Fire safety and hot works

This talk is about fire on this site, and about hot work: anything that makes heat, sparks or flame. HSE's construction fire FAQ says a fire needs three things: a source of ignition, a source of fuel, and oxygen. Ignition on a site includes heaters, lighting, naked flames, electrical equipment, hot processes such as welding or grinding, smokers' materials, and anything else that can get very hot or cause sparks. Fuel includes petrol, paint, varnish, white spirit, wood, paper, plastic, rubber or foam, LPG, acetylene, loose packaging, waste and furniture. If any one of those is in the way of the other, we deal with it before we start.

Duties are split, and both matter. Under the Construction (Design and Management) Regulations 2015, HSE says clients, designers, principal designers, and contractors, including principal contractors and construction workers, have duties to eliminate and control fire risks. The Regulatory Reform (Fire Safety) Order 2005 in England and Wales, and the Fire (Scotland) Act 2005, put duties on a responsible person or a dutyholder. That is usually the employer, the owner or the occupier. They assess the risk and put measures in place, such as escape routes and warning systems. HSE's process-fire page says the Fire Safety Order sets the law on general fire safety on a construction site, including means of escape, and that CDM 2015 also requires the risk from fire to be prevented. Timber-frame building needs more than the ordinary precautions. HSE points that work to HSG168 and to timber-frame guidance. This talk is not that extra set.

The aim is that people can get out, quickly, to a place of safety. What you need depends on the risk. A timber-frame or multi-storey site needs more. HSE's list of measures is emergency plans, raising the alarm, limiting spread by compartmentation, escape routes and fire exits, and firefighting. On a small low-risk site the alarm may be raised by shouting. On a high-risk or larger site you need a fixed, interconnected system of call points and sounders. The signal has to be distinctive and heard above the site noise. Everyone here needs to know what the alarm sounds like, how to raise it, which route is clear, and where to assemble. Escape routes are kept clear. Rubbish in a corridor is a fire problem and an escape problem.

HSE says each year there are serious fires on construction sites and in buildings being refurbished, and that many could be avoided by planning and control. Refurbishment is a particular risk when there is a lot of dry timber, and later in a job when adhesives, insulation and soft furnishings are present. Keep the amount of combustible material in the work area down until it is needed. Store it outside where you can, especially LPG and other volatile materials. If it has to be inside, plan the place so it does not put people at risk. Specify less combustible materials where that is possible, and remember that working on a material can make it easier to ignite, for example when a solid becomes dust. Protective coverings and scaffold sheeting can add to the risk. Flame-retardant materials reduce that. Bonfires should not normally be allowed. Have another way to get rid of waste. Secure the site against arson, especially at night and at weekends. High fire-loading sites, or sites with a history of vandalism, may need extra lighting, out-of-hours security or CCTV. Nobody sleeps in a building under construction or refurbishment. HSE is clear on that.

Hot work is the part people rush. HSE's process-fire page says all hot work that generates heat, sparks or flame can cause a fire. The precautions on that page are: clear the area of combustible materials, have suitable fire extinguishers, and keep a careful watch throughout the work. A permit to work can help manage the risk on larger projects. HSG168, HSE's fire safety in construction book, defines hot work as any process that generates flame, sparks or heat, including oxy-fuel cutting and welding, grinding and cutting metal, torch-applied roofing, heat guns and soldering irons. It says hot works should be designed out where practicable and replaced with cold methods, and that where combustible material is present you use alternatives. The book then sets the precautions I want read out, because the short page does not give the times.

Before the work, look at the area, especially on a refurbishment where you may not know what is in the fabric. Remove loose combustible materials in and around the work, inside any gap in a wall, floor or ceiling where heat or sparks could go, in the area underneath, and on the other side of a wall if you are only working one side. Protect what you cannot remove, and any openings, with non-combustible board. Have at least two suitable fire extinguishers within reach of the hot work and of any fire-watch position. Keep a watch while the work is going on, and during breaks, including spaces you cannot see if the heat can pass through. HSG168 says there should be a continuous fire watch for at least an hour after the hot work ends, then at least one more check two hours after it ends. Some materials can smoulder for a long time before they ignite. All hot works should be finished two hours before the end of the working day, so those checks can be done. Closing a permit includes a visual inspection of the area. If the site has security staff, they should be told to keep checking former hot-work areas.

Extinguishers are not a reason to fight a fire you are not trained for. HSE says the number and type depend on the hazard, and that the primary purpose is to aid escape. In some limited circumstances a trained person may tackle a fire in the early stages. The FAQ matches types to fires: water for wood, paper, textile and solid material; powder for liquid and electrical fires; foam for liquid fires; carbon dioxide for liquid and electrical fires. They sit at identifiable fire points on each storey exit, and they are serviced. Hot work needs its own extinguishers as well. Know which one is for this fuel before you need it.

What we do on this job: what can burn within reach of the spark, who is watching, including the other side of the wall and the floor below, where the extinguishers are, how we raise the alarm, and who is still here for the hour after we stop, and for the check two hours after. If we cannot finish in time to do those checks before the site empties, we do not start the hot work.