Residential/commercial spaces install the number of smoke detectors according to the guidelines
Whether you’re a homeowner, contractor, property management company, real estate developer, brand owner, or engineer, you’ll face the same confusion: “How many smoke alarms do I actually need?” during the project evaluation and initiation phases.
CFS has over 20 years of experience in smoke detector R&D and manufacture. We have compiled a systematic guide to help you accurately calculate the number of smoke detectors needed and know how to design them. This guide draws on EN14604, UL217 and AS3786, and client installation case studies.
What is your plan for the installation of smoke alarm?
You should have a different construction plan for different commercial or residential buildings. There are different building types, different floors, different areas, different rooms, and different building structures; the number of smoke alarms will be different.
The smoke detectors, alarms, or system can accurately detect smoke and issue an alert within the first 2 minutes fire, you will escape with more time.
Why do you need to calculate the number of smoke alarms?
The configuration of the number of fire detectors in the fire alarm project is not arbitrary. Many people have misconceptions: that installing only one alarm is sufficient, or that it only needs to be installed in the living room, or that it should only be installed near the kitchen because it can easily catch fire. They do not comply with fire safety principles.
According to common design principles, an independent space with an area of less than 80 ㎡ requires at least one detector to achieve effective monitoring. However, in practical applications, it is recommended to use two cross-coverage detectors for rooms larger than 30 ㎡. Detectors are “electronic sentinels” for the room, and not enough detectors may cause monitoring blind spots. There are two main reasons:
1. Smoke spread not fast
Doorways, corridors, floor structure, and air flow can affect the spread of smoke in a building. Your smoke alarm may detect smoke after 8 minutes or even longer if there is a fire on the other side of the building. But it is usually 3–5 minutes to save your life in a fire, and you may lose the chance to escape.
2. Nighttime Fire Risk
People decrease their sense of smell and need more time to act at night. It is necessary to have a smoke alarm in the bedroom, so people can wake up in time to avoid 50% deadly fires at night.
Where must install smoke alarms？
According to EN14604, UL217 and AS3786 standards, the following areas have to be installed with smoke detectors:
Not recommended for smoke detectors, but suitable for heat detectors :
You need to consider three key factors for installing detectors:
- Coverage range: Each detector has an effective monitoring radius of approximately 6.7 meters.
- Environmental interference: light beams, columns, and other structures can create shadow areas for monitoring.
- Risk level: High-risk areas need more detectors, such as kitchens.
These factors together determine that the answer to “at least how many” will vary depending on the scenario.
| One detector or alarm protection area A and protection radius R | ||||||||
| Fire alarm type | Area S(㎡) | Room height h(m) | roof slopeθ | |||||
| θ<=15° | 15°<θ<=30° | θ>30° | ||||||
| A(㎡) | R(m) | A(㎡) | R(m) | A(㎡) | R(m) | |||
| Smoke alarm | S<=80 | h<=12 | 80 | 6.7 | 80 | 7.2 | 80 | 8.0 |
| S>80 | 6<h<=12 | 80 | 6.7 | 100 | 8.0 | 120 | 9.9 | |
| h<=6 | 60 | 5.8 | 80 | 7.2 | 100 | 9.0 | ||
| Heat alarm | S<=30 | h<=8 | 30 | 4.4 | 30 | 4.9 | 30 | 5.5 |
| S>30 | h<=8 | 20 | 3.6 | 30 | 4.9 | 40 | 6.3 | |
Typical Solution for ordinary area (40-60 ㎡):
- Square Space: Two detectors arranged diagonally.
- Long and Narrow Space: One detector installed every 8 meters.
- Special Areas: install more smoke alarms in stairwells, corridors, or machine rooms, and flammable and explosive locations such as chemical plants or oil depots.
How to calculate the number of smoke alarms?
We make the simple calculation model for your reference. Due to differences in project and building construction, the actual number of installations will vary. CFS will adjust the quantities based on your specific needs.
Residents Calculation Formula:
Number of Smoke Detectors = Number of Bedrooms + Number of Floors + Number of Living Rooms + Number of Stairwells + Number of Corridors
Commercial calculation Formula:
Number of smoke detectors = Total area / 80 + Number of functional areas + Number of floors + Number of stairwells + Number of corridors
For example:
In the application, we build a house project. There are approximately 200 square meters including 3 Bedrooms + 1 Living room + Stairwell/Corridor + Attic storage areas. We used total 7 pcs smoke alarms.
- 3pcs smoke detectors for 3 bedrooms
- 1pcs smoke detectors for living room
- 2pcs smoke detectors for Stairwell/Corridor
- 1pcs smoke detectors for attic storage areas
Another project for the hotel. There are 5 floors and 62 guest rooms + 1200 m² Corridors & Public passageways + 2000 m² Restaurant & Meeting Rooms & Business Center + Lobby + Relaxation area + Restroom.
- 62pcs smoke detectors for 62 guest rooms (1pcs alarm per room)
- 15pcs (1200÷80) smoke detectors for approximately 1200 m² corridors and public passageways
- 25pcs (2000÷80) smoke detectors for approximately 2000 m² restaurant, Meeting Rooms, Business Center
- 10pcs smoke detectors for Lobby, relaxation area and restroom
How many smoke alarms for different buildings：
We make the list for different buildings for your reference.
No. | Type | Configuration | Quantity of smoke alarms |
|---|---|---|---|
1 | 2 bedrooms +1 living room+1 corridor | 4 | |
2 | 5 Bedrooms + 1 Living room + 4 Stairwell/Corridor + 1 Attic storage | 10 | |
3 | 3000㎡ Production area + 1500㎡ Storage areas + 500㎡ Office | 72 | |
4 | 100 Rooms + 5 Floors 200㎡+ Lobby 180㎡ + Relaxation area + Restroom + Public rooftop area | 120 | |
5 | 30 Classrooms + 1 Special Education Room + 1,000㎡ Corridors+ 5,000 m²( Laboratories + Library + Computer Rooms, etc.) | 103 | |
6 | 1200㎡ Corridors and waiting areas + 2500㎡ Inspection and auxiliary functions area + 40 Patient room. | 86 | |
7 | spacious lobby+ ticket area+ snack bar+ lounge+ auxiliary areas+ 10 screening rooms | 45 | |
8 | Entrance/exit + Lobby area + Children’s reading room + Electronic reading room + Multi-purpose room + Local history archive + Corridors | 16 | |
9 | Equipment cabinet + UPS/Battery cabinet + Power distribution + Supply area | 4 | |
10 | Entrance + Selling tickets area + Public corridors + Snack bars + Lounge + Auxiliary areas + 498-seat Auditorium | 30 |
Please send your project information and drawings, we can freely evaluate the number of fire alarms. Please contact us.
What kind of Smoke Alarms should I choose?
CFS provides 6 types of smoke alarms, including 10-year battery-operated photoelectric smoke alarms, hardwired photoelectric smoke alarms, wireless interconnected smoke alarms, combo smoke and carbon monoxide alarms, Wi-Fi smoke alarms, combo smoke and heat alarms, and so on! You can download our catalog or browse our website to select more smoke and fire alarms!
FAQ
Summary
Planning the number of smoke detectors is a crucial part of hotel or apartment fire safety.
Please make sure to install them in every bedroom, each floor, hallways, the living room, and some high fire risk areas. If you install smoke detectors correctly and save lives in advance by several minutes, you greatly improve your and your clients’ safety.
If you need:
Contact us for professional solutions.
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