Article Overview
Practical guidance for real-world site decisions.
A building under construction has no working fire alarm of its own, yet it is full of people, fuel, hot works and changing escape routes. Here is how temporary fire alarm systems fill that gap.
At a Glance
- Construction sites need a way to raise the alarm long before the permanent fire alarm is commissioned.
- CDM 2015 requires suitable fire detection and alarm arrangements, and HSE guidance HSG168 sets out how.
- Wireless temporary systems use linked call points, detectors and sounder beacons that need no cabling.
- Coverage should be reviewed and moved as floors, stairs and welfare areas change.
Section 01
Why construction sites need a temporary fire alarm
A building under construction is at its most vulnerable before its own fire alarm works. It is full of combustible materials, temporary electrics, hot works and people who may be spread across several floors, scaffolding and compounds at once.
Shouting, air horns and manual bells rarely reach everyone on a large or noisy site, and they cannot tell the people at the far end of the building what is happening. A linked temporary fire alarm makes sure that when one person raises the alarm, everyone on site hears it at the same time.
Section 02
What the rules expect
The Construction (Design and Management) Regulations 2015 require suitable and sufficient fire detection and fire alarm arrangements on construction sites, based on the risks present. The principal contractor is normally responsible for making sure those arrangements are planned, in place and maintained.
The HSE’s guidance on fire safety in construction, HSG168, explains how to assess fire risk and plan detection, warning and escape on a changing site. Many insurers also expect the industry’s Joint Code of Practice on fire prevention on construction sites to be followed on larger projects.
None of these documents prescribe a single product. They expect a system that suits the site, is maintained and is understood by everyone working there.
Section 03
What a good temporary system includes
A typical wireless temporary fire alarm is built from a small number of device types, linked together so that any one of them can trigger every alarm on site.
- Manual call points at exits, stair cores and key work areas, so anyone can raise the alarm
- Automatic detectors in higher-risk areas such as welfare cabins, stores and out-of-hours zones
- Weatherproof sounder beacons so the alarm is heard and seen indoors, outdoors and on scaffolding
- Spoken announcements, which help on sites with mixed-language teams
- A wireless mesh link between every unit, with fault reporting if a device loses connection
Section 04
Planning coverage on a site that keeps changing
The hardest part of construction fire safety is that the building keeps moving. Escape routes change as stairs go in, floors are enclosed, and welfare cabins are relocated. A fixed, cabled system cannot keep up with that.
Battery-powered wireless devices can be repositioned as the build progresses. The useful habit is to review the layout every time the fire plan changes: add call points to new escape routes, move sounders as work areas shift, and remove devices from areas that are no longer occupied.
Section 05
Testing, logging and handover
A temporary system only protects people if it works and is trusted. Testing is typically carried out weekly, rotating which call point is used, with the results recorded in the site fire log. Faults and low batteries should be dealt with immediately.
When the permanent fire alarm is commissioned, the temporary system can be removed area by area, so there is never a gap in cover during the handover.
Temporary fire alarm options on site
| Option | Wireless linked system | Standalone bells or air horns |
|---|---|---|
| Everyone alerted at once | Yes, every unit sounds | Only those within earshot |
| Automatic detection | Available | No |
| Moves with the build | Yes, no cabling | Yes, but coverage is patchy |
| Fault reporting | Yes | No |
Frequently Asked
Questions we get asked about this
Is a temporary fire alarm a legal requirement on construction sites?
CDM 2015 requires suitable fire detection and alarm arrangements based on the site’s risks. On most sites of any size, a linked temporary fire alarm is the practical way to meet that requirement.
Who is responsible for the temporary fire alarm?
Normally the principal contractor, as part of the site fire risk assessment and construction phase plan.
Do wireless temporary fire alarms need cabling or mains power?
No. The devices are battery-powered and link wirelessly, so they can be installed quickly and moved as the site changes.
How often should a temporary fire alarm be tested?
Typically weekly, using a different call point each time, with results recorded in the site fire log.
Need help applying this to your site?
We can turn the principles in this article into a practical recommendation based on your building, procedures, and response priorities.