Window Replacement in Sunnyvale: Retrofits, Eichlers, Heritage

Tall arched double windows with divided panes in a white paneled room. Photo: WesselArtPublic, CC BY-SA 4.0, via Wikimedia Commons.

The houses here

Single-pane glass held in wood trim, and street walls kept nearly solid

Sunnyvale's Eichler guidelines date the city's Eichlers from the late 1940s to the early 1970s and list the window traits a replacement has to live with. Front facades are relatively solid, with vertical slot windows and sidelights that often use translucent glass, plus horizontal and triangular windows at the roof eaves. The large fixed panes were usually single glass, held against the adjacent posts or walls by wood trim inside and out, and trellises shaded some windows. The guidelines count updating windows for energy and current code among the special challenges of these slab-floored, open-beam houses. Outside the tracts, the Taaffe-Frances blocks keep traditional wood windows and trim.

The work

Sunnyvale window projects, from a sash swap to a covered atrium

A retrofit with no permit at all
The exemption is narrow: the new window has the same configuration as the old one and the existing manufactured frame stays in place, the job the city calls retrofit window replacement. A different operating type may not count as the same configuration, and pulling the old frame out of the wall leaves the exemption behind. The list also says an exemption does not authorize work that breaks the building codes, so safety glass and Energy Code limits still apply to a window set without a permit.
Narrow frames for fixed Eichler panes
For fixed glass, guideline 3.5.2 asks for double glazing held by wood trim like the original detail, or windows with narrow frames; the guidelines' sidebar notes that a very narrow anodized aluminum frame is the more common choice. Operable windows should be sliders or casements with narrow jamb, head and sill profiles. Double-hung, bay, divided-light and projecting garden windows, and windows with snap-in grids, are discouraged in general and to be avoided where the street sees them. Trim stays narrow, painted to match the wall.
Bedroom windows that open onto the atrium
Interior and entry atriums are on the guidelines' list of standard Eichler features, and the same document warns that covering one can collide with the building code: where bedroom emergency exit windows open onto the courtyard, an atrium cover may not be permitted. The residential code wants each escape opening to open into a public way, or into a yard or court that opens to one. Settle any atrium plans with the Building Safety Division before ordering new bedroom windows that face it.
Taaffe-Frances wood windows and real muntins
The Taaffe-Frances Heritage Neighborhood guidelines, adopted March 24, 2009, list changes to existing windows and new windows among the improvements that need design review. They call wood the desired choice for styles that used it, accept vinyl-clad wood only where it looks like wood, and steer away from metal windows except on a Moderne house. Divided lights are true or double-pane units with dimensional muntins inside and out; flat snap-in grids are out. Most styles want wood trim at least 3 1/2 inches wide, with projecting sills and heads.
Skylights, the glazing permit filed online
Skylight is on Sunnyvale's list of Minor Building Permits that can be applied for online, with the permit card emailed once the fees are paid. A house in an HOA needs an approval letter from the association and applies for a regular building permit instead. Under Section R324.6 of the 2025 residential code, skylight glass is limited to laminated, fully tempered, heat-strengthened or wired glass or approved rigid plastics, and tempered or heat-strengthened glass needs a retention screen below it unless the code's size and height conditions are met.

Permits and local rules

Sunnyvale documents that decide a window job

Work not requiring a building permit
Revised in January 2026 and tied to Section 105.2 of the 2025 California Building Code, the list exempts window replacements where the new window keeps the previous configuration and the existing manufactured window frame remains unchanged, commonly called retrofit window replacement. Shade cloth structures and window awnings on houses and duplexes are exempt too, if they hang on an exterior wall, project no more than 54 inches and need no extra support. The city notes the list is not all-inclusive and that an exemption grants no authority to break the codes.
Source: City of Sunnyvale Building Safety Division (sunnyvale.ca.gov)
Eichler Design Guidelines
Adopted July 28, 2009, the guidelines replace the city's single-family guidelines for homes in the mapped Eichler neighborhoods, covering Eichler-built houses and non-Eichlers inside the boundaries alike. They govern design review, which is required for a new house, a floor area increase of 20 percent or more, any second-story element, and an exterior change that significantly alters the home's look. Within a Heritage Resource District, minor changes go through administrative design review, and the guidelines state that they do not rule out window upgrades.
Source: City of Sunnyvale, Eichler Design Guidelines (sunnyvale.ca.gov)
Taaffe-Frances Heritage Neighborhood guidelines
The neighborhood is zoned R-0/HH, low-density residential inside a Heritage Housing combining district, and its homes carry a higher level of protection than other single-family houses. Minor exterior changes are reviewed by Planning staff against the guidelines; major exterior changes go to a public hearing before the Heritage Preservation Commission, with notice to the neighbors. When many windows are replaced, the guidelines ask for types that suit the house's style: double-hungs on a Craftsman, casements on Mission or Spanish Eclectic houses.
Source: City of Sunnyvale, Taaffe-Frances Design Guidelines (sunnyvale.ca.gov)
Shading as a path through Zone 4's heat gain limit
Replacement windows meet the U-factor and solar heat gain rules of Sections 150.1(c)3A and 150.1(c)4 of the 2025 Energy Code. Where a maximum SHGC applies, as it does in Climate Zone 4, Section 150.1(c)4 accepts the glass itself, a permanently fastened exterior shading device that meets the limit, a mix of the two, or, for south-facing glass only, an overhang that fully shades it at solar noon on August 21 and leaves it substantially exposed at solar noon on December 21. Ask whether an Eichler's eaves or trellis count before choosing glass.
Source: California Energy Commission, 2025 Energy Code (energy.ca.gov)

State license for this work: C-17 Glazing, B General Building. Look up a contractor's license on the CSLB website (cslb.ca.gov).

Before you hire

What to settle with a Sunnyvale window contractor

Will each new unit keep the old window's configuration and sit in the existing manufactured frame, so no building permit is needed?
On an Eichler street front, are the operable units narrow-profile sliders or casements, with no snap-in grids and no double-hungs?
Does any bedroom window open onto an atrium we might cover later, and how would a cover affect its escape route?
For a Taaffe-Frances house, will you prepare what Planning needs for design review before setting a delivery date?
Is the C-17 Glazing license active at cslb.ca.gov, and will each unit's label show a U-factor and SHGC that meet Zone 4?

Questions

Sunnyvale window questions from Eichler tracts and heritage blocks

Do we need a permit to replace the aluminum sliders in our Sunnyvale Eichler?

Not if the job is a retrofit: the new slider keeps the old one's configuration and goes into the existing manufactured frame, which Sunnyvale's 2026 list of work needing no building permit exempts. Tearing out the frame, enlarging the opening or changing the window type is a different matter, so ask the Building Safety Division before ordering if the new units will not match the old ones.

Can a retrofit window in Sunnyvale skip the Energy Code because no permit is pulled?

No. The city's list says an exemption from a permit does not authorize work that violates the building codes. A replacement window in Climate Zone 4 still meets the 2025 Energy Code: U-0.40 and SHGC 0.35 when 75 square feet or less is replaced, U-0.27 and SHGC 0.23 on larger jobs. Keep the labels on the units so the figures can be checked.

We want to cover the atrium in our Fairbrae Eichler. Does that affect the bedroom windows?

It can. Sunnyvale's Eichler guidelines warn that where bedroom emergency exit windows open onto the courtyard, an atrium cover may not be permitted, because each escape opening has to lead to a public way or to a yard or court open to one. Talk to the Building Safety Division before designing the cover, and before replacing any bedroom window that faces the atrium.

Our house is in the Taaffe-Frances neighborhood. Can vinyl replacement windows go in?

Only if they look like wood. The neighborhood guidelines name wood as the desired choice for styles that traditionally used it and allow materials such as vinyl-clad wood windows only where their appearance matches wood. Metal windows are generally to be avoided except on a Moderne house, and changes to existing windows go through Planning's design review before work starts.

Does a skylight on our flat Eichler roof need a full plan review in Sunnyvale?

Not on a house outside an HOA: skylight is one of the Minor Building Permits Sunnyvale takes online, with the permit card emailed after payment. Inside an HOA, the city wants the association's approval letter and a regular building permit application. Either way, a unit skylight on a roof pitched under 3 in 12 goes on a curb at least 4 inches high unless the maker's instructions say otherwise.

Keep exploring

More on window replacement work and Sunnyvale

Where these facts come from

Checked against these public sources in October 2026. Rules and programs change: confirm permit requirements with the city before work starts, and a contractor's license on the CSLB website.

sunnyvale.ca.gov: 639107281821070000 (sunnyvale.ca.gov)
sunnyvale.ca.gov: 638403254140770000 (sunnyvale.ca.gov)
sunnyvale.ca.gov: 638273442749170000 (sunnyvale.ca.gov)
sunnyvale.ca.gov: 638273444043400000 (sunnyvale.ca.gov)
energy.ca.gov: CEC 400 2025 010 F (energy.ca.gov)
energy.ca.gov: BuildingClimateZonesByZIPCode ada (energy.ca.gov)
codes.iccsafe.org: chapter 3 building planning
cslb.ca.gov: Licensing Classifications Detail (cslb.ca.gov)

Sunnyvale windows, from permit-free retrofits to Taaffe-Frances wood sash

Get quotes for window replacement work in Sunnyvale

Single-pane glass held in wood trim, and street walls kept nearly solid

Sunnyvale window projects, from a sash swap to a covered atrium

A retrofit with no permit at all

Narrow frames for fixed Eichler panes

Bedroom windows that open onto the atrium

Taaffe-Frances wood windows and real muntins

Skylights, the glazing permit filed online

Sunnyvale documents that decide a window job

Work not requiring a building permit

Eichler Design Guidelines

Taaffe-Frances Heritage Neighborhood guidelines

Shading as a path through Zone 4's heat gain limit

What to settle with a Sunnyvale window contractor

Sunnyvale window questions from Eichler tracts and heritage blocks

More on window replacement work and Sunnyvale

Window replacement in other cities

Other trades in Sunnyvale

Guides and smaller jobs

Where this page belongs

Where these facts come from

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