Window replacement cost is easy to quote badly. A price per window looks simple, but it hides the decision that matters most: whether the new window goes into the old frame or the old frame comes out. On a house in Redondo Beach, Hermosa or San Pedro, where salt air and wind-driven rain have been working on the openings for decades, that decision often decides whether the new windows stay dry.
Here is what moves the number, in the order it usually comes up.
Retrofit or full-frame, and why it changes the quote
A retrofit window is built to fit inside the existing frame. The old sashes and glass come out, the frame stays, and the new unit is set inside it with trim to cover the gap. Stucco and interior drywall are left alone. It is faster and costs less.
A full-frame replacement removes the whole window down to the rough opening. The opening can then be checked for rot, repaired, and flashed with a sill pan and new tape before the new window goes in. Stucco or siding around the opening has to be cut back and patched, and the interior trim is usually replaced.
The price difference per opening is real, because full-frame adds exterior patching and interior finish work. On a coastal house the question to ask is not which is cheaper, but whether the existing frame and the wall under it are dry. If there are stains under a sill, soft wood at the frame or a leak history, a retrofit seals a new window into an opening that is already failing.
A good contractor will tell you which windows can be retrofitted and which need full-frame, rather than pricing the whole house one way.
Frame materials that last in marine air
Frame material is the next big line in the quote.
- Vinyl does not corrode and needs no paint. It is the most common replacement frame and usually the least costly. Darker colors can expand in strong sun, so check the manufacturer's limits for south and west walls.
- Fiberglass costs more than vinyl. It moves very little with temperature, takes paint, and stays stiff in larger sizes, which helps on wide openings that face the water.
- Aluminum gives narrow frames and modern lines. Near salt air, look for a marine-grade finish and thermal breaks, or it will pit and sweat.
- Wood and clad wood look warm inside. Near the ocean the exterior cladding has to be well kept or moisture reaches the wood.
Hardware matters too. Stainless steel or coated locks, rollers and hinges outlast plain steel in salt air, especially on sliding patio doors.
Glass packages and Title 24 energy rules
California's energy code, Title 24, sets performance limits for replacement windows, expressed as a maximum U-factor and solar heat gain. Most dual-pane low-E windows sold for California meet it. Upgrades such as laminated glass for noise or security, tempered glass where the code requires it near doors and floors, and special coatings all add to the price. Ask the contractor to list the glass package for each opening rather than one line for the whole house.
Permits, measuring and lead times
In many Los Angeles County cities, like-for-like window replacement needs an energy compliance form and sometimes a permit. Changing the size of an opening needs a building permit and may need a header sized for the new span. Inside the coastal zone or under an HOA, frame color and grid patterns may need approval. A contractor who works in your city should know which applies.
Custom-sized windows are made to order after a site measure, so the quote should state how measuring is done and who is responsible if a unit arrives the wrong size.
Windows and doors covers how we decide between retrofit and full-frame on each opening.
What a written window quote should list
When you compare quotes, look for these lines:
- The number of openings, with sizes, and retrofit or full-frame for each one
- Frame material, color and the glass package for each opening
- How the openings will be flashed, especially sill pans on full-frame units
- Exterior patching of stucco or siding around full-frame openings
- Interior trim, paint and cleanup
- Permit or energy forms, and who files them
- Disposal of the old windows
If two quotes differ a lot, it is usually because one is full-frame and one is retrofit, or because one leaves out the stucco patching. Line items make that visible.
Questions to settle first
Before you sign, it is worth knowing which windows truly need replacing now, which can wait, and whether any of the leaks you have seen are coming from the windows at all rather than from the stucco above them. A short visit with a moisture meter answers most of that.