How to Install Replacement Windows
Ready-to-install replacement units give you high performance and good looks with a minimum of fuss
When Maddy Krauss and her husband, Paul Friedberg, first laid eyes on their 1897 Shingle-style home, they fell in love with its handcrafted turn-of-the-century construction, wide front porch, and massive entry-hall staircase. They were also delighted to find that many of the original architectural details were still intact, including wood paneling, exquisite carvings, stained-glass windows, and an ornate cast-bronze fireplace.
The windows were another story. The originals had been swapped out a decade earlier for low-quality sash kits that were drafty, ugly, and completely inappropriate for the graceful Victorian-era home, This Old House TV's fall 2007 project in Newton, Massachusetts. The solution: Call in TOH general contractor Tom Silva and his crew to install energy-efficient replacements.
Because the existing window frames were sound and square, Tom could use insert replacement units—in this case, Andersen's Woodwright Insert Replacement Windows, vinyl-clad wood units fitted with energy-saving, low-e insulated glass. These fully assembled, ready-to-install windows slip right into the existing openings. When the job was done, the house had beautiful new double-hungs that looked right, worked smoothly, and gave Maddy and Paul one more thing to love about their old house. Here's a look at how Tom made the switch, with tips for choosing and installing replacement windows.
Unlike full-frame windows, which are designed for new construction, replacement windows are made to fit into existing window openings. They're available in dozens of standard sizes, from as narrow as 11 ½ inches to as wide as 68 inches, and come in wood, vinyl, fiberglass, vinyl-clad wood, and aluminum-clad wood.
There are three basic types of replacement windows: sash kits, insert replacements, and full-frame units. Sash-replacement kits—what Tom found on the Newton house—give an old window frame new movable parts, including jamb liners and sash. The liners are fastened to the side jambs of the window opening, then the sash are slipped in between. For these to work, the existing window frame must be level and square. An insert replacement window consists of a fully assembled window in a ready-to-install secondary frame. Sometimes called a pocket window, an insert replacement slips into the existing opening and is then fastened to the old side jambs. Because you're adding new jambs and liners, the glass area will be slightly smaller than it was before.
Full-frame replacement windows are similar to inserts, except that they have a complete frame that includes head jamb, side jambs, and sill. These are the only option when the old window frame, sill, or jambs are rotted. To install these, you must strip the window opening down to its rough framing, inside and out.