AF Series

AF [ F I R E  R A T E D ]

F R A M E  S E R I E S


Our innovative AF series blends Safety, Security and Style into one, state-of-the-art window and door frame series. To achieve this, we combine the narrow sight-line, high efficiency and extreme durability of our EBE series with internal, firebreak technology. The result is a system that aesthetically reflects our non-rated windows and doors but also possesses the fire resistance and smoke protection necessary to keep people safe and minimize property damage during the event of a fire. The versatility of this series grants designers and architects the freedom to customize their system like never before while ensuring their clients utmost safety. Additionally, the Fire Rated series has the ability to accommodate a variety of UL fire rated glazing and tested glass options to meet any specific glazing requirements.


Integrates the style of steel with fire resistance that saves lives and thermal efficiency that saves money. 



Glass Options

Thermally Broken Steel USA is one of the only suppliers of steel frames with the option of Factory Glazing.  Factory glazing insures precise, quality avoiding the inconveniences that present themselves while glazing a unit in the field (rain, temperature change, surface preparation, etc…).

The glass is locked by the glazing beads that snap on the clips fastened on the frame. To further secure the glass in the frame, high quality, black EPDM gaskets are inserted between the glazing bead and glass. Lastly, a combination of DOW 795 caulk and closed cell gaskets lock the glass in place and insure a water tight and weather resistant seal.


  • Fire Rated (20 – 90 minute)
  • Tempered (Safety Glass)
  • Safety-Rated Wired Glass
  • Laminated
  • Annealed
  • Low-E
  • Argon Gas (added between panes)
  • Satin and Stained glass
  • Leaded glass options

fire rated ADVANTAGES

  • True or Simulated Divided glazing
  • Available in single or double glazing up to 40 mm (1 19/32″).
  • UL fire rated glazing and tested glass options available to meet any specific glazing requirements.
  • Ability to accommodate custom, over-sized units.
  • Triple pane glass options available.
  • Standard Dual glazing utilizes 1/8″ (3mm) double strength glass offering durability and clarity over thinner glass.

caulk color chart

Custom colors available upon request.

Glass options are endless, so please contact us for more information. We can surely meet the requirements of your project. Also, be sure to refer to our FAQ page for possible answers to questions you may have regarding terminology and much more.

Custom Sizes

The narrow but extremely durable properties our Fire Rated series frame allows it to be available to a wide range of custom sizes and configurations. All of our custom units are designed and constructed to meet the structural and aesthetic needs of our clients. To discuss the needs and desired size of your system, please contact us to speak with a specialist.

Hardware Options

Hardware Collage 1_Thermally Broken Steel USA_Hardware





Multi-Point locking systems available for all door systems.

Flush Mounted and External closers available upon request.

Glazing Bead Options

The rectangular glazing bead is available in numerous sizes for various glazing thicknesses. It also meets all fire proof requirements without the application of visible screws or fasteners.

*All glazing bead options utilize a state-of-the-art stainless steel fastening system. 

Refer to our FAQ page for possible answers to questions you may have regarding terminology and much more.


Fire Rated

As a general rule of thumb, a door or window may not be claimed as “fire resistant” unless the entire design has been subjected to one of the following full scale, fire resistance tests: BS 476-22 (British Standard) or BS EN 1634 -1 (European Normative Standard). Both tests are certified methods for the determination of the fire resistance of non-loadbearing elements of construction. Building elements and structures are tested and further classified by their fire separation (resistance) performance and smoke tightness (insulation) according to a system that indicates the properties using a specific letter (R, E or I), as well as an index that accurately reflects the time (in minutes) for which the unit maintains its desired standards (20, 30, 45, 60, 90). “E” stands for Fire Resistance, which is defined as a units ability to prevent hot fumes from passing through. “I” stands for Insulation, which is defined as a units ability to contain the temperature level on the side not exposed to the fire.

Fire Rated Specifications

Fire Performance (E)
EI 30
Smoke Insulation (I)
Mechanical Strength/Durability
200,000 cycles
Radiation Resistance
1 meter from unexposed face

Tested by the European Certifying Labs under reference standards EN 1634-1 and EN 1634-3.


The “thermal break,” otherwise known as a “thermal barrier,” refers to the homogeneous blend of high-density polyurethane and fiberglass that runs down the center of our frames — thereby structurally bonding the two half’s together. Due to metal’s natural tendency to conduct (transfer) thermal energy, our polyurethane fiberglass resin (a non-metal) acts as a barrier to greatly reduce the transfer of such thermal energy. From an atomic perspective, metal is full of free moving electrons (electrons carry heat) and as they move about randomly, thermal energy is being transferred. For example, during the winter months, a metal (steel, aluminum, etc…) framed window or door tends to get very cold to the touch. This is due to heats natural tendency to transfer from a higher temperature to a lower temperature, as well as the First Law of Thermodynamics which states that “the total energy of an isolated system is constant; energy can be transformed from one form to another, but cannot be created or destroyed.” Therefore, to keep your home warm, you pay for some form of added energy (electric, natural gas, oil, etc…). Our solution greatly reduces this need for added energy because it reduces the transfer of thermal energy to the outdoors. Since windows and doors account for roughly 80% of thermal losses, our frames will play a huge role in boosting the efficiency of your home.Click the link below for a downloadable version of our Thermal Transmittance data.

 Thermal Transmittance (U-value) Data – US Standard
 Thermal Transmittance (U-value) Data – Metric Standard


The Fire Rated series features sight-lines as narrow as 72 mm (2 27/32″). The term “profile” refers to the physical geometry to which the frame has been formed. This profile is what determines the size of the window or door “sight-line.” As it may sound, the sight-line, is the size (width) of the “line” created by the frame. The wider the sight-line, the less viewing area available. Likewise, the narrower the sight-line, the more viewing area available. By utilizing high quality materials and state of the art machinery, we are able to create windows and doors that meet all design and structural requirements while continuing to offer the narrowest sight-line on the thermally broken market.


The innovative design of our Fire Rated series ensures superior thermal efficiency and sound insulation by utilizing triple neoprene gaskets and our extremely efficient, fiber glass infused, polyurethane Thermal Break . Units feature welded or mechanically joined sections, numerous unique glazing bead options and have the ability to accommodate true or simulated glazing. The diagram above shows our innovative Fire Rated frame series consisting of:
(1) Glazing bead, (2) Flush faced steel profile on the exterior and interior, (3) Interior Rebate Fire seal (4) External Rebate Fire seal, (5) Engineered Expanding Fire seal, (6) Inert cooling element, and (7) Thermally Broken, Fireproof resins.


The Fire Rated series is constructed using two steel profiles bonded together with our highly efficient and extremely durable Thermal Break.  The steel profiles are formed from 1.5 mm (1/16″) thick, cold rolled steel coils. This method increases the Tensile Strength of the finished product through strain hardening by up to 20% as well as controls the dimensional tolerances much better than a hot rolled steel product. With that said, the exact strength of the system depends on the overall size of the unit and the material chosen. When comparing our system to that of an aluminum window or door system, our steel options for the EBE series are 67% (500 MPa) to 150% (750 MPa) stronger than 6061-T6 aluminum (300 MPa).

The robust construction of our Fire Rated steel profiles offer the option of larger, over-sized glass possibilities. This optimizes creativity, and expresses modern architecture and style. Our state of the art models are durable and dependable. They excel far beyond the capabilities of standard aluminum framing, maximizing the potential of your windows and doors and granting architects and designers the freedom to expand their capabilities like never before.


A window or door’s ability to resist airborne sound transfer at frequencies between 125 Hz 4000 Hz is compared utilizing the STC Rating (Sound Transmission Class) which is measured in decibels (dB). Such ratings are used for windows and doors as a way to quantify (measure) the amount of “noise” allowed to transmit through them. Therefore, STC ratings are the only legitimate way to compare the noise reduction abilities for a particular window or door. It is crucial to remember that a larger STC rating directly corresponds to a higher quality of noise isolation (the ability to stop sound waves from passing through a certain partition). Typical aluminum window and door units have an average STC rating of  20 to 31. Our steel framed window and door units maintain a superior STC rating between 40 and 55.

Need Help Building the Perfect System?


Let’s build it together.

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 For more information regarding our Fire Rated frame series, please contact us.

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