What Happens During a Retrofit Window Install on a Stucco Home

Back view of worker in checkered shirt drilling window frame during renovation process in apartment

Nothing about a replacement window is decided by the glass, because the first call is whether the old frame stays or goes. In San Bernardino, CA, the work splits into two jobs, and the sequence described (as it is laid out at replacement windows san bernardino host cell) follows each one from the opening outward. An insert or retrofit install places a new window inside the existing frame, while a full frame install removes the old frame down to the rough opening. Neither is automatically the better job. The wall and the condition of the old frame decide it.

Stucco and the fin

A modern green house under construction with blue skies and workers outside.

Original windows in stucco walls usually have a nailing fin buried behind the stucco. Pulling that unit means cutting the stucco back and patching it afterward. Many stucco homes avoid that by using a retrofit frame with a flush fin, sometimes called a Z bar style, which laps over the old frame so the stucco stays uncut. Not every stucco home needs stucco removed to replace windows. A sound old frame in a sound wall is often left alone.

Checking the opening

Two-story residential building under construction, featuring scaffolding and roof tiles.

Before the new unit is set, the opening gets checked for square, level and plumb. A racked opening makes sashes bind or leaves uneven gaps. A double hung that drags on one side or a casement that will not close tight at the top corner usually traces back to a frame set into an opening that was never true. The check takes a few minutes with a level and a tape across both diagonals.

Shims and gap fill

Shims go at specific points, near the corners and at the lock and hinge locations, so the frame is supported without being bowed. A double pane unit with insulated glass is heavy, and a frame squeezed by overtight shims will not operate right. Gaps between frame and opening are typically filled with low expansion foam, or with backer rod and sealant. High expansion foam can push a frame out of shape as it cures. Caulking alone does not keep water out of an opening. The flashing, the fin or the lap over the old frame does that work, and the sealant backs it up.

Sliders and weep holes

A slider, whether an aluminum window or a vinyl window, has weep holes or slots in the sill track that let water drain to the outside. Those must not be sealed over. Painters and caulk guns close them more often than anything else. After install, a small cup of water poured into the track should run out through the slots, and that test is worth doing on every sliding unit.

Trim and cleanup

Interior trim or stops may be reused or replaced, and that choice sets how much painting or caulking is left. Reused trim usually means touch-up paint and a fresh bead at the joints. New trim means priming and a full coat. Homes in Redlands, Loma Linda and across San Bernardino County vary a lot in age, so trim condition is looked at before the old window comes out, not after. Once the sash is tested, the track is cleared and the debris is hauled off, the job is done.