Missing Fire Stopping Around Service Penetrations: An Inspection Checklist

Part of the guide: The Construction Defect Field Guide: 40 Defects by Trade, With Photos

Most defects on a site walk cost money. This one costs lives, and it is the one most likely to be hidden above a ceiling by the time anyone with a torch goes looking. A fire-resistance rated wall is only rated for as long as it is continuous; every cable, pipe and duct that passes through it is a hole, and each hole is either sealed with a tested product or it is the point where the wall stops working. This guide is the inspection: where to look, what missing fire stopping looks like, the six questions to ask at every penetration, and how to write it so it gets fixed properly rather than foamed.

What fire stopping is, and what it is not

Fire stopping is the sealing of openings and gaps in fire-resisting construction, compartment walls and floors, shaft and riser walls, corridor walls, the junction where a wall meets the slab above it, so that the element keeps its rated resistance to fire and smoke for its stated period (30, 60, 90 or 120 minutes). It is done with tested systems: sealants, mortars, batts, collars, wraps and pillows that have been shown in a furnace test, with that service, in that opening, in that wall, to hold for that period. The rules are Approved Document B in England, the IBC's Chapter 7 in the United States, the NCC with AS 1530.4 and AS 4072.1 in Australia, and equivalents elsewhere; the test standards are EN 1366-3, ASTM E814 and UL 1479.

It is not: expanding foam from a builder's merchant, mineral wool pushed into a hole, plasterboard offcuts screwed over a gap, a plastic collar on a pipe that was never rated, or a bead of ordinary silicone. All of these are found above ceilings on completed buildings, and all of them are what this inspection exists to find.

Where does fire stopping go missing?

1. Above suspended ceilings, on compartment lines. The single largest source. Services run above the ceiling, cross every wall in their path, and the ceiling closes before anyone checks. Get the compartment plan, walk each line with a torch and a stepladder, and lift a tile either side of every wall.
2. Riser and shaft walls. Every floor, every service entering the riser. Often sealed on the riser side and open on the corridor side, or the other way round.
3. The head of the wall. Where a compartment wall meets the underside of the slab or deck. A profiled metal deck leaves flutes that need their own fire stopping; a wall built to a ceiling instead of the slab is not a compartment wall at all.
4. Plastic pipes. Waste, soil and rainwater pipes soften and drop out of a wall in a fire, leaving an open hole. They need an intumescent collar or wrap that closes the hole as the pipe melts, and the collar has to be fixed to the wall, not to the pipe.
5. Ducts and dampers. A duct through a compartment wall needs a fire damper at the wall, and the damper needs to be installed to its tested detail and be accessible for testing. A duct with no damper is a chimney.
6. Later work. The fit-out contractor who pulled two data cables through a sealed penetration and did not reseal it. The fire stopping was fine at handover; the hole is new. Look for clean cables through old sealant.

What does a bad penetration seal look like?

An open annular gap. The service passes through and daylight passes with it. The most obvious and the most common, especially around pipes with lagging, where the lagging is continuous through the wall and the gap is behind it.

Loose fill. Pink or yellow insulation stuffed around the cables. Not tested, not fixed in place, and gone the next time a cable is added. If the fill is mineral wool with a coated, painted face and a label, it may be a tested batt system; if it is bare and fluffy, it is not.

Foam. Yellow, over-expanded, uncut. Ordinary polyurethane foam burns; fire-rated foam is rated only in the configurations it was tested in, which almost never include a bundle of mixed services in an oversized hole. Foam with no label and no test evidence is a fail.

The plastic pipe without a collar. A soil or waste pipe through a rated wall with sealant round it and nothing else. The sealant will hold; the pipe will not.

One-sided. Neat on the corridor side, open on the shaft side. Most systems need to be applied to both faces, or to a specified depth; a seal you cannot see the back of is unverified, not passed.

Unlabelled. A proper installation carries a label at the seal, installer, product, date, rating: and an entry in a register. No label usually means no specialist, which usually means no tested system. Not always, but it is the question to ask.

Damaged. A tested seal with a new cable through it and a fresh hole beside it. The system was fine; the building has changed.

How do you check a penetration?

Six questions, in order, at every hole through a rated element. The answers are the report.

1. Is this element fire-rated? Check the compartment plan or the fire strategy, not the wall's appearance. Many walls look the same; only some of them matter. If there is no compartment plan on site, that is the first item.
2. What passes through, and what is the opening? Service by service: cable bundle, tray, steel pipe, insulated pipe, plastic pipe, duct. Measure the opening, because tested systems have size limits and an oversized hole is outside every one of them.
3. What is the seal? Identify the product or say that you cannot. Tested products are recognisable: coated batts, red or grey intumescent sealants, mortar, collars with a manufacturer's name. Foam and loose wool are answers too, just bad ones.
4. Is it complete? Full depth, both faces where required, no gaps at the edges of the batt, the collar fixed to the wall with the correct fixings, the lagging cut back or wrapped. Run a torch beam along the seal from an angle.
5. Is it labelled and registered? Find the label. Ask for the register and the installer's certificate. A seal with paperwork is worth ten without.
6. Has anything changed since? New cables, new holes, new damage. Look for the clean service through the old seal.

This sequence is the fire safety section of the site inspection checklist, expanded; the defect field guide keeps it to a line, because in a full inspection it is one of forty things. On a compartmentation survey it is the whole day.

Why is it so often missing?

Sequencing. Walls are built, then the mechanical and electrical trades run their services through them, each making its own hole, each assuming someone else will seal it. The fire stopping subcontractor, if there is one, comes once, seals what exists at that moment, and leaves. Two more trades punch through after. The ceiling contractor closes the ceiling. Nobody sees the wall again until a fire risk assessor lifts a tile a year later.

Add three beliefs that are wrong and widespread, that foam is fire-rated, that mineral wool is fire stopping, that "the specialist has been" means every hole is sealed, and the result is the photographs above. The fix is procedural: a hole permit or a penetration register that makes each opening somebody's, a fire stopping inspection before every ceiling closes, and a report that lists every penetration by location so that "the specialist has been" can be checked.

Severity, and how to report it

Missing or defective fire stopping on a compartment line is high severity as a floor: it is a life-safety and compliance defect regardless of how small the hole is. It is critical when the building is occupied and the breach is in a wall that protects an escape route, a stair or a sleeping area, and the report should say that the fire risk assessor and the building's responsible person need to know now, not at the next meeting.

The item has to survive being handed to a subcontractor who was not there. It needs:

• Location to the wall and the point on it: level, grid reference or room either side, "above ceiling" or "in riser", and which face was inspected.
• The services, one by one, and the opening size.
• What was found: no seal, foam, loose wool, collar missing, seal damaged, no label.
• Photographs: one wide enough to show the wall line and a grid or room label so the location is provable; one close-up per opening; the other face of the wall, or a note that it was not accessible.
• Action: seal with a tested system appropriate to the service and the element, with the product named where you can; label; register; certificate before the ceiling closes. Never "make good" and never "fire foam".

The box at the end of this article is one such line. Multiply it by every penetration you found; a compartmentation survey of a mid-sized building is a hundred of them, which is why the location field matters more here than on any other defect. The inspection report guide covers how a schedule of that size is organised so that a contractor can work from it wall by wall.

What to ask for at handover

• The compartment plan and the fire strategy: which walls and floors are rated, and for how long.
• The fire stopping register: every penetration, its location, the product, the installer and the date, with photographs. In England this is part of the golden thread for higher-risk buildings; on any building it is the only way to know the work was done.
• The installer's certification: a third-party accredited fire stopping contractor (FIRAS or equivalent in the UK) and the manufacturer's installation instructions for each system used.
• Test evidence for anything unusual: an oversized opening, a mixed bundle, a product used outside its standard details.
• A pre-close inspection record for every ceiling and riser: who looked, when, and what they found.

If the answer to most of these is a shrug, the report's first item is the paperwork, and the second is a compartmentation survey with a torch. If you carry out that survey, the superintendents' page shows how a hundred numbered penetrations with photographs and grid references come out of a phone as one schedule, and the architects' page the same for a defects schedule issued under a contract.

Questions people ask

Is expanding foam fire stopping?

Ordinary polyurethane foam is not; it burns. Some foams are sold as fire-rated, and they hold that rating only in the specific opening sizes, wall types and services they were tested with, which is rarely the hole they end up in. Treat foam as a red flag unless the installer can show the test evidence for that exact configuration, and even then expect a label.

Is mineral wool or fibreglass stuffed in a hole fire stopping?

No. Loose insulation packed into an opening is not a tested seal: it shrinks, falls out when the next cable is pulled, and does nothing to stop smoke. Mineral wool is a component of many tested systems, always in combination with a coating, sealant or board that holds it in place and closes the gaps. On its own it is a hole with insulation in it.

Who is responsible for fire stopping on a construction project?

Contractually, usually a specialist fire stopping subcontractor or the trade that made the hole, and the main contractor for coordinating both. In practice nobody, which is why it is missing. The inspection's job is not to allocate blame but to record every unsealed penetration with a location, so the contractor can allocate it.

Do I need to see both sides of the wall?

Yes. A seal that is only applied on one face may be acceptable for some products and not for others, and a hole that is neat on one side is often a crater on the other. If the far side is in another tenancy or a shaft, say in the report that it was not accessed, so nobody reads silence as a pass.

How common is missing fire stopping?

Common enough that surveys of existing buildings routinely find it on most compartment lines, and that it is the single most frequent item raised by fire risk assessors in recently completed buildings. The cause is sequencing, not bad faith: services go in after the walls, ceilings close, and the hole is never seen again until someone lifts a tile.