Understanding T-Bar vs. Common Mull: Choosing the Right Solution for Your Design
At Awake Window & Door Co., we pride ourselves on delivering flexible and innovative solutions to meet the needs of our clients. Our T-Bar and Common Mull options provide architects, builders, and homeowners with unique ways to connect our window and door systems seamlessly while prioritizing stunning sightlines and structural integrity. Here’s what you need to know to make the right choice for your project.
Please download this handy cheat sheet for future reference:
What is a Common Mull?
A Common Mull connects multiple products, such as casements, awnings, fixed windows, patio doors, and pivot doors, either vertically or horizontally. This approach utilizes the same extrusion profile when mulling compatible products, creating a clean and cohesive look.
Key Features
- Shared Frame Profile: Most of our products are 4.5” in depth and can be mulled together using a mull clip. In most cases, the use of a mull allows more individual units to be glazed at the factory vs. On site as long as they are under 60 square feet.
- Verticals Run Through: For most (though not all) mulled combinations utilizing fixed windows, we have the ability to run vertical jambs through the configuration which results in some units being factory mulled and giving a consistent vertical line for added structure.
- Field Mulling: The expectation is that the majority of mulling is done in the field, by inserting a mull clip and connecting and then anchoring the product together. Please see our easy to use Mulling Instructions on our website.
- Enhanced Strength: A .75-inch Structural Mull Bar can be added for greater durability in high-stress installations.
Best Use Cases
- When you desire more factory glazing in an application.
- When you are trying to minimize sightline by putting two different products next to each other (i.e. fixed window next to casement, fixed window next to patio door, fixed window next to hinged door).
What is a T-Bar?
The T-Bar is an ultra-narrow 1-3/8” structural option, inspired by commercial curtain wall systems yet including residential features such as thermal break, nail fins, and steel insert capabilities.
Key Features
- 1-3/8-Inch Sightline: Perfect for projects where the thinnest possible sightline is required vertical or horizontally when bringing two pieces of glass together
- Matching Sightlines: It is very common to have large clerestories above or adjacent to our multi-slide doors. We have a 1-3/8” interlock available in our multi-slide which can match exactly the vertical 1-3/8” t-bar to create a symmetry across product families and make sightlines match exactly.
- Insert Options: In some projects, a consistent vertical or horizontal line of 1-3/8” is desired across various configurations in the project. When that line is a driver, customers can keep the t-bar, and then insert or other products (operable windows, patio doors, hinged doors, pivot doors) into the glazing cavity of the t-bar in lieu of common mulling them to a fixed window.
Best Use Cases
- When aesthetics demand the narrowest possible sightline when two pieces of glass meet (i.e. 1-3/8” vs. 2”)
- When aesthetics demand matching vertical sightlines across various products. The 1-3/8” t-bar is a perfect match to our patio door and one of the interlock options on our multi-slide product.
Factory-Assembled vs. Field Mulling: What to Expect
To balance precision and practicality, we carefully determine whether products are factory-assembled or shipped as knocked-down (KD) frames for field glazing:
- KD Frame & Field Glazed – when any of the following is true:
- Short size is greater than 96”
- Long side is greater than 240”
- Any butt glazed corner units
- Factory Assembled frame & field glazed – when any of the following is true:
- Long side is greater than 168”
- Glass greater than 100 square feet
- All 425 series using 1.375” t-bar will come factory assembled frame & glass EXCEPT when the following is true:
- Long side greater than 144”
- Glass is greater than 60 square feet
- Common Mull – Horizontal and Vertical notes
- Only 425 series fixed windows that share the same jamb, head and sill style can be built as 1 unit glazed in the factory if it falls under the dimensions listed above. Mulls across different product types always require a field mull.
A Note on Higher Costs of Inserts
Building a unit with multiple product types utilizing T-Bar inserts when not required can significantly increase costs. Be sure to evaluate your design needs carefully and consult with our team to determine the best approach and if a common mull application would work and potentially save money and sightline.
Less Us, More View
At Awake Window & Door Co., our motto reflects our commitment to maximizing glass and minimizing distractions. Whether you choose a T-Bar or Common Mull solution, rest assured that you’re investing in a product designed to deliver beauty, performance, and innovation.
For questions about mulling options or to discuss your next project, contact your local territory manager today.