Thermal Guide — Steel Doors & Windows

Keep the view. Lose the heat.

Steel is celebrated for its strength and remarkably slim sightlines — but on its own, it readily conducts heat and cold. A thermally broken system separates the interior and exterior steel with an insulating barrier, maintaining indoor comfort while preserving the clean architectural look that defines premium steel windows and doors.

© Secco Sistemi

What Is a Thermal Break

An insulating barrier inside the steel.

A thermal break is a non-metallic insulating barrier built into the steel profile. Instead of allowing heat or cold to transfer directly through the frame, it interrupts that path — reducing thermal conductivity and improving overall energy performance.

The result is a stronger, more efficient steel system that performs in demanding climates without compromising its elegant appearance.

Profile Cross-Section — Ottostumm W50 TB
Cut-away of the Ottostumm W50 TB thermally broken steel profile
Exterior · Heat / Cold Break — Interrupted Interior · Stable
The non-metallic barrier inside the profile breaks the conductive path between outside and inside steel — no added bulk to the sightline.

When Do You Need It

Recommended for exterior openings.

  • Exterior entry doors
  • Exterior windows
  • Sliding & bi-fold doors
  • Window walls
  • Hot, cold, or mixed climates
  • Energy-efficient building performance
Interior openings

When a thermal break isn't required.

Interior steel doors and partitions typically don't require a thermal break, since both sides of the opening sit within conditioned space. For these, our slim non-thermal profiles are the right choice.

Why It Matters

Performance without sacrificing sightlines.

A thermally broken profile lets you specify slim steel for demanding exterior applications — comfort and efficiency built into the frame itself.

01

Improved energy efficiency

Less heat lost through the frame means a system that works with your building envelope, not against it.

02

Reduced unwanted heat transfer

The insulating core keeps outdoor temperature swings from crossing straight through the steel.

03

Increased interior comfort

Warmer frames near glazing mean fewer cold spots and drafts along the opening.

04

Minimized frame condensation

Warmer interior frame surfaces resist the condensation that forms on cold, non-thermal steel.

05

Supports energy-code goals

The right category of product when a project must meet modern performance targets.

06

Slim steel sightlines, kept

The thermal technology integrates inside the frame — sightlines stay as slim as the profile intends.

California Title 24

The right category for Title 24.

For California projects, thermally broken steel is the right category of product to be looking at for Title 24 energy performance. Title 24 compliance for windows and doors is calculated using each unit's certified U-factor and solar heat gain rating.

Our systems are currently completing that certification process. In the meantime, thermally broken construction paired with high-performance Low-E glazing is the foundation Title 24 compliance is built on.

We're happy to walk your architect through where each configuration currently stands.

Our Profile Systems

Established European systems.

BlackFramed fabricates using established European profile systems, chosen for their engineering and performance history.

Thermally Broken — Exterior

For conditioned exterior openings.

Insulated profiles for entry doors, windows, and window walls where energy performance matters.

  • Secco OS2-75Thermal Break
  • Ottostumm W50 TBThermal Break
Interior Profiles

For openings within conditioned space.

Slim non-thermal profiles for interior doors, partitions, and room dividers.

  • BF-S20Signature Slim
  • Ottostumm W20Hot-Rolled Steel

Frequently Asked

Thermal break, answered.

No. Interior doors and partitions generally don't require one. Exterior openings should typically use thermally broken profiles for better comfort and energy performance.

No. These European profile systems maintain slim sightlines while integrating the thermal technology inside the frame.

For exterior applications, yes — improved comfort, reduced heat transfer, and long-term energy savings make it worthwhile, especially in climates with significant temperature swings.

Certification for our fabricated configurations is currently in process. We'll share results as soon as they're issued, and can walk through current performance targets with you or your architect in the meantime.

Build for your climate

Specify with confidence.

Whether you're designing a modern California residence or a project with demanding performance requirements, we'll help you select the right profile system for your opening, climate, and architectural vision.