As the economy moves slowly back to some semblance of normalcy, news reports predict an uptick in commercial residential construction. Regardless of whether time will prove the pundits correct, you should be aware of a number of changes to the chapter in NFPA 72 2010, the National Fire Alarm and Signaling Code, which contains the requirements for residential smoke alarms and residential fire alarm systems.

By knowing about these new or changed requirements, you can prevent costly errors in your installations and speed up approvals from your local fire inspector. Chapter 29 contains the requirements for one- and two-family homes, but these requirements also apply to the individual living units in multifamily apartments and condominiums.

Compared to the 2007 edition of the code, the technical committee has not modified all the living unit protection requirements. But, for clarity, here are all requirements from the current section 29.5.1.1, as follows (the asterisk indicates explanatory material in Annex A):

“29.5.1.1 * Where required by other governing laws, codes, or standards for a specific type of occupancy, approved single and multiple-station smoke alarms shall be installed as follows:

“(1) *In all sleeping rooms and guest rooms”

“(2) *Outside of each separate dwelling unit sleeping area, within 21 ft (6.4 m) of any door to a sleeping room, with the distance measured along a path of travel”

“(3) On every level of a dwelling unit, including basements”

“(4) On every level of a residential board and care occupancy (small facility), including basements and excluding crawl spaces and unfinished attics”

“(5) *In the living area(s) of a guest suite”

“(6) In the living area(s) of a residential board and care occupancy (small facility)”

“29.5.1.2 Where the area addressed in 29.5.1.1 (2) is separated from the adjacent living areas by a door, a smoke alarm shall be installed in the area between the door and the sleeping rooms, and additional alarms shall be installed on the living area side of the door as specified by 29.5.1.1 and 29.5.1.3.”

“29.5.1.3 In addition to the requirements of 29.5.1.1 (1) through (3), where the interior floor area for a given level of a dwelling unit, excluding garage areas, is greater than 1,000 ft2 (93 m2), smoke alarms shall be installed per 29.5.1.3.1 and 29.5.1.3.2.”

“29.5.1.3.1 *All points on the ceiling shall have a smoke alarm within a distance of 30 ft (9.1 m) travel distance or shall have an equivalent of one smoke alarm per 500 ft2 (46 m2) of floor area. One smoke alarm per 500 ft2 (46 m2) is evaluated by dividing the total interior square footage of floor area per level by 500 ft2 (46 m2).”

“29.5.1.3.2 Where dwelling units include great rooms or vaulted cathedral ceilings extending over multiple floors, smoke alarms located on the upper floor that are intended to protect the aforementioned area shall be permitted to be considered as part of the lower floor(s) protection scheme used to meet the requirements of 29.5.1.3.1.”

The installation requirements for smoke alarms in NFPA 72 2011 offer more details than previous editions of the code. Most of these changes attempt to provide improved life safety protection while minimizing false alarm issues.

You must always follow the manufacturer’s published installation instructions, as these requirements always become part of the UL listing. In addition, you must not locate smoke alarms and smoke detectors where ambient conditions, including humidity and temperature, exceed the limits that the manufacturer’s published instructions specify. Some of the areas where you must not install smoke alarms are within unfinished attics or garages or in other spaces where temperatures can fall below 40°F or exceed 100°F.

In another cautionary note, the code states that, where the mounting surface on which you plan to install the smoke alarm could become considerably warmer or cooler than the room, such as a poorly insulated ceiling below an unfinished attic or an exterior wall, you must mount smoke alarms and smoke detectors on an interior wall.

Over the years, smoke alarms and smoke detectors installed too close to cooking appliances have initiated many false alarms. Therefore, you should avoid installing smoke alarms and smoke detectors in kitchen spaces. NFPA 72 2010 has mandated that you not install smoke alarms and smoke detectors within an area of exclusion determined by a 10-foot radial distance along a horizontal flow path from all stationary or fixed cooking appliances, unless listed for installation in close proximity to cooking appliances. Additionally, smoke alarms and smoke detectors installed between 10 and 20 feet along a horizontal flow path from a stationary or fixed cooking appliance must be equipped with the means to silence an alarm, or you must use photoelectric detection.

The code has some exceptions to these rules, such as reducing the 10-foot requirement to 6 feet by using a photoelectric detector if the kitchen or cooking area and adjacent spaces have no clear interior partitions or headers and the 10-foot exclusion would prohibit the installation of a required smoke alarm.

Bathrooms can present another source of false alarms. The code requires that you not install a smoke alarm or smoke detector within 36 inches of the horizontal path from a door to a bathroom containing a shower or tub.

Many residential living rooms have circulating ceiling fans installed to lower heating and cooling costs. The code will not allow you to install a smoke alarm any closer than 36 inches in the horizontal path from the tip of the blade of a ceiling-suspended (paddle) fan.

This same requirement applies to installations near the supply registers of a forced air heating or cooling system. In these cases, you must install the smoke alarms in a location outside of the direct airflow from those registers.

Some of the final installation requirements reference where stairs lead to other occupied levels. In these cases, you must locate a smoke alarm or smoke detector so that an intervening door or obstruction cannot prevent smoke rising in the stairway from reaching the smoke alarm or smoke detector. And, for stairways leading up from a basement, you must locate smoke alarms or smoke detectors on the basement ceiling near the entry to the stairs.

Generally speaking, you can best locate a smoke alarm or smoke detector on the ceiling. However, the code permits wall mounting. The biggest change in NFPA 72 2010 regarding wall mounting of smoke detectors comes from the removal of the requirement to avoid locating smoke alarms and smoke detectors in what was known as the 4-inch “dead-air” space at the ceiling wall juncture. You may now install a smoke alarm or smoke detector on the side wall 12 inches down for the ceiling-wall interface. And, for tray-shaped ceilings (coffered ceilings), you must install smoke alarms and smoke detectors on the highest portion of the ceiling or on the sloped portion of the ceiling within 12 inches (300 mm) down vertically from the highest point.

Many designers now use system smoke detectors with an integral horn in the detector’s base to “act like” a smoke alarm in lieu of the standard device. This allows the owner to more accurately monitor alarms from each living unit and eliminate the need for replacing the 9-volt batteries in all of the smoke alarms. It also provides additional security for the owner by helping to ensure that occupants do not remove or tamper with the smoke detectors.

All of these requirements outlined above apply to both smoke alarms and smoke detectors installed in residential fire alarm system installations.

So, whether the words of the pundits prove right or wrong, you will eventually install fire alarm systems and smoke alarms in new residential applications. The same holds true for upgrading existing residential buildings. Knowing the requirements of NFPA 72 2010 will help ensure you are not saddled with expensive revisions to your installation.


MOORE, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a past chair of the NFPA 72 Technical Correlating Committee. Moore is a principal with Hughes Associates Inc. at the Warwick, R.I., office. He can be reached at wmoore@haifire.com.