New solutions address building professionals’ biggest pain points in building mulled assemblies.

Keeping up with a popular home building trend can be a challenge—especially when the trend requires extra planning, specifying and installation care. Such is the case with homeowners’ renewed interest in large window walls that open spaces to the outdoors and create the opportunity for impressive views. Builders know, however, that these walls come with equally impressive requirements to make their vision come to life.

Combining windows into large assemblies is a smart, affordable and certainly a beautiful way to let light in and open up a space—but attaching windows together to form an aesthetic, energy efficient window wall system comes with its own set of challenges.

Uncertain Structural Performance. As window assemblies grow larger, structural performance comes into question. How does the assembly handle wind loads, and air and water resistance? How does it perform in a coastal environment?

AAMA 450 Certification. Does the window wall meet American Architectural Manufacturers Association (AAMA) standards? Has it been tested to minimize callbacks and the even more costly possibility of litigation from installing an unproven assembly?

Difficult Field Conditions. Field mulling is seldom ideal. Materials, weather conditions and lack of assembly stations often work against the level of precision and craftsmanship expected from factory mulling.

Lack of Ordering Confidence. “What did I forget?” is an understandable question when ordering mulling sealants, fasteners, clips, mull caps and other accessories. With so many parts, something is bound to be forgotten, which then causes delays.

Hard-to-Find Resources. There aren’t many architectural detail manuals (ADMs) that present all of a manufacturer’s performance-tested mulling options in one place, complete with tributary width and span detail.

For every residential architect, developer, builder, general contractor, subcontractor and installer who has faced one or more of these issues, there’s good news, says Jeff Siverhus, a Senior Product Manager for Marvin.

First-Of-Its-Kind Mulling Solution

Introduced in January at the International Builders’ Show, our new focus on simplifying mulling processes for building professionals has customers’ needs at heart.

“We’ve worked hard to address builders’ window wall concerns,” says Siverhus.

Our focus on providing architects with AAMA 450 certification transparency can help a designer determine if a particular window wall assembly achieves code before the order system.

For example, our new ADM features dozens of performance charts across 11 assembly types. While the International Building Code requires either physical testing or calculations to determine performance ratings, we use both to determine performance grade (PG) ratings. Each chart in the ADM presents mullion performance ratings based on our high internal standards, showing a PG of 20, 30, 40 or more. The dual determination presents a more accurate picture of the mull material’s allowable stress. That insight offers designers and specifiers more design range and ordering confidence—saving time and trouble.

The all-inclusive assembly solution also helps speed construction timelines by incorporating all of the necessary fasteners, clips, caps and other parts—which reduces specifying time and the risk of missing parts and lost time at the job site.

When Field Mulling Is Required

We recognize many window wall projects ship in sub-assemblies that must be mulled at the jobsite. As such, we are releasing a Prep for Field Mull option, which means window walls that won’t fit on a truck if mulled in a factory will be delivered in large sub-assemblies. “All mull components that can be applied in the factory will be. All necessary components are automatically included in the order and cut to length for quick on-site assembly. Just follow the instructions and the assembly is AAMA 450-certified,” explains Siverhus of the process.

Home builders looking for a simpler, more confident way to meet homeowners’ window wall needs now have a proven win-win solution, says Siverhus. “It’s time home builders had a surprise-proof mulling option that installs easily and performs great,” he adds.

Posted by:Marvin

Marvin is a fourth-generation family-owned and -operated business, headquartered in Warroad, Minnesota, with more than 5,500 employees across 15 cities in North America. The Marvin portfolio of products for builders, architects and homeowners is designed to provide exceptional solutions for any project with a focus on creating better ways of living. Marvin products are distributed nationally through a network of independent dealers and are also exported internationally. Visit to learn more.

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