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Cased vs. Kerfed (Trimless) Windows

cased vs kerfed windows

Over the past 15 years, more and more of our homeowners have sought ways big and small to update their design aesthetic as well as creatively and cohesively integrate traditional, transitional, and modern elements into their custom homes. One design selection that makes a big impact throughout the interior of the home is whether to go with CASED windows or KERFED (aka trimless) windows.

When considering what kind of window trim treatment you’d like for your home, think about how you would like your windows to integrate into the walls. Several factors affect this, including the thickness of the walls and window frames, the type of window frame, and the interior design aesthetic you’re going for. Ultimately, you’ll want to ask yourself if you’d like your windows frames to stand out and draw attention, or if you’d like a more seamless, understated transition from the window to the rest of the wall. Both CASED and KERFED (trimless) interior window options are detailed in this article.  

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Window casing is the functional (and decorative) molding used to frame your windows. In the past, window casing hid the inner workings of the window’s sash weights, but today’s trim is mostly used for decoration as well as to hide any gaps or imperfections.

Including casing around your windows fits very well with a more TRADITIONAL interior design aesthetic. Moldings that surround all four sides are often called complete casings, but you can also consider including just sills and header moldings. Typically, whatever casing treatment is used on the windows matches or cohesively coordinates with the door casings.

Cost-wise, for cased windows, you’ll spend more on trim material and labor as well as a bit more on painting, but you’ll potentially save on drywall detailing.

Here are several photos that illustrate CASED WINDOWS:

cased windowscased windows 2cased windowscased windows


If you’re hoping to incorporate more of a TRANSITIONAL or MODERN design aesthetic in your home, there is a good chance you’ll want to consider foregoing interior window casing altogether. As you’ll see in the photos below, kerfed (aka trimless) windows are a cleaner, sleeker way to have your windows integrate into the walls.

One way to install trimless windows is to return the drywall back into the window opening. This is the most simple and clean kerfed treatment and eliminates the need for any additional trim which will save on trim material and labor costs. However, because drywall is not a highly durable material, you will spend a bit more on high quality drywall labor to perfect and reinforce all perimeter corners with drywall corner beads. There is a very good chance with drywall-return kerfed windows that you will need to regularly touch-up the paint on the sills and surround.

Here are several photos of KERFED WINDOWS with a DRYWALL RETURN:

kerfed windowskerfed windows
kerfed windows

Another way to install kerfed or trimless windows is by using jamb extensions. A jamb extension is an interior piece of trim that extends the full depth of the wall. Typically, it matches the material of the window frame itself which gives the impression that it’s actually an extension of the window frame. Sometimes, the jamb extension is painted the same color as the surrounding drywall to make it virtually disappear.

Cost-wise, the kerfed jamb extension treatment costs more than the kerfed drywall returns because it uses more material as well as labor due to the added complexity of installation.

Here are several photos of KERFED WINDOWS with a JAMB EXTENSION:

kerfed windows

kerfed windows

kerfed windowsWe hope this article has been helpful in illustrating the difference between cased and kerfed (trimless) windows. Choosing which window trim treatment you’d like in your custom home will be one of the earliest design selections you’ll need to make with your builder as they work to compile a comprehensive cost projection for your home. Happy building!

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Marie Sims

As a veteran team member of Sims Luxury Builders, Marie enjoys sharing what she’s learned with the world.


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