A firestop is something designed to seal up openings or pass-throughs in fire-rated walls, ceilings or floors to slow the spread of flames. They are also known as Multi Cable Transits (MCTs) in cable pass-through situations.
In a fire-resistance rated structure, any opening between rooms that is unprotected will negate the rating, as it will allow fire to spread throughout the building in too quick a manner. Firestop devices fill said openings with materials that are fire resistant to block — at least temporarily — the spreading of flames through these gaps.
Openings that can affect the fire-resistance rating of a building include light fixtures (usually in ceilings), air and/or grease ducts (in walls and ceilings), cable pathways (usually in walls) and pipe penetrations (typically in floors and/or walls). There are several different devices available to properly restore fire ratings in these types of situations, so let's look at our options:
LIGHT FIXTURE COVERS
These covers fit around the anterior of lighting fixtures or troffers, in the area typically hidden from view (within the ceiling). They're constructed of an intumescent material that expands when it encounters flames, sealing up the surrounding area in order to block the spread of fire through the fixture. They are available for both single light fixtures and troffers for fluorescent lights in modular ceilings. Often, they can be installed quickly and easily, with no necessary tools.
Any duct that penetrates through a fire-rated wall, whether it's used for ventilation, kitchen grease in restaurants or other applications, must be properly wrapped with firestop material to maintain its rating. The duct wrap material is wrapped around the duct to completely enclose it, sealing it off and protecting it from fire damage for up to 2 hours, while simultaneously preventing smoke and flames to be spread through a facility through the ducts.
WALL PATHWAYS & SLEEVES
There are a number of solutions that are designed to protect the fire-rating of cable penetrations within walls, which include everything from protective enclosed pathway systems to sealing putty plugs to grommets with sealing foam membranes.
Pathway kits are usually composed of an outer sleeve — typically steel — with intumescent gaskets on either end. The sleeve can be sealed at either end with firestop putty. These are more suited to cable bundles. For single cable penetrations, there are plenum rated firestop grommets with intumescent filler that expands upon contact with fire.
A pipe collar protects penetrations in walls and floors where plastic pipes pass through them. It consists of a galvanized steel shell with tabs for installation via anchor bolts. This shell fits around the pipe behind the wall or under the floor and contains intumescent material inside to seal around the hole in the event of a fire, thus preventing the spread of smoke and flame between floor and wall. Though they are typically available in pre-formed, pre-sized collars, there are also wrap strip versions available that can conform to your specific pipe circumference.