The Most Common Fire Door Failures I Encounter as an Fire Door Inspector in London

FD30 Door Label from BWF

Fire Door Inspector in London Experience: Why Even New Doors Fail Compliance

As a qualified fire door inspector working across London, I’d like to share what I regularly see on site — not based on theory, but on real, practical inspections.

Fire doors often appear compliant to others, especially when freshly installed. But for me, issues are visible immediately — even when I’d rather not see them, eg during holidays or shopping 🙂. Unfortunately, even brand-new doors can hide faults that compromise fire resistance completely. Below are the defects I most frequently encounter and the reasons they matter.

1. Incorrect Door Gaps

This is by far the most common and underestimated problem.

I often find side and top gaps that exceed 4mm (the largest I’ve encountered so far was 18mm!), and threshold gaps larger than 10mm. And for FD30S - FD120S, smoke-sealed doors, the maximum allowable threshold gap is only 3mm — a crucial detail that is frequently ignored.

Important clarification: Uneven flooring is not the cause of incorrect threshold gaps — poor installation is. But uneven flooring does often become a barrier to effective remedial work. It can prevent the door from being realigned properly, and in some cases, results in the door catching or binding once gaps are corrected.

2. Unsafe Lock and Latch Choices

This is a frequent and concerning failure. I regularly see standard euro cylinders fitted to door — leaving a large, open hole through the centre of the leaf. This offers a direct path for fire and smoke to breach the door.

Deadlocks/sashlocks are another example — they’re commonly used, yet many are not fire-rated.

The frustrating part is that fire-rated alternatives are widely available and not expensive. If fire performance is considered at the installation stage, it’s a simple and cost-effective choice. But when this is overlooked, changing hardware later requires extra labour and risks damaging the door.

Non-compliant eurocylinder & sashlock.

3. Missing Intumescent Hinge Pads

This issue is far too common — and far more serious than people think.

Imagine having three exposed hinge points in a fire door with no fire protection whatsoever. That’s three direct paths through the door leaf for heat and smoke. It’s quite a lot, don’t you think?

Even when fire-rated hinges are used, they must be installed with intumescent hinge pads. These pads expand in the heat of a fire and seal the fixing points. Without them, the fire door cannot perform as tested — and the integrity of the entire door is compromised.

The same applies to intumescent pads around locks and latches.

Visible no intumescent protection behind the hinge.

4. Incorrect or Non-Compliant Seals

FD30S - FD120S doors are required to have smoke seals — not just standard intumescent strips. Yet I often find these incorrectly installed, damaged, or even missing entirely.

Worse, I’ve seen new doors where the intumescent strips were joined together mid-length rather than being continuous. This is a failure in both workmanship and compliance — and it completely undermines the door’s resistance during a fire.

Painted seals. Both seals are intumescent only, but based on the building type and fire strategy, they should be smoke seals to provide adequate smoke protection.

5. Closers Set Too Strong — Damaging the Door

One of the saddest and most frustrating defects I encounter is when a perfectly good fire door is slowly destroyed by a closer that was adjusted too strongly — especially at the latching stage.

Over time, that constant force causes the timber around the closer or the hinges to split. In metal doors, an overly strong door closer can cause the frame to warp or gradually detach from the wall due to loosening fixings. We've already encountered numerous cases where excessive force from the closer led to remedial works. It's important to ensure the closer is correctly adjusted to avoid structural issues over time.

I often inspect doors that are less than a year old, already showing signs of structural failure caused entirely by an aggressive closer setting. All of it could have been avoided with a simple adjustment.

Closer readjustment. Here in metal doors.

6. Doors That Have Dropped Through Use

It’s completely normal for fire doors to drop slightly over time — they’re heavy and in constant use. But whether this drop becomes a problem depends entirely on the quality of the original installation.

If the gaps were compliant at installation or post-remedial (typically 2–4mm), then a drop is usually easy to fix by adjusting the hinges. However, if the gaps were incorrect to begin with, a drop means frame packing — which is invasive, time-consuming, and usually requires redecorating.

In some cases, I’ve seen frame packing completed — but with no follow-up decoration. This leaves visible damage and affects the overall appearance of the door. In our team, we always include professional decorators to restore the door to a clean, compliant finish.

Dropped doors, 6mm gap

7. Damaged Threshold Drop Seals

The threshold drop-down seal is another frequent point of failure. The rubber element tears, detaches, or fails to activate correctly — especially in high-traffic areas. Sometimes this is wear and tear, but often it's due to poor alignment or an uneven floor interfering with the seal's operation.

Pro tip: Choose well-supported, standard fire doors with commonly available, tested components. That way, if something like a drop seal needs replacing, you're not stuck searching for discontinued parts. Planning for maintenance starts at the point of installation.

Broken threshold device visible. Additionally, the drop-down seal activation button is pressing against the intumescent seal instead of a solid surface.

8. Dangerous Adjustments by Maintenance Teams

In many cases, I arrive on site and find that someone has already attempted to adjust the door — but done it completely wrong.

One of the most common mistakes I see is the removal of the intumescent pad from the top hinge, instead of properly packing the bottom hinge to lift the door. This weakens the hinge point and compromises the door’s structure.

These types of adjustments are often made by remedial or maintenance teams from other companies, not by the original installer. It’s a clear reminder that all remedial work on fire doors must be carried out by competent persons — ideally with an inspector's input before and after.

Hinge pad removed by previous company!

9. Unauthorised Penetrations and Poor Repairs

I frequently come across fire doors that have been drilled, cut, or otherwise modified without appropriate protection and not in accordance with fire test documentation.

Any penetration — even small ones — must be sealed with intumescent wood filler or repaired using compliant fire-rated materials, but only if the fire test permits it. Always check with the manufacturer whether the alteration you intend to make has been tested and whether the components used were included in the fire test.

Fire doors are tested as complete units. Altering them without using properly tested fire-stopping materials undermines their entire purpose — they may simply fail to perform in the event of a fire.

To be clear: Grilles should not be installed on a door unless the door was specifically designed and certified for that use. Adding grilles to a standard fire door is not compliant.

Non-fire-rated grilles installed into fire-rated doors — I call them fire holes. They completely undermine the door’s purpose and create an easy path for smoke and flames to pass through.

10. Missing or Removed Certification Labels

It may seem harmless, but removing the certification label from a fire door creates major issues.

That small label contains vital information: the fire rating, manufacturer ID, and often batch or performance data. It’s the only way to trace the door’s specification.

Please don’t remove fire door labels. They’re not stickers — they’re a critical part of the certification chain.

11.Hidden Failures from Other Contractors

I’m often asked to re-inspect work that was previously “signed off” by others. And unfortunately, I often find signs of shortcuts.

For example: joined intumescent strips instead of continuous ones, missing hinge pads, or poor workmanship masked by paint.

These aren’t oversights. They’re risks.

I wanted to highlight this because it’s what we found hidden beneath a metal plate attached to the door leaf — in a nearly new building. Severe damage to the door leaf, with exposed core and unapproved filler material used to patch the area. It was clearly an attempt to conceal the issue, likely so the client would assume everything was fine, when in fact it was a result of mistake during installation.

There are also some less frequent but still important issues, such as missing fire door signage and, notably, poorly installed door stops. A misplaced door stop can prevent the door from closing fully, which is critical to its performance — and definitely worth mentioning.

A Living System in Human Hands

Fire doors are not static products. They’re in constant use — opened, closed, pushed, pulled, and leaned on every single day.

They don’t sit idle. They work — and because of that, they need to be looked after.

My motto is simple:

A fire door is always in someone’s hand

— so it must always be under someone’s eye.

Final Tips

Buy certified, tested fire doors from reputable sources. Install them properly, with all components — and all documentation. Maintain them regularly. Inspect them thoroughly. And work with people who take it seriously.

Avoid unsupported door systems. I’ve been in buildings where a simple threshold seal in metal door couldn’t be replaced because the manufacturer no longer existed — and no alternative parts were available. That’s a preventable problem, if you make the right choices at the start.

In fire safety, shortcuts lead to consequences.

About Agata Rakotoson – Fire Door Inspector

Agata Rakotoson is a fire door inspector based in London. She began her career in fire alarms along her husband, David, but developed a strong passion for fire doors, combining technical knowledge with practical experience. Known for her attention to detail and problem-solving mindset, Agata also manages remedial projects — giving her unique insight into the causes of defects and the best methods of repair.