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Your Guide to Replacing Windows in a Log Home

4 common questions (and answers) about log home window replacement.

Illustration by Randy Sweizer
Back in the day, most log homes were built with wood-framed windows. Though seemingly right in line with an all-wood home like a log home, over time, these windows can become difficult to open or close, either due to expansion/contraction with the weather or because years of paint build-up has caused them to stick. 
If a home’s been built in the past 10 to 15 years, chances are the windows are aluminum or vinyl-clad and are in good operational order. However, even if they function well, recent advances in the window and door industry have brought an abundance of exciting new products to the marketplace, and you may be thinking about taking advantage of their benefits. These new windows are Energy Star rated, have better insulation properties and enhanced features, like argon-gas filled cavities or low-E coatings that protect against UV rays.
But log home window replacement can be daunting to a homeowner. As a builder and remodeler, I’m asked the same questions about replacing windows in a log home time and again, so, I thought I’d share my Q&A top three with you and lend some peace of mind.
Let's start with some common terms you'll need to know:

Window Trim Terminology

Apron: A flat piece of trim immediately below the stool of a window.
Casing: The finished pieces of wood around the perimeter of a window.
Extension jambs: The wood strips nailed to the inside edge of jambs to make up the difference in depth between window and wall.
Stool: The flat piece of wood upon which the window shuts down.
Window buck: The square or rectangular box that’s installed where the window will go. The window is attached to the buck rather than to the logs so that it will remain stationary as the logs expand, contract or settle.

Q: When shopping for a replacement window, how do I know what size to buy? 

A: First you have to remove the exterior trim so you can see the perimeter of the window itself and measure its length and its height. That’s your rough opening and the measurement you’re going to use when ordering its replacement, not the dimensions of the trim. That’s hugely important, because the trim always measures larger than the actual window opening does. Then measure the jamb (the vertical sides of the opening). The new window should have the same jamb size as the width of the log. There is something called a jamb extension, which can fill the depth of the wall space from the inside face of the window frame when the opening is not a standard size; however, this process is more expensive. It’s better for your contractor and your budget to buy a window with the correct jamb and rough opening proportions. 

Q: Can I enlarge my existing window openings? 

A: Usually, as long as you have what’s called a “continuous header” — one solid log going the full length above the window space. You typically can’t put a window where a butt joint is supporting a roof load. In other words, if your wall employs shorter logs that butt against each other to make the length of the wall, and one of those joints would fall above the window, it wouldn’t be structurally sound. 
You also have to consider how your logs were secured. Do you have a through-bolt system in your house, a lag-bolt (12-inch lag screws) system or did the builder use pole-barn-style nails? A through-bolt system could limit your expansion capabilities because you can’t cut through the bolt. If it’s a lag-bolt, you can take those out, but take care not to hit the bolt with the saw. Barn-nails are easy to remove or relocate.

Q: Do I need to be concerned with log settlement?

A: Not really. Chances are if you’re replacing windows in a log home, the house has already been around for a while. Most log homes are completely settled within five years. You’re better served to look for signs of rot, where water may have penetrated below the jamb, collected on the sill and settled into the log. A few quick pokes of a screwdriver into the surface will tell you if the log is nice and solid.

Q: What is a window buck? 

A: In modern log home construction, a window opening will have what’s called a “buck,” which is a stick-framed box attached to the log walls allowing the logs to slide while the window itself stays static. Older log homes may not have window bucks, however. If yours does not, you’ll want to install them so that there’s a flat surface for the new windows to attach to, versus trying to attach the window to the logs themselves.
See also Choosing the Perfect Windows
Dan Mitchell owns Eagle CDI in Tennessee and has built close to 100 log homes in his 30-year career. He is the 2017 President of the Greater Knoxville HBA.

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