How do the correct gaps around fire doors slow down and prevent the spread of fire?

Fire doors are a crucial line of defence if a building is affected by fire. When a serious fire breaks out, the majority of fatalities that occur are not caused by burns but by smoke inhalation. The more the fire can be contained, the lower the chances of smoke spreading throughout the building and causing problems. Fire doors are essential tools, both to help keep a fire contained and to ensure that smoke isn’t freely moving throughout the building.

Why the gaps around fire doors are essential

Gaps around fire doors may seem fairly inconsequential. However, ensuring that these are the correct width is fundamental to the way that fire doors function. Fires require oxygen to continue to burn and a fire in a closed room will start to consume all the oxygen in that space. If the gaps that have been left around the fire doors in the building are too large this will provide a constant supply of fresh oxygen to the fire. This can enable the fire to continue to grow and, as it does so, an intense pressure starts to form towards the ceiling of the space.

As the pressure increases, smoke and hot air are forced up and out through the gaps towards the top of the fire doors. This means that areas that are supposed to be protected by the fire doors are not because the gaps are creating openings where hot air and smoke can get through.

Ensuring your fire doors function properly

Gaps between a fire door and the door frame should never be more than 4mm or less than 2mm. It’s essential to have fire doors fitted by a professional with extensive experience or your safety investment could be completely undermined. There are a number of other ways to ensure that your fire doors are fulfilling the function they were created for.

Professional recommendations

Get some professional advice on how fire doors should function as part of your fire safety precautions. Designing the right combination of active and passive fire safety measures requires specific knowledge and experience – for example, most fire door gaps should be 3mm; any smaller and there may not be space for intumescent strips to activate.

Ongoing maintenance requirements

Maintenance is essential. The Regulatory Reform (Fire Safety) Order – 2005 requires that a “responsible person” ensures that life saving assets on site, such as fire doors, have been properly maintained so that they can function if there is a fire.

Complementary fire protection

It’s not just the door itself that is important. If you have other fire protection measures in place – such as smoke seal protection – it’s crucial that these are also properly installed and maintained. If not they could allow space for smoke to get through, undermining the fire protection that should be provided by the fire door.

Fire doors – and the gaps that should surround them – are a highly effective way to protect a building and its occupants. If you’d like some advice on how to upgrade measures you currently have in place, we can help. Contact us to find out more.

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About Us

Hillmoore Fire Protection Ltd are specialist contractors for all forms of passive fire protection. The ethos and aim of Hillmoore is to provide our clients with an un-rivalled service for the Design, Supply and Installation of all passive fire protection requirements, be it within a new build, refurbishment or upgrading project, or as part of the change of use of a property.