Thermally Broken vs Standard Aluminum Storefront Frames
Aluminum is strong, light and durable, but it moves heat quickly. A thermally broken frame splits the aluminum into inside and outside halves joined by a low-conductivity strip. A standard frame is solid aluminum from outside to inside.
Choose thermally broken frames if…
- Winters are cold or summers are very hot
- Condensation or frost on frames has been a problem
- The project must meet current energy code
Choose standard (non-thermal) frames if…
- The climate is mild and the space is lightly conditioned
- The opening is interior or in a vestibule
- Budget is tight and code allows it
Thermally broken frames vs standard (non-thermal) frames: how they compare
Relative ratings from 1 to 5 (5 is best) for typical commercial storefront use. Your building, climate and budget can change the answer.
| Thermally broken frames | Standard (non-thermal) frames | |
|---|---|---|
| Construction | Inside and outside aluminum joined by polyamide or polyurethane | One-piece aluminum through the frame |
| Heat flow | Much lower through the frame | High: the frame acts like a heat bridge |
| Inside frame temperature | Close to room temperature | Close to outside temperature |
| Condensation | Rare in normal conditions | Common in cold weather |
| Cost | Higher | Lower |
| Best fit | Exterior storefronts in most U.S. climates | Interior glass, mild climates, vestibules |
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Related matchups and guides for the same decision.
How a thermal break works
Two common methods are used. Pour-and-debridge fills a channel in the extrusion with polyurethane, then cuts away the metal bridge. Strut systems slide polyamide strips between separate inside and outside extrusions. Both stop the frame from carrying cold or heat straight through to the room.
Why condensation matters
When warm, humid indoor air touches a cold frame, water forms on it. Over a winter that means wet sills, damaged flooring, mold risk and corrosion. Thermally broken frames keep the inside surface warmer, which is often the deciding factor for restaurants, medical spaces and cold climates.
The glass and frame work together
A high-performance insulated unit in a non-thermal frame still loses heat through the metal. For full benefit, pair low-E insulated glass with a thermally broken frame and warm-edge spacers.
Thermally broken frames vs standard (non-thermal) frames: common questions
Are thermally broken frames required?
For new and fully replaced exterior storefronts, energy codes in many climate zones effectively require them. Interior and some mild-climate applications may not.
Can an existing storefront be thermally upgraded?
Not by modifying the frame itself. Options are replacing it with a thermally broken system or adding interior secondary glazing.
Do thermally broken frames look different?
From the outside, usually not. Profiles can look the same, though frames are often slightly deeper.