 

derive the estimates, can be found in the document “Data Sources and National Estimates Methodology Overview 

for the U.S. Fire Administration’s Topical Fire Report Series (Volume 21)” (https://www.usfa.fema.gov/downloads/pdf/

statistics/data-sources-and-national-estimates-methodology-vol21.pdf). This document also addresses the specific 

NFIRS data elements analyzed in the topical reports, as well as “unknown” data entries and missing data.

To request additional information, visit: http://www.usfa.fema.gov/contact.html. Provide feedback on this report.

Notes:

1

National estimates are based on 2017 to 2019 native Version 5.0 data from the NFIRS, residential structure fire loss estimates from the 

National Fire Protection Association’s (NFPA’s) annual surveys of fire loss, and the USFA’s residential building fire loss estimates: http://www.

usfa.fema.gov/data/statistics/order_download_data.html. Further information on the USFA’s residential building fire loss estimates can be 

found in the “National Estimates Methodology for Building Fires and Losses,” August 2012, http://www.usfa.fema.gov/downloads/pdf/statistics/

national_estimate_methodology.pdf. For detailed information regarding the NFPA’s survey methodology, see the NFPA’s “Methodology used 

in calculating national estimates from NFPA’s fire experience survey,” August 2020, https://www.nfpa.org/-/media/Files/News-and-Research/

Fire-statistics-and-reports/US-Fire-Problem/Methodsfirelossandothers.ashx. In this topical report, fires are rounded to the nearest 100, deaths 

to the nearest 5, injuries to the nearest 25 and dollar loss to the nearest $100 million.

2

In NFIRS Version 5.0, a structure is a constructed item of which a building is one type. In previous versions of the NFIRS, the term “residential 

structure” commonly referred to buildings where people live. To coincide with this concept, the definition of a residential structure fire for the 

NFIRS 5.0 includes only those fires where the NFIRS 5.0 Structure Type is 1 or 2 (enclosed building and fixed portable or mobile structure) with 

a residential property use. Such structures are referred to as “residential buildings” to distinguish these buildings from other structures on 

residential properties that may include fences, sheds and other uninhabitable structures. In addition, confined fire incidents that have a residential 

property use, but do not have a structure type specified, are presumed to occur in buildings. Nonconfined fire incidents that have a residential 

property use without a structure type specified are considered to be invalid incidents (Structure Type is a required field) and are not included. 

3

USFA, Topical Fire Report Series, “Residential Building Fires (2017-2019),” Volume 21, Issue 2, May 2021, https://www.usfa.fema.gov/downloads/

pdf/statistics/v21i2.pdf. 4

The percentages shown here are derived from the national estimates of one- and two-family residential building fires as explained in Endnote 1 

and the summary data resulting from the NFPA’s annual fire loss surveys (Ahrens, Marty and Evarts, Ben, “Fire Loss in the United States During 

2019,” NFPA, September 2020; Evarts, Ben, “Fire Loss in the United States During 2018,” NFPA, October 2019; Evarts, Ben, “Fire Loss in the United 

States During 2017,” NFPA, October 2018).

5

National Oceanic and Atmospheric Administration’s National Weather Service, “Summary of Natural Hazard Statistics for 2019 in the United 

States,” https://www.weather.gov/media/hazstat/sum19.pdf (accessed June 2, 2021).
TFRS Volume 21, Issue 6 | One- and Two-Family Residential Building Fires (2017-2019)

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6

Multifamily residential buildings include structures such as apartments, town houses, row houses, condominiums and other tenement properties.

7

Fire department participation in the NFIRS is voluntary; however, some states do require their departments to participate in the state system. 

Additionally, if a fire department is a recipient of a Fire Act Grant, participation is required. From 2017 to 2019, 68% of the NFPA’s annual average 

estimated 1,309,800 fires to which fire departments responded were captured in the NFIRS. Thus, the NFIRS is not representative of all fire 

incidents in the U.S. and is not a “complete” census of fire incidents. Although the NFIRS does not represent 100% of the incidents reported to 

fire departments each year, the enormous dataset exhibits stability from one year to the next without radical changes. Results based on the 

full dataset are generally similar to those based on part of the data.

8

In the NFIRS, confined fires are defined by Incident Type Codes 113 to 118.

9

The NFIRS distinguishes between “content” and “property” loss. Content loss includes losses to the contents of a structure due to damage by 

fire, smoke, water and overhaul. Property loss includes losses to the structure itself or to the property itself. Total loss is the sum of the content 

loss and the property loss. For confined fires, the expectation is that the fire did not spread beyond the container (or rubbish for Incident Type 

Code 118), and hence, there was no property damage (damage to the structure itself) from the flames. However, there could be property damage 

as a result of smoke, water and overhaul.

10The average fire death and fire injury loss rates computed from the national estimates do not agree with average fire death and fire injury loss 

rates computed from NFIRS data alone. The fire death rate computed from national estimates is 1,000 x (2,220/230,500) = 9.6 deaths per 1,000 

one- and two-family residential building fires, and the fire injury rate is 1,000 x (7,250/230,500) = 31.5 injuries per 1,000 one- and two-family 

residential building fires. 

11For this report, the time of the fire alarm is used as an approximation for the general time at which the fire started. However, in the NFIRS, it 

is the time at which the fire was reported to the fire department.

12USFA, “Cooking Fires in Residential Buildings (2017-2019),” Volume 21, Issue 5, July 2021, http://www.usfa.fema.gov/downloads/pdf/statistics/

v21i5.pdf. 13The USFA Structure Fire Cause Methodology was used to determine the cause of residential building fires. The cause methodology and 

definitions can be found in the document “National Fire Incident Reporting System Version 5.0 Fire Data Analysis Guidelines and Issues,” July 

2011, https://www.usfa.fema.gov/downloads/pdf/nfirs/nfirs_data_analysis_guidelines_issues.pdf. 14Fires caused by intentional actions include, but are not limited to, fires that are deemed to be arson. Intentional fires are those fires that are 

deliberately set and include fires that result from the deliberate misuse of a heat source and fires of an incendiary nature (arson) that require fire 

service intervention. For information and statistics on arson fires only, refer to the Uniform Crime Reporting Program arson statistics from the 

U.S. Department of Justice, FBI, Criminal Justice Information Services Division, https://www.fbi.gov/about-us/cjis/ucr/ucr (accessed June 2, 2021). 15Other residential buildings include boarding houses (e.g., shelters), hotels/motels (i.e., residential and commercial), residential board and care 

facilities (e.g., long-term care and assisted living facilities), dormitories, sorority and fraternity houses, and barracks.

16The American Housing Survey does not indicate the number of fireplaces, chimneys and fireplace-related equipment; however, it does collect 

data on fireplaces, etc., as the primary heating unit, which applies to this analysis. U.S. Department of Housing and Urban Development (HUD) 

and U.S. Census Bureau, 2019 American Housing Survey – Table Creator, select “2019 (Year) National (Area) Housing Unit Characteristics (Table); 

Units by Structure Type (Variable 1),” https://www.census.gov/programs-surveys/ahs/data/interactive/ahstablecreator.html?s_areas=00000&s_

year=2019&s_tablename=TABLE0&s_bygroup1=3&s_bygroup2=1&s_filtergroup1=1&s_filtergroup2=1 (accessed June 2, 2021). 17Smith, Linda E. and McCoskrie, Dennis, “What Causes Wiring Fires in Residences?” Fire Journal, January/February 1990.

18Dini, David A., “Residential Electrical System Aging Research Project,” Fire Protection Research Foundation, Quincy, Massachusetts, July 1, 2008, 

https://ewh.ieee.org/cmte/pses/ffat/support/RESAReport.pdf (accessed June 2, 2021). 19The American Housing Survey does not have a category for one- and two-family residences that conforms to the definition used by NFIRS. 

Housing age given here is an estimate based on the information presented for single-family attached and detached housing. HUD and U.S. 

Census Bureau, 2019 American Housing Survey — Table Creator, select “2019 (Year) National (Area) Housing Unit Characteristics (Table); Units 

by Structure Type (Variable 1),” https://www.census.gov/programs-surveys/ahs/data/interactive/ahstablecreator.html?s_areas=00000&s_

year=2019&s_tablename=TABLE1&s_bygroup1=1&s_bygroup2=1&s_filtergroup1=1&s_filtergroup2=1 (accessed June 2, 2021). 20Dini, David A., “Residential Electrical System Aging Research Project,” Fire Protection Research Foundation, Quincy, Massachusetts, July 1, 2008, 

https://ewh.ieee.org/cmte/pses/ffat/support/RESAReport.pdf (accessed June 2, 2021). 21As noted previously, confined building fires are small fire incidents that are limited in scope, are confined to noncombustible containers, rarely 

result in serious injury or large content loss, and are expected to have no significant accompanying property loss due to flame damage. In the 

NFIRS, confined fires are defined by Incident Type Codes 113 to 118.

22Total does not add up to 100% due to rounding.

23Here, at least 23% of nonconfined fires in occupied one- and two-family residential buildings had no smoke alarms present — the 23% that 

were known to not have smoke alarms and some portion (or as many as all) of the fires where the smoke alarm presence was undetermined.

24Greene, Michael and Andres, Craig, “2004-2005 National Sample Survey of Unreported Residential Fires,”

Division of Hazard Analysis, Directorate for Epidemiology, U.S. Consumer Product Safety Commission, July 2009. The “2004-2005 National 

Sample Survey of Unreported Residential Fires,” however, suggests that this may not be the case. It is observed that “if this conjecture is true, 

it would suggest that the percentage decrease in fire department-attended fires would have been greater than unattended fires in the 20-year 

period between the surveys.”

25In confined fires, the entry “smoke alarm did not alert occupants” can mean no smoke alarm was present; the smoke alarm was present but 

did not operate; the smoke alarm was present and operated, but the occupant(s) was already aware of the fire; or there were no occupants 

present at the time of the fire.
TFRS Volume 21, Issue 6 | One- and Two-Family Residential Building Fires (2017-2019)

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26As confined fire codes are designed to capture fires contained to noncombustible containers, it is not recommended to code a fire incident as 

a small-, low- or no-loss confined fire incident if the AES operated and contained the fire as a result. The preferred method is to code the fire as 

a standard fire incident with fire spread confined to the object of origin and provide the relevant information on AES presence and operation.

27HUD and U.S. Census Bureau, American Housing Survey for the United States: 2011, September 2013, “Health and Safety Characteristics-All 

Occupied Units (National),” Table S-01-AO, https://www.census.gov/content/dam/Census/library/publications/2013/demo/h150-11.pdf (accessed 

June 2, 2021).

28Claussen, Joshua, “Cadiz Duplex Destroyed in Fire,” www.wkdzradio.com, Feb. 15, 2021, https://www.wkdzradio.com/2021/02/15/cadiz-duplexdestroyed-in-fire/ (accessed June 2, 2021). 29Volpenhein, Sarah, “Milwaukee House Fire that Killed 10-Year Old Boy Likely Caused by a Candle,” www.msn.com, April 26, 2021, https://www.

msn.com/en-us/news/us/milwaukee-house-fire-that-killed-10-year-old-boy-likely-caused-by-a-candle/ar-BB1g4OkQ (accessed June 2, 2021). 30“UPDATED: HVAC Issue to Blame for Ashburn House Fire,” www.insidenova.com, May 20, 2021, https://www.insidenova.com/headlines/updatedhvac-issue-to-blame-for-ashburn-house-fire/article_7f0a96d6-b908-11eb-ae62-3f22c7518e31.html (accessed June 2, 2021).