Window Replacement Done Right

By Larry Walton

Steps for a window replacement done the right way.

It was one of those rare occasions when everything in the house was quiet. No kids fighting, no TV, no booming stereo, which explains why I could hear an ominous noise. It was our first winter in a “new” home. The Oregon rain was doing its usual make-everything-green thing. I slowly turned my attention to a rhythmic noise and realized it was the sound of water dripping somewhere in the first floor dining room. Not good. Hmm, no plumbing here, no plumbing upstairs above this room …

Upon inspection I discovered that there was a significant puddle of water on the window sill and more drops were joining the party. Could be a roofing issue, I thought, but seeing rain hitting the glass on the exterior (a common sight on the south side of houses in our region), I figured it must be a window issue. That’s when I noticed the screws. Why were there screws going through the window frame?

This was my second clue (water on the window sill being the first) that this house had fallen victim to a run-and-gun window replacement scheme under the guise of weatherization. The screws go through the window frame and into the house framing because there were no nailing flanges on the windows.

Some homeowners, including the previous owner of our house, buy into the idea that these “weatherization” companies deliver energy savings and windows clear of condensation. However, few suspect the potential long-term water damage these quick-to-install, flangeless windows can cause to their homes. This is a case where shortcuts produce serious compromises. An install job like this would never pass inspection in new construction, so what makes the installers think it’s okay on a remodel?

As you might guess, a window install done right takes more steps and is more work than one done poorly. But it’s well worth it to get the home sealed properly. This is one of those home improvement projects that produces several positive returns. These benefits include significant energy savings by improving the insulation characteristics of the window itself, which both reduces the cost of cooling the home in the summertime and the cost of heating the home in the wintertime.

Of course, there are other reasons to replace windows: to prevent condensation; to repair damage; to make changes in the design of a room; to go from solid glass to grids, or the other way around; or to get a window that operates easily for opening and closing.

Of these window replacements, one of the most frequent jobs is changing single-pane, aluminum windows for double-pane insulated vinyl frame windows.

When done right, the exterior trim (if applicable) is removed, the flange of the existing aluminum window is exposed, and the flange is released from the house.

There are several different ways you can handle the interior trim of the window. You can either remove the interior trim to be replaced, or you can remove the interior trim and cut the surrounds after the new windows are installed (so they’re the proper depth). You can also remove the aluminum window, cut the window surrounds in place to the correct depth, then install the vinyl window so the inside surface contacts the window surround as the flange seals to the exterior of the house. This is the method we explain in this how-to.


Job Done Right

Window replacement done right is how I like to describe the technique that Stan Davis of Schar Construction in Eugene, Oregon, uses for his windows. Of course, the window opening must be measured and the window ordered and on site before this process takes place.

Stan starts his window installation by using painter’s plastic on the inside of the window to completely seal all the way around the casing of the window.

Working on a second floor window

Working on a second floor window, Stan sets up his planking or his scaffolding to give a nice, solid, safe work surface from which to complete the exterior part of the window.

Next, he cuts the siding around the outside of the window with a circular saw to expose the flange of the existing window.

In some cases, this operation can be done simply by removing the exterior trim.

With the siding cut through, simply using the side of the saw base as a guide, Stan removes the pieces of siding using a small pry bar or chisel to loosen the pieces.

You may also need to peel off some roofing felt or tarpaper to expose the flanges of the existing windows.

Stan uses a couple of different techniques to release the window flange from the framing on the existing window. One is to use a center punch and drive the head of the nail through the flange.

Another technique is to use an old chisel and cut the flange around the nail heads. With all of the nails defeated, he tips the window frame out of the rough opening.

He then removes the active part of the window and the screen and carefully places them so they don’t fall off the scaffolding. This makes the window lighter and easier to handle.

He can then handle the window and carry it down the ladder and off the scaffolding.

Next, he measures the depth of the window frame from the flange to the inside edge of the window to determine the depth of the window surround.

He then uses an “old school” technique of grabbing his tape at the proper depth and using the end of the tape and the pencil to mark the point where he wants to cut the surround.

Next, Stan marks the depth of the window frame from the flange to the inside of the window on the base of a small, worm-drive circular saw using a sharpie.

He then attaches a block of wood to the bottom of the circular saw along the marked line on the base.

The block of wood on the base of the saw serves as a depth gauge so he can cut the window surround.

The circular saw cannot reach the corners of the window surround so Stan uses a Multi-master by Fein to finish the cuts.

After completing the cuts on the surround, he removes the outside portion of the surround to make room for the new vinyl window.

He finishes cleaning up the cuts in the corners using a chisel.

He then uses a small shop vac to vacuum up the sawdust and debris left in the inside window surround.

After removing the active side of the window and the screen, he takes the new vinyl window up the ladder to position it in the window opening.

He puts a nail or two just above the window flange to hold the window from tipping out of the opening.

Stan then goes inside the house and removes the masking.

He puts the active half of the new vinyl window in the frame. He then measures the reveal of the vinyl window to the window surround on both sides, and moves it so the window is centered.

Back at the exterior of the window, he uses a pencil to mark the location of the outside of the window flange.

He then removes the window and sets it aside so he can run a bead of caulk where the flange attaches.

He then puts the vinyl window back in place by tipping it in bottom first, and then tipping it up into place at the top.

He double-checks to make sure that the weep hole that lets water out of the window frame is properly positioned at the bottom.

He then nails the window flange onto the framing using the manufacturer’s recommended nail spacing. He finishes setting the nails by using a nail set (turned around for more surface area on the nail head) to avoid damaging the vinyl window frame with his hammer.

Next, Stan uses a piece of the exterior window trim up against the vinyl window as a gauge to mark where to cut the siding. Notice that he has pre-painted the window trim.

Using a circular saw he then cuts on the marked line to make room for the exterior window trim.

He finishes the corners of the cuts with the Fein tool as he did with the window surround.

Next, he uses a window seal product. In this case, Moistop E-Z Seal Flashing to seal the windows. He installs the bottom, then the sides, and finishes with the top by tucking the flashing underneath the siding.

After installing the window seal flashing, he then applies a bead of caulk where the siding meets the flashing and where the window frame meets the flashing before installing the exterior trim boards.

Stan then cuts one of the exterior trim boards to the horizontal dimension of the window and installs it at the bottom using casing nails.

He then hooks the tape at the bottom of the first trim board and measures to the top of the window frame, then cuts the two side trim pieces and installs them.

Note: When you have a tight fit, it’s often a good idea to use a softer wood like a cedar shingle to soften the blows when putting the trim piece into position.

With the side trim pieces in place, he hooks to the outside of one of the side trim pieces and measures over to the outside of the second piece to get the length of the final piece of trim board, which is the horizontal piece at the top.

Before installing the top trim board, he fits a piece of metal flashing to wrap over the ends of the board. He puts it in place…

…marks the other end, cuts the flashing about 1/2-inch long and shapes it around the other end of the board as well.

Next he fits the piece of flashing into place by sliding the top portion underneath the siding.

He then adds caulking all the way around the perimeter where the top trim board goes.

He then puts the top trim board in place by first tucking it underneath the flashing and then tipping it into place along the lower edge.

With all of the trim boards in place, Stan runs a bead of caulk all the way around the outside of the trim boards to make the transition between the trim boards and the siding.

With everything in place the interior trim fits properly using the existing window surround and casing…

…and the exterior portion of the window is trimmed and properly sealed.

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