Where Does a CO2 Fire Extinguisher Belong on a Roofing Site?

Every torch-applied roof puts an open flame next to timber, insulation and felt. Fire crews in England attended 1,587 construction fires between January 2015 and March 2019. Home Office figures tie 28% of them to hot work and other heat sources.

Owning an extinguisher is not the same as owning the right one. An explainer on CO₂ extinguishers and where they belong shows what the black-banded cylinder can safely tackle. The same logic decides where each unit sits across a roofing job.

Why Do Torch-Applied Roofs Start So Many Fires?

Torch-on systems combine three things fire loves: a naked flame, combustible decks and hidden voids. A stray flame can smoulder inside insulation for hours before anyone smells smoke. By then the crew has often packed up and driven away.

The consequences can be severe. The Beechmere retirement complex in Crewe burned down in August 2019, forcing around 150 residents from their homes. The hot works prosecution that followed put six construction firms before the courts over roof repairs.

Losses on that scale explain why insurers now read hot works clauses so closely. One missed step in a permit can void cover for a whole contract.

How Do You Set Up a Fire Point Before Torching?

A proper fire point follows a fixed drill and takes minutes to arrange. The NFRC’s Safe2Torch guidance gives crews a survey-first method for every torch-on job.

1. Survey before pricing. Map every detail the torch must not touch and mark torch-free zones on the drawing.

2. Issue a hot works permit. Name the operative, the task, the kit and the cut-off time for flame work.

3. Clear the zone. Move gas bottles, solvents and loose felt offcuts well away from the work area.

4. Stage extinguishers at roof level. A 9-litre water or foam unit handles deck timber and membranes.

5. Match the extras to the risk. Add dry powder where LPG hoses run and a CO₂ unit beside powered kit.

6. Post a fire watch. Keep someone checking the roof and its voids after the last flame goes out.

What Does a CO₂ Extinguisher Actually Put Out?

Carbon dioxide suits two jobs: live electrical equipment and Class B flammable liquids. The gas smothers flames by displacing oxygen, then disperses without leaving residue. That makes it the standard choice for 110-volt transformers, chargers and corded power tools.

It is the wrong tool for burning timber, felt or insulation. The gas knocks down visible flames but never cools the fuel, so Class A fires simply relight. UK units come in 2 kg and 5 kg sizes, each carried on a red body with a black band.

Two hazards deserve respect. The discharge horn drops far below freezing and can frostbite bare skin within seconds. In a plant room or sealed loft void, the gas can also push oxygen below breathable levels.

Which Extinguisher Matches Each Roofing Fire Risk?

Match the cylinder to the fuel, not the other way round. The table below pairs the risks a roofing crew meets most weeks with the right first response.

Three checks matter before anyone squeezes a CO₂ handle:

• Confirm the space has ventilation before discharging indoors.
• Hold the moulded grip, never the black horn itself.
• Watch the fuel afterwards, because the gas gives no cooling.

How Should Roofers Site and Service Their Extinguishers?

Siting follows BS 5306-8, the British Standard for placing portable extinguishers. Nobody should travel more than 30 metres to reach a Class A unit. On a roof, that means kit at the access point and at the work face, not locked in the van.

Servicing is a yearly job for every cylinder on the fleet. CO₂ units then need a full overhaul at 10 years, against 5 for most other types. A monthly walk-round catches missing pins, corrosion and blocked horns.

The job does not end when the torch does. HSE’s construction fire guidance treats hot works as a headline risk, and most permits demand a fire watch of at least 60 minutes. Insurers and the NFRC also back widespread thermal imaging so crews can scan voids before leaving site. Handheld cameras cost about £400 and pay for themselves on the first smoulder they find.

Fire Kit Notes for the Roofline

• Hot work and other heat sources caused 28% of England’s 1,587 recorded construction fires between January 2015 and March 2019.
• CO₂ handles live electrical kit and Class B liquids, never timber, felt or insulation.
• Stage water or foam at the torch, dry powder near LPG, and CO₂ beside powered tools.
• Site units to BS 5306-8, with no more than 30 metres of travel to a Class A extinguisher.
• Service every cylinder yearly and overhaul CO₂ units at the 10-year mark.
• Hold a fire watch of at least 60 minutes once torching ends, then scan the voids.

The Right Cylinder in the Right Place

No single extinguisher protects a torch-on roof, and pretending one does is how buildings burn. Water or foam guards the deck, powder guards the gas, and CO₂ guards the electrics. Put each unit where its fire actually starts, and the black band earns its keep.

FAQ

Can a CO₂ Extinguisher Put Out a Bitumen Fire?

Only a very small, contained one. Hot bitumen behaves as a Class B liquid, and CO₂ gives no cooling, so re-ignition is likely. Crews normally keep foam or dry powder beside bitumen boilers.

Why is CO₂ the First Choice for Electrical Fires?

The gas does not conduct electricity, so it can be used on live equipment. It also leaves no residue, which matters around chargers and site office IT. Isolate the supply first whenever possible.

How Many Extinguishers Does a Torch-On Job Need?

Two at the work area is the accepted minimum for hot works. The exact count comes from the risk assessment and the permit conditions. Larger roofs need extra units at each access point.

Should a Roofing Van Carry Its Own CO₂ Unit?

A 2 kg CO₂ unit is a sensible fit beside battery chargers and power tools. Keep it clamped, visible and inside its service date. Pair it with a small foam unit for the van’s other risks.