Picture the upstairs bedroom of a new accessory dwelling unit (ADU) built over a detached garage. The floor sits about 10 feet off the ground. Standing at the window, your eyes are roughly 15 feet up. Four feet away, at the property line, there's a brand-new 6-foot fence.
Now draw a straight line from your eyes to a spot in the neighbor's yard 20 feet from your wall. Where that line crosses the fence, it's still about 12 feet in the air. The fence is half as tall as it would need to be, and it's in the wrong place.
Those numbers come from a simple geometry model, not from a code rule or from any particular yard. The pattern they show holds on almost every lot, though. On a second floor, privacy is decided by where the windows go and by the order those decisions get made in. What you put in front of the glass comes last.
This guide covers two-story detached ADUs and ADUs built over a detached garage, in Sacramento and the Bay Area.
Why won't a fence or hedge stop a second-floor view?
A fence or hedge close to your own wall sits below the sightline from an upstairs window, so the view passes right over it. The higher the window, the steeper that line runs, and the more of the neighbor's yard it reaches.
Here's the model behind the opening example. The ADU's second floor sits 10 feet above the ground. A standing adult's eyes are about 5 feet above that floor, so roughly 15 feet above grade. A 6-foot fence stands 4 feet from the ADU wall.
- A line to the ground 20 feet away crosses the fence line at about 12 feet high.
- A line to the ground 30 feet away crosses it at about 13 feet high.
A screen only works when it's close to the thing you're trying to hide. Move that same 6-foot screen out to 16 feet from the wall, 4 feet short of the spot in the yard, and the sightline passes it at about 3 feet. Now the screen blocks that spot. That's why a mature tree well inside the neighbor's yard can do more than a hedge planted along your own wall. If a tree is already part of your plan, our guide on planning an ADU around an existing tree covers what it takes to keep it.
A yard and a window are two different problems
Looking down into a yard takes a steep downward angle. In the same model, looking at the ground 20 feet away means looking down about 37 degrees. Looking into a neighbor's second-floor window across the same gap is close to a level gaze. A high windowsill or a louver along the bottom of the glass handles the steep view well. It does much less against a level, window-to-window view. Shifting the window sideways, so it doesn't line up with the neighbor's, does the opposite.
Plants take time, and sometimes they're restricted
A hedge only screens at the height it has actually reached. Unless the screening is already tall on the day you move in, treat it as a backup layer, not the plan. On lots inside a mapped fire hazard area, dense planting near a building can also run into vegetation rules under the 2025 California Wildland-Urban Interface Code. Check your parcel's designation before you count on a hedge.
In what order should you decide your second-floor windows?
Decide them in five steps, in this order. Each answer limits the choices in the step after it.
- Can this wall have openings at all? Fire-separation rules for walls near a property line answer this, separately from zoning.
- Where does each bedroom's emergency escape window go? Every sleeping room needs one, and it has to meet fixed size and height limits.
- How does each room get its required light and fresh air? Windows are one way, but the code also allows electric lighting and mechanical ventilation in many rooms.
- Privacy. Window placement, sill height, glass type, and screening.
- Energy. The California Energy Code limits how much glass you can have, how much heat it lets in, and in some climates how much faces west.
Most people start at step 4. A privacy fix chosen first can turn out to break a fire or escape rule, and then the window gets redrawn during plan check. We draw the plans and process the permit, so we work through the steps in this order before the drawings go to the city.
Can the wall facing your neighbor have windows at all?
Not always. A wall can sit where zoning allows it and still be limited to fewer windows, or none, because it's close to the property line.
Those limits come from section R302.1 of the California Residential Code (CRC), which ties the window and door openings allowed in an exterior wall to how far that wall sits from the property line. The City of Sacramento's own guidance points out that R302.1 applies to ADUs on the same lot and has to be checked separately from what land-use rules permit. Getting approval to build 4 feet from the line doesn't settle whether that wall can have windows.
That changes a common plan. "We'll just put a few small frosted windows on the property-line wall" may not be allowed at all, or may be capped. Moving the daylight to a skylight or to a wall facing your own yard can solve the fire problem and the privacy problem in one step.
The exact distances and opening percentages are in the 2025 CRC table and your city's local amendments. Ask your designer to show you which band your wall falls in before the window layout goes any further. Fire separation is only one site limit that shapes a design. Our piece on whether your property can actually support an ADU covers septic, electrical service, fire zones, and buildable yard space.
Why can't a high window be your bedroom's only window?
Because a bedroom needs an emergency escape opening, and the California Residential Code (CRC) caps that opening's sill at 44 inches above the floor. A clerestory set 5 or 6 feet up can't do that job.
Under section R319 of the 2025 CRC, in effect since January 1, 2026, a sleeping room's escape opening generally has to meet all of these, subject to the section's exceptions:
- A net clear opening of at least 5.7 square feet, or 5.0 square feet at grade floor.
- A clear opening at least 24 inches high.
- A clear opening at least 20 inches wide.
- The bottom of the clear opening no more than 44 inches above the floor.
A high privacy window can still be a second bedroom window for light. It just can't be the one that counts for escape.
The window can't be too low either
Section R321.2 of the CRC covers fall protection. If an operable window's lowest opening sits less than 24 inches above the floor and more than 72 inches above the ground outside, it needs an opening limiter or a compliant fall-prevention device. On an escape window, that device can't shrink the opening below the R319 minimums. On a second floor, that leaves a fairly narrow band for the sill.
What to do when the bedroom faces the neighbor
- Put the escape window on another wall. A wall facing your own yard, or a side wall that doesn't line up with a neighbor's window, is the cleanest fix.
- Use privacy glass in a window that still opens fully. Frosted glass in a properly sized, fully operable escape window keeps both functions.
- Move the bedroom. On a small floor plan, swapping the bedroom with the bathroom or stair often solves the whole wall.
One more thing to watch. Older ADU handouts often cite R310 for escape openings and R303 for light and ventilation. Those were the section numbers in earlier code editions. In the 2025 CRC they're R319 and R325.
Which rooms should face your neighbor?
Put the stair, bathroom, closets, storage, and often the kitchen on the side that faces your neighbor. Put the living room and your main windows on the side that faces your own yard.
The California Residential Code (CRC) makes this easier than most people expect. Under section R325.2, a bathroom can skip the window entirely if it has the required electric lighting and local exhaust. A bathroom with a tub or shower needs a mechanical exhaust fan regardless, so its window was never doing that job anyway.
Living spaces have some flexibility too. Section R325.1 normally asks for glass equal to 8 percent of a habitable room's floor area and openable area equal to 4 percent. It also allows electric lighting that averages 6 footcandles at 30 inches above the floor in place of the glass. And it drops the natural ventilation requirement for most habitable rooms when a qualifying mechanical ventilation system is installed. Bedrooms still need their escape opening, whatever happens with light and air.
ADUs over a detached garage
An ADU over a garage starts with its occupied floor already high, so ordinary fences and plantings screen very little of the view. Start with the fire-separation limits on each wall, then lay out the rooms. Service rooms go toward the property line. Stepping the upper floor back from the line, even a little, moves your eye farther from the neighbor's side.
Sacramento County has seen this approach on a real application. In a 2024 environmental review record for a second-story ADU over a new garage, the county noted the unit had been designed with limited windows on the wall nearest the neighbor, and identified that as reducing privacy concerns.
Frosted, reeded, film, or smart glass: which actually blocks the view?
Frosted or acid-etched glass is the most predictable way to block a view through a window you keep. It also blocks your view out, in both directions. The other options behave differently than their labels suggest.
Frosted or acid-etched glass
A fully diffusing glass removes image detail. It still lets in soft daylight, and in an operable window it still lets in air. It's a strong choice for bathrooms and stairs, where you weren't going to stand and look out anyway. It's a poor choice for the only real window in a studio or living room.
Reeded, textured, or fritted glass
These distort the view rather than erasing it. Up close, and especially when someone is backlit, shapes and silhouettes can still read through. Don't assume they match frosted glass for privacy.
Window film
Frosted film works much like frosted glass and costs much less. It can also be removed later. Reflective or dark film is different. It depends on which side is brighter, so at night, with your lights on, people outside can often see in.
Smart glass
Electrochromic glass darkens on command. The research behind it is strong for controlling glare and daylight. Tinting isn't the same as obscuring, though, and tinted glass shouldn't be counted on for privacy at night. Switchable glass that turns cloudy is a different product, and performance varies by manufacturer.
Whichever glass you're considering, ask to see a full-size sample in realistic light, day and evening. "Privacy glass" on a spec sheet isn't a measurement.
Don't frost every window facing the neighbor by default. A living room with no clear view out feels small fast. In most cases, moving the window costs less and gives up less than frosting it.
How else can you narrow the view and keep the window?
Change the window's geometry so it doesn't point at anything sensitive. Each of these keeps clear, operable glass.
Offset the window
Slide the window sideways so it doesn't line up with the neighbor's window. Then the only remaining view is a sharp angle from one edge of the glass. This works especially well for window-to-window privacy, and it costs almost nothing when it's decided before framing.
Deep reveals and vertical fins
A deep window opening or a narrow vertical fin beside the glass cuts off that leftover angled view. Fins work best against sideways views. On an escape window, a fin can't block the required clear opening.
Horizontal louvers
Louvers block steep downward views into a yard while keeping sky light and air. They also shade the glass, which helps on hot walls.
Angled windows and bays
A window angled toward your own yard keeps clear glass while its solid side blocks the neighbor's direction. Near a property line, a bay or projection raises fire-separation questions, and waterproofing gets harder. An angled reveal in a flat wall often gets most of the benefit with fewer complications.
Skylights
A skylight gives strong daylight with almost no view into anyone's yard. A fixed skylight doesn't ventilate. Skylights count as glazing under the California Energy Code, so they need sizing and sometimes shading, not just adding.
Does Sacramento's heat change where the glass should go?
Yes. In Sacramento, moving all your glass to one private wall can run into energy limits that a San Francisco ADU wouldn't face.
The California Energy Commission places Sacramento in Climate Zone 12 and San Francisco in Climate Zone 3. Under the prescriptive path of the 2025 California Energy Code, the window limits differ like this.
Climate Zone 12, including Sacramento
- Maximum U-factor of 0.27.
- Maximum solar heat gain coefficient (SHGC) of 0.23. SHGC measures how much of the sun's heat the window lets through.
- Total window area capped at 20 percent.
- West-facing window area capped at 5 percent.
Climate Zone 3, including San Francisco
- Maximum U-factor of 0.27.
- Total window area capped at 20 percent.
- No prescriptive limit on solar heat gain coefficient (SHGC).
- No prescriptive limit on west-facing window area.
In Sacramento, a design that solves privacy by moving every big window onto a west-facing wall toward your own yard can bump into that 5 percent cap. Even where it complies, it can overheat badly on summer afternoons. Better options are east-facing glass for morning light, high north-facing glass, and exterior shading or fins on any west glass you keep.
The prescriptive path isn't the only route. The Energy Code also allows performance compliance, where the whole design is modeled in approved software and trade-offs are allowed. A layout outside the simple limits can sometimes still comply that way.
"Bay Area" isn't one climate zone. Inland and South Bay locations can fall in warmer zones than San Francisco. Look up your address with the California Energy Commission's climate zone tool before you assume either set of limits.
Does your city have its own window privacy rule?
Some cities do, and the rules vary. Check your own city's current ADU ordinance before the window layout is final.
Cities with an explicit rule
- Martinez requires certain second-story windows facing neighboring property lines to be either a clerestory with a sill at least 6 feet up or frosted or opaque glass. The rule ties whether the window opens to egress requirements, so it accounts for bedrooms.
- Mill Valley states the goal as a sightline. ADU windows shouldn't have a direct line of sight into windows on the adjacent property, and obscured glass or clerestories can be used to meet it.
- Redwood City adopted second-story ADU privacy provisions for windows and balconies in 2019. Whether the same rule is in force today wasn't confirmed, so ask the planning department for the current text.
Cities where no rule was confirmed
For the City of Sacramento, Sacramento County, Elk Grove, Roseville, San Jose, Oakland, Berkeley, and San Francisco, we didn't find a current, published second-story ADU window privacy rule in official materials. That isn't the same as no rule existing. Objective design standards, local amendments, and staff bulletins can all carry one. Ask the planning counter directly.
Sacramento County is a useful example of why. Its general single-family design guidelines advise against second-story windows that face directly into a neighbor's house or private yard. We didn't confirm that guidance as a required standard for ADUs.
City web pages also lag behind the law sometimes. Some local ADU codes still show limits that state law has already overridden, as with Sacramento's backyard ADU count. The adopted ordinance is what counts, not the summary page.
Pre-approved plans don't settle it
Many cities now offer pre-approved ADU plans. Those plans still go through site-specific review for zoning, fire, and utilities. A pre-approved window layout was drawn for no particular neighbor, so it may not suit yours.
What should your drawings show before the window layout is final?
Your drawings should prove privacy with lines, not adjectives. Before you sign off on second-floor windows, ask whoever is designing your ADU to show you:
- A cross-section from a standing eye and a seated eye at each sensitive window to the neighbor's yard and windows.
- A floor-plan view of the angle each window can see through, edge to edge.
- The heights and distances of any fence, wall, or tree you're relying on.
- The sill and head height of every window on the neighbor-facing walls.
- Which opening is each bedroom's emergency escape window, with its clear dimensions.
- Which California Energy Code climate zone your address falls in, and how much glass faces west.
With those in hand, "privacy screen provided" becomes something you can check. Without them, it's a promise.
This approach suits homeowners who want the windows settled on paper before anyone frames a wall. Sometimes the answer is to move the bedroom, give up a window you liked, or put a skylight where you pictured a view. That's easier to accept on a drawing than after the glass is ordered.
We draw the plans, process the permit, and build, so the fire, egress, light, privacy, and energy decisions all land in one set of drawings. Our ADU design and construction page walks through what that covers.
