What Happens During a Vinyl Window Installation

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The cost of a window job is driven less by the glass than by what turns up behind the old frame. Opening a wall in Carlsbad, CA often means rot at the sill or flashing that was never lapped, and a full frame vinyl window install takes longer than the way vinyl windows carlsbad fretboard summit lays out a plain retrofit swap. Salt air and the marine layer keep stucco and framing damp for long stretches, so the sill is where trouble shows first.

Retrofit and full frame are different jobs

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A retrofit, also called an insert install, leaves the existing frame in the wall and fits the new unit inside or over it. A full frame install removes the old window down to the rough opening. That is the only way to inspect the framing and the flashing behind it. The two jobs differ in labor, in risk, and in what gets found, so they should never be priced as if they were the same work.

Stucco changes the method

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Many stucco homes between Oceanside and Encinitas have aluminum frames set years ago. Many retrofit windows use a flange that covers the old frame, so the exterior stucco does not have to be cut. That saves patching, but it also hides whatever is going on in the old frame. A new construction style window uses a nailing fin that attaches to the wall framing and is integrated with the weather barrier. That fin needs the stucco opened up around the unit.

Measuring the opening

The opening gets measured at more than one point in width and in height. Older openings are often out of square, and the smallest reading sets the size. A double hung or a slider that is ordered off a single tape pull will either bind in the frame or leave a gap too wide to fill properly. Check the sill for level and the jambs for plumb before anything is ordered.

Flashing goes on in layers

Flashing tape is applied in shingle fashion. Upper layers lap over lower ones, so water is directed outward and down. The sill tape goes first, then the jambs, then the head. Taping in the wrong order sends water behind the layer below it, and the leak will not show for a season or two. Insulated glass units are heavy, and a unit that sags on a poorly shimmed sill will crack the tape seal over time.

Weep holes and the gap fill

Weep holes at the bottom of the frame let water that enters the sill track drain outside. They must not be sealed shut, and more caulk does not make a window more watertight. A casement or a vinyl window that has its drain slots blocked will hold water in the track. Gaps between the window and the opening are typically filled with low expansion foam, or with backer rod and sealant. High expansion foam can bow the frame and make a sash drag, so it stays on the shelf.