What is Fire Stopping?
Fire stopping refers to the materials and methods used to seal openings and joints in fire-rated walls and floors.
In practice, it includes:
- Sealing service penetrations (pipes, cables, trunking, ductwork)
- Closing linear gaps at junctions (e.g., wall-to-floor)
- Installing cavity barriers where required
The goal is to maintain the building’s designed fire-resisting lines so fire and smoke don’t move uncontrolled through compartments, risers, or voids.
Where fire stopping shows up in real buildings
If you manage occupied buildings, the most frequent locations are:
- risers and service shafts
- plant rooms and electrical intake cupboards
- corridor ceilings and above ceiling voids
- behind service boxing
- around kitchens/bathrooms where M&E routes are dense
These are also the places where “small” works (new cabling, pipe alterations) can create new breaches.
Why It Matters
- Maintains compartmentation lines
- Prevents fire and smoke spread
- Required by Building Regulations
For dutyholders and property teams, the practical issue is that fire stopping is often disturbed by change: refits, M&E works, additional cabling, or incomplete making-good.
Fire stopping vs compartmentation
People often use these terms interchangeably:
- Compartmentation is the overall fire-resisting strategy: walls, floors, shafts, and protected routes.
- Fire stopping is the set of solutions used to keep those lines intact at openings and joints.
Most failures happen at the interfaces — particularly penetrations that were never sealed, were sealed incorrectly, or were later disturbed.
What good looks like (in plain terms)
“Good” fire stopping is not about a neat finish - it’s about using a suitable, tested system for the specific penetration and substrate, installed in line with the system documentation.
You should be able to answer:
- What system was used for this penetration/joint?
- Is it appropriate for the services, opening size, and substrate?
- Is it installed to the system requirements (depths, backing materials, collars/wraps etc.)?
- Is it recorded clearly so it can be audited later?
If you can’t answer those questions quickly, treat it as an indicator that you need a more structured approach (survey + register + remedials + close-out).
What to record (minimum) so it stays under control
Fire stopping programmes often fail later because teams can’t prove what was installed or where. A lightweight register is usually enough.
| Field | Example | Why it helps |
|---|---|---|
| Reference | RS-01-L3-FB-07 | Links inspection, remedial, and close-out |
| Location | Block A / Riser 1 / Level 3 / Face B | Lets someone find it without “local knowledge” |
| Service type(s) | Mixed cables + tray | Drives system selection and competence |
| Substrate | Masonry wall / slab | Affects suitable system options |
| Defect | Unsealed opening around tray | Clear scope for remedials |
| Priority + target date | Planned / 2026-03-15 | Makes it a programme, not a list |
| Close-out evidence | Photo link + notes | Defensible handover and future audits |
Common Issues
Common issues we see in real buildings include:
| Issue | What it usually looks like | Why it matters |
|---|---|---|
| Penetrations left unsealed | Daylight around pipes/cables, gaps behind tray | Direct smoke/fire path through a fire line |
| “Stuffed” openings | Foam, rags, loose mortar with no system | Often fails audit and may not perform as assumed |
| Wrong system for the service | Sealant used where collars/wraps are required | Plastic pipes can melt away and open a void |
| Poorly reinstated risers/boxing | Gaps at edges, missing linings, loose boards | Creates hidden paths within shafts/voids |
| Missing/damaged cavity barriers | Voids not subdivided, barriers absent or broken | Allows rapid hidden smoke/fire spread |
| No records | “We think it’s been done” with no IDs/photos | Forces re-surveys and repeats work |
What to ask for when scoping remedials
If you’re procuring a remedial programme, insist on:
- a defect register with precise locations (block/level/room/face)
- clear priority definitions (urgent vs planned)
- an approach that references suitable system types for each defect category
- confirmation of exclusions and assumptions (e.g., “behind fixed boxing not opened”)
How to approach fire stopping (practical steps)
- Start with the risk picture - work from the FRA and any compartmentation reports.
- Survey and scope - identify defect locations and agree priorities.
- Remediate using suitable systems - install to manufacturer specifications and tested system documentation.
- Record and hand over - provide evidence and a clear record of what was installed.
FAQs
Is expanding foam acceptable for fire stopping?
Not as a general assumption. Fire stopping should be based on suitable, tested systems for the specific opening, service types, and substrate. Ad-hoc materials are a common reason defects fail audit.
Do we need a full compartmentation survey before doing any remedials?
Not always. You can start with targeted surveys in high-risk areas (risers/plant) and build a register over time. The key is that works are tracked and evidenced.
How do we stop new penetrations creating new breaches?
Set a site rule: any new penetration must be made good to an agreed standard and recorded (location + system + evidence). Without that, remediation becomes a repeating cycle.
Related pages
Note
This article is general information and isn’t a substitute for a site-specific fire risk assessment or professional advice.