Perimeter Fire Containment

What is Perimeter Fire Containment (PFC)?

Architects and curtain wall designers have long recognized that the void created between the floor slab and exterior wall if left unprotected, would allow fire and smoke to propagate to the floor above. The logical fix seemed to be to fill the void with fire-resistant material. However, if the void is simply filled with mineral wool and a portion of the spandrel area is left unprotected, the curtain wall will fall, causing the mineral wool to fall out of the void. Once the mineral wool at the void is lost, fire will propagate through the opening, allowing fire to engage combustibles in the floor above.

Mineral Wool Insulation – Mechanically Attached

UL/Intertek Approved Mineral Wool Spandrel Insulation

Reinforcement Member Mechanically Attached

Compression-Fit UL/Intertek Approved Mineral Wool Safing Insulation Not shown: Curtain Wall Anchor Protection

Protect Mullions with UL/Intertek Approved Mineral Wool Mullion Cover Insulation

Smoke

Architects and curtain wall designers have long recognized that the void created between the floor slab and exterior wall, if left unprotected, would allow fire and smoke to propagate to the floor above. The logical fix seemed to be to fill the void with fire resistant material. However, if the void is simply filled with mineral wool and a portion of the spandrel area is left unprotected, the curtain wall will fall, causing the mineral wool to fall out of the void. Once the mineral wool at the void is lost, fire will propagate through the opening, allowing fire to engage combustibles in the floor above.

Perimeter Fire Containment is designed to prevent flame and hot gasses from entering the room above via the void created at the intersection of the floor slab and the interior of the exterior wall assembly. WHY is this necessary? THE ANSWER: The unprotected void at the edge of slab becomes a chimney or flue for fire to rage up the inside of the building, transmitting fire from floor to floor in the building. Often overlooked is how much exposure is actually created by the void at the edge of the building. A small building with a perimeter of 200′ x 200′ and a typical void of 3″ creates 200 square feet of open area that will allow smoke and hot gasses to flow freely to the floor above. Multiply this open area times the number of floors and the risk to life safety of the occupants and first responders becomes a magnitude unthinkable to a building owner or community.

Mineral Wool Insulation – Mechanically attached

Mechanical Attachment- is defined as the positive connection of fastening devices by welding or screw- attachment of curtain wall insulation. Mechanical attachment is typically required for aluminum-framed curtain walls.

Reference UL/Intertek system for type of fastener as well as spacing of fasteners.

Types of fasteners cannot be mixed and matched from tested listed system to system. Fastener installation is specific to tested/listed system.

Caution- adhesive or glue applied fasteners will not adequately perform at under fire conditions.

Curtain Wall Insulation is not generic. Manufacturers use proprietary formulations, patented technology around fiber formation, fiber optimization and other product performance attributes when it comes to perimeter fire protection. Mineral wool insulation products that are suitable for thermal/acoustical applications may not be suitable for fire containment assemblies.

Check with mineral wool manufacturers to determine the correct insulation product that has been tested to ASTM E 2307.

Mineral wool spandrel insulation needs to be slightly oversized to fit within spandrel opening. There should be no gaps or spaces between framing and edges of curtain wall insulation. These gaps would allow for flame and hot gases to pass through any openings.

Typically vertical seams are not allowed without proper reinforcement member to support the seams.

Horizontal seams allowed, however, reference tested listed system for location and number of seams allowed.

Spandrel insulation typically foil faced on one side. Foil facing (FSK or FSP) provides a vapor barrier. Seams at spandrel insulation edges to be taped with aluminum foil tape to provide continuous vapor barrier. Reference tested/listed assemblies.

Spandrel Insulation installed flush with interior face of the framing.

Min. 1” air space required between spandrel insulation and glass.

Spandrel Insulation to be mineral wool, check UL or Intertek Listing for approved manufacturer.

UL systems will list spandrel insulation by product name, manufacturer and required thickness and nominal density.

Exterior wall Insulation to be mineral wool, check UL or Intertek Listing for approved manufacturer.

UL systems will list Exterior wall insulation by product name, manufacturer and required thickness and nominal density.

Exterior wall Insulation typically friction fit to completely fill all stud cavities of curtain wall above and below top of slab. See specific system for details. Some

UL/Intertek assemblies allow for glass fiber insulation in the stud cavity for some steel-framed exterior walls.
(note: all ASTM E2307-listed assemblies for aluminum-framed curtain walls require mineral wool insulation)

Reinforcement Member Mechanically Attached

Some form of backer/reinforcement is required in perimeter fire containment systems for appropriate backer/reinforcement..

This is required to keep the Spandrel insulation from bowing due to the compression of the safing insulation within the void between the floor slab and exterior wall.

If proper compression is not maintained, then voids created at the cu