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Get your free estimateCWS Window Replacement: The San Francisco Owner’s Guide
If your CWS window has failed, we stock and install CWS-compatible replacement windows and parts throughout San Francisco, with most full-unit replacements running between $900 and $2,400 per opening installed. We can usually match your CWS model within one visit after taking frame measurements and reading the manufacturer label. Owners typically find us after a foggy morning reveals condensation between the panes, or a bedroom window that once slid open with two fingers now needs a shoulder.
CWS built its reputation on impact-rated and thermally efficient frames developed for coastal climates, which is exactly why we see so many of them in the Sunset, Richmond, and Presidio neighborhoods. The marine air that rolls through San Francisco every afternoon and evening is harder on window hardware than most owners realize. A CWS unit that performed beautifully in a dryer inland climate can show seal fatigue and track wear noticeably sooner when it lives three blocks from Ocean Beach. We read every existing frame carefully before removing a single panel because the original installation matters as much as the original window. Keith Yamada has worked on enough CWS retrofits in this city to know that the frame tells you things the label does not.
We are an independent service provider and not affiliated with CWS. What that means for you is that our recommendation is based on what fits the opening and what will hold up to San Francisco weather, not on moving a particular brand’s inventory. Since 2010, we have carried eight manufacturer lines, including PGT, CGI, ES Windows, and CWS, specifically because no single brand is right for every house on every block of this city.
Which CWS Models This Applies To
CWS window replacement in San Francisco generally falls into three categories. First, there are the single-hung and horizontal sliders common in the city’s 1970s and 1980s housing stock. These are the workhorse units: aluminum frames, single thermal break, mechanically sound but prone to track wear and roller failure over two or three decades of daily use. Second are the impact-rated casement and picture-window units found in newer construction and coastal-adjacent remodels. These carry heavier laminated glass and multi-point locking hardware, and the hardware sees more torque than the standard residential window. Third are the thermally improved fixed and operable units CWS produced for mid-rise and mixed-use projects, which we see less often but know how to size and source when a homeowner or HOA calls.
Identifying your exact CWS model is a two-minute job. Open the sash and look at the spacer between the glass panes; most CWS units print the series number and date code right on the metal edge. If that has worn or faded, check the frame’s top channel for a silver or white decal. Take two measurements: the visible glass width and height, measured to the nearest sixteenth, and the frame depth from the interior stop to the exterior nosing. Those three numbers, plus a photo of the corner joint, tell us whether you need a factory-match OEM replacement or a quality aftermarket equivalent that will perform identically. For CWS specifically, the OEM route matters most when we are matching an impact-rated unit in a code-governed zone or preserving a warranty on a newer building. For most residential sliders and single-hungs in San Francisco, a properly specified aftermarket unit from a brand we already stock will deliver the same performance at roughly ten to twenty percent less.
Styles & brands we work with










Signs Your CWS Window Replacement Is Failing
- Persistent fogging between the panes. This usually means the edge seal has let go and the inert gas between the glass has been replaced by San Francisco’s damp coastal air. Cleaning the exterior glass will not help because the condensation is trapped inside the insulated unit itself. Once the seal fails, the window loses most of its thermal performance and the only true fix is replacing the IGU or the entire sash.
- Increasingly stiff or grinding operation. CWS tracks and rollers wear unevenly in salt-air environments. If you hear a gritty roll or feel a catch halfway through the sash travel, the rollers are likely pitted and the track may have started to score. Ignoring it usually ends with the sash cocking in the frame, which then damages the locking hardware.
- Drafts you can feel on foggy mornings. A cold spot near a closed and locked window is a sign the weatherstripping has compressed beyond recovery or the frame has shifted slightly out of square. San Francisco’s daily fog cycle is humid enough that a Draft can be checked with a simple candle flame test on a calm evening, but the source is often inside the frame assembly, not something you can see from the room.
- Lock hardware that no longer engages cleanly. CWS multi-point locks are strong but dependent on the sash sitting square in the frame. If you have to lift, push, or wiggle the sash to throw the lock, the frame is telling you that the sash hardware or alignment has drifted. Forced locking bends the strike plate and the problem compounds.
- Visible frame corrosion or paint bubbling. Aluminum frames in the Outer Sunset and Richmond regularly meet airborne salt. Once the factory coating is breached and the aluminum begins to oxidize, the corrosion spreads under the coating. A corroded CWS frame is never worth reskinning because the structural web underneath is already compromised.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
| Replacement Type | Typical Installed Range (San Francisco) |
|---|---|
| IGU glass pack only | $350 – $700 per unit |
| Single sliding sash or fixed panel | $500 – $1,100 per opening |
| Full CWS window replacement (standard aluminum) | $900 – $1,800 per opening |
| Impact-rated CWS replacement | $1,500 – $2,400 per opening |
Those numbers include the part or unit, haul-away of the old sash or frame, finish sealing matched to the exterior, and our written warranty on the installation. The range is driven by two factors: opening size and whether the existing frame is sound enough to accept a sash replacement or needs a full tear-out. Full tear-outs cost more because we are rebuilding the rough opening, re-flashing the perimeter, and frequently bringing the frame into compliance with current San Francisco building code. We give you a written line-item price before any work starts, and that price does not change when the crew walks in the door. If a rotted subsill or hidden framing issue surfaces during the work, we stop, show you, and put the revised number in writing before touching anything else. No invoice surprise at the end of the day. Ever.
DIY or Call Us?
For a CWS window, some things are safe to do yourself and some are genuinely not. You can absolutely remove the sash and clean the track with a mild degreaser, inspect the weatherstripping for compression, and check the corner joints for separation. You can tighten accessible hardware screws with a quality driver. What you should not attempt is replacing an IGU, spring-loading a new balance into a single-hung frame, or handling impact-rated laminated glass, which is heavy enough to injure someone if it shifts during handling. CWS frames in San Francisco’s older buildings are often installed with hidden fasteners into framing that has moved over decades; pulling one without the correct shimming sequence is how a smooth project becomes a wall repair. If the window is in a second-floor or higher opening, or faces the ocean side of the building, call us before climbing anything. Keith’s approach applies here too: measure it until it’s boring, then cut once. Most CWS replacements we complete in San Francisco are done in a single day, and we leave the site the way our C.A.R.E. values require. Call (831) 480-4124 and we will walk you through what to photograph and measure so the first visit is the productive one.
FAQs
A properly installed CWS window in San Francisco should give you 20 to 30 years, but the marine layer shortens the glass seal lifespan compared to inland installs, and many units we replace are 15 to 25 years old with failed seals or worn tracks. If your CWS unit is under 10 years old and showing seal failure, that typically points to an installation issue rather than a manufacturing defect. Call (831) 480-4124 and we will look at the installation history and the unit in person.
In many cases, yes: a fogged IGU can be swapped, a worn roller set can be replaced, and a misaligned sash can be re-squared in the frame. If the frame itself is corroded, the lock mechanism is stripped, or the glass is impact-rated and cracked, replacement becomes the honest recommendation because repair costs approach replacement costs. We will always show you the repair option first when it makes financial sense.
A single sash or IGU replacement usually takes one to two hours on site, and a full-frame CWS replacement runs four to six hours per opening, including finish sealing and clean-up. We schedule around your family’s time, quiet hours, and whether there are kids or pets in the room, and we photograph the clean-up before we leave. For an exact timeline based on your openings, call (831) 480-4124.
We keep common CWS rollers, locks, weatherstripping profiles, and standard-sized IGUs on our trucks, so many residential repairs in San Francisco are completed same-day without a parts wait. For specialized or impact-rated CWS units, we source the OEM or matched aftermarket part directly and give you a written ETA before work begins. The best way to know which bucket your unit falls into is to call (831) 480-4124 and describe what you are seeing.
If your CWS window is showing signs of age or has already failed, call (831) 480-4124 for a free estimate. We will name exactly what needs replacing, what it will cost, and what the wall and floor will look like when we leave.
Written by Keith Yamada, Owner, Lightwell Windows San Francisco at Lightwell Windows San Francisco, serving San Francisco and nearby areas.
Six Reasons Homeowners Choose Lightwell Windows San Francisco
Laminated glass and reinforced frames hold up to wind-driven rain, hail and flying debris, so your openings stay sealed when the weather turns.
Low-E insulated impact glass from our manufacturer lines commonly cuts monthly cooling bills 20-30%.
Laminated impact glass shuts out up to 40% of outside noise - traffic, neighbors, weather.
Monitoring services run $30-90 a month. Laminated impact glass resists forced entry around the clock, with no subscription.
Tighter seals and insulated glass even out hot and cold rooms and stop the drafts at the frame.
A full impact package upgrades curb appeal, buyer confidence and appraised value in one project.