Firestopping is what keeps a compartment a compartment after the services have gone through it. Every pipe, cable, duct and tray crossing a fire separating wall or floor is a hole, and the seal around it has to restore the fire resistance of the element. It is buried work, done late, by whichever trade is last on site, and it is the largest source of hidden compartmentation defects in occupied buildings.
What a seal has to achieve
The same fire resistance as the element it sits in, for integrity and usually for insulation, tested as a system with the specific services passing through it. That means the product, its thickness, the substrate, the service material and diameter, and the spacing between services are all part of what was tested. A seal is not a generic act of filling a hole.
The product families
Coated batts for large openings with mixed services. Intumescent collars and wraps for plastic pipes, which expand and crush the pipe as it softens so the hole closes. Mortars for large or heavily loaded openings. Sealants and mastics for small gaps and linear joints. Pillows for openings that are opened and re-sealed frequently. Each has a defined field of application and none is universal.
Where installations fail
Services added after the seal was made and the seal not reinstated, which is the single most common finding. Plastic pipes sealed with mastic and no collar. Cable trays sealed around the tray rather than through it. Seals applied to one face where the system required both. Gaps left at the top of a riser opening because the last cable went in from above. Every one of these is invisible behind a riser door.
Finding what a building has
Sample opening up in risers, ceiling voids and plant areas, recorded per location with photographs. A survey that reports a percentage of seals inspected and their condition is the starting point for a remediation programme. Where a building has never been surveyed, the safe assumption is that it has defects, because the trades that create them do not know they have.
Questions people ask about firestopper
Is firestopping part of the fire risk assessment?
The assessment has to consider compartmentation, and that means somebody has to look. An assessment that has never had a riser opened has assumed rather than assessed it.
Can a maintenance team seal a new penetration?
Only with the correct tested system and the manufacturer's instructions, and the work should be recorded. In practice this needs a contractor or trained staff, not a tube of general mastic.
What record should exist?
Location, system used, services passing through, date, installer and a photograph. Without it, the next survey starts from nothing.