Mid-century clerestory windows are the narrow bands of glass set high in a wall, often just under the roof. Along with the full-height window walls at the back of the house, they explain how a modern house with almost no street-facing windows can still be full of daylight.
This guide covers where clerestories and window walls appear on Eichlers and similar post-and-beam houses, the privacy logic behind them, the heat they let in and what Palo Alto's Eichler guidelines suggest when windows need work. The details come from those guidelines, the National Register nominations for Eichler tracts in Palo Alto and San Jose, and Caltrans' statewide study of postwar tract housing.
What a clerestory window is
Palo Alto's guidelines define a clerestory as "a high section of a wall that contains windows above eye level," whose purpose is to admit light, fresh air or both. The National Park Service's Preservation Brief 3, on energy efficiency in historic buildings, lists clerestories with operable windows, interior courtyards and skylights as features that provide natural light and ventilation and can reduce the need for mechanical systems.
The key phrase is "above eye level." A clerestory lets light in without letting anyone see in or out at standing height, which is why it suits a house designed to turn its back to the street.
Where clerestories show up on an Eichler
Over the garage door. The Greenmeadow nomination describes fixed transom glass above the garage doors and across the entire front, and San Jose's draft National Register documentation places fixed clerestory windows above the garage doors.
Under a gable. Palo Alto's guidelines say front clerestories may be horizontal or triangular at the gable ends, with vertically divided plate glass. Greenmeadow's Model Five fills the triangular gaps under its low center-pitched roof with trapezoidal clerestory glass.
Between two roof heights. In Greenmeadow's first two models, an eight-foot level roof in front meets a ten-foot level roof behind, and clerestory windows in the gap bring diffused light into the back of the house. Models Three and Six use shed roofs to create the same kind of gap.
Over the main room. In San Jose's Fairglen Additions, Plan SJ-4 raises a ten-foot level roof with clerestory windows over the living and dining areas.
At the front door. Several Fairglen models pair a flush entry door with a clerestory and a sidelight.
The Greenmeadow nomination ties this to the architecture: the low-pitched roof forms of the Jones & Emmons models enabled more daylight through clerestories beneath the eaves.
Window walls: what post-and-beam made possible
The other half of the daylight story is at the back of the house. Caltrans' study explains that in post-and-beam construction, the spaces between posts can be filled with glass or with non-structural wall panels, which made it easier to give a house a much higher proportion of glass to solid wall than stud framing allows. Our post and beam construction page explains the system.
Greenmeadow: floor-to-ceiling glass and a sliding glass door that together usually extend the width of the building, with an overhang of about three feet above and a paved concrete patio below.
San Jose: rear walls of floor-to-ceiling glass and a sliding glass door that usually span the width of the building, interrupted by brick fireplaces, plus floor-to-ceiling, wall-to-wall plate glass opening onto the atrium or courtyard.
Palo Alto: full-height rear glazing of large plate glass with vertical wood divisions, typically fixed in wood frames or set as sliders in aluminum frames, with fully glazed aluminum sliding doors.
Side walls get less glass. Greenmeadow houses typically have one window on each side, about four feet by four feet on the bedroom side and floor-to-ceiling on the living room side. For how this glass connects rooms to the yard, see our indoor-outdoor living page.
The privacy logic: high glass in front, open glass in back
The Greenmeadow nomination says almost no street-facing windows were used and that the designs emphasize privacy, presenting relatively blank façades to the street. Palo Alto's guidelines add that Eichler houses were arranged so that windows don't directly face their neighbors.
The same thinking runs through the guidelines' advice for new work:
On additions, one example in the guidelines puts larger windows on the front and uses clerestories on the side walls, which "allow in light but are above the occupants' eye-line."
Where daylight is wanted, the guidelines say it can come from clerestory windows and skylights, and obscure glass can be used for windows where privacy matters.
For a detached accessory dwelling unit or a garage conversion, the guidelines call clerestories above eye level far more appropriate than eye-level windows facing the main house's outdoor space.
Modern houses weren't alone in this. Caltrans notes that tract Ranch houses often used a shallow window set just below the eave to light bedrooms and bathrooms while keeping them private. For the bigger picture, see our page on the difference between an Eichler and mid-century modern.
Heat, glare and the south and west walls
All that glass has a cost. Caltrans' study cites Edward Eichler, Joseph's son, who noted that the growing expectation of air conditioning diminished the appeal of the Eichler house. The company's radiant floor heating couldn't be adapted for air conditioning, and extensive glass made the houses hard to keep cool in summer, particularly when the glazed rear walls faced south or west.
Overhangs were part of the original answer. The Greenmeadow nomination says the extensive overhangs provide shade in summer but let in sunlight in winter. Palo Alto's guidelines suggest other ways to reduce the need for air conditioning:
Window coverings, including exterior or interior roller shades, which the guidelines say were original window treatments for Eichlers.
Plantings that provide shade.
Applied window film that lowers heat gain without replacing the windows. The guidelines say high-quality clear films are available and that a reflective effect is discouraged.
Replacing clear glass with non-clear or reflective glass is generally discouraged in the guidelines, except where privacy matters, such as sidelites beside entry doors and bathroom windows.
Keeping the pattern when windows need work
Palo Alto's guidelines treat the window pattern as part of an Eichler's character:
Repair original windows in place when possible. If replacement is needed, matching the original sash material, configuration and openings is preferred.
Keep limited glass on the front and expansive glass at the rear.
Don't divide windows into smaller units, and in particular avoid dividing fixed clerestory windows and full-height rear windows. Full-pane glass is preferred.
New vinyl windows are discouraged, and projecting bay windows and garden windows are strongly discouraged.
If you replace single-pane glass with insulated glass, choose units sized to fit the existing openings, and consider reusing the existing sash and frames.
Our Eichler renovation guide and mid-century modern design guidelines pages go further. Palo Alto's guidelines are voluntary, and window rules vary by city, so check with your building department and a licensed window contractor before you order replacements.
Frequently asked questions
What is a clerestory window?
It is a window set high in a wall, above eye level, to bring in light, fresh air or both. On mid-century houses, clerestories often sit above the garage door, under a gable or in the gap between two roof heights.
Why do Eichlers have so few front windows?
Privacy. The Greenmeadow nomination says the designs presented relatively blank façades to the street, with almost no street-facing windows, while floor-to-ceiling glass opened the back of the house to a private patio. Clerestories bring light into the front rooms without exposing them.
Do clerestory windows open?
Not always. The Greenmeadow and San Jose documents describe fixed glass above the garage doors, and Palo Alto's guidelines refer to fixed clerestory windows. The general definition covers windows for light, fresh air or both, so check each window on a tour.
Can I add clerestories to an addition?
Palo Alto's guidelines encourage them on side walls and on detached units where privacy matters. Your city's planning and building departments set the actual rules, so confirm with them before you design.
Related reading
Butterfly Roof Houses and Other Mid-Century Rooflines Explained
Mid-Century Sliding Glass Doors: Repair, Replace and Keep the Look
Mid-Century Modern Design Principles: Overhangs, Orientation and Glass
Want a second look at the light in a house before you buy? Call or text the Boyenga Team at Compass at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team and we'll walk the house with you.
