Clerestory Windows and How They Light the Middle of a House

The middle of most houses is dark. Hallways, stairwells and the back half of open-plan kitchens sit too far from the outside walls for ordinary windows to reach, so the lights stay on at noon. Clerestory windows are one of the oldest answers to that problem, and they work by putting glass where it can do the most good: high up, above the roof line of the rooms around them.

This guide explains how clerestory windows bring daylight deep into a plan, where they work best, what they cost to build or add, and the mistakes that turn a lovely band of light into an overheated, glaring strip.

What clerestory windows are

A clerestory is a row of windows set high in a wall, above eye level, usually where one part of the roof rises above another. The name comes from "clear storey," the upper level of a church nave that rose above the side aisles and filled the interior with light. Roman basilicas used the idea, Gothic cathedrals pushed it to extremes, and Frank Lloyd Wright brought it into ordinary homes with his Usonian houses in the 1930s and 1940s.

In a house, a clerestory typically appears in one of three forms:

Split-level roof. Two mono-pitch roofs meet at different heights, and the vertical gap between them is glazed.
Raised central section. The middle of the house, often a living area or corridor, rises above the surrounding rooms with windows on one or both sides.
High wall band. A strip of windows sits just under the ceiling on an exterior wall, common in bathrooms and bedrooms where privacy matters.

Why clerestory windows light deeper than normal windows

Daylight from a side window reaches roughly 1.5 to 2 times the height of the window head into a room. A standard window with its top at 2.1 metres usefully lights the first 3 to 4 metres. Beyond that, the room depends on artificial light even on a bright day.

Raise the window head to 3.5 or 4 metres and the useful daylight zone extends to 6 or 7 metres. That is why a clerestory over the spine of a house can light a corridor and the inner edge of rooms on both sides. The light also arrives from above, bouncing off the ceiling and spreading more evenly than the harsh patch a low window throws across the floor.

Clerestories offer a second benefit that skylights struggle with: ventilation. Warm air rises, so an openable high window lets heat escape at the top of the house while cooler air enters through lower windows. This stack effect can move a surprising amount of air on a still summer evening without any fan.

Orientation decides whether it works

A clerestory facing the wrong way can make a house worse. The direction of the glass matters more than its size, which is the same principle we covered in why building orientation decides a home's comfort.

Facing (northern hemisphere)	Light quality	Main risk	Best use
North	Soft, even, no direct sun	Heat loss in winter	Studios, kitchens, workspaces
South	Bright, warm, winter sun	Summer overheating without shading	Living areas with a deep overhang
East	Strong morning light	Early glare in bedrooms	Kitchens, breakfast areas
West	Low afternoon sun	Glare and heat in late summer	Usually best avoided

In the southern hemisphere, swap north and south. A south-facing clerestory there gives the soft studio light, and a north-facing one needs shading.

For a sun-facing clerestory, a roof overhang above the glass is essential. A projection of around 450 to 600 millimetres over a window 600 millimetres tall blocks high summer sun while letting low winter sun through. Our piece on deep eaves and roof overhangs walks through the geometry.

The case against glazing every high wall

Designers and homeowners often treat clerestories as pure upside. More high glass means more light, the logic goes, so run the band the full length of the house. I think that advice causes more problems than it solves.

High windows are hard to reach, which makes them hard to clean, hard to open and hard to cover. A clerestory 4 metres up needs either a motorised opener, a long pole or a ladder every time you want air or privacy. Blinds for high glass often cost two to three times as much as standard ones because they need motors or custom tracks. Many owners simply never shade them, and the room overheats in July.

Glass also loses heat. Even a good double-glazed unit insulates five to ten times worse than a well-built wall. A long band of high glass in a cold climate puts that heat loss exactly where warm air collects.

The better approach is to place a few clerestory openings where they solve a specific problem: lighting a dark stair, venting a hot kitchen, bringing sky into a deep living room. Two well-placed units 1.2 metres wide will often outperform a continuous 10-metre strip, and cost far less.

What clerestory windows cost

Prices vary by region and specification, but rough figures help with early planning:

Fixed clerestory glazing in a new build: around 400 to 900 dollars per square metre installed, similar to other quality windows.
Openable units with motors: add 500 to 1,200 dollars per window for the actuator, wiring and controls.
Retrofitting into an existing roof: a far bigger job, because the roof structure has to be raised or reframed. Expect a project in the tens of thousands, plus engineering and permits.

Because retrofits are expensive, clerestories are best decided at the design stage. If you are planning a new home or a major extension, list the dark zones you want daylit and the rooms that run hot, and put both in your brief. Our guide on how to write an architect brief shows how to describe those needs without prescribing the solution.

Details that make or break a clerestory

Sill height: keep it above 1.8 metres in bathrooms and bedrooms for privacy, higher if neighbours overlook.
Light shelves: a horizontal shelf below the glass bounces light onto the ceiling and deeper into the room.
Ceiling finish: a pale, matte ceiling spreads light evenly. Dark timber ceilings swallow much of it.
Flashing: the junction between the upper wall and lower roof is a classic leak point. Insist on proper step and apron flashing.
Access plan: decide before construction how you will clean and service the glass.

Frequently asked questions

Are clerestory windows better than skylights?

They are usually easier to shade and less prone to leaks, and vertical glass picks up less summer heat than a flat skylight. Skylights deliver more light per square metre because they face the open sky. Many houses benefit from clerestories in living areas and small skylights in corridors or bathrooms.

Do clerestory windows make a house hot?

They can if they face the sun without shading. A south or west facing clerestory in the northern hemisphere needs an overhang or external shade. Openable clerestories often make a house cooler, because they let warm air escape at the highest point.

Can you add clerestory windows to an existing house?

Yes, but it usually means raising part of the roof, which requires structural work, an engineer and planning approval. A simpler retrofit is a high wall band of windows on an existing exterior wall, which can often be done within the current roof line.