The Real Cost of Exterior Window Trim

exterior window trim

Can longer trim lengths save you money in the long run? This article examines the installed trim lengths for four of the most common exterior window trim openings. Find out how your takeoffs and POs compare to the installed footage. 

Average Exterior Window Trim Measurements

The average new home will have 15 windows. The most common widths are 24”, 28”, 32”, 36” and the most common heights are 36”, 48”, 60” and 72”. With these measurements in hand, we analyze an eleven-window package of various window sizes and compare the trim options to see which length is most optimal. 

Nearly all windows are ½-inch shy all the way around to make sure they fit the rough opening. Thus a 3060 is actually 35.5” x 71.5”. For our purposes we will trim the windows with 1×4 (net width of 3.5”).  

30,60 and 40,50 Windows

On the left is a 30,60 and right is a 40,50. Notice they require the same amount of inches, 228” even though the 40,50 window is 2 square feet larger. Note: Diagonal corner cuts should never be used. When the caulk joints open, water can work its way behind the window into the wall assembly.


Navigating Material & Reducing Waste

In a perfect world with zero waste, these windows need 2,468 inches of trim material.

The goal is to find out how close each length can get to the magic number of 2,468. We used a handy cut optimizer to get our totals.  Since we are still in a perfect world, neither example factors in any broken, knotted or damaged boards. The first layout shows the cut totals and optimization plan for 16’ sticks. 

Exterior Window Trim Results

Fiber cement only comes in 12’ lengths so it takes 20 boards to make all your cuts. In other words it takes 2,880 inches to cover the 2,468 for the windows. The fiber cement waste factor is 16.7%.  Solid wood comes in many lengths, but 16’ is the most common. It takes 14 boards or 2,688 inches to trim the windows. In comparison, Belco XT® Trim‘s waste factor is 8.9% or more than 46% less than the fiber cement.

But of course, no one builds in a perfect world. Knowing the ideal numbers can help motivate your vendors and suppliers in the quest for continual improvement.

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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