Start with what a damper is supposed to do
A fire damper sits inside your ductwork where it passes through a fire-rated wall or floor. In normal use it stays open so air can move. When a fire raises the temperature, it closes and seals the opening, stopping fire and smoke travelling through the ventilation system into the next compartment. That is its entire job. If it cannot close, the hole you cut through your compartment wall to run ductwork becomes an open route for fire to spread.
Because a damper does nothing visible in normal use, a jammed or blocked one looks identical to a working one until the day it is needed. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person has to keep fire safety measures like this in efficient working order. That is an ongoing duty, not a check at installation, and BS 9999 recommends dampers are tested at least annually, by drop test. The problem is that dampers fail quietly. Nobody sees them, nobody hears them, and the fault only shows up when someone finally opens the access panel.
The most common fire damper faults
1. Painted, rusted or seized in the open position. The single most common finding. A spring-loaded or fusible-link damper relies on moving parts. Over years, corrosion, grease from a kitchen extract, or a decorator with a paint roller can lock the blades solid. A drop test, releasing the mechanism to confirm the damper actually closes, is the only way to prove it still works. A visual inspection tells you nothing about whether the blades will move.
2. Fusible link removed, wrong or missing. The fusible link is the small heat-sensitive element that releases the blade at a set temperature. We find links snipped out during "maintenance" to stop a damper closing accidentally, links replaced with the wrong temperature rating, and links simply absent. A damper with no link is a hole in your wall dressed up as protection.
3. It can't be reached to be tested. A damper that cannot be accessed cannot be tested, and an untested damper cannot be signed off. Plasterboard fixed over the access point, ductwork boxed in during a refurbishment, or a suspended ceiling with no hatch all produce the same result: a report full of gaps rather than results. DW/145 sets out that dampers must be installed so they can be inspected and maintained. If yours can't, that is a defect in its own right, not an inconvenience.
4. Debris and grease inside the duct. A damper cannot close against a duct full of dust, insulation offcuts or kitchen grease. In extract systems serving commercial kitchens the grease is also fuel, which is why fire dampers should not be fitted in kitchen extract ductwork at all; any found in older systems need testing at least annually or removing. TR/19 covers the cleaning standard for ventilation and extract ductwork, and a damper sitting in a dirty duct will neither close cleanly nor seal.
5. Fixed in a way that stops it closing. Screws driven through the casing into the blade path, incorrect retaining angles, or a damper fitted the wrong way round in the airflow all prevent proper closure. A damper only performs to its fire rating if it is installed exactly as tested. We cover the most common version of this in the issues tek screws cause fire dampers.
6. It isn't sealed into the compartment wall. The damper and the wall it passes through are meant to work as one barrier. If the gap around the damper sleeve has been left open, or filled with ordinary expanding foam rather than a tested fire-stopping system, fire travels around the damper through the hole in the wall. The damper can be in perfect working order and the compartment line still fails.
7. Loose, or fallen out of the wall. Ductwork moves, fixings loosen, and a poorly installed damper can drop out of the wall opening entirely, leaving an unsealed gap. The damper might be lying in the duct, technically "there" but doing nothing.
8. No record it was ever tested. A damper with no paperwork is, for compliance purposes, a damper that has not been tested. You cannot show you have met your duty without records of what was inspected, when, by whom, and what the result was. A damper that has sat untouched for a decade is not a working damper. It is an assumption.
Several of these faults are not wear and tear at all: they were built in on the day the damper was installed. If you have taken on an older building, faults you inherit rather than cause explains what to expect from a first survey.
A scenario you will recognise
A facilities manager took over a mixed-use block and inherited a maintenance file that mentioned fire dampers but held no test certificates. He commissioned a survey. Of the eighteen dampers on the mechanical drawings, engineers could physically reach eleven. Of those eleven, four failed the drop test: two seized with corrosion, one painted shut during a refurbishment, one with its fusible link missing. The other seven were behind sealed ceilings with no access at all.
He did not have a testing problem. He had an access problem, a maintenance-history problem and a hidden-defect problem all at once. The fix meant cutting access panels, putting the failed units right, and starting a documented annual programme. None of it was visible from the corridor. All of it was his legal responsibility.
What to do about it
Start by finding out how many dampers you actually have and where they are. The mechanical drawings and O&M manuals should tell you, and if they do not, that is itself a finding. Commission a competent contractor to drop-test every damper on a documented programme, not a visual glance, and insist the report says which dampers could not be reached and why. That distinction matters: an untested damper is not a passed damper.
Where access panels are missing, get them installed rather than letting "no access" sit as a permanent entry. Where dampers have failed, fix them and keep the certificate. Then put the whole thing on an annual programme and keep the records, including the ones that record faults, because the record of a problem found and fixed is what proves you are managing the risk.
Fire dampers fail for boring, predictable reasons. That is the good news: predictable problems can be planned out of existence.