How to Retro-fit a Window

RON HAZELTON:
Well I've got a long trip ahead of me today. I'm on my way to Pacific Grove, California to visit Alan and Marla Martin. Now the Martins are no strangers to home improvement. In fact, they're remodeling their kitchen right now. But when it comes to replacing windows, Alan has had a few false starts and could use a bit of help and guidance.

So I guess we do this one. You and I will do it together. We'll run through the, the process here and then you'll be — you'll be all set to make the others.
[BOTH SPEAK AT ONCE]
ALAN MARTIN:
Then I can go ahead and do the other three. I'll feel much more comfortable doing it.
RON HAZELTON:
While Marla takes the kids into town, Alan and I begin by removing the trim from around the old window, using a hammer and a pry bar.

Okay, Alan, the next thing I want to do is pull these — pull these panes out here, okay. Probably that's going to be best done from the inside.

I ask Alan to remove as much of the glass as he can, safely. This reduces the risk of a pane breaking when we take the window out later on. Like most windows, this one has a flange surrounding it. This flange or fin is a metal strip, usually an inch-and-a-half wide which is nailed into the framing of the house. In order to access the flange, we need to cut away some of the exterior siding that covers it. Using a compass, Alan draws a cut line about two inches from the edge of the window frames.

Here's the — here's a saw I'd like to use. This is a little three-and-a-half-inch circular saw.
ALAN MARTIN:
Oh.
RON HAZELTON:
You just want to hold the guard back like this. Rest the front of the foot right on the siding.

We've adjusted our saw so that the blade will cut completely through the siding but not into the framing below. With the cutting complete, we begin removing the pieces of siding.

Okay, well these are loose right now. That's great. I think if you use this curved pry bar, Alan, you'll be able to — there we go.
ALAN MARTIN:
There we go.
RON HAZELTON:
Yeah, well let — take, take the one above it.

Now it's time to remove the nails that have been driven through the flange. These are the only things now holding the window frame to the house.

Okay, that's it?
ALAN MARTIN:
[INAUDIBLE]
RON HAZELTON:
Out with the old. Next, we remove a 2 x 4 that the old window was resting on.

Well, here's the new one.
[BOTH SPEAK AT ONCE]
ALAN MARTIN:
A little bigger than the old one.
RON HAZELTON:
This is a double-hung, double-glazed window. It's going to give you a lot more insulation value here. Yeah, we can just —

Our new window is 45 inches wide by 47 inches high. The width of our rough opening is two inches wider than the new window, but the height is a bit too tight.

You know what I think we should do is — let's take out this piece of wallboard right here.

I break out the wallboard with a pry bar, revealing the corner bead, a metal strip that reinforces the corner. We need to remove this strip without damaging the interior wall. First, I tap against it with my pry bar. The tapping produces a crack along the edge of the corner beam, which Alan deepens with a utility knife. A few more taps on the corner bead, pushes the nail head slightly out. Alan removes them with a nail puller.
ALAN MARTIN:
Okay, that's it.
RON HAZELTON:
Now, now, here you go — how's the — yeah, see? Nice —
ALAN MARTIN:
Yep, nice. Hey, look who's back. Hey, Riley.
RON HAZELTON:
Riley returns from the parade and helps us measure.
ALAN MARTIN:
There you go —
RON HAZELTON:
Our rough opening is considerably wider than our window so we'll layer up pieces of lumber on the sides, and nail them in place.

This is a nailing flange right here. Okay, we're just going to bend this out.
The nailing flange is what allows us to attach our new window to the framing of the house. It also provides a seal.

Alan lays a bead of caulk down the center of the flange — our first of several moisture and air seals. Now, we're ready to set the window in place.

All right, so we'll set the bottom of the window right on the sill there. Okay.
ALAN MARTIN:
All right.
RON HAZELTON:
Do it?
ALAN MARTIN:
Mm-hmm [AFFIRMATIVE].
RON HAZELTON:
Okay, then let's tip it up.

We slide the window in until the flange is in contact with the frame. Then I send Alan inside to make sure the window is centered in the opening.

Okay, yeah, we're a little bit low on this corner right here.
ALAN MARTIN:
This corner?
RON HAZELTON:
Yeah.
ALAN MARTIN:
Okay.
RON HAZELTON:
So I'll lift it up. Alan, just slip a — slip a shim under there, will you?
ALAN MARTIN:
Okay. Right on.
RON HAZELTON:
Perfect.

Next, we drive rust-resistant galvanized roofing nails through the flange and into the framing. For places too tight for a hammer head, Alan uses a drift pin.

All right, so we've got a good seal all the way around with this fin or flange right here, except right here in this corner. You can —

To cover these gaps, we'll use these self-adhesive rubber corner seals. As an additional barrier against air and moisture, we lay in strips of roofing paper and tuck the edges behind the siding, using a putty knife.

Next, we apply a bead of caulk where the roofing paper meets the edge of the siding, our second barrier. Important, since even a small water leak over time can cause significant damage.

Okay, now, let's fill up these gaps here, Alan, with these pieces of wood. I'll just drop it right in there. Okay, here's the last one.

We nail in the strips and now we're ready to attach the trim. We start with the top piece and use a side piece to align the end.

Okay, that's good.

We use rust-resistant finish nails for the job. Alan adds a final bead of caulk around the trim. I smooth it out, using my finger to press the caulk down into the grooves of the siding. Then we head inside.

These are called jamb extensions. What they do is, they extend the jamb, this part of the frame out, so that it's flush with the wall.Aptly named, right?
ALAN MARTIN:
Okay [LAUGHS]. Extend the jamb.
RON HAZELTON:
And — and so they go right up here.

We attach the jamb extensions with a pneumatic pin nailer. Our final step is nailing up the molding.

Is that cool? Well, you're going to stay nice and cozy in here now. Double panes of glass. Daddy's got — about three more to do?
ALAN MARTIN:
Got three more to do and —
RON HAZELTON:
So I thought I'd leave some of my tools here with you guys to finish up the job.
[SEVERAL SPEAK AT ONCE]
I left Pacific Grove, knowing the Martins would do just fine with the rest of the windows.

Do a Little Demolition to Resize the Window Opening and Retro-fit an Inefficient Window with a Double-hung Double-glazed Replacement

Retro-fit an existing sliding window with a double-hung double-glazed replacement. If it's a different size from the original, the project will require removing the window frames and wooden siding to custom fit the old window opening prior to installing the new window. Once this project is successfully completed, retrofitting your remaining windows should be a breeze.

cutting away exterior siding for the window retro-fit

Step 1

Remove Old Window and Trim for the Window Retro-fit Project

Begin the retro-fit by prying up and retaining existing trim for reuse. Remove the moving glass panes. Cut away the window flange, any exterior siding that covers it and the two-by-four on which the old window rests.

removing the corner bead as part of the window retro-fit

Step 2

Increase the Height of the Opening for the Window Retro-fit

Measure the new window and opening to assess fit. This window opening is too short for the retro-fit, so create extra height by breaking out the perimeter wallboard. Remove the corner bead without damaging the interior wall.

narrowing the gap for the new window retro-fit

Step 3

Narrow the Window Opening to Prepare for the Window Retro-fit

Decrease the opening width to accommodate the new retro-fitted window. Fill in the extra width with strips of exterior-grade lumber on each side. Layer outward to reach the desired dimension and secure the strips with a pneumatic nail gun.

bending out the flange as part of the window retro-fit

Step 4

Prepare and Position the New Window for the Retro-fitted Project

Bend the new window's nailing flanges outward. Run exterior caulking down the center of each flange as part of the window retro-fit. Set the bottom edge in place and tip the centered window upward to contact the frame.

inserting shims to level the retro-fit window

Step 5

Level and Secure the New Window for the Retro-fit Project

Plumb and level the new window using a bar level. Insert shims as necessary for the window retro-fit. Hold the positioned window in place and secure it with rust-resistant galvanized roofing nails driven through the flange, shims and framing.

applying corner seals on the retro-fitted window flanges

Step 6

Cover the Gaps and Caulk for the Window Retro-fit

Seal the gaps at the corners of the window flanges with self-adhesive rubber corner seals. Insert strips of roofing paper around the perimeter of the retro-fitted window and where the roofing paper meets the siding.

reattaching original trim for the window retro-fit

Step 7

Replace the Original Trim for the Window Retro-fit

Fill remaining hollows with nailed strips of exterior lumber to bring the surface flush with the exterior of the house. Replace the original exterior trim removed earlier in the window retro-fit project. Secure it with rust-resistant finish nails.

caulking as part of the window retro-fit

Step 8

Add Caulk around the Trim to Seal the Window Retro-fit

Squeeze a bead of exterior-grade caulk around the trim, sealing the gap between it and the siding. Smooth out the bead with your finger, forcing the caulk into the grooves of the siding to complete work on the outside of the window retro-fit.

Step 9

Add Interior Jamb Extensions for the Window Retro-fit

Install jamb extensions to the retro-fitted window, working from the interior of the house, to bring the surface of the jamb flush with the wall. Attach the jamb extensions with a pneumatic pin nailer.

securing interior molding to finish the window retro-fit project

Step 10

Nail up Interior Molding to Complete the Window Retro-fit

Secure mitered strips of interior molding with the pneumatic pin nailer to cover the jamb extensions. Dress the nail holes and paint as necessary to complete the final part of the window retro-fit.