Replacing Windows: Step-By-Step Guide

If you’re living in an older house, there will come a time when you have to replace the windows. The wood in an older house begins to warp, affecting not only how the windows look and operate but also the insulation that they provide. This article will walk you through all of the steps necessary to replace those windows correctly the first time (without having to hire a contractor).

For this guide, I am assuming that your window frames are solid; if this is the case, you simply need to insert replacement units. To replace window frames, please check back for further instructions.

There are three types of replacement windows: insert replacements, sash kits and full-frame units. We’re going to be working with an insert replacement.

Step 1: Measure

Before going any further into the process, make sure that you measure out the windows for your replacements. To start, measure the inside width of the old window frame (jamb to jamb). You should do this in three places: the top, the middle and the bottom. If the measurements are different, write down whichever is the smallest out of the three.

After that, measure the height of the frame. Start from the top of the sill to the underside of the head jamb. Again, do this in three places – left, center and right – and record the smallest measurement.

Check the squareness of the frame by measuring the diagonals. If there is a difference of more than 1/4 of an inch, you’re going to need to make adjustments to the frame.

Use an angle-measuring tool to determine the slope of the sill. Record this as well.

Installing windows is a lengthy process but is well worth it. It'll add value to your house, make it look better and offer more insulation.

Installing windows is a lengthy process but is well worth it. It’ll add value to your house, make it look better and offer more insulation.


Step 2: Removing the Sash and Jamb Liners

Removing the old sash from the window frame requires either prying it off or unscrewing t he interior wooden stops. Start with the bottom sash; after the bottom is removed, take out the parting beads so that the upper sash is free. Press on the jamb liners and pull the top sash forward to free it.

Next, take off the jamb liners. Use a flat bar to pry them free and remove any remaining wooden stops from the frame.

Step 3: Getting Your Frame Prepared

There’s going to be a mess left of old paint and loose wood. Scrape that off and then patch any holes or cracks with wood putty. Sand the jambs smooth so that you have a clean finish. Finish it up with some primer and paint.

Check if there are original sash weights in place – if so, remove them and insulate behind the frame. You need to unscrew the access panel on each side to pull the weights out.

Step 4: Insulation

Polyurethan foam is great for windows. It’s much more effective at blocking air than fiberglass foam. It’s important, however, to only use low-pressure that expands very minimally. Make sure that the foam is produced solely for windows and doors. Drill holes into the jamb, one at each end and one in the middle, on all four sides.

Now for the fun part… shoot the foam into each hole until it begins to ooze out. Don’t forget to fill in the sash-weight pockets that we emptied. Let the foam sit for at least 6 hours so that it can harden; then, break off the excess foam so that you have a flush surface.

Step 5: Caulking and Installing the Window

We’re about to install the window. First, however, we want to caulk the exposed inner face. Apply it to the blind stops on the top and sides of the frame, as well as beads along the window sill.

Finally, it’s time to install the window. You want to be working from the inside of the room, placing the bottom onto the sill and tipping it forward into the opening. Press the window forward, making sure it is tight against the exterior casings or blind stops.

Step 6: Screw It In and Inserting Shims

Have someone hold the window in place. Using a 2-inch screw, loosely attach the upper side jamb and the framing. Do not tighten it too much – it should be just enough to hold the frame in place.

Grab some shims and insert accordingly under the sill and behind the side jambs. You want to make sure that the window is in the center of the space. Measuring diagonally, these measurements should be the same. Take a utility knife and trim the excess.

Step 7: More Caulking, More Priming, More Painting

Now, operate from the outside of the window. Measure gaps in the frame and casing. If any gaps are less than 1/4 of an inch, fill them with the elastomeric caulk. Use a rubber backer rod for anything larger than 1/4 of an inch. Next, head back inside and fill gaps with the expanding foam. Install your window stops, prime and paint.

Step 8: Sit Back and Enjoy

You worked hard. Take some time to relax. Stare out the window.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s