Fire and the Historic Building: Why Compartmentation Matters
Submitted by Andy_B on Thursday, 01 October 2026 Page Views: 3
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Fire has shaped the story of Britain's buildings more than almost anything else. Whole streets, churches and palaces have been lost in a single night, and some of the finest buildings we have today only exist because an earlier one burned down. Every major fire teaches the same lessons, and one of the most important is simple. Fire needs to be held back long enough for people to get out and for firefighters to get in.For owners of historic buildings, that lesson comes with a special challenge. How do you slow a fire in a building that was never designed to resist one, without destroying the character that makes it worth protecting?
Lessons written in ash
The Great Fire of London in 1666 began in a bakery on Pudding Lane and spread through the closely packed timber houses of the old city for several days. Much of medieval London was lost, including the old St Paul's Cathedral. The rebuilding that followed brought in brick and stone and, in time, Christopher Wren's new cathedral.Much more recently, the Windsor Castle fire of 1992 started in the Private Chapel and spread through roof spaces and hidden voids into some of the grandest rooms in the castle. The restoration took years. In 2019, the world watched as the roof and spire of Notre Dame in Paris burned, and Glasgow School of Art, the famous building by Charles Rennie Mackintosh, suffered serious fires in 2014 and again in 2018.
These fires were very different, but a pattern runs through them. Historic buildings often have open roof spaces, hidden voids behind panelling, and stairs and corridors that connect everything. Once fire gets into those spaces, it can spread quickly and out of sight.
What compartmentation means
Compartmentation is the idea of dividing a building into separate sections, or compartments, using walls, floors and doors that resist fire for a set period. If a fire starts in one compartment, it should be held there long enough for people to escape and for the fire service to tackle it. It also limits smoke, which is often the bigger danger to life.In a modern building, compartments are designed in from the start. In a historic building they have to be added later, and that is far harder. Roof spaces may need fire barriers. Gaps around old beams and pipes may need fire stopping. Floors and walls may need upgrading from above or below. Each of these jobs has to be balanced against the need to protect historic fabric.
Doors are usually the weakest point. A wall or floor can be upgraded once and left alone, but a door has to open and close thousands of times. It also has to look right in a building where the joinery may be one of its most admired features. Getting that balance right is skilled work, which is why owners are told to use accredited fire door installers rather than a general joiner.
Fire doors in listed buildings
In many historic buildings, the original doors are thin panelled timber, beautiful to look at but offering very little resistance to fire. There are a few ways to deal with this, and the right answer depends on the building and the door.Sometimes an existing door can be upgraded. Specialist products such as intumescent strips, which swell up in heat to seal the gap around a door, can be fitted to the frame. Panels can sometimes be upgraded, and self closing devices can be added so the door does not get left open. Where this can be done well, it keeps the historic door in use.
In other cases, a new door is needed. It can often be made to match the old one in style, with the historic door stored safely or reused somewhere less critical. Occasionally, the best option is to add a new fire door in a different position, such as a lobby, so that the historic door can stay exactly as it is.
Whichever route is chosen, the detail matters enormously. A fire door is not just a thick door. It is a tested assembly of leaf, frame, hinges, closer, seals and glazing, and it only works as tested if every part is right and the gaps around it are correct. That is where accreditation earns its keep. Installers who belong to a recognised third party scheme have been trained and checked, and their work can be traced and certified. In a listed building, where the conservation officer and the fire safety adviser may both need to be satisfied, that paper trail is very valuable.
Listed building consent will usually be needed for changes to historic doors and walls, so the plan should be agreed with the council before work begins.
Keeping protection in place
Fitting fire doors is only half the job. They have to keep working, year after year. In busy historic buildings, doors are often wedged open for convenience or to help visitors find their way. Seals get painted over, closers wear out and hinges drop. A fire door that does not close properly is little better than an ordinary door.In England and Wales, the Regulatory Reform (Fire Safety) Order 2005 places duties on the responsible person for most non domestic premises, including many heritage sites open to the public. Regular checks of fire doors form part of looking after a building properly. Where doors need to stay open during the day, hold open devices linked to the fire alarm can release them automatically when the alarm sounds.
Staff training matters as much as hardware. Volunteers and guides at heritage sites are often the people who notice a door that no longer latches or a seal that has been damaged. A simple routine of walking the building, closing each fire door and checking it shuts fully into its frame can pick up most problems long before they matter.
Protecting the past for the future
Every historic building that is lost to fire is gone for good. Paintings and furniture can sometimes be rescued, and rooms can be rebuilt, but the original fabric cannot be replaced. Compartmentation is one of the most effective ways to stop a small fire becoming a disaster.Done well, it can be almost invisible. A visitor admiring a panelled corridor may never notice that the door at the end has been quietly upgraded, or that the roof space above has been divided into sections. That is exactly how it should be. The building keeps its character, and it has a far better chance of surviving for the next few centuries.
With many thanks to A Chesley for the Creative Commons photo at top.
