Compartmentation is critical for life safety, code compliance and providing structural integrity through protection of exterior wall components of the building in the event of a fire. This is where specification and installation of a tested and listed perimeter fire containment system featuring ROCKWOOL insulation can meet code requirements and contribute to safeguarding people and property.

Because curtain walls are not fire rated, the risk of fire propagation is found at the perimeter void – the space between the edge of the floor slab and the exterior curtain wall. If a fire strikes in a high-rise building, the consequences can be serious.

At the forefront of any fire containment system strategy is the use of mineral wool insulation — the only material tested to stay in place when exposed to fire. Understanding of proper compartmentation with passive fire protection systems is critical for the safety of building occupants, as well as emergency responders.

ROCKWOOL is committed to providing solutions that help building professionals design, specify, and install durable systems for curtain wall structures.


Keep reading to see information on a NEW set of three perimeter fire containment system listings that provide unrivelled design freedom and flexibility in aluminum framed, backpan and CLT construction. 
Learn more about these systems

Critical components of a perimeter fire containment system

For a perimeter fire containment system to meet building code requirements and provide passive fire protection as intended, the following six critical design elements must be considered. The complete system must be tested and approved to ASTM E2307.

  1. Spandrel Insulation –
    ROCKWOOL Curtainrock®
  2. Fastening/Insulation Securement
  3. Stiffener/backer reinforcement
  4. Safing insulation –
  5. Mullion Covers –
    ROCKWOOL Curtainrock®
  6. Firestop sealant/smoke barrier


Perimeter Fire Application Page Assembly Solutions
Krisro Metals works closely with the ROCKWOOL team to produce highly efficient and accurate architectural products to support the curtain wall industry...

Tyler Bessey, Krisro Metal Industries

Supply Projects Manager

ROCKWOOL Curtainrock®

ROCKWOOL Curtainrock is a semi-rigid stone wool board insulation design to be used in tested perimeter fire containment systems as the insulation for the spandrel and mullion cover applications. Available in either a nominal 4 pcf density (Curtainrock 40) or nominal 8 pcf density (Curtainrock 80), these products meet the specifications of different listings requirements tested per ASTM E2307.

  • Noncombustible product with a melting point of approximately 2150 °F (1177 °C)
  • Repels water; does not rot or promote growth of mildew, fungi or bacteria
  • Can be fabricated and faced with reinforced foil facings
Perimeter Fire Application Page Assembly Solutions


ROCKWOOL ROXUL Safe is a lightweight, semi-rigid stone wool insulation that provides firestopping and acoustical properties. It is designed to fill perimeter gaps between concrete floor slabs and exterior wall systems, between firewalls and ceiling slabs, through penetrations, and around conduit pipes and duct openings through walls and floor slabs.

  • Non-combustible stone wool insulation with a melting point of approximately 2150 °F (1177 °C)
  • Does not promote smoke or flame spread when exposed to flame
  • Minimal shrinkage to maintain critical line of defence against fire
Perimeter Fire Application Page Assembly Solutions


ROCKWOOL makes it easy to specify our products. For more information about our full line of stone wool insulation products including Curtainrock 40, Curtainrock 80 and ROXUL Safe for use in perimeter fire containment systems (curtain wall) use the link to download the specifications that you need. Contact our technical department with any questions about specifications and products.

Curtain wall solutions

Through partnerships with firestop manufacturers in the North American market, ROCKWOOL offers an extensive breadth of tested systems that are tested and approved under ASTM E2307, including:

  • Galvanized steel and aluminum-framed backpans
  • Aluminum-framed systems with options for lower sill heights, shorter spandrel panels, flush-still designs, and all-vision glass; high-performance bracket system solutions are also available
  • Cross Laminated Timber (CLT) construction
  • Precast concrete panels
  • Glass fiber reinforced concrete (GFRC) panels
  • EIFS and steel stud design

NEW Flexible Design Listings

In partnership with Specified Technologies Inc., ROCKWOOL is proud to offer a set of three perimeter fire containment system listings that provide unrivelled design freedom and flexibility in aluminum framed, backpan and CLT construction. 

Each design listing covers multiple assembly options, including insulated spandrel panel, valance insulated panel, and zero spandrel systems for both field and shop installations.

Perimeter Fire Containment System Assembly Renders - 120-09

Aluminum-Framed Designs

Non-backpan aluminum-framed assemblies are offered and have been tested for a variety of system types whether factory-built unitized or field-fabricated stick construction. The options include bracket systems, continuous angle, hat channel, insulation hanger, I Mull, and flush sill/short-transom spacing.


Perimeter Fire Application Page Assembly Solutions

Aluminum-Framed Backpan Design

Insulated backpan assemblies have become increasingly popular, particularly within the unitized construction market where glaziers and fabricators are able to benefit from economies of scale during the production process by pre-insulating the glazed units. Tested assembly options include flush sill or raised transom designs with multiple spandrel types such as transparent or opaque glass panels, aluminum panels and stone panels, aluminum composite panels, and metal composite panels.

Perimeter Fire Application Page Assembly Solutions

Precast, GFRC and EIFS/Steel Stud Designs

Precast insulated and non-insulated designs offer flexibility of reduced spandrel panel height and vision panel sill height. Glass fiber reinforced concrete (GFRC) systems have been tested with tubular or stud framing, and reduced sill height. EIFS / steel-framed exterior wall designs are available that meet common steel stud configurations, offer low sill heights for windows and accept multiple exterior finishes.

Perimeter Fire Application Page Assembly Solutions

All Vision Glass Designs

All-vision glass curtain wall assemblies provide a modern design concept focused on maximizing the vision glass area for building occupants. We offer system designs that use a sheet metal pan attached to the upper transom and vertical mullions that hide the firestopping system at the floor line. The pans can be painted or finished with a look that will be visibly pleasing from the exterior of the building while occupying only a small area of the vision glass.

Perimeter Fire Application Page Assembly Solutions

Case Studies

Exterior Wall Applications

Downloads and resources

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