Window replacement Redwood City

New windows for Redwood City houses, from Mount Carmel to the Shores

Redwood City's list of work exempt from permits names window awnings, not windows, so replacing a window goes through a building permit. What makes the job local is egress: a bedroom retrofit can be held to the code in force when the house was first permitted, if the application says so and the opening does not shrink. Every Redwood City ZIP code is in Energy Code Climate Zone 3, where replacement glass has a U-factor limit but no solar heat gain cap.

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  • Rules on this page checked against 13 public sources, October 2026

Get quotes for window replacement work in Redwood City

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Free to request, and you agree the scope and price with the person you hire before work starts. In California, a job over $1,000 in labor and materials, or one that needs a building permit, must be done by a contractor licensed by the CSLB in the right class. Ask for the license number and check it at cslb.ca.gov.

Before you hire

Ask these before a Redwood City window order is placed

  1. Will you write the egress statement, with the year the house was built, into the scope of work on the permit application?
  2. For each bedroom, will the new clear opening be at least as large as the code allowed when the house was permitted?
  3. What U-factor is on each NFRC label, and does the job stay under 75 square feet of glass or meet 0.27?
  4. Does your firm hold EPA or state certification for lead-safe renovation, since the house was built before 1978?
  5. Is the C-17 Glazing license current on the cslb.ca.gov lookup, and who pulls the building permit?
Energy Code zone
Climate Zone 3 in 94061, 94062, 94063 and 94065
Replacement glass, Zone 3
U-factor 0.27 or less; no solar heat gain maximum
Egress table begins
Permits filed from June 11, 1962; 48-inch sills until July 1977
Historic district windows
Planning Commission approval before any building permit
Redwood City's City Hall
Redwood City's City Hall. Photo: King of Hearts, CC BY-SA 4.0, via Wikimedia Commons.

The houses here

Pre-war Mount Carmel, post-war hill tracts and a city built onto the bay

The General Plan describes Redwood City growing in rings out from downtown. Mount Carmel, southwest of El Camino Real, is largely a pre-World War II neighborhood, with more than 40 percent of its housing built before the war. The population then went from 12,500 at the start of the war to more than 46,000 by 1960, as tracts such as Woodside Plaza and Farm Hill climbed the hillsides, and Redwood Shores followed after the city annexed tidelands in the mid-1960s. For a window job the age of the house matters twice: a house built before 1978 brings federal lead-safe rules, and the year its permit was filed decides which egress standard a replacement bedroom window has to meet.

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The work

Four window projects and what each one sets off in Redwood City

  1. A same-size retrofit in a bedroom

    The city's Window Replacement Guideline allows minor reductions in the clear opening of an existing egress window. Where the change is more than minor, the contractor can still avoid today's dimensions by showing that the old window met the code enforced when the house was permitted and that the new one will not fall below it. The scope of work on the permit application then carries a statement that the egress window will meet the code in force at that time, with the year the house was built, and the inspector checks the sill height and opening at the final.

  2. Enlarging a bedroom window to current size

    The city's egress handout, revised in January 2026 and citing CRC Section R319, calls for a net clear opening of 5.7 square feet, or 5 at grade-floor level, at least 24 inches high and 20 inches wide, with its bottom no more than 44 inches above the floor. The two minimums together fall short of the area, so the handout's chart pairs them: a 20-inch-wide opening needs 41 inches of height, and a 24-inch-high one needs about 34 inches of width.

  3. Old wood sash on a pre-1978 house

    EPA's renovation rule exempts small jobs that disturb no more than 6 square feet of painted surface per room inside, or 20 square feet outside, but the exemption does not reach work that involves window replacement. A firm doing that work in a pre-1978 house needs EPA or state certification, and its renovators need training from an accredited provider. Keeping the frame changes the energy side: the Energy Code counts new glass in an existing sash, or new sashes in an existing frame, as a repair, provided the result performs at least as well as the original.

  4. Glass beside a tub or shower

    Redwood City's remodel requirements, revised in January 2026, call for safety glass, tempered or laminated, in windows in walls facing a tub or shower when the glass is less than 60 inches above the standing surface and within 60 inches horizontally, citing CRC R324.4. A bathroom window over the tub is where a stock replacement with ordinary glass most often fails, so the glass type belongs on the order before it is placed.

Permits and local rules

Redwood City and state documents a window bid has to answer

  • Work requiring and work exempt from permits

    Section 105.1 requires a permit to alter or repair a building, and the city's January 2026 list of exempt work names window awnings that project no more than 54 inches from the wall, painting, cabinets and counters, but not windows. Its definition of ordinary repairs, which need no application at all, excludes removing or changing a required means of egress and any rearrangement that affects the egress requirements, which govern every bedroom escape window.

    City of Redwood City Building Division (opens in a new tab)

  • The Window Replacement Guideline

    Revised in February 2023, the guideline lists the code editions Redwood City enforced by the date a house's permit application was filed. Applications from June 11, 1962 through July 5, 1977, under the 1961 to 1973 editions of the Uniform Building Code, were allowed a sleeping-room sill up to 48 inches above the floor; from July 6, 1977 the limit is 44 inches, with the minimum opening area and dimensions changing from one edition to the next. That table is what a grandfathered retrofit is measured against.

    City of Redwood City Building Division (opens in a new tab)

  • Chapter 40 and windows in a historic district

    The chapter defines an exterior architectural feature to include the type and style of all windows, and Section 40.8 makes it unlawful to alter one on a designated landmark or within a historic district without the Planning Commission's written approval; no city officer may grant a permit for the work first. The Historic Resources Advisory Committee reviews the application and sends its recommendation within 60 days, and an alteration in a district goes to a public hearing.

    Redwood City City Code, Chapter 40 (opens in a new tab)

  • Glass limits in Climate Zone 3

    Section 150.2(b)1B of the 2025 Energy Code holds replacement windows to Table 150.1-A, which for Climate Zone 3 sets a maximum U-factor of 0.27 and no maximum solar heat gain coefficient. A job replacing no more than 75 square feet of vertical glass may use a U-factor up to 0.40, and that exception's heat gain cap applies only in zones 2, 4 and 6 through 15, so it does not apply here either. Replaced skylights are held to a U-factor of 0.40 and a coefficient of 0.30.

    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).

Part by part

Parts of Redwood City where the window rules shift

  • Stambaugh-Heller and Mezesville

    Stambaugh-Heller, in the Eastern Addition southeast of Main Street, holds the city's largest number of pre-1900 buildings, and the Mezesville district keeps one- and two-story wood-frame houses from the early and middle 20th century. A different window on either is an exterior alteration under Chapter 40, which puts the Planning Commission ahead of the Building Division.

  • Mount Carmel

    With so many houses here built before World War II, a large share predate the guideline's table, which starts with permits filed in June 1962. For a pre-war bedroom window, ask the Building Division what standard it will accept before ordering a retrofit that keeps the old sill height.

  • Woodside Plaza and Farm Hill

    These post-war tracts reached into the western hills as the city grew. A house there whose permit was filed between June 1962 and early July 1977 was built under a 48-inch maximum sill, a figure a retrofit can keep under the city's guideline if the opening does not shrink.

  • Redwood Shores

    Any change to the outside of a property in ZIP code 94065, new windows included, needs approval from the design review board with architectural control over that part of the Shores before work begins. The Redwood Shores Owners Association covers developments built since 1981, and the Redwood Shores Community Association's board covers the older homes.

Free, no obligation. Next, add your details in the request form.

Questions

Window questions Redwood City owners bring to the permit counter

Our 1968 house has bedroom sills 48 inches off the floor. Do the new windows have to sit lower?

Not necessarily. Redwood City's guideline lets a retrofit keep the standard in force when the house was permitted, and its table shows a 48-inch maximum sill for permit applications filed from June 1962 through early July 1977. The new window cannot reduce the opening below what that code required, the permit's scope of work has to say so along with the year the house was built, and the inspector checks the dimensions at the final.

Why don't the window quotes we got in Redwood City mention a solar heat gain limit?

Because the city does not set one. All four of its ZIP codes are in Energy Code Climate Zone 3, and Table 150.1-A gives that zone a U-factor limit of 0.27 but no maximum solar heat gain coefficient. Palo Alto, a few miles south, sits in Zone 4, where the same table caps the coefficient at 0.23.

Do new windows mean rewiring our smoke alarms?

Usually not. Redwood City's remodel requirements allow battery-only smoke alarms for alterations solely on the exterior and name new windows as an example. Hard-wired, interconnected alarms are required when the work removes wall or ceiling finishes that could carry the wiring or has an accessible attic usable for it. The alarms still go where new houses need them: in each sleeping room, outside each sleeping area and on each story.

Our house is in the Stambaugh-Heller district. Can the old sash be repaired without going to the Planning Commission?

Yes, if the repair keeps the window as it was. Chapter 40 does not prevent ordinary maintenance or repair that involves no change in design, material or external appearance. A window of a different type, style or material is an alteration of an exterior architectural feature, which needs the commission's written approval, after the Historic Resources Advisory Committee's review, before any permit can be issued.

Can we keep security bars on a bedroom window?

Only bars that release from inside. The city's egress handout requires bars, grilles, covers and screens on an emergency escape opening to be releasable or removable from the inside, with an approved exterior opening device for the fire department where one is required, and the opening's control device must work from inside the room without a key, a tool or special knowledge.

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.

Window replacement work in Redwood City? Tell us what you see.

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