In Gilroy, the window conversation almost always starts with summer. Afternoon sun on the west side of the house, rooms that hold heat long after sunset, and a cooling bill that climbs from June through September — a lot of that load comes straight through single-pane or older aluminum-framed windows with no coating to turn back the sun. Bay Area Siding Company replaces them with units that actually manage solar heat gain. We're a Larkspur-based (Marin) siding and window contractor working across the South Bay, and we run the whole job: measuring, glass and frame selection, permitting, removal, flashing and air-sealing, and the final check.

Ready to cut the heat gain? Request an estimate or call (415) 619-5167.

The three decisions that matter most

Getting windows right in a hot inland climate is mostly about a few choices made deliberately:

• Glass and solar control. For Gilroy, the coating package does the heavy lifting. Dual-pane insulated glass with a Low-E coating cuts the radiant heat coming through the sunny elevations while still letting light in — the single biggest comfort difference most homeowners feel. California's Title 24 energy code sets the performance windows have to hit, and the exact targets depend on the climate zone and code cycle in effect, so we confirm the current numbers at permit time rather than quoting a figure that may already be out of date.
• Frame material. Vinyl, fiberglass, aluminum-clad wood, and aluminum each balance cost, thermal performance, and looks differently. On an older Gilroy home with wood trim, clad-wood or a profile that respects the original opening usually reads best; on a newer tract home, vinyl or fiberglass is often the practical pick.
• Retrofit vs. new-construction install. A retrofit (insert) install keeps the existing frame in place and is less invasive. A new-construction (full-frame) install takes the window out to the rough opening so the flashing can be fully renewed — the right call when there's rot, water damage, or a frame that's failed. We do both and recommend based on what the opening actually needs.

Comparing brands

We install several window lines and will match the brand to your budget, exposure, and the look you're after. Start with the window hub, then read the specifics for Anlin, Milgard, Andersen, Marvin, and Pella. We install aluminum windows as well where the application calls for it.

Permits, Title 24, and the hillside exception

Permitting. Window replacement is permitted work in Gilroy — the City of Gilroy Building Division lists window replacements among the residential exterior projects it issues permits for, and it enforces the adopted 2025 California Building Standards Code, including the Energy Code. A Title 24 energy compliance form is part of that submittal for fenestration. We pull and manage the permit through the City's process so you don't have to.

The fire-zone glazing wrinkle. Gilroy's valley core generally isn't affected, but the hills and grasslands that ring the city — toward the western foothills and east toward Henry W. Coe — carry designated Fire Hazard Severity Zones, and the City adopted Cal Fire's 2025 maps in June 2025. On parcels with that designation, California Building Code Chapter 7A governs exterior glazing, and altered openings generally have to use multi-pane units with at least one tempered pane, among other requirements. Whether it applies turns on your parcel's designation and whether the work is classed as a repair or an alteration — so if you're near the edge of town, we confirm that against the City's maps as part of scoping before ordering glass.

Fitting the look of an older home

Gilroy's older downtown and near-downtown homes — Victorians and early-1900s houses — often still carry their original single-pane sash, which is exactly why the jump to a modern dual-pane, Low-E unit is so noticeable in both comfort and quiet. Keeping the character is a matter of frame profile and finish: clad-wood, and certain vinyl and aluminum profiles, can be matched to the proportions of the original openings so the upgrade doesn't flatten the front of the house.

What affects the cost

We don't quote online because every home is different. The drivers are the number and size of openings, the frame material and brand, retrofit vs. full-frame install, whether a hillside parcel triggers tempered/multi-pane fire glazing, the condition of the existing framing (rot repair adds scope), and access — upper-story openings take more setup. A walkthrough is how we price it accurately.

Frequently asked questions

Do I need a permit to replace windows in Gilroy? Yes. The City of Gilroy Building Division issues permits for window replacement and a Title 24 energy compliance form is part of the submittal. We handle the permitting.

What glass should I get for Gilroy's summers? Dual-pane insulated glass with a Low-E coating is the baseline — it's what manages the solar heat gain on the sunny elevations. The specific package has to meet the Title 24 target in effect at permit time, which we confirm before ordering.

I'm near the hills — do my windows need to be tempered? Possibly, if your parcel is in a designated Fire Hazard Severity Zone and the work is an alteration. Chapter 7A generally requires altered openings in those areas to use multi-pane glazing with at least one tempered pane. The exact obligation depends on your parcel and scope, which we confirm first.

Retrofit or new-construction — which do I need? Retrofit keeps the existing frame and is less disruptive; new-construction takes the opening back to the framing so the flashing can be renewed, which is the better route where there's rot or water intrusion. We assess and recommend per opening.

Get started

Let's get your windows sized, specced for the heat, and installed right the first time. Request an estimate or call Bay Area Siding Company at (415) 619-5167. Handling the walls too? See Gilroy siding replacement and Gilroy James Hardie siding. We serve the wider South Bay and post finished work in our project gallery.