D.qling mulled windows

[IROM two simple double-hung windows joined togeth- I-' er, to multiple connected window units, mulled windows are a dramatic addition to any project. And, dealers are profiting from their rising popularity.

"Today we are seeing an increased number of mulled units that are significantly larger and more sophisticated than ever before," says Tom Sinning, sales manager at Marvin Windows & Doors. "Part of the reason is that homeowners want to draw more natural light into their homes and take advantage of views to the outdoors. Mulled units help add more drama to a home."

Dealers play a crucial role in the orocess,

Bill Lazor, senior brand manager for Simonton Windows, explains, "As most professionals know, mulling can be done either in a manufacturing facility as windows are constructed, or in the field by builders and remodelers. Some of the most common mulled configuration requests we get are for two or three single-hung or double-hung units joined together. We can exceed that size by comfortably mulling units up to 144 inches wide by 106 inches tall. Due to transportation issues, configurations larger than that are generally considered 'field mulls' and are done by qualified contractors."

Lazor points out that virtually any combination of windows can be mulled together to create an attractive wall of windows. Oftentimes half-rounds are mulled to the top of single-hungs and double-hungs. Another popular choice is to mull a variety of fixed geometric windows to operable windows, or mulling an assortment of operable windows together, such as when a bow window is constructed of several casements.

To properly specify mulled units for a project, the single most important aspect is educating yourself on local building codes. The American Architectural Manufacturers Association recommends becoming very familiar with the design pressure rating for the specific geographic area where the mulled units will be installed. The structural limitations associated with the mulled unit must match up with the local codes, and mulled units should never be used in a situation that cannot meet those codes.

"Discuss large mulled configurations directly with the window manufacturer prior to ordering the units," suggests Lazor. "Consult the manufacturer's technical experts on the thermal expansion and contraction of mulled units along with any limitations of the product. Many manufacturers will suggest that whenever the amount of expansion and contraction is projected to exceed the recommended maximum joint movement (or the allowable clearance), that you consider dividing up the mulled units into smaller rough openings."

Another consideration is the directional location of a wall of windows in a structure pertaining to north, south, east or west...and how the location relates to elevation from ground level. These factors all come into play when the contractor needs to ensure adequate framing is in place to secure the unit in the opening, especially for larger mulled units. Simonton recommends never shortcutting the required mullion for a given rating. Testing shows that the mullion ultimately determines the strength of the mulled unit. Working to make sure the design pressure ratings match up with the correct mullion system is critical.

Since mulled units can weigh hundreds of pounds each, it's essential that support is available in the construction to accommodate the units' specific weight. Window manufacturers can provide specific installation instructions, including information on providing the proper structural support needed for an opening.

Although mulled units are often custom-made, dealers play a crucial role in the process. Melinda Connell, marketing rep for Milgard, says dealers "order, store and deliver. We also offer the option of delivering directly to the job site. if that is what the dealer would like us to do."

"Dealers perform a very important logistical role in making sure a mulled unit gets to a job site," adds Sinning.

Mulled windows are bulky, heavy units that require the proper equipment for loading and unloading. The manpower and equipment to safely move, store and handle the mulled units are needed at manufacturing facilities, dealerships and on the job site.

Sinning suggests, "First of all, it's important to have a loading dock that sits at dock height. This eliminates the hassle of lowering or physically lifting a unit onto ground level. Second, dealers should make sure they have the proper personnel and/or equipment because the mulled units can be very large and heavy. Dealers may also have to be on hand at a job site to help the contractor get the window in place."

Mulled units should be stored on and against a flat, even surface. "Mulled windows should be stored by keeping them upright-they are often leaned onto one another," advises Connell. "They should not lay flat."

Lazor says, "While extra considerations are important. they shouldn't 'scare off industry professionals from mulled units. Stunning mulled window configurations can make any home or commercial project more appealing."