Fire doors play a critical role in protecting lives and properties, particularly in Houses in Multiple Occupation (HMOs) where multiple families or tenants reside. They are specifically designed to withstand fire for a certain duration (e.g. 30 minutes), allowing occupants more time to evacuate and minimising the spread of smoke and flames.

However, improper installation and alterations, such as excessive trimming, can compromise the integrity of these doors and invalidate their fire certification. In this article, we’ll explore the construction of fire doors, permissible trimming limits, the consequences of over-trimming, and why it’s crucial to adhere to regulations when installing fire doors in HMOs.

How Fire Doors Are Constructed

Fire doors are not just ordinary doors; they are built with multiple layers of fire-resistant materials. Typically, they have a solid core construction, often made of materials such as solid timber, particleboard, or mineral cores, which provide the necessary density and heat resistance to slow down the spread of fire.

Additionally, fire doors must be used in conjunction with intumescent strips, which can be installed either along the edges of the door itself or in the door frame. These strips expand when exposed to high temperatures, sealing any gaps between the door and the frame to prevent fire and smoke from passing through. Furthermore, fire doors are rigorously tested to meet specific standards, such as BS 476-22 in the UK or NFPA 80 in the USA. The doors must pass these tests to be certified, ensuring they perform as required during a fire.

Trimming Limits for Fire Doors: What’s Allowed?

While some trimming is allowed when fitting fire doors, strict limits apply to avoid compromising their fire resistance. According to most manufacturers and fire safety guidelines:

Sides: You can generally trim up to 4mm from each side.

Bottom: Trimming up to 6-10mm is usually permissible, depending on the door type.

Top: Trimming the top edge of a fire door is strictly prohibited, as this edge often contains the certification label, which is necessary for the door to be legally recognized as fire-rated.

Exceeding these limits can expose non-fire-rated core material, which reduces the door’s ability to withstand heat and pressure during a fire. This can make the door ineffective, putting lives at risk and violating fire safety regulations.

What Happens If Carpenters Trim More Than Allowed?

If a carpenter trims a fire door beyond the manufacturer’s recommendations, several issues arise:

• Loss of Fire Rating: The door’s fire rating can be entirely voided. This means that in the event of a fire, the door will not perform as expected, allowing fire and smoke to spread rapidly through the building​.
• Structural Weakness: The structural integrity of the door can be compromised, leading to warping or bending when exposed to high temperatures. This not only reduces its fire resistance but may also cause the door to fail under pressure, further reducing the escape time for occupants.
•  Regulatory Non-Compliance: Over-trimming can result in non-compliance with HMO fire safety regulations, which require fire doors to maintain their certification. This could lead to legal repercussions for property owners and potential fines if the building is found to be non-compliant during an inspection.

Ethical Challenges

When installing fire doors in HMOs, we often encounter landlords looking to reduce costs by requesting modifications that push beyond regulatory limits, such as trimming more from the door to fit existing frames. While this may seem like a quick solution, compromising on safety standards can have dire consequences.

Landlords must recognize that decisions made to save on renovations could endanger lives. The tragedy of Grenfell Tower in 2017 serves as a grim reminder of the consequences when fire safety is overlooked. In that case, corners were cut to save money, leading to non-compliant installations and a catastrophic fire that claimed 72 lives. While the primary issue there was with cladding, the principle is the same—any compromise on fire safety regulations, including fire doors, can have lethal outcomes.

Fire doors are crucial in preventing the spread of fire and smoke, and altering them beyond approved limits means they may not perform as designed. Ethically, landlords have a duty to provide a safe living environment for their tenants. Over-trimming a fire door for a cheaper fit undermines that duty and risks turning a property into a death trap during a fire. Cutting corners on fire safety to save on building costs is not just financially irresponsible; it’s morally indefensible.

Installing fire doors that comply with regulations is the only ethical choice, ensuring tenants have the best chance of safe evacuation. When landlords insist on over-trimming doors, they’re not just ignoring fire safety standards—they’re potentially risking lives to save money. The proper solution is to build new frames to fit the door correctly, even if it involves higher costs. It’s an investment in safety, compliance, and peace of mind, which is worth far more than the savings gained from unsafe practices.

The Solution: Building a New Door Frame to Fit the Door

Instead of compromising the fire door’s integrity by over-trimming, the correct solution is to build a new door frame that perfectly fits the fire door’s dimensions. This ensures that the door can perform as expected in the event of a fire, maintaining the safety of the building’s occupants.

Yes, this approach can be more expensive. Constructing a new frame often requires additional materials and labour, and it may extend the timeline for project completion. However, the cost of non-compliance—both in terms of potential loss of life and legal consequences—is far greater. As a responsible service provider, we adhere to ethical standards and regulations, ensuring that every fire door we install is compliant and up to code.

Why We Refuse to Over-Trim Fire Doors

Over-trimming is not just a technical issue; it’s an ethical one. Cutting corners by modifying fire doors improperly may save a few pounds initially, but it endangers lives and could lead to significant financial and legal repercussions for both the installer and the property owner. As specialists in HMO fire door installations, we take our responsibility seriously. We refuse to carry out work that violates fire safety regulations and put tenants at risk.

Conclusion

HMO Fire doors are crucial safety components in any HMO property, providing a barrier to the spread of fire and smoke. Proper installation and adherence to manufacturer specifications are paramount to ensure these doors function effectively in the event of a fire. While landlords may sometimes pressure installers to cut corners by over-trimming doors to fit existing frames, it is the duty of professionals to refuse such requests and suggest building new door frames instead. This may be a more expensive solution, but it is the only ethical and regulatory-compliant option.

When it comes to fire safety, there can be no compromise. The safety of HMO occupants depends on every fire door functioning as designed, without modifications that could reduce its effectiveness. For property owners, choosing compliance and safety over short-term savings is not just the right thing to do—it’s a legal obligation.

If you need fire doors installed in your HMO, contact us today for a consultation. We prioritize safety and compliance, providing you with peace of mind and ensuring that your property meets all necessary fire safety standards.