Windows are doing more work on a Los Altos home than on most. The ranch and Eichler-era houses that define much of this city were built to bring the outside in — wide glass walls, clerestories, sliders opening to the garden — and the custom homes going up now push even larger, more deliberate openings. That's exactly why the glass matters: it's a large share of the home's comfort, its energy bill, and its architectural character all at once. Bay Area Siding Company, a Larkspur-based siding and window contractor, installs replacement windows across Los Altos and the South Bay with those three things treated as one decision, not three afterthoughts.

Ready to talk it through? Request an estimate or call (415) 619-5167.

What you're actually deciding

On a home with a lot of glass, three choices carry most of the outcome:

• Glass performance. Dual-pane insulated glass with a Low-E coating is the baseline; on the big south- and west-facing expanses common here, the coating and glazing package are what keep a room from overheating in the afternoon while still letting light in. California's Title 24 energy code sets maximum U-factor and SHGC values for replacement windows, and those numbers vary by climate zone and code cycle — so rather than quote a fixed figure, we confirm the values in effect at permit time and spec to them.
• Frame material and sightline. Vinyl, fiberglass, aluminum-clad wood, and aluminum each trade cost, thermal performance, and appearance differently. On a mid-century or Eichler home the sightline is as important as the spec — a narrow, clean frame profile preserves the glass-forward look, where a chunky frame can quietly wreck it. On a period ranch, matching the original proportion matters just as much.
• Retrofit vs. new-construction install. A retrofit (insert) window keeps the existing frame and is less invasive; a new-construction (full-frame) install removes the window down to the rough opening so the flashing can be fully renewed — the right call where there's rot, water intrusion, or you're changing the opening. We do both and recommend based on what the opening actually needs.

Comparing brands

The right window depends on the opening, the look you're keeping, and your performance target — so it helps to compare lines. Start at our window replacement hub, then read the specifics for Anlin, Milgard, Andersen, Marvin, and Pella. We also install aluminum windows, which are often the honest choice when a mid-century home's original narrow-line aluminum sightlines are part of the design.

How the job goes

We keep it straightforward: a walkthrough of your existing windows and openings; precise field measurements for each one; a glass, frame, and finish selection sized to meet Title 24 and hold your home's look; the City permit; removal with the openings inspected for rot or damage; installation set level and plumb, flashed and air-sealed against water and drafts; then trim, an operation check, and a walkthrough with you. Where openings sit under a mature tree canopy or a protected tree is nearby, we plan access so the work doesn't put the canopy at risk.

Los Altos specifics

Permits. Window replacement is a permitted project submitted to the City of Los Altos Building Division, and because it's treated as an alteration under the energy code, a Title 24 fenestration compliance form is part of the submittal. We prepare and handle that as part of scoping.

Not a fire-glazing issue for most parcels. In the foothill fire zones to the west, altered window openings can trigger tempered/multi-pane glazing requirements under Chapter 7A. Most of Los Altos sits on the flat valley floor and is not within a mapped high fire-hazard severity zone, so those glazing rules generally don't apply here the way they do up in Los Altos Hills — but designation is parcel-specific, and if you're near the western edge we confirm your address before ordering.

Older glass, real comfort gains. Many Los Altos homes still carry their original single-pane units, and on a house designed around its windows the upgrade to a modern dual-pane, Low-E package is felt immediately — fewer drafts, less afternoon heat gain, and quieter rooms.

What affects the cost

We don't quote prices online because every home is different. The drivers are the number and size of openings (and Los Altos has some big ones), frame material and brand, retrofit vs. full-frame installation, the glazing package needed to hit Title 24, the condition of the existing framing (rot repair adds scope), and access — upper-story openings and staging around protected trees take more setup.

Frequently asked questions

Do I need a permit to replace windows in Los Altos? Yes. Window replacement is permitted through the City of Los Altos Building Division, and a Title 24 fenestration compliance form is part of the submittal because the work is treated as an energy-code alteration. We handle it.

Can you keep the clean, narrow-frame look of my Eichler or mid-century home? Yes — sightline is part of the spec. We select frame material and profile to preserve the glass-forward proportions these homes depend on, including aluminum where the original narrow lines are part of the design.

Do my windows need tempered or special fire glazing? For most Los Altos parcels, no — the city is largely off the valley floor's mapped fire zones, so the Chapter 7A glazing rules that apply in the western foothills generally don't apply. Because designation is parcel-specific, we confirm your address before ordering.

Retrofit or new-construction — which is right for me? Retrofit keeps the existing frame and is less invasive; new-construction removes the window to the rough opening so the flashing is fully renewed, which is the better choice where there's rot or water damage. We assess each opening and recommend.

Get started

Get your Los Altos windows sized, specced, and installed right the first time. Request an estimate or call Bay Area Siding Company at (415) 619-5167. Doing the exterior too? See Los Altos siding replacement and James Hardie siding, browse the project gallery, or explore the South Bay service area.