Mulled Windows – Viwinco Windows Mulled Windows - Viwinco Windows

Mulled Windows

Viwinco's New Construction Mulled Casement/Transoms in white

Window mulling is when two or more window units are joined together by the frame. Viwinco offers the option of factory mulled windows, to ensure your windows arrive structurally sound and ready for installation. Mull kits are also available to allow for units to be mulled together onsite.

Our powerful structural mullion system makes it possible to create mulled windows of the same or different sizes, by adding strength and stability between horizontally and/or vertically adjacent mounted windows. Mulling windows together allows you to create expansive window walls, opening the possibility to limitless customization. Our Integral Mullion provides a continuous head and sill, perfect for joining casement, picture and awning windows. Our OceanView Structural Mullion has been tested and rated by the American Architectural Manufacturers Association (AAMA) and attaches directly to the rough opening with the use of our robust mounting bracket, delivering strength and stability, resulting in a clean finished look. Our mulled windows also come with an unobtrusive drip cap to protect the mullion from water infiltration along the top of the unit.

When it comes to personalizing your home, the level of customization that mulled windows offer is unparalleled. They allow homeowners to mix and match window styles and functionality, while simultaneously allowing tons of light to flood into the home. Mulled units create expansive views of the outside and create a powerful focal point in any room. If you are interested in seeing some of mulled units we have used on previous projects, be sure to check out our searchable photo gallery which has a wide variety of combinations.

Viwinco integral mullion

Integral Mullion
(continuous head and sill)
for mulling casement, picture,
and awning windows.

Viwinco's Structural Mullion

Structural Mullion
used to mull two or
more units together.
Interior view.

Viwinco's Drip Cap with Bracket

Drip Cap
with Bracket
to attach mullion
to the rough opening.

Viwinco H-Mull for Edgemont Replacement Windows


Used to mull Edgemont twin
and triples for double-hung or
picture units

Mulled Combination Options

Viwinco half round windows over twin, single, or double-hung Viwinco windows drawing.

Half-Round over
Twin Single/Double-Hung

Diagram of twin single or double-hung Viwinco window drawing.

Twin-Single or Double-Hung

Triple single or double-hung Viwinco window drawing.

Triple Single or Double-Hung

Drawing of Viwinco arrangement of double-hung and picture windows.



Drawing of Viwinco arrangement of casement and picture windows.


Quarter round window over picture of casement Viwinco window drawing.

Extended Arch flanked
by Arch Trapezoids over
Triple Picture or
Casement Window

Viwinco extended arch window flanked by arch trapezoid over picture or casement window drawing.

over Picture
or Casement Window

Transom window over single or double-hung Viwinco windows drawing.

over Single or

Trapezoid window over twin picture or awning Viwinco windows drawing.

Trapezoids over
Twin Picture
or Awning Window

Triple transom windows over triple picture Viwinco window drawing.

Triple Transom over
Triple Picture Window