Replacing a vinyl window

Vinyl replacement window

Vinyl replacement windows come mounted in a new jamb, and are simply tilted into the old frame and fastened in place.

Close up

Top frame cutaway. The inside stop molding helps hold the new window in place.

Vinyl trim and caulk seal the gap at the bottom of the new window. The window fits against the existing stool on the inside.

Installing replacement windows looks complicated, but actually requires only basic tools and skill—despite the high prices charged by some window replacement companies.

However, before deciding to tackle the job yourself, check the condition of your existing window frames. If they’re rotten or badly out of square, the whole unit, including the frame, may need replacing. This is a much bigger and more complicated job than installing a vinyl window insert and may require a pro.

If the frames are sound, the next step is to measure the interior width and height of each window frame side to side and top to sill. Double-check these measurements to ensure their accuracy so you don't end up with a window that doesn't fit. In most cases, the old frame dimensions will match a standard- size vinyl window.

Use these measurements to order the windows from a lumberyard or home center. The price will vary depending on the manufacturer and the features you request. Order windows with insulated glass (two layers). Then consider whether to copy the style (single or multiple glass panes) of the old windows or to change it.

The windows install from the inside. Give yourself at least half a day to install the first unit. Once you've learned the steps, the second installation will go much faster.

Here's a summary of the steps:

1. Remove and save the inside stop. It'll be reused in the same place.
2. Remove the old lower window sash (not shown).
3. Pull out the parting stop (see top frame detail). Don’t worry about breaking it; you won’t be reusing it.
4. Remove the old top sash (not shown).
5. Either remove the sash liners and springs or open the sash pockets and pull out the weights. Remove the sash cord pulleys and stuff the weight pockets with fiberglass insulation.
6. Push the new vinyl unit into place tight against the outside stop and drive the mounting screws in the sides.
7. Caulk around the outside and install the vinyl trim pieces.