Firestopping and Penetration Seals
for Rated Walls and Floors
A rated wall or floor holds for its rated period until something passes through it. At that opening the rating is void. Firestopping is what reinstates it, and which system does the reinstating depends on what is passing through and what that thing does when it gets hot. Toggle the section below to see all three states.
In service: a steel pipe and a uPVC pipe of the same diameter pass through one rated wall. The steel pipe has fire-rated sealant in its annular gap. The uPVC pipe has an intumescent collar on the exposed face. Every dimension shown, the annular gap and the wall thickness, is written into the certificate for the system that seals it.
Auto-plays on scroll · tap to switch. The third state is the most common defect on site: a plastic pipe sealed as though it were a metal one.
What decides the system
The question that decides a firestop is not what the opening looks like. It is what the penetrant does when it gets hot.
Steel and copper pipes and conduits. Metal stays put. It does not burn and it does not collapse, so the only breach is the annular gap between the pipe and the edge of the opening. Small clean gaps take a fire-rated sealant, acrylic where movement is limited, silicone where the joint moves or is exposed to weather, graphite-loaded where the system calls for expansion. The complication is heat, not collapse. A bare metal pipe conducts enough heat to ignite material touching it on the unexposed face, which is why some tested systems require local insulation either side of the seal.
Plastic pipes. uPVC, CPVC, PP and HDPE do the opposite. They soften and burn away, leaving an open bore the full diameter of the pipe. Sealing the gap around such a pipe achieves nothing, because within minutes there is no pipe. These take an intumescent collar fixed to the face of the construction, or a wrap set into the opening, sized to the pipe diameter and the wall or slab type in the tested system. Whether the system needs protection on one face or both is set by the test, not by the site.
Cables. Metal conductors stay, sheaths and insulation burn, and the gaps around a bundle are irregular. A few cables through a modest opening are sealed with a fire-rated mastic. Larger openings, cable trays and busbars are closed with a coated mineral wool batt, where the batt fills the void and an ablative or intumescent coating on both faces seals it and reacts under heat. Where services will be added or removed over the building’s life, a modular transit block keeps the seal certified through the change.
Large and mixed openings. Shafts, risers and multi-service openings take fire-rated mortar or a board system, both widely specified in India for floor openings serving vertical shafts. Mortar suits permanent openings where the service mix is fixed. Boards and coated batts suit openings that may be reopened.
Openings that stay open. Air transfer openings in a rated wall or door cannot be sealed, because they have to pass air in normal use. These take an intumescent air grille, which holds the free area open in service and closes it under heat.
Retrofit and temporary work. Firestop pillows close cable openings during construction and in areas under change, and are removable and refittable. Putty pads seal electrical back boxes where they interrupt a rated partition, which is a common omission on residential and hospital projects.
Openings formed in advance. A cast-in device is placed in the slab before the pour and carries the intumescent element in the device itself. A plain sleeve, steel or plastic, only forms the opening. It creates a clean hole for a service to pass through later and is not a firestop on its own. The seal goes in or around it afterwards. Some proprietary sleeves do carry a rating; assume yours does not until the test report says so.
Linear joints. A gap between two building elements, at the head of a wall, at a floor edge or in a movement joint, is not a penetration and is not tested the same way. Head-of-wall and perimeter joints move, so the seal has to accommodate the stated movement while holding integrity and insulation.
In one line each
- Metal pipe or conduit: sealant for small gaps, mortar or coated batt for larger openings, insulation where the system calls for it.
- Plastic pipe: collar or wrap, never plain sealant alone.
- Cables, small: fire-rated mastic. Cables, large or mixed: coated batt, or a transit block where services will change.
- Shafts and large openings: mortar or board system.
- Air transfer opening: intumescent grille.
- Electrical back box: putty pad.
- Temporary or changing: pillows.
- Linear joint: a joint seal tested to the movement, not a penetration seal.
Firestopping, penetration sealing, fire stop sealing: what specifiers mean
Indian tender documents call the same work four names, so it pays to be precise on the BOQ. Fire penetration sealing system is the usual BOQ line, often written as providing and fixing a named material in a floor or wall opening. Fire stop sealing system is the common alternate. Penetration seal is the term the test standard uses. Firestopping is what the consultant writes in the specification. All four describe the same thing: reinstating the fire resistance of a wall or floor where a service crosses it.
A linear joint seal is a different item. It closes a gap between two building elements rather than the space around a service, and it is tested under a different part of the standard, so a certificate for one does not support the other. Head-of-wall, floor-edge and movement joints fall here.
Both are distinct from a cavity barrier, which closes a concealed cavity in a facade or void rather than an opening in a rated element. Different junction, different tested system.
The word sleeve causes the most confusion. Most sleeves are formers. They create a correctly sized opening and carry no rating. A firestop goes in or around them afterwards. A minority are proprietary sleeves with the intumescent element built in, and those are specific tested products rather than a general category.
Getting the vocabulary right matters because of what a certificate covers. A firestop is certified for a tested configuration: the construction type and thickness, the service type and diameter, the annular space, the orientation, the number of services in the opening. Change any one and the test evidence may no longer apply. A collar certified for a 110 mm pipe in a 150 mm slab is not evidence for a 160 mm pipe in a 115 mm block wall, and having used the same product before is not evidence for a different detail.
What standard are firestopping systems tested to in India?
Penetration seals are tested to EN 1366-3 and linear joint seals to EN 1366-4, with results classified to EN 13501-2 as an EI or E rating for a stated period. EI covers integrity and insulation; E covers integrity alone. Older specifications reference BS 476 Part 20 and Part 22, and some tenders call the American framework instead, ASTM E814 with listing under UL 1479 or FM 4990. Check the edition on the certificate. Testing to a withdrawn edition does not support a current performance claim.
Does NBC 2016 or NBCS 2026 apply to my project?
NBC 2016 was withdrawn on 30 April 2026 and replaced by SP 7:2026, the National Building Construction Standards. NBCS 2026 is advisory at BIS level and becomes binding only where a state or local authority has written it into its building byelaws, so several jurisdictions are still working to NBC 2016 while their byelaws catch up. The operative document is whichever version your approving authority has adopted. Confirm it before the specification is issued rather than after.
Why does a plastic pipe need a collar when sealant works on a steel pipe?
Because the pipe will not be there. A steel pipe holds its shape in a fire, so the annular gap is the only breach and a sealant closes it. A plastic pipe softens and burns back, leaving a hole the full bore of the pipe, and sealant around the outside of it seals nothing once that happens. The collar carries intumescent material that expands under heat and crushes the pipe closed before it disappears.
Does a fire-resistant cable still need a penetration seal?
Yes. A fire-survival cable is engineered to keep a circuit running while a fire burns around it, which is a property of the cable along its length. It says nothing about the wall it passes through. The cable keeps the circuit alive and the seal keeps the compartment intact. Two requirements, one location. More on where each product applies.
Can one certificate cover several penetrations in the same shaft?
Only if the tested configuration covers them. Multi-service systems are tested with a stated combination of services, spacings and opening size. A shaft carrying a different mix, or the same mix at closer centres, sits outside that test. Where the mix is uncertain or will change, a system tested for mixed services or a modular transit block is the safer specification.
Specifying or pricing firestopping? Send the service type and size, the construction it passes through, the rating required and the opening detail, and we will match it to a tested configuration and supply the certificate for that configuration. Supply, or supply, installation, testing and commissioning.