Choosing and Installing Windows

Choosing Windows

You can get really confused choosing windows these days, but the job doesn’t have to be complicated, at least as far as your cabin goes.

1. Start by choosing double-hung models with divided lites. Some manufacturers call these “grilles”, and though they are fake in most windows these days, they add a surprising amount of good looks to any traditional building.

2. Visit to find manufacturers with products that have met independent performance standards for energy performance and integrity. Click on the link for “Approved Manufacturers” for a list of names. We chose North Star windows for our cabin. There are many other good brands out there.

3. Consider innovative features. Triple-glazing not only saves energy, but reduces the tendency for windows to fog up in cold weather. Pre-finished window jambs are another option worth looking at. The imitation woodgrain on our windows is applied to the vinyl window sashes themselves and the window jamb. It’s tougher than wood, completely convincing in appearance, and impervious to water stains should you accidentally leave the window open when it rains.

When it comes to installing windows, the process is simpler than it looks after you’ve seen the next video.

Installing a Window

There’s more than one way to install a window properly, and the most practical window installation details will vary depending on window design. Here’s how I’ve come to install windows over the last 25 years:

VIDEO: Installing Windows

1. Set a window in it’s opening with two pairs of wedges at each side, both on the bottom. Have the wedges adjusted in relation to each other so they hold the window up about 1/2” to 3/4” off the bottom of the rough opening. Most windows include exterior molding (called “brick mould”) preinstalled, so this means the windows need to be set into position from outside the cabin. In the case of our cabin, we used polyurethane caulking on the back face of the exterior molding, to seal the window with the surrounding waterproof wall membrane. Some windows include flanges on the outside edges of the exterior molding, made for anchoring windows with large-headed nails. The windows we installed are not held in place mechanical in any way, but they’re solid just the same. Very solid. Spray foam is the reason why. It holds every bit at least as well as nails or screws.

2. Check that the window is level, adjusting the thickness of pairs of wedges at the bottom of each side accordingly. Aim for a similar size gap at the bottom and top of the window.

3. Install another pair of wedges at the top of each window, along the sides, adjusting their relative thicknesses so they hold the window firmly while also having the sides of the window jamb straight up-and-down.

4. Add more pairs of wedges at each corner, to lock the window in place.

5. Next, you need to make a spacer to support the middle part of the frame and prevent it from bowing inwards while foam is applied to the gap. Cut a piece of scrap 1×2 1/8” longer than the interior dimensions of the window frame at the top or bottom, then slip this wood in between the frame at the middle. Install wedges in the gap at either end of the spacer, to hold the spacer in place. Your spacer is slightly longer than the width of the window to allow for any springing inwards that might occur after the removal of the spacer because of foam expansion.

6. Fill the gap between window and rough frame with low-expansion, low-pressure foam. This is different than just low-expansion foam and it’s much less likely to cause inward bowing of the window frames. Even with low pressure foam on your side, apply only an inch or two of foam in the deepest recess of the gap first, then let it harden before adding more. Window frames that are bowed inwards make it difficult or impossible to open and close the window, so you want to take every measure to avoid trouble.

7. Finish filling the gaps with foam, then use your trusty hacksaw blade to trim away excess foam from the inside of the cabin when it’s hard.