Replacing Windows in a Stucco Home: What Happens to the Stucco?

Why Stucco Changes the Conversation

In a wood-sided home, replacing a window is mostly a carpentry job. In a stucco home it is a carpentry job and a plastering job. Stucco is a hard shell bonded to the wall, with a weather barrier and metal lath behind it. Once you cut into it, you have to rebuild all three layers and match the color and texture of a finish that has been in the sun for years.

How the stucco is built also depends on the wall behind it. See stucco on wood frame, block or adobe.

That is why the first question on any stucco window job is not "which window?" It is "do we have to open the wall?"

In many stucco homes, the original window was set with a nailing fin, a flange around the frame that is screwed to the framing and then buried behind the stucco. If that frame is still square and solid, the insert method is possible and the stucco can stay put.

Insert (Retrofit) Replacement: The Stucco Stays

An insert replacement leaves the old frame in the wall. The installer removes the sashes, glass and stops, cleans up the old frame, and sets the new window inside it. The joint on the outside is covered with a trim flange or sealed with a high-grade exterior sealant.

What that means for your stucco: nothing happens to it. No cutting, no patching, no color matching, and the house is never open to the weather.

The trade-offs are real but small. As Pro Remodeler's comparison of the two methods explains, an insert sits inside the old frame, so you give up some glass area. You also keep whatever is behind the old frame: if there is hidden rot or a past leak, an insert covers it rather than fixing it, and if the old frame is out of square, the new window will be too.

For a home with sound frames, insert is the common method on stucco homes.

Full-Frame Replacement: Cutting Back the Stucco

A full-frame replacement takes everything out: sashes, frame and nailing fin. To get at the fin, the stucco is cut back a few inches around the opening, the rough framing is exposed, and the new window goes in the way it would on a new house, with flashing tape and a sill pan tied into the weather barrier. This Old House describes the same trade-off: more work and cost, in exchange for a window flashed the way the manufacturer intended.

Then the stucco has to come back: new lath lapped under the existing, a base coat, and a color coat matched to the wall. On traditional three-coat stucco, each coat needs time to cure, so the window and the stucco are usually separate visits a few days apart.

Full-frame is the right choice when:

• The old frame is rotted, corroded or water-damaged.
• You are changing the size or shape of the opening.
• You want to maximize glass area.
• The window has leaked before and you want the flashing done right.

Will the New Windows Crack the Stucco?

Not if the job is done right.

With an insert install, the stucco is not touched. The only risk is a window that is forced into a tight frame and stresses the wall around it. Accurate measuring solves that.

With a full-frame install, the stucco is cut on purpose, and the patch is where problems show up. Hairline cracks around a patch usually mean the new lath was not tied into the old, or the new stucco dried too fast in our heat. A proper patch laps the new lath under the existing, is kept damp while it cures, and gets a color coat matched to the surrounding wall. Stucco and plastering is licensed work under New Mexico's Construction Industries Licensing Act, so on a full-frame job, ask who is doing the patch and under what license.

Matching the Stucco Color

A full-frame patch will usually be visible for a while, even when it is done well. Stucco color fades in New Mexico sun, so a fresh patch can read slightly different from the wall around it until it weathers. Options:

• Let it weather in. On lighter earth tones this is often hard to see after a season.
• Feather the color coat past the patch so the transition is softer.
• If several windows on one wall are being replaced, recoat that whole elevation so it all matches. Our stucco page covers patching and recoating.

On stucco that has been painted or coated with elastomeric, the patch is painted to match, which is simpler.

Permits in Albuquerque

Window and door replacement is permitted work. The City of Albuquerque lists window and door replacements among the "small repair/minor alterations" eligible for its express permitting program, which can issue qualifying permits the same day. The City notes that the required inspections still apply. Neither the City's program nor New Mexico's permit rule lists window replacement as exempt from a permit.

Outside Albuquerque city limits, permits come from the state Construction Industries Division or the local jurisdiction. Changing the size of an opening adds structural and egress review. For specifics on your project, the City's Planning Department is at 505-924-3860.

The practical point: ask your installer who is pulling the permit before you sign.

What to Ask Before You Sign

1. Insert or full-frame, and why? For your windows, not in general.
2. If full-frame, who patches the stucco, and under what license?
3. How is the window flashed? Sealant only (insert) or flashing tape and a sill pan (full-frame)?
4. What glass package? In New Mexico, a Low-E coating that controls solar heat gain matters as much as anything (see energy-efficient windows for Albuquerque's climate). Our guide to U-factor and SHGC explains the label.
5. Who pulls the permit?
6. Who covers what warranty? The manufacturer covers the window; the installer covers the installation. You want both in writing.

If your existing windows are fogging between the panes, see our guide to foggy windows first; sometimes only the glass unit needs replacing.

Timberwolf is an authorized Climate Solutions dealer for the 8100 Series double-hung window, installed by a vetted, contracted installation team. See Windows & Doors for the product.