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Wood Exterior Window Trim: Best Materials Get Excellent Results

wood exterior window trim

Estimated reading time: 8 minutes

Exterior window trim is a purely architectural design. But this design feature is based around window elements.  Wood exterior window trim has traditionally been the material of choice. But using the best wood materials can help in easy installation and long lasting curb appeal. Using the wrong wood or other material can sabotage achieving an excellent, long lasting result.

Some new modern home looks even eliminate window trim altogether and rely solely on the window frame to either blend in or leave a small border around the glass panes.  However, I personally believe this is just a trend like skinny jeans.  

Trim around windows can elevate the look of the home if done properly using the right materials. 

For example, wider window trim on traditional craftsman style homes adds charm and character and helps anchor the house in the craftsman esthetic.  In addition, it gives the exterior facade a nice blended two-tone look while tying together belly bands and corner wrap for a unified look. 

Trim has no structural value and it doesn’t need to be included for a house to be secure against the onslaught of weather. However, it does have protection value!

Window trim is the first barrier to water penetration at a vulnerable position on the home.  Therefore, if the window wrap or caulking fails, there is a huge opportunity for water to start mold buildup, decay, and damage. 

There are other safeguards behind the window trim such as flashing tape to seal the flange from water penetration.  However, it is best not to let any water get past the original barrier in the first place.

Wood Exterior Window Trim Materials

The common materials used for exterior window trim are broadly categorized into two areas:  real wood and non-wood. I’ll examine the real wood area first, after that I’ll tackle non-wood products. 

Real Wood

Traditionally and historically, real wood exterior window trim is the material of choice.

Real wood has had a poor reputation for exterior trim use and sometimes, justifiably so.  Most wood types just can’t handle the abuse that weather conditions and exposure to sunlight dish out. 

In the past poor paint adhesion, rotting, mildew, surface cracks, warping and decay have all taken their toll on real wood, even if they have been primed with paint.

Some manufacturers prime the raw wood with primer paint. That product is commonly called Primed White Wood, or PWW.  Other manufacturers add a preservative into their primer paint to address some of these issues.  Not all manufacturers follow best practices, though. 

But there are plenty of good reasons why wood is  the best option. Let’s look at the two choices in the real wood category.

Wood Exterior Window Trim with Belco XT® Trim

Belco XT® Trim with preservative treatment installed as window trim and before final painting.

Preservative Treated XT Trim by Belco For Exterior Wood Window Trim

Preservative treated XT Trim by Belco solves all of the above issues and then some. It is ideal for wood exterior window trim and is by far the best material for excellent results.  It lands in the Primed White Wood category of wood, but it is setting the new standard for trim products both inside and outside the PWW arena. 

XT Trim has a unique process that uses a Wolman Preservative on the bare wood of each board.  After the treated wood is dry, it is painted with a quality primer and oven-baked for maximum durability. Moreover,  XT Trim has a 20-year warranty against rot.

Not only that, it comes with a budget-friendly price.

It is fairly lightweight, therefore making it easy on the installer.  This trim cuts and installs beautifully without the need for special tools.  

Like cedar, XT Trim is a real wood product that makes it naturally resistant to cracking.

Moreover, since XT Trim is a real wood product, the cut ends will accept paint just as well as the face.  

All the remarkable features of XT Trim by Belco make it the undeniable best choice for wood exterior window trim or for any category of trim for that matter,  for all climates.

For a thorough explanation of the benefits of XT Trim by Belco, stop by our website https://belcofp.com/products/xt-trim/ 



Cedar is a great material for exterior trim.  It has been used in many applications from cedar shakes to porch posts, siding, trim, and fascia. 

It is naturally resistant to rot, mold, and mildew while being fairly lightweight.  Natural cedar is strong enough to have structural use. Easily installed, it is available in versatile sizes. 

Cedar is an excellent choice for window trim based on durability and dependability alone.  However, it is by far the most expensive window trim option on the market today, and it typically isn’t offered with a warranty. 

It may be the perfect option for someone when construction costs don’t matter, but for the rest of us, the sticker shock pushes us to other options. 

Non-Wood Fascia For Exterior Window Trim

There are modern manufactured fascia options that are not all wood components or solid wood. Let’s take a look at them.

OSB Based Products

OSB Based Products are commonly used for window wrap and functions well in this arena about 90% of the time. 

Best used in arid climates OSB is strong, fairly cost-effective, easily cut, and readily available.  Because of the resin content, it is very resistant to rot, mildew and decay.

There are some downsides, however.  OSB will swell if exposed to water. Especially the cut ends will deform and not resume shape when dry.  Here’s the kicker: when swelling occurs, it is unsightly and reduces the curb appeal on a home. 

Another area where OSB falls short as window trim is in architectural styles that require the top and bottom of the window trim to extend past the side legs to give a classic craftsman look.   Unless the top and bottom trim pieces can be mitered and terminated into the ends of the legs, it will leave a very rough edge that doesn’t accept paint very well.  

Think about trying to paint the edge of a piece of OSB; it just doesn’t work. 

Fiber Cement

Fiber cement fixes the issues with OSB products in the fact that it doesn’t swell.  The cut butt ends will accept paint just as well as the face. 

It is a great option in damp and humid climates however, there are problems with fiber cement that need to me mentioned.

In arid sunny climates, cracking will be most common on the walls exposed to the sun the most. Let’s face it, in arid climates, there aren’t that many places on a house that are unexposed to direct or indirect sunlight. 

Fiber cement is heavy and brittle.  Using it is tiring on the installer.  It chips and can break fairly easily. All of this can add costs to your bottom line as you factor in labor and breakage.

As houses settle, fiber cement boards become vulnerable to cracking, which increases the potential for water intrusion down the road. 

Here’s a tip: it is always wise to purchase more boards of fiber cement than you plan on using to accommodate having pieces break during installation or handling. 

Picture of Fiber Cement Around a Window as Trim

Fiber cement trim being used as window trim. Notice the trim is being installed on top of the siding.


So, which product to use for exterior window trim?  Several factors have to be considered. 
Tally up the checklist below.  I think you’ll find that XT Trim by Belco is the clear winner for an excellent results.  

  • Budget
  • Ease of installation
  • Longevity against weather
  • 20-year warranty
  • Accepts paint uniformly
  • Lightweight
  • No special tools required
  • Does not swell on end cuts
  • Readily available
  • Strong without being brittle                                                                                                             

Moisture Resistant-Preservative Treated Belco XT® Trim used as window trim

Properly caulked and sealed preservative treated Belco XT® Trim including 1″ material installed as a window sill prior to final paint coating.

Additional Information

There are many other uses for exterior trim.  For example, trim is used as a window sill.  It has additional needs because it often has prolonged contact with water.  Here’s the link for more information about window sills on our site: https://belcofp.com/window-sill-trim/

In addition, door openings have a lot in common with windows, but they have unique trim specifications for exterior applications. Our introductory article will answer your questions about door trim: https://belcofp.com/exterior-door-trim/

One overlooked issue is design.  Yet this can make or break the street appeal of your window. For ideas on several different approaches to window trims, check out our design options: https://belcofp.com/exterior-window-trim-ideas/

Download the Window Trim Cutlist Guide

Reduce trim waste with this guide to the optimal window trim cutlist. Download the Guide

Our Happy Customers

Preservative treated, primed, and available with a combed, brushed, resawn, or smooth face. The real beauty of your home comes to life through a well made trim package.

Preservative treated, primed, and available with a combed or smooth face. These glulam columns are strong, beautiful, and enhance any exterior design. 

Belco XT®-T&G is graded smooth face with edge vees on all four edges and a textured ungraded back.

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